summaryrefslogtreecommitdiff
path: root/compiler/main/DriverPipeline.hs
blob: 488df37a79fd0cf794e79ee84c76720705a747d9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
{-# OPTIONS -fno-cse #-}
{-# LANGUAGE NamedFieldPuns #-}
-- -fno-cse is needed for GLOBAL_VAR's to behave properly

-----------------------------------------------------------------------------
--
-- GHC Driver
--
-- (c) The University of Glasgow 2005
--
-----------------------------------------------------------------------------

module DriverPipeline (
        -- Run a series of compilation steps in a pipeline, for a
        -- collection of source files.
   oneShot, compileFile,

        -- Interfaces for the batch-mode driver
   linkBinary,

        -- Interfaces for the compilation manager (interpreted/batch-mode)
   preprocess,
   compile, compile',
   link,

  ) where

#include "HsVersions.h"

import Packages
import HeaderInfo
import DriverPhases
import SysTools
import HscMain
import Finder
import HscTypes
import Outputable
import Module
import UniqFM           ( eltsUFM )
import ErrUtils
import DynFlags
import StaticFlags      ( v_Ld_inputs, opt_PIC, opt_Static, WayName(..) )
import Config
import Panic
import Util
import StringBuffer     ( hGetStringBuffer )
import BasicTypes       ( SuccessFlag(..) )
import Maybes           ( expectJust )
import ParserCoreUtils  ( getCoreModuleName )
import SrcLoc
import FastString
import LlvmCodeGen      ( llvmFixupAsm )
import MonadUtils
import Platform

import Exception
import Data.IORef       ( readIORef )
import System.Directory
import System.FilePath
import System.IO
import Control.Monad
import Data.List        ( isSuffixOf )
import Data.Maybe
import System.Environment
import Data.Char

-- ---------------------------------------------------------------------------
-- Pre-process

-- | Just preprocess a file, put the result in a temp. file (used by the
-- compilation manager during the summary phase).
--
-- We return the augmented DynFlags, because they contain the result
-- of slurping in the OPTIONS pragmas

preprocess :: HscEnv
           -> (FilePath, Maybe Phase) -- ^ filename and starting phase
           -> IO (DynFlags, FilePath)
preprocess hsc_env (filename, mb_phase) =
  ASSERT2(isJust mb_phase || isHaskellSrcFilename filename, text filename)
  runPipeline anyHsc hsc_env (filename, mb_phase)
        Nothing Temporary Nothing{-no ModLocation-} Nothing{-no stub-}

-- ---------------------------------------------------------------------------

-- | Compile
--
-- Compile a single module, under the control of the compilation manager.
--
-- This is the interface between the compilation manager and the
-- compiler proper (hsc), where we deal with tedious details like
-- reading the OPTIONS pragma from the source file, converting the
-- C or assembly that GHC produces into an object file, and compiling
-- FFI stub files.
--
-- NB.  No old interface can also mean that the source has changed.

compile :: HscEnv
        -> ModSummary      -- ^ summary for module being compiled
        -> Int             -- ^ module N ...
        -> Int             -- ^ ... of M
        -> Maybe ModIface  -- ^ old interface, if we have one
        -> Maybe Linkable  -- ^ old linkable, if we have one
        -> SourceModified
        -> IO HomeModInfo   -- ^ the complete HomeModInfo, if successful

compile = compile' (hscCompileNothing, hscCompileInteractive, hscCompileBatch)

compile' :: 
           (Compiler (HscStatus, ModIface, ModDetails),
            Compiler (InteractiveStatus, ModIface, ModDetails),
            Compiler (HscStatus, ModIface, ModDetails))
        -> HscEnv
        -> ModSummary      -- ^ summary for module being compiled
        -> Int             -- ^ module N ...
        -> Int             -- ^ ... of M
        -> Maybe ModIface  -- ^ old interface, if we have one
        -> Maybe Linkable  -- ^ old linkable, if we have one
        -> SourceModified
        -> IO HomeModInfo   -- ^ the complete HomeModInfo, if successful

compile' (nothingCompiler, interactiveCompiler, batchCompiler)
        hsc_env0 summary mod_index nmods mb_old_iface maybe_old_linkable
        source_modified0
 = do
   let dflags0     = ms_hspp_opts summary
       this_mod    = ms_mod summary
       src_flavour = ms_hsc_src summary
       location    = ms_location summary
       input_fn    = expectJust "compile:hs" (ml_hs_file location)
       input_fnpp  = ms_hspp_file summary

   debugTraceMsg dflags0 2 (text "compile: input file" <+> text input_fnpp)

   let basename = dropExtension input_fn

  -- We add the directory in which the .hs files resides) to the import path.
  -- This is needed when we try to compile the .hc file later, if it
  -- imports a _stub.h file that we created here.
   let current_dir = takeDirectory basename
       old_paths   = includePaths dflags0
       dflags      = dflags0 { includePaths = current_dir : old_paths }
       hsc_env     = hsc_env0 {hsc_dflags = dflags}

   -- Figure out what lang we're generating
   let hsc_lang = hscTarget dflags
   -- ... and what the next phase should be
   let next_phase = hscPostBackendPhase dflags src_flavour hsc_lang
   -- ... and what file to generate the output into
   output_fn <- getOutputFilename next_phase
                        Temporary basename dflags next_phase (Just location)

   let dflags' = dflags { hscTarget = hsc_lang,
                                hscOutName = output_fn,
                                extCoreName = basename ++ ".hcr" }
   let hsc_env' = hsc_env { hsc_dflags = dflags' }

   -- -fforce-recomp should also work with --make
   let force_recomp = dopt Opt_ForceRecomp dflags
       source_modified
         | force_recomp || isNothing maybe_old_linkable = SourceModified
         | otherwise = source_modified0
       object_filename = ml_obj_file location

   let handleBatch HscNoRecomp
           = ASSERT (isJust maybe_old_linkable)
             return maybe_old_linkable

       handleBatch (HscRecomp hasStub _)
           | isHsBoot src_flavour
               = do when (isObjectTarget hsc_lang) $ -- interpreted reaches here too
                       liftIO $ touchObjectFile dflags' object_filename
                    return maybe_old_linkable

           | otherwise
               = do (hs_unlinked, unlinked_time) <-
                        case hsc_lang of
                          HscNothing ->
                            return ([], ms_hs_date summary)
                          -- We're in --make mode: finish the compilation pipeline.
                          _other -> do
                            maybe_stub_o <- case hasStub of
                               Nothing -> return Nothing
                               Just stub_c -> do
                                 stub_o <- compileStub hsc_env' stub_c
                                 return (Just stub_o)
                            _ <- runPipeline StopLn hsc_env' (output_fn,Nothing)
                                              (Just basename)
                                              Persistent
                                              (Just location)
                                              maybe_stub_o
                                  -- The object filename comes from the ModLocation
                            o_time <- getModificationUTCTime object_filename
                            return ([DotO object_filename], o_time)
                    
                    let linkable = LM unlinked_time this_mod hs_unlinked
                    return (Just linkable)

       handleInterpreted HscNoRecomp
           = ASSERT (isJust maybe_old_linkable)
             return maybe_old_linkable
       handleInterpreted (HscRecomp _hasStub Nothing)
           = ASSERT (isHsBoot src_flavour)
             return maybe_old_linkable
       handleInterpreted (HscRecomp hasStub (Just (comp_bc, modBreaks)))
           = do stub_o <- case hasStub of
                            Nothing -> return []
                            Just stub_c -> do
                              stub_o <- compileStub hsc_env' stub_c
                              return [DotO stub_o]

                let hs_unlinked = [BCOs comp_bc modBreaks]
                    unlinked_time = ms_hs_date summary
                  -- Why do we use the timestamp of the source file here,
                  -- rather than the current time?  This works better in
                  -- the case where the local clock is out of sync
                  -- with the filesystem's clock.  It's just as accurate:
                  -- if the source is modified, then the linkable will
                  -- be out of date.
                let linkable = LM unlinked_time this_mod
                               (hs_unlinked ++ stub_o)
                return (Just linkable)

   let -- runCompiler :: Compiler result -> (result -> Maybe Linkable)
       --            -> m HomeModInfo
       runCompiler compiler handle
           = do (result, iface, details)
                    <- compiler hsc_env' summary source_modified mb_old_iface
                                (Just (mod_index, nmods))
                linkable <- handle result
                return (HomeModInfo{ hm_details  = details,
                                     hm_iface    = iface,
                                     hm_linkable = linkable })
   -- run the compiler
   case hsc_lang of
      HscInterpreted -> runCompiler interactiveCompiler handleInterpreted
      HscNothing     -> runCompiler nothingCompiler     handleBatch
      _other         -> runCompiler batchCompiler       handleBatch

-----------------------------------------------------------------------------
-- stub .h and .c files (for foreign export support)

-- The _stub.c file is derived from the haskell source file, possibly taking
-- into account the -stubdir option.
--
-- The object file created by compiling the _stub.c file is put into a
-- temporary file, which will be later combined with the main .o file
-- (see the MergeStubs phase).

compileStub :: HscEnv -> FilePath -> IO FilePath
compileStub hsc_env stub_c = do
        (_, stub_o) <- runPipeline StopLn hsc_env (stub_c,Nothing)  Nothing
                                   Temporary Nothing{-no ModLocation-} Nothing

        return stub_o

-- ---------------------------------------------------------------------------
-- Link

link :: GhcLink                 -- interactive or batch
     -> DynFlags                -- dynamic flags
     -> Bool                    -- attempt linking in batch mode?
     -> HomePackageTable        -- what to link
     -> IO SuccessFlag

-- For the moment, in the batch linker, we don't bother to tell doLink
-- which packages to link -- it just tries all that are available.
-- batch_attempt_linking should only be *looked at* in batch mode.  It
-- should only be True if the upsweep was successful and someone
-- exports main, i.e., we have good reason to believe that linking
-- will succeed.

link LinkInMemory _ _ _
    = if cGhcWithInterpreter == "YES"
      then -- Not Linking...(demand linker will do the job)
           return Succeeded
      else panicBadLink LinkInMemory

link NoLink _ _ _
   = return Succeeded

link LinkBinary dflags batch_attempt_linking hpt
   = link' dflags batch_attempt_linking hpt

link LinkDynLib dflags batch_attempt_linking hpt
   = link' dflags batch_attempt_linking hpt

panicBadLink :: GhcLink -> a
panicBadLink other = panic ("link: GHC not built to link this way: " ++
                            show other)

link' :: DynFlags                -- dynamic flags
      -> Bool                    -- attempt linking in batch mode?
      -> HomePackageTable        -- what to link
      -> IO SuccessFlag

link' dflags batch_attempt_linking hpt
   | batch_attempt_linking
   = do
        let
            home_mod_infos = eltsUFM hpt

            -- the packages we depend on
            pkg_deps  = concatMap (map fst . dep_pkgs . mi_deps . hm_iface) home_mod_infos

            -- the linkables to link
            linkables = map (expectJust "link".hm_linkable) home_mod_infos

        debugTraceMsg dflags 3 (text "link: linkables are ..." $$ vcat (map ppr linkables))

        -- check for the -no-link flag
        if isNoLink (ghcLink dflags)
          then do debugTraceMsg dflags 3 (text "link(batch): linking omitted (-c flag given).")
                  return Succeeded
          else do

        let getOfiles (LM _ _ us) = map nameOfObject (filter isObject us)
            obj_files = concatMap getOfiles linkables

            exe_file = exeFileName dflags

        linking_needed <- linkingNeeded dflags linkables pkg_deps

        if not (dopt Opt_ForceRecomp dflags) && not linking_needed
           then do debugTraceMsg dflags 2 (text exe_file <+> ptext (sLit "is up to date, linking not required."))
                   return Succeeded
           else do

        compilationProgressMsg dflags $ showSDoc $
            (ptext (sLit "Linking") <+> text exe_file <+> text "...")

        -- Don't showPass in Batch mode; doLink will do that for us.
        let link = case ghcLink dflags of
                LinkBinary  -> linkBinary
                LinkDynLib  -> linkDynLib
                other       -> panicBadLink other
        link dflags obj_files pkg_deps

        debugTraceMsg dflags 3 (text "link: done")

        -- linkBinary only returns if it succeeds
        return Succeeded

   | otherwise
   = do debugTraceMsg dflags 3 (text "link(batch): upsweep (partially) failed OR" $$
                                text "   Main.main not exported; not linking.")
        return Succeeded


linkingNeeded :: DynFlags -> [Linkable] -> [PackageId] -> IO Bool
linkingNeeded dflags linkables pkg_deps = do
        -- if the modification time on the executable is later than the
        -- modification times on all of the objects and libraries, then omit
        -- linking (unless the -fforce-recomp flag was given).
  let exe_file = exeFileName dflags
  e_exe_time <- tryIO $ getModificationUTCTime exe_file
  case e_exe_time of
    Left _  -> return True
    Right t -> do
        -- first check object files and extra_ld_inputs
        extra_ld_inputs <- readIORef v_Ld_inputs
        e_extra_times <- mapM (tryIO . getModificationUTCTime) extra_ld_inputs
        let (errs,extra_times) = splitEithers e_extra_times
        let obj_times =  map linkableTime linkables ++ extra_times
        if not (null errs) || any (t <) obj_times
            then return True
            else do

        -- next, check libraries. XXX this only checks Haskell libraries,
        -- not extra_libraries or -l things from the command line.
        let pkg_map = pkgIdMap (pkgState dflags)
            pkg_hslibs  = [ (libraryDirs c, lib)
                          | Just c <- map (lookupPackage pkg_map) pkg_deps,
                            lib <- packageHsLibs dflags c ]

        pkg_libfiles <- mapM (uncurry findHSLib) pkg_hslibs
        if any isNothing pkg_libfiles then return True else do
        e_lib_times <- mapM (tryIO . getModificationUTCTime)
                          (catMaybes pkg_libfiles)
        let (lib_errs,lib_times) = splitEithers e_lib_times
        if not (null lib_errs) || any (t <) lib_times
           then return True
           else checkLinkInfo dflags pkg_deps exe_file

-- Returns 'False' if it was, and we can avoid linking, because the
-- previous binary was linked with "the same options".
checkLinkInfo :: DynFlags -> [PackageId] -> FilePath -> IO Bool
checkLinkInfo dflags pkg_deps exe_file
 | not (platformSupportsSavingLinkOpts (platformOS (targetPlatform dflags)))
 -- ToDo: Windows and OS X do not use the ELF binary format, so
 -- readelf does not work there.  We need to find another way to do
 -- this.
 = return False -- conservatively we should return True, but not
                -- linking in this case was the behaviour for a long
                -- time so we leave it as-is.
 | otherwise
 = do
   link_info <- getLinkInfo dflags pkg_deps
   debugTraceMsg dflags 3 $ text ("Link info: " ++ link_info)
   m_exe_link_info <- readElfSection dflags ghcLinkInfoSectionName exe_file
   debugTraceMsg dflags 3 $ text ("Exe link info: " ++ show m_exe_link_info)
   return (Just link_info /= m_exe_link_info)

platformSupportsSavingLinkOpts :: OS -> Bool
platformSupportsSavingLinkOpts os
  | os == OSSolaris2 = False -- see #5382
  | otherwise        = osElfTarget os

ghcLinkInfoSectionName :: String
ghcLinkInfoSectionName = ".debug-ghc-link-info"
   -- if we use the ".debug" prefix, then strip will strip it by default

findHSLib :: [String] -> String -> IO (Maybe FilePath)
findHSLib dirs lib = do
  let batch_lib_file = "lib" ++ lib <.> "a"
  found <- filterM doesFileExist (map (</> batch_lib_file) dirs)
  case found of
    [] -> return Nothing
    (x:_) -> return (Just x)

-- -----------------------------------------------------------------------------
-- Compile files in one-shot mode.

oneShot :: HscEnv -> Phase -> [(String, Maybe Phase)] -> IO ()
oneShot hsc_env stop_phase srcs = do
  o_files <- mapM (compileFile hsc_env stop_phase) srcs
  doLink (hsc_dflags hsc_env) stop_phase o_files

compileFile :: HscEnv -> Phase -> (FilePath, Maybe Phase) -> IO FilePath
compileFile hsc_env stop_phase (src, mb_phase) = do
   exists <- doesFileExist src
   when (not exists) $
        ghcError (CmdLineError ("does not exist: " ++ src))

   let
        dflags = hsc_dflags hsc_env
        split     = dopt Opt_SplitObjs dflags
        mb_o_file = outputFile dflags
        ghc_link  = ghcLink dflags      -- Set by -c or -no-link

        -- When linking, the -o argument refers to the linker's output.
        -- otherwise, we use it as the name for the pipeline's output.
        output
         | StopLn <- stop_phase, not (isNoLink ghc_link) = Persistent
                -- -o foo applies to linker
         | Just o_file <- mb_o_file = SpecificFile o_file
                -- -o foo applies to the file we are compiling now
         | otherwise = Persistent

        stop_phase' = case stop_phase of
                        As | split -> SplitAs
                        _          -> stop_phase

   ( _, out_file) <- runPipeline stop_phase' hsc_env
                            (src, mb_phase) Nothing output
                            Nothing{-no ModLocation-} Nothing
   return out_file


doLink :: DynFlags -> Phase -> [FilePath] -> IO ()
doLink dflags stop_phase o_files
  | not (isStopLn stop_phase)
  = return ()           -- We stopped before the linking phase

  | otherwise
  = case ghcLink dflags of
        NoLink     -> return ()
        LinkBinary -> linkBinary dflags o_files []
        LinkDynLib -> linkDynLib dflags o_files []
        other      -> panicBadLink other


-- ---------------------------------------------------------------------------

data PipelineOutput
  = Temporary
        -- ^ Output should be to a temporary file: we're going to
        -- run more compilation steps on this output later.
  | Persistent
        -- ^ We want a persistent file, i.e. a file in the current directory
        -- derived from the input filename, but with the appropriate extension.
        -- eg. in "ghc -c Foo.hs" the output goes into ./Foo.o.
  | SpecificFile FilePath
        -- ^ The output must go into the specified file.

-- | Run a compilation pipeline, consisting of multiple phases.
--
-- This is the interface to the compilation pipeline, which runs
-- a series of compilation steps on a single source file, specifying
-- at which stage to stop.
--
-- The DynFlags can be modified by phases in the pipeline (eg. by
-- OPTIONS_GHC pragmas), and the changes affect later phases in the
-- pipeline.
runPipeline
  :: Phase                      -- ^ When to stop
  -> HscEnv                     -- ^ Compilation environment
  -> (FilePath,Maybe Phase)     -- ^ Input filename (and maybe -x suffix)
  -> Maybe FilePath             -- ^ original basename (if different from ^^^)
  -> PipelineOutput             -- ^ Output filename
  -> Maybe ModLocation          -- ^ A ModLocation, if this is a Haskell module
  -> Maybe FilePath             -- ^ stub object, if we have one
  -> IO (DynFlags, FilePath)     -- ^ (final flags, output filename)

runPipeline stop_phase hsc_env0 (input_fn, mb_phase)
            mb_basename output maybe_loc maybe_stub_o
  = do
  let dflags0 = hsc_dflags hsc_env0
      (input_basename, suffix) = splitExtension input_fn
      suffix' = drop 1 suffix -- strip off the .
      basename | Just b <- mb_basename = b
               | otherwise             = input_basename

      -- Decide where dump files should go based on the pipeline output
      dflags = dflags0 { dumpPrefix = Just (basename ++ ".") }
      hsc_env = hsc_env0 {hsc_dflags = dflags}

        -- If we were given a -x flag, then use that phase to start from
      start_phase = fromMaybe (startPhase suffix') mb_phase

  -- We want to catch cases of "you can't get there from here" before
  -- we start the pipeline, because otherwise it will just run off the
  -- end.
  --
  -- There is a partial ordering on phases, where A < B iff A occurs
  -- before B in a normal compilation pipeline.

  when (not (start_phase `happensBefore` stop_phase)) $
        ghcError (UsageError
                    ("cannot compile this file to desired target: "
                       ++ input_fn))

  -- this is a function which will be used to calculate output file names
  -- as we go along (we partially apply it to some of its inputs here)
  let get_output_fn = getOutputFilename stop_phase output basename

  -- Execute the pipeline...
  let env   = PipeEnv{ stop_phase,
                       src_basename = basename,
                       src_suffix = suffix',
                       output_spec = output }

      state = PipeState{ hsc_env, maybe_loc, maybe_stub_o = maybe_stub_o }

  (state', output_fn) <- unP (pipeLoop start_phase input_fn) env state

  let PipeState{ hsc_env=hsc_env', maybe_loc } = state'
      dflags' = hsc_dflags hsc_env'

  -- Sometimes, a compilation phase doesn't actually generate any output
  -- (eg. the CPP phase when -fcpp is not turned on).  If we end on this
  -- stage, but we wanted to keep the output, then we have to explicitly
  -- copy the file, remembering to prepend a {-# LINE #-} pragma so that
  -- further compilation stages can tell what the original filename was.
  case output of
    Temporary ->
        return (dflags', output_fn)
    _other -> 
        do final_fn <- get_output_fn dflags' stop_phase maybe_loc
           when (final_fn /= output_fn) $ do
              let msg = ("Copying `" ++ output_fn ++"' to `" ++ final_fn ++ "'")
                  line_prag = Just ("{-# LINE 1 \"" ++ input_fn ++ "\" #-}\n")
              copyWithHeader dflags msg line_prag output_fn final_fn
           return (dflags', final_fn)

-- -----------------------------------------------------------------------------
-- The pipeline uses a monad to carry around various bits of information

-- PipeEnv: invariant information passed down
data PipeEnv = PipeEnv {
       stop_phase   :: Phase,       -- ^ Stop just before this phase
       src_basename :: String,      -- ^ basename of original input source
       src_suffix   :: String,      -- ^ its extension
       output_spec  :: PipelineOutput -- ^ says where to put the pipeline output
  }

-- PipeState: information that might change during a pipeline run
data PipeState = PipeState {
       hsc_env   :: HscEnv,
          -- ^ only the DynFlags change in the HscEnv.  The DynFlags change
          -- at various points, for example when we read the OPTIONS_GHC
          -- pragmas in the Cpp phase.
       maybe_loc :: Maybe ModLocation,
          -- ^ the ModLocation.  This is discovered during compilation,
          -- in the Hsc phase where we read the module header.
       maybe_stub_o :: Maybe FilePath
          -- ^ the stub object.  This is set by the Hsc phase if a stub
          -- object was created.  The stub object will be joined with
          -- the main compilation object using "ld -r" at the end.
  }

getPipeEnv :: CompPipeline PipeEnv
getPipeEnv = P $ \env state -> return (state, env)

getPipeState :: CompPipeline PipeState
getPipeState = P $ \_env state -> return (state, state)

instance HasDynFlags CompPipeline where
    getDynFlags = P $ \_env state -> return (state, hsc_dflags (hsc_env state))

setDynFlags :: DynFlags -> CompPipeline ()
setDynFlags dflags = P $ \_env state ->
  return (state{hsc_env= (hsc_env state){ hsc_dflags = dflags }}, ())

setModLocation :: ModLocation -> CompPipeline ()
setModLocation loc = P $ \_env state ->
  return (state{ maybe_loc = Just loc }, ())

setStubO :: FilePath -> CompPipeline ()
setStubO stub_o = P $ \_env state ->
  return (state{ maybe_stub_o = Just stub_o }, ())

newtype CompPipeline a = P { unP :: PipeEnv -> PipeState -> IO (PipeState, a) }

instance Monad CompPipeline where
  return a = P $ \_env state -> return (state, a)
  P m >>= k = P $ \env state -> do (state',a) <- m env state
                                   unP (k a) env state'

io :: IO a -> CompPipeline a
io m = P $ \_env state -> do a <- m; return (state, a)

phaseOutputFilename :: Phase{-next phase-} -> CompPipeline FilePath
phaseOutputFilename next_phase = do
  PipeEnv{stop_phase, src_basename, output_spec} <- getPipeEnv
  PipeState{maybe_loc, hsc_env} <- getPipeState
  let dflags = hsc_dflags hsc_env
  io $ getOutputFilename stop_phase output_spec
                         src_basename dflags next_phase maybe_loc

-- ---------------------------------------------------------------------------
-- outer pipeline loop

-- | pipeLoop runs phases until we reach the stop phase
pipeLoop :: Phase -> FilePath -> CompPipeline FilePath
pipeLoop phase input_fn = do
  PipeEnv{stop_phase} <- getPipeEnv
  PipeState{hsc_env}  <- getPipeState
  case () of
   _ | phase `eqPhase` stop_phase            -- All done
     -> return input_fn

     | not (phase `happensBefore` stop_phase)
        -- Something has gone wrong.  We'll try to cover all the cases when
        -- this could happen, so if we reach here it is a panic.
        -- eg. it might happen if the -C flag is used on a source file that
        -- has {-# OPTIONS -fasm #-}.
     -> panic ("pipeLoop: at phase " ++ show phase ++
           " but I wanted to stop at phase " ++ show stop_phase)

     | otherwise
     -> do io $ debugTraceMsg (hsc_dflags hsc_env) 4
                         (ptext (sLit "Running phase") <+> ppr phase)
           dflags <- getDynFlags
           (next_phase, output_fn) <- runPhase phase input_fn dflags
           pipeLoop next_phase output_fn

-- -----------------------------------------------------------------------------
-- In each phase, we need to know into what filename to generate the
-- output.  All the logic about which filenames we generate output
-- into is embodied in the following function.

getOutputFilename
  :: Phase -> PipelineOutput -> String
  -> DynFlags -> Phase{-next phase-} -> Maybe ModLocation -> IO FilePath
getOutputFilename stop_phase output basename
 = func
 where
        func dflags next_phase maybe_location
           | is_last_phase, Persistent <- output     = persistent_fn
           | is_last_phase, SpecificFile f <- output = return f
           | keep_this_output                        = persistent_fn
           | otherwise                               = newTempName dflags suffix
           where
                hcsuf      = hcSuf dflags
                odir       = objectDir dflags
                osuf       = objectSuf dflags
                keep_hc    = dopt Opt_KeepHcFiles dflags
                keep_s     = dopt Opt_KeepSFiles dflags
                keep_bc    = dopt Opt_KeepLlvmFiles dflags

                myPhaseInputExt HCc       = hcsuf
                myPhaseInputExt MergeStub = osuf
                myPhaseInputExt StopLn    = osuf
                myPhaseInputExt other     = phaseInputExt other

                is_last_phase = next_phase `eqPhase` stop_phase

                -- sometimes, we keep output from intermediate stages
                keep_this_output =
                     case next_phase of
                             As      | keep_s     -> True
                             LlvmOpt | keep_bc    -> True
                             HCc     | keep_hc    -> True
                             _other               -> False

                suffix = myPhaseInputExt next_phase

                -- persistent object files get put in odir
                persistent_fn
                   | StopLn <- next_phase = return odir_persistent
                   | otherwise            = return persistent

                persistent = basename <.> suffix

                odir_persistent
                   | Just loc <- maybe_location = ml_obj_file loc
                   | Just d <- odir = d </> persistent
                   | otherwise      = persistent


-- -----------------------------------------------------------------------------
-- | Each phase in the pipeline returns the next phase to execute, and the
-- name of the file in which the output was placed.
--
-- We must do things dynamically this way, because we often don't know
-- what the rest of the phases will be until part-way through the
-- compilation: for example, an {-# OPTIONS -fasm #-} at the beginning
-- of a source file can change the latter stages of the pipeline from
-- taking the via-C route to using the native code generator.
--
runPhase :: Phase       -- ^ Run this phase
         -> FilePath    -- ^ name of the input file
         -> DynFlags    -- ^ for convenience, we pass the current dflags in
         -> CompPipeline (Phase,               -- next phase to run
                          FilePath)            -- output filename

        -- Invariant: the output filename always contains the output
        -- Interesting case: Hsc when there is no recompilation to do
        --                   Then the output filename is still a .o file


-------------------------------------------------------------------------------
-- Unlit phase

runPhase (Unlit sf) input_fn dflags
  = do
       output_fn <- phaseOutputFilename (Cpp sf)

       let unlit_flags = getOpts dflags opt_L
           flags = map SysTools.Option unlit_flags ++
                   [ -- The -h option passes the file name for unlit to
                     -- put in a #line directive
                     SysTools.Option     "-h"
                   , SysTools.Option $ escape $ normalise input_fn
                   , SysTools.FileOption "" input_fn
                   , SysTools.FileOption "" output_fn
                   ]

       io $ SysTools.runUnlit dflags flags

       return (Cpp sf, output_fn)
  where
       -- escape the characters \, ", and ', but don't try to escape
       -- Unicode or anything else (so we don't use Util.charToC
       -- here).  If we get this wrong, then in
       -- Coverage.addTicksToBinds where we check that the filename in
       -- a SrcLoc is the same as the source filenaame, the two will
       -- look bogusly different. See test:
       -- libraries/hpc/tests/function/subdir/tough2.lhs
       escape ('\\':cs) = '\\':'\\': escape cs
       escape ('\"':cs) = '\\':'\"': escape cs
       escape ('\'':cs) = '\\':'\'': escape cs
       escape (c:cs)    = c : escape cs
       escape []        = []

-------------------------------------------------------------------------------
-- Cpp phase : (a) gets OPTIONS out of file
--             (b) runs cpp if necessary

runPhase (Cpp sf) input_fn dflags0
  = do
       src_opts <- io $ getOptionsFromFile dflags0 input_fn
       (dflags1, unhandled_flags, warns)
           <- io $ parseDynamicFilePragma dflags0 src_opts
       setDynFlags dflags1
       io $ checkProcessArgsResult unhandled_flags

       if not (xopt Opt_Cpp dflags1) then do
           -- we have to be careful to emit warnings only once.
           unless (dopt Opt_Pp dflags1) $ io $ handleFlagWarnings dflags1 warns

           -- no need to preprocess CPP, just pass input file along
           -- to the next phase of the pipeline.
           return (HsPp sf, input_fn)
        else do
            output_fn <- phaseOutputFilename (HsPp sf)
            io $ doCpp dflags1 True{-raw-} False{-no CC opts-} input_fn output_fn
            -- re-read the pragmas now that we've preprocessed the file
            -- See #2464,#3457
            src_opts <- io $ getOptionsFromFile dflags0 output_fn
            (dflags2, unhandled_flags, warns)
                <- io $ parseDynamicFilePragma dflags0 src_opts
            io $ checkProcessArgsResult unhandled_flags
            unless (dopt Opt_Pp dflags2) $ io $ handleFlagWarnings dflags2 warns
            -- the HsPp pass below will emit warnings

            setDynFlags dflags2

            return (HsPp sf, output_fn)

-------------------------------------------------------------------------------
-- HsPp phase

runPhase (HsPp sf) input_fn dflags
  = do
       if not (dopt Opt_Pp dflags) then
           -- no need to preprocess, just pass input file along
           -- to the next phase of the pipeline.
          return (Hsc sf, input_fn)
        else do
            let hspp_opts = getOpts dflags opt_F
            PipeEnv{src_basename, src_suffix} <- getPipeEnv
            let orig_fn = src_basename <.> src_suffix
            output_fn <- phaseOutputFilename (Hsc sf)
            io $ SysTools.runPp dflags
                           ( [ SysTools.Option     orig_fn
                             , SysTools.Option     input_fn
                             , SysTools.FileOption "" output_fn
                             ] ++
                             map SysTools.Option hspp_opts
                           )

            -- re-read pragmas now that we've parsed the file (see #3674)
            src_opts <- io $ getOptionsFromFile dflags output_fn
            (dflags1, unhandled_flags, warns)
                <- io $ parseDynamicFilePragma dflags src_opts
            setDynFlags dflags1
            io $ checkProcessArgsResult unhandled_flags
            io $ handleFlagWarnings dflags1 warns

            return (Hsc sf, output_fn)

-----------------------------------------------------------------------------
-- Hsc phase

-- Compilation of a single module, in "legacy" mode (_not_ under
-- the direction of the compilation manager).
runPhase (Hsc src_flavour) input_fn dflags0
 = do   -- normal Hsc mode, not mkdependHS

        PipeEnv{ stop_phase=stop,
                 src_basename=basename,
                 src_suffix=suff } <- getPipeEnv

  -- we add the current directory (i.e. the directory in which
  -- the .hs files resides) to the include path, since this is
  -- what gcc does, and it's probably what you want.
        let current_dir = takeDirectory basename
            paths = includePaths dflags0
            dflags = dflags0 { includePaths = current_dir : paths }

        setDynFlags dflags

  -- gather the imports and module name
        (hspp_buf,mod_name,imps,src_imps) <- io $
            case src_flavour of
                ExtCoreFile -> do  -- no explicit imports in ExtCore input.
                    m <- getCoreModuleName input_fn
                    return (Nothing, mkModuleName m, [], [])

                _           -> do
                    buf <- hGetStringBuffer input_fn
                    (src_imps,imps,L _ mod_name) <- getImports dflags buf input_fn (basename <.> suff)
                    return (Just buf, mod_name, imps, src_imps)

  -- Build a ModLocation to pass to hscMain.
  -- The source filename is rather irrelevant by now, but it's used
  -- by hscMain for messages.  hscMain also needs
  -- the .hi and .o filenames, and this is as good a way
  -- as any to generate them, and better than most. (e.g. takes
  -- into accout the -osuf flags)
        location1 <- io $ mkHomeModLocation2 dflags mod_name basename suff

  -- Boot-ify it if necessary
        let location2 | isHsBoot src_flavour = addBootSuffixLocn location1
                      | otherwise            = location1


  -- Take -ohi into account if present
  -- This can't be done in mkHomeModuleLocation because
  -- it only applies to the module being compiles
        let ohi = outputHi dflags
            location3 | Just fn <- ohi = location2{ ml_hi_file = fn }
                      | otherwise      = location2

  -- Take -o into account if present
  -- Very like -ohi, but we must *only* do this if we aren't linking
  -- (If we're linking then the -o applies to the linked thing, not to
  -- the object file for one module.)
  -- Note the nasty duplication with the same computation in compileFile above
        let expl_o_file = outputFile dflags
            location4 | Just ofile <- expl_o_file
                      , isNoLink (ghcLink dflags)
                      = location3 { ml_obj_file = ofile }
                      | otherwise = location3

            o_file = ml_obj_file location4      -- The real object file

        setModLocation location4

  -- Figure out if the source has changed, for recompilation avoidance.
  --
  -- Setting source_unchanged to True means that M.o seems
  -- to be up to date wrt M.hs; so no need to recompile unless imports have
  -- changed (which the compiler itself figures out).
  -- Setting source_unchanged to False tells the compiler that M.o is out of
  -- date wrt M.hs (or M.o doesn't exist) so we must recompile regardless.
        src_timestamp <- io $ getModificationUTCTime (basename <.> suff)

        let hsc_lang = hscTarget dflags
        source_unchanged <- io $
          if not (isStopLn stop)
                -- SourceModified unconditionally if
                --      (a) recompilation checker is off, or
                --      (b) we aren't going all the way to .o file (e.g. ghc -S)
             then return SourceModified
                -- Otherwise look at file modification dates
             else do o_file_exists <- doesFileExist o_file
                     if not o_file_exists
                        then return SourceModified       -- Need to recompile
                        else do t2 <- getModificationUTCTime o_file
                                if t2 > src_timestamp
                                  then return SourceUnmodified
                                  else return SourceModified

  -- get the DynFlags
        let next_phase = hscPostBackendPhase dflags src_flavour hsc_lang
        output_fn  <- phaseOutputFilename next_phase

        let dflags' = dflags { hscTarget = hsc_lang,
                               hscOutName = output_fn,
                               extCoreName = basename ++ ".hcr" }

        setDynFlags dflags'
        PipeState{hsc_env=hsc_env'} <- getPipeState

  -- Tell the finder cache about this module
        mod <- io $ addHomeModuleToFinder hsc_env' mod_name location4

  -- Make the ModSummary to hand to hscMain
        let
            mod_summary = ModSummary {  ms_mod       = mod,
                                        ms_hsc_src   = src_flavour,
                                        ms_hspp_file = input_fn,
                                        ms_hspp_opts = dflags,
                                        ms_hspp_buf  = hspp_buf,
                                        ms_location  = location4,
                                        ms_hs_date   = src_timestamp,
                                        ms_obj_date  = Nothing,
                                        ms_textual_imps = imps,
                                        ms_srcimps      = src_imps }

  -- run the compiler!
        result <- io $ hscCompileOneShot hsc_env'
                          mod_summary source_unchanged
                          Nothing       -- No iface
                          Nothing       -- No "module i of n" progress info

        case result of
          HscNoRecomp
              -> do io $ touchObjectFile dflags' o_file
                    -- The .o file must have a later modification date
                    -- than the source file (else we wouldn't be in HscNoRecomp)
                    -- but we touch it anyway, to keep 'make' happy (we think).
                    return (StopLn, o_file)
          (HscRecomp hasStub _)
              -> do case hasStub of
                      Nothing -> return ()
                      Just stub_c ->
                         do stub_o <- io $ compileStub hsc_env' stub_c
                            setStubO stub_o
                    -- In the case of hs-boot files, generate a dummy .o-boot
                    -- stamp file for the benefit of Make
                    when (isHsBoot src_flavour) $
                      io $ touchObjectFile dflags' o_file
                    return (next_phase, output_fn)

-----------------------------------------------------------------------------
-- Cmm phase

runPhase CmmCpp input_fn dflags
  = do
       output_fn <- phaseOutputFilename Cmm
       io $ doCpp dflags False{-not raw-} True{-include CC opts-}
              input_fn output_fn
       return (Cmm, output_fn)

runPhase Cmm input_fn dflags
  = do
        PipeEnv{src_basename} <- getPipeEnv
        let hsc_lang = hscTarget dflags

        let next_phase = hscPostBackendPhase dflags HsSrcFile hsc_lang

        output_fn <- phaseOutputFilename next_phase

        let dflags' = dflags { hscTarget = hsc_lang,
                               hscOutName = output_fn,
                               extCoreName = src_basename ++ ".hcr" }

        setDynFlags dflags'
        PipeState{hsc_env} <- getPipeState

        io $ hscCompileCmmFile hsc_env input_fn

        return (next_phase, output_fn)

-----------------------------------------------------------------------------
-- Cc phase

-- we don't support preprocessing .c files (with -E) now.  Doing so introduces
-- way too many hacks, and I can't say I've ever used it anyway.

runPhase cc_phase input_fn dflags
   | any (cc_phase `eqPhase`) [Cc, Ccpp, HCc, Cobjc, Cobjcpp]
   = do
        let platform = targetPlatform dflags
            cc_opts = getOpts dflags opt_c
            hcc = cc_phase `eqPhase` HCc

        let cmdline_include_paths = includePaths dflags

        -- HC files have the dependent packages stamped into them
        pkgs <- if hcc then io $ getHCFilePackages input_fn else return []

        -- add package include paths even if we're just compiling .c
        -- files; this is the Value Add(TM) that using ghc instead of
        -- gcc gives you :)
        pkg_include_dirs <- io $ getPackageIncludePath dflags pkgs
        let include_paths = foldr (\ x xs -> "-I" : x : xs) []
                              (cmdline_include_paths ++ pkg_include_dirs)

        let gcc_extra_viac_flags = extraGccViaCFlags dflags
        let pic_c_flags = picCCOpts dflags

        let verbFlags = getVerbFlags dflags

        -- cc-options are not passed when compiling .hc files.  Our
        -- hc code doesn't not #include any header files anyway, so these
        -- options aren't necessary.
        pkg_extra_cc_opts <- io $
          if cc_phase `eqPhase` HCc
             then return []
             else getPackageExtraCcOpts dflags pkgs

        framework_paths <-
            case platformOS platform of
            OSDarwin ->
                do pkgFrameworkPaths <- io $ getPackageFrameworkPath dflags pkgs
                   let cmdlineFrameworkPaths = frameworkPaths dflags
                   return $ map ("-F"++)
                                (cmdlineFrameworkPaths ++ pkgFrameworkPaths)
            _ ->
                return []

        let split_objs = dopt Opt_SplitObjs dflags
            split_opt | hcc && split_objs = [ "-DUSE_SPLIT_MARKERS" ]
                      | otherwise         = [ ]

        let cc_opt | optLevel dflags >= 2 = "-O2"
                   | otherwise            = "-O"

        -- Decide next phase
        let next_phase = As
        output_fn <- phaseOutputFilename next_phase

        let
          more_hcc_opts =
                -- on x86 the floating point regs have greater precision
                -- than a double, which leads to unpredictable results.
                -- By default, we turn this off with -ffloat-store unless
                -- the user specified -fexcess-precision.
                (if platformArch platform == ArchX86 &&
                    not (dopt Opt_ExcessPrecision dflags)
                        then [ "-ffloat-store" ]
                        else []) ++

                -- gcc's -fstrict-aliasing allows two accesses to memory
                -- to be considered non-aliasing if they have different types.
                -- This interacts badly with the C code we generate, which is
                -- very weakly typed, being derived from C--.
                ["-fno-strict-aliasing"]

        let gcc_lang_opt | cc_phase `eqPhase` Ccpp  = "c++"
                         | cc_phase `eqPhase` Cobjc = "objective-c"
                         | cc_phase `eqPhase` Cobjcpp = "objective-c++"
                         | otherwise                = "c"
        io $ SysTools.runCc dflags (
                -- force the C compiler to interpret this file as C when
                -- compiling .hc files, by adding the -x c option.
                -- Also useful for plain .c files, just in case GHC saw a
                -- -x c option.
                        [ SysTools.Option "-x", SysTools.Option gcc_lang_opt
                        , SysTools.FileOption "" input_fn
                        , SysTools.Option "-o"
                        , SysTools.FileOption "" output_fn
                        ]
                       ++ map SysTools.Option (
                          pic_c_flags

                -- Stub files generated for foreign exports references the runIO_closure
                -- and runNonIO_closure symbols, which are defined in the base package.
                -- These symbols are imported into the stub.c file via RtsAPI.h, and the
                -- way we do the import depends on whether we're currently compiling
                -- the base package or not.
                       ++ (if platformOS platform == OSMinGW32 &&
                              thisPackage dflags == basePackageId
                                then [ "-DCOMPILING_BASE_PACKAGE" ]
                                else [])

        -- We only support SparcV9 and better because V8 lacks an atomic CAS
        -- instruction. Note that the user can still override this
        -- (e.g., -mcpu=ultrasparc) as GCC picks the "best" -mcpu flag
        -- regardless of the ordering.
        --
        -- This is a temporary hack.
                       ++ (if platformArch platform == ArchSPARC
                           then ["-mcpu=v9"]
                           else [])

                       ++ (if hcc
                             then gcc_extra_viac_flags ++ more_hcc_opts
                             else [])
                       ++ verbFlags
                       ++ [ "-S", "-Wimplicit", cc_opt ]
                       ++ [ "-D__GLASGOW_HASKELL__="++cProjectVersionInt ]
                       ++ framework_paths
                       ++ cc_opts
                       ++ split_opt
                       ++ include_paths
                       ++ pkg_extra_cc_opts
                       ))

        return (next_phase, output_fn)

-----------------------------------------------------------------------------
-- Splitting phase

runPhase Splitter input_fn dflags
  = do  -- tmp_pfx is the prefix used for the split .s files

        split_s_prefix <- io $ SysTools.newTempName dflags "split"
        let n_files_fn = split_s_prefix

        io $ SysTools.runSplit dflags
                          [ SysTools.FileOption "" input_fn
                          , SysTools.FileOption "" split_s_prefix
                          , SysTools.FileOption "" n_files_fn
                          ]

        -- Save the number of split files for future references
        s <- io $ readFile n_files_fn
        let n_files = read s :: Int
            dflags' = dflags { splitInfo = Just (split_s_prefix, n_files) }

        setDynFlags dflags'

        -- Remember to delete all these files
        io $ addFilesToClean dflags' [ split_s_prefix ++ "__" ++ show n ++ ".s"
                                     | n <- [1..n_files]]

        return (SplitAs,
                "**splitter**") -- we don't use the filename in SplitAs

-----------------------------------------------------------------------------
-- As, SpitAs phase : Assembler

-- This is for calling the assembler on a regular assembly file (not split).
runPhase As input_fn dflags
  = do
        -- LLVM from version 3.0 onwards doesn't support the OS X system
        -- assembler, so we use clang as the assembler instead. (#5636)
        let whichAsProg | hscTarget dflags == HscLlvm &&
                          platformOS (targetPlatform dflags) == OSDarwin
                        = do
                            llvmVer <- io $ figureLlvmVersion dflags
                            return $ case llvmVer of
                                -- using cGccLinkerOpts here but not clear if
                                -- opt_c isn't a better choice
                                Just n | n >= 30 ->
                                    (SysTools.runClang, cGccLinkerOpts)

                                _ -> (SysTools.runAs, getOpts dflags opt_a)

                        | otherwise
                        = return (SysTools.runAs, getOpts dflags opt_a)

        (as_prog, as_opts) <- whichAsProg
        let cmdline_include_paths = includePaths dflags

        next_phase <- maybeMergeStub
        output_fn <- phaseOutputFilename next_phase

        -- we create directories for the object file, because it
        -- might be a hierarchical module.
        io $ createDirectoryIfMissing True (takeDirectory output_fn)

        io $ as_prog dflags
                       (map SysTools.Option as_opts
                       ++ [ SysTools.Option ("-I" ++ p) | p <- cmdline_include_paths ]

        -- We only support SparcV9 and better because V8 lacks an atomic CAS
        -- instruction so we have to make sure that the assembler accepts the
        -- instruction set. Note that the user can still override this
        -- (e.g., -mcpu=ultrasparc). GCC picks the "best" -mcpu flag
        -- regardless of the ordering.
        --
        -- This is a temporary hack.
                       ++ (if platformArch (targetPlatform dflags) == ArchSPARC
                           then [SysTools.Option "-mcpu=v9"]
                           else [])

                       ++ [ SysTools.Option "-c"
                          , SysTools.FileOption "" input_fn
                          , SysTools.Option "-o"
                          , SysTools.FileOption "" output_fn
                          ])

        return (next_phase, output_fn)


-- This is for calling the assembler on a split assembly file (so a collection
-- of assembly files)
runPhase SplitAs _input_fn dflags
  = do
        -- we'll handle the stub_o file in this phase, so don't MergeStub,
        -- just jump straight to StopLn afterwards.
        let next_phase = StopLn
        output_fn <- phaseOutputFilename next_phase

        let base_o = dropExtension output_fn
            osuf = objectSuf dflags
            split_odir  = base_o ++ "_" ++ osuf ++ "_split"

        io $ createDirectoryIfMissing True split_odir

        -- remove M_split/ *.o, because we're going to archive M_split/ *.o
        -- later and we don't want to pick up any old objects.
        fs <- io $ getDirectoryContents split_odir
        io $ mapM_ removeFile $
                map (split_odir </>) $ filter (osuf `isSuffixOf`) fs

        let as_opts = getOpts dflags opt_a

        let (split_s_prefix, n) = case splitInfo dflags of
                                  Nothing -> panic "No split info"
                                  Just x -> x

        let split_s   n = split_s_prefix ++ "__" ++ show n <.> "s"

            split_obj :: Int -> FilePath
            split_obj n = split_odir </>
                          takeFileName base_o ++ "__" ++ show n <.> osuf

        let assemble_file n
              = SysTools.runAs dflags
                         (map SysTools.Option as_opts ++

        -- We only support SparcV9 and better because V8 lacks an atomic CAS
        -- instruction so we have to make sure that the assembler accepts the
        -- instruction set. Note that the user can still override this
        -- (e.g., -mcpu=ultrasparc). GCC picks the "best" -mcpu flag
        -- regardless of the ordering.
        --
        -- This is a temporary hack.
                          (if platformArch (targetPlatform dflags) == ArchSPARC
                           then [SysTools.Option "-mcpu=v9"]
                           else []) ++

                          [ SysTools.Option "-c"
                          , SysTools.Option "-o"
                          , SysTools.FileOption "" (split_obj n)
                          , SysTools.FileOption "" (split_s n)
                          ])

        io $ mapM_ assemble_file [1..n]

        -- Note [pipeline-split-init]
        -- If we have a stub file, it may contain constructor
        -- functions for initialisation of this module.  We can't
        -- simply leave the stub as a separate object file, because it
        -- will never be linked in: nothing refers to it.  We need to
        -- ensure that if we ever refer to the data in this module
        -- that needs initialisation, then we also pull in the
        -- initialisation routine.
        --
        -- To that end, we make a DANGEROUS ASSUMPTION here: the data
        -- that needs to be initialised is all in the FIRST split
        -- object.  See Note [codegen-split-init].

        PipeState{maybe_stub_o} <- getPipeState
        case maybe_stub_o of
            Nothing     -> return ()
            Just stub_o -> io $ do
                     tmp_split_1 <- newTempName dflags osuf
                     let split_1 = split_obj 1
                     copyFile split_1 tmp_split_1
                     removeFile split_1
                     joinObjectFiles dflags [tmp_split_1, stub_o] split_1

        -- join them into a single .o file
        io $ joinObjectFiles dflags (map split_obj [1..n]) output_fn

        return (next_phase, output_fn)

-----------------------------------------------------------------------------
-- LlvmOpt phase

runPhase LlvmOpt input_fn dflags
  = do
    ver <- io $ readIORef (llvmVersion dflags)

    let lo_opts  = getOpts dflags opt_lo
        opt_lvl  = max 0 (min 2 $ optLevel dflags)
        -- don't specify anything if user has specified commands. We do this
        -- for opt but not llc since opt is very specifically for optimisation
        -- passes only, so if the user is passing us extra options we assume
        -- they know what they are doing and don't get in the way.
        optFlag  = if null lo_opts
                       then [SysTools.Option (llvmOpts !! opt_lvl)]
                       else []
        tbaa | ver < 29                 = "" -- no tbaa in 2.8 and earlier
             | dopt Opt_LlvmTBAA dflags = "--enable-tbaa=true"
             | otherwise                = "--enable-tbaa=false"


    output_fn <- phaseOutputFilename LlvmLlc

    io $ SysTools.runLlvmOpt dflags
               ([ SysTools.FileOption "" input_fn,
                    SysTools.Option "-o",
                    SysTools.FileOption "" output_fn]
                ++ optFlag
                ++ [SysTools.Option tbaa]
                ++ map SysTools.Option lo_opts)

    return (LlvmLlc, output_fn)
  where 
        -- we always (unless -optlo specified) run Opt since we rely on it to
        -- fix up some pretty big deficiencies in the code we generate
        llvmOpts = ["-mem2reg", "-O1", "-O2"]

-----------------------------------------------------------------------------
-- LlvmLlc phase

runPhase LlvmLlc input_fn dflags
  = do
    ver <- io $ readIORef (llvmVersion dflags)

    let lc_opts = getOpts dflags opt_lc
        opt_lvl = max 0 (min 2 $ optLevel dflags)
        rmodel | opt_PIC        = "pic"
               | not opt_Static = "dynamic-no-pic"
               | otherwise      = "static"
        tbaa | ver < 29                 = "" -- no tbaa in 2.8 and earlier
             | dopt Opt_LlvmTBAA dflags = "--enable-tbaa=true"
             | otherwise                = "--enable-tbaa=false"

    -- hidden debugging flag '-dno-llvm-mangler' to skip mangling
    let next_phase = case dopt Opt_NoLlvmMangler dflags of
                         False                            -> LlvmMangle
                         True | dopt Opt_SplitObjs dflags -> Splitter
                         True                             -> As
                        
    output_fn <- phaseOutputFilename next_phase

    io $ SysTools.runLlvmLlc dflags
                ([ SysTools.Option (llvmOpts !! opt_lvl),
                    SysTools.Option $ "-relocation-model=" ++ rmodel,
                    SysTools.FileOption "" input_fn,
                    SysTools.Option "-o", SysTools.FileOption "" output_fn]
                ++ map SysTools.Option lc_opts
                ++ [SysTools.Option tbaa]
                ++ map SysTools.Option fpOpts)

    return (next_phase, output_fn)
  where
        -- Bug in LLVM at O3 on OSX.
        llvmOpts = if platformOS (targetPlatform dflags) == OSDarwin
                   then ["-O1", "-O2", "-O2"]
                   else ["-O1", "-O2", "-O3"]
        -- On ARMv7 using LLVM, LLVM fails to allocate floating point registers
        -- while compiling GHC source code. It's probably due to fact that it
        -- does not enable VFP by default. Let's do this manually here
        fpOpts = case platformArch (targetPlatform dflags) of 
                   ArchARM ARMv7 ext -> if (elem VFPv3 ext)
                                      then ["-mattr=+v7,+vfp3"]
                                      else if (elem VFPv3D16 ext)
                                           then ["-mattr=+v7,+vfp3,+d16"]
                                           else []
                   _                 -> []

-----------------------------------------------------------------------------
-- LlvmMangle phase

runPhase LlvmMangle input_fn dflags
  = do
      let next_phase = if dopt Opt_SplitObjs dflags then Splitter else As
      output_fn <- phaseOutputFilename next_phase
      io $ llvmFixupAsm dflags input_fn output_fn
      return (next_phase, output_fn)

-----------------------------------------------------------------------------
-- merge in stub objects

runPhase MergeStub input_fn dflags
 = do
     PipeState{maybe_stub_o} <- getPipeState
     output_fn <- phaseOutputFilename StopLn
     case maybe_stub_o of
       Nothing ->
         panic "runPhase(MergeStub): no stub"
       Just stub_o -> do
         io $ joinObjectFiles dflags [input_fn, stub_o] output_fn
         return (StopLn, output_fn)

-- warning suppression
runPhase other _input_fn _dflags =
   panic ("runPhase: don't know how to run phase " ++ show other)

maybeMergeStub :: CompPipeline Phase
maybeMergeStub
 = do
     PipeState{maybe_stub_o} <- getPipeState
     if isJust maybe_stub_o then return MergeStub else return StopLn

-----------------------------------------------------------------------------
-- MoveBinary sort-of-phase
-- After having produced a binary, move it somewhere else and generate a
-- wrapper script calling the binary. Currently, we need this only in
-- a parallel way (i.e. in GUM), because PVM expects the binary in a
-- central directory.
-- This is called from linkBinary below, after linking. I haven't made it
-- a separate phase to minimise interfering with other modules, and
-- we don't need the generality of a phase (MoveBinary is always
-- done after linking and makes only sense in a parallel setup)   -- HWL

runPhase_MoveBinary :: DynFlags -> FilePath -> IO Bool
runPhase_MoveBinary dflags input_fn
    | WayPar `elem` (wayNames dflags) && not opt_Static =
        panic ("Don't know how to combine PVM wrapper and dynamic wrapper")
    | WayPar `elem` (wayNames dflags) = do
        let sysMan = pgm_sysman dflags
        pvm_root <- getEnv "PVM_ROOT"
        pvm_arch <- getEnv "PVM_ARCH"
        let
           pvm_executable_base = "=" ++ input_fn
           pvm_executable = pvm_root ++ "/bin/" ++ pvm_arch ++ "/" ++ pvm_executable_base
        -- nuke old binary; maybe use configur'ed names for cp and rm?
        _ <- tryIO (removeFile pvm_executable)
        -- move the newly created binary into PVM land
        copy dflags "copying PVM executable" input_fn pvm_executable
        -- generate a wrapper script for running a parallel prg under PVM
        writeFile input_fn (mk_pvm_wrapper_script pvm_executable pvm_executable_base sysMan)
        return True
    | otherwise = return True

mkExtraObj :: DynFlags -> Suffix -> String -> IO FilePath
mkExtraObj dflags extn xs
 = do cFile <- newTempName dflags extn
      oFile <- newTempName dflags "o"
      writeFile cFile xs
      let rtsDetails = getPackageDetails (pkgState dflags) rtsPackageId
      SysTools.runCc dflags
                     ([Option        "-c",
                       FileOption "" cFile,
                       Option        "-o",
                       FileOption "" oFile]
                      ++ map SysTools.Option (getOpts dflags opt_c) -- see #5528
                      ++ map (FileOption "-I") (includeDirs rtsDetails))
      return oFile

-- When linking a binary, we need to create a C main() function that
-- starts everything off.  This used to be compiled statically as part
-- of the RTS, but that made it hard to change the -rtsopts setting,
-- so now we generate and compile a main() stub as part of every
-- binary and pass the -rtsopts setting directly to the RTS (#5373)
--
mkExtraObjToLinkIntoBinary :: DynFlags -> IO FilePath
mkExtraObjToLinkIntoBinary dflags = do
   let have_rts_opts_flags =
         isJust (rtsOpts dflags) || case rtsOptsEnabled dflags of
                                        RtsOptsSafeOnly -> False
                                        _ -> True

   when (dopt Opt_NoHsMain dflags && have_rts_opts_flags) $ do
      hPutStrLn stderr $ "Warning: -rtsopts and -with-rtsopts have no effect with -no-hs-main.\n" ++
                         "    Call hs_init_ghc() from your main() function to set these options."

   mkExtraObj dflags "c" (showSDoc main)

  where
    main
      | dopt Opt_NoHsMain dflags = empty
      | otherwise = vcat [
             ptext (sLit "#include \"Rts.h\""),
             ptext (sLit "extern StgClosure ZCMain_main_closure;"),
             ptext (sLit "int main(int argc, char *argv[])"),
             char '{',
             ptext (sLit "    RtsConfig __conf = defaultRtsConfig;"),
             ptext (sLit "    __conf.rts_opts_enabled = ")
                 <> text (show (rtsOptsEnabled dflags)) <> semi,
             case rtsOpts dflags of
                Nothing   -> empty
                Just opts -> ptext (sLit "    __conf.rts_opts= ") <>
                               text (show opts) <> semi,
             ptext (sLit "    return hs_main(argc, argv, &ZCMain_main_closure,__conf);"),
             char '}',
             char '\n' -- final newline, to keep gcc happy
           ]

-- Write out the link info section into a new assembly file. Previously
-- this was included as inline assembly in the main.c file but this
-- is pretty fragile. gas gets upset trying to calculate relative offsets
-- that span the .note section (notably .text) when debug info is present
mkNoteObjsToLinkIntoBinary :: DynFlags -> [PackageId] -> IO [FilePath]
mkNoteObjsToLinkIntoBinary dflags dep_packages = do
   link_info <- getLinkInfo dflags dep_packages

   if (platformSupportsSavingLinkOpts (platformOS (targetPlatform dflags)))
     then fmap (:[]) $ mkExtraObj dflags "s" (showSDoc (link_opts link_info))
     else return []

  where
    link_opts info = hcat [
          text "\t.section ", text ghcLinkInfoSectionName,
                                   text ",\"\",",
                                   text elfSectionNote,
                                   text "\n",

          text "\t.ascii \"", info', text "\"\n" ]
          where
            info' = text $ escape info

            escape :: String -> String
            escape = concatMap (charToC.fromIntegral.ord)

            elfSectionNote :: String
            elfSectionNote = case platformArch (targetPlatform dflags) of
                               ArchARM _ _ -> "%note"
                               _           -> "@note"

-- The "link info" is a string representing the parameters of the
-- link.  We save this information in the binary, and the next time we
-- link, if nothing else has changed, we use the link info stored in
-- the existing binary to decide whether to re-link or not.
getLinkInfo :: DynFlags -> [PackageId] -> IO String
getLinkInfo dflags dep_packages = do
   package_link_opts <- getPackageLinkOpts dflags dep_packages
   pkg_frameworks <- case platformOS (targetPlatform dflags) of
                     OSDarwin -> getPackageFrameworks dflags dep_packages
                     _        -> return []
   extra_ld_inputs <- readIORef v_Ld_inputs
   let
      link_info = (package_link_opts,
                   pkg_frameworks,
                   rtsOpts dflags,
                   rtsOptsEnabled dflags,
                   dopt Opt_NoHsMain dflags,
                   extra_ld_inputs,
                   getOpts dflags opt_l)
   --
   return (show link_info)

-- generates a Perl skript starting a parallel prg under PVM
mk_pvm_wrapper_script :: String -> String -> String -> String
mk_pvm_wrapper_script pvm_executable pvm_executable_base sysMan = unlines $
 [
  "eval 'exec perl -S $0 ${1+\"$@\"}'",
  "  if $running_under_some_shell;",
  "# =!=!=!=!=!=!=!=!=!=!=!",
  "# This script is automatically generated: DO NOT EDIT!!!",
  "# Generated by Glasgow Haskell Compiler",
  "# ngoqvam choHbogh vaj' vIHoHnISbej !!!!",
  "#",
  "$pvm_executable      = '" ++ pvm_executable ++ "';",
  "$pvm_executable_base = '" ++ pvm_executable_base ++ "';",
  "$SysMan = '" ++ sysMan ++ "';",
  "",
  {- ToDo: add the magical shortcuts again iff we actually use them -- HWL
  "# first, some magical shortcuts to run "commands" on the binary",
  "# (which is hidden)",
  "if ($#ARGV == 1 && $ARGV[0] eq '+RTS' && $ARGV[1] =~ /^--((size|file|strip|rm|nm).*)/ ) {",
  "    local($cmd) = $1;",
  "    system("$cmd $pvm_executable");",
  "    exit(0); # all done",
  "}", -}
  "",
  "# Now, run the real binary; process the args first",
  "$ENV{'PE'} = $pvm_executable_base;", --  ++ pvm_executable_base,
  "$debug = '';",
  "$nprocessors = 0; # the default: as many PEs as machines in PVM config",
  "@nonPVM_args = ();",
  "$in_RTS_args = 0;",
  "",
  "args: while ($a = shift(@ARGV)) {",
  "    if ( $a eq '+RTS' ) {",
  "        $in_RTS_args = 1;",
  "    } elsif ( $a eq '-RTS' ) {",
  "        $in_RTS_args = 0;",
  "    }",
  "    if ( $a eq '-d' && $in_RTS_args ) {",
  "        $debug = '-';",
  "    } elsif ( $a =~ /^-qN(\\d+)/ && $in_RTS_args ) {",
  "        $nprocessors = $1;",
  "    } elsif ( $a =~ /^-qp(\\d+)/ && $in_RTS_args ) {",
  "        $nprocessors = $1;",
  "    } else {",
  "        push(@nonPVM_args, $a);",
  "    }",
  "}",
  "",
  "local($return_val) = 0;",
  "# Start the parallel execution by calling SysMan",
  "system(\"$SysMan $debug $pvm_executable $nprocessors @nonPVM_args\");",
  "$return_val = $?;",
  "# ToDo: fix race condition moving files and flushing them!!",
  "system(\"cp $ENV{'HOME'}/$pvm_executable_base.???.gr .\") if -f \"$ENV{'HOME'}/$pvm_executable_base.002.gr\";",
  "exit($return_val);"
 ]

-----------------------------------------------------------------------------
-- Look for the /* GHC_PACKAGES ... */ comment at the top of a .hc file

getHCFilePackages :: FilePath -> IO [PackageId]
getHCFilePackages filename =
  Exception.bracket (openFile filename ReadMode) hClose $ \h -> do
    l <- hGetLine h
    case l of
      '/':'*':' ':'G':'H':'C':'_':'P':'A':'C':'K':'A':'G':'E':'S':rest ->
          return (map stringToPackageId (words rest))
      _other ->
          return []

-----------------------------------------------------------------------------
-- Static linking, of .o files

-- The list of packages passed to link is the list of packages on
-- which this program depends, as discovered by the compilation
-- manager.  It is combined with the list of packages that the user
-- specifies on the command line with -package flags.
--
-- In one-shot linking mode, we can't discover the package
-- dependencies (because we haven't actually done any compilation or
-- read any interface files), so the user must explicitly specify all
-- the packages.

linkBinary :: DynFlags -> [FilePath] -> [PackageId] -> IO ()
linkBinary dflags o_files dep_packages = do
    let platform = targetPlatform dflags
        verbFlags = getVerbFlags dflags
        output_fn = exeFileName dflags

    -- get the full list of packages to link with, by combining the
    -- explicit packages with the auto packages and all of their
    -- dependencies, and eliminating duplicates.

    pkg_lib_paths <- getPackageLibraryPath dflags dep_packages
    let pkg_lib_path_opts = concat (map get_pkg_lib_path_opts pkg_lib_paths)
        get_pkg_lib_path_opts l
         | osElfTarget (platformOS platform) &&
           dynLibLoader dflags == SystemDependent &&
           not opt_Static
            = ["-L" ++ l, "-Wl,-rpath", "-Wl," ++ l]
         | otherwise = ["-L" ++ l]

    let lib_paths = libraryPaths dflags
    let lib_path_opts = map ("-L"++) lib_paths

    extraLinkObj <- mkExtraObjToLinkIntoBinary dflags
    noteLinkObjs <- mkNoteObjsToLinkIntoBinary dflags dep_packages

    pkg_link_opts <- getPackageLinkOpts dflags dep_packages

    pkg_framework_path_opts <-
        case platformOS platform of
        OSDarwin ->
            do pkg_framework_paths <- getPackageFrameworkPath dflags dep_packages
               return $ map ("-F" ++) pkg_framework_paths
        _ ->
            return []

    framework_path_opts <-
        case platformOS platform of
        OSDarwin ->
            do let framework_paths = frameworkPaths dflags
               return $ map ("-F" ++) framework_paths
        _ ->
            return []

    pkg_framework_opts <-
        case platformOS platform of
        OSDarwin ->
            do pkg_frameworks <- getPackageFrameworks dflags dep_packages
               return $ concat [ ["-framework", fw] | fw <- pkg_frameworks ]
        _ ->
            return []

    framework_opts <-
        case platformOS platform of
        OSDarwin ->
            do let frameworks = cmdlineFrameworks dflags
               -- reverse because they're added in reverse order from
               -- the cmd line:
               return $ concat [ ["-framework", fw] | fw <- reverse frameworks ]
        _ ->
            return []

        -- probably _stub.o files
    extra_ld_inputs <- readIORef v_Ld_inputs

        -- opts from -optl-<blah> (including -l<blah> options)
    let extra_ld_opts = getOpts dflags opt_l

    let ways = wayNames dflags

    -- Here are some libs that need to be linked at the *end* of
    -- the command line, because they contain symbols that are referred to
    -- by the RTS.  We can't therefore use the ordinary way opts for these.
    let
        debug_opts | WayDebug `elem` ways = [
#if defined(HAVE_LIBBFD)
                        "-lbfd", "-liberty"
#endif
                         ]
                   | otherwise            = []

    let
        thread_opts | WayThreaded `elem` ways = [
#if !defined(mingw32_TARGET_OS) && !defined(freebsd_TARGET_OS) && !defined(openbsd_TARGET_OS) && !defined(netbsd_TARGET_OS) && !defined(haiku_TARGET_OS)
                        "-lpthread"
#endif
#if defined(osf3_TARGET_OS)
                        , "-lexc"
#endif
                        ]
                    | otherwise               = []

    rc_objs <- maybeCreateManifest dflags output_fn

    SysTools.runLink dflags (
                       map SysTools.Option verbFlags
                      ++ [ SysTools.Option "-o"
                         , SysTools.FileOption "" output_fn
                         ]
                      ++ map SysTools.Option (
                         []

                      -- Permit the linker to auto link _symbol to _imp_symbol.
                      -- This lets us link against DLLs without needing an "import library".
                      ++ (if platformOS platform == OSMinGW32
                          then ["-Wl,--enable-auto-import"]
                          else [])

                      -- '-no_compact_unwind'
                      -- C++/Objective-C exceptions cannot use optimised
                      -- stack unwinding code. The optimised form is the
                      -- default in Xcode 4 on at least x86_64, and
                      -- without this flag we're also seeing warnings
                      -- like
                      --     ld: warning: could not create compact unwind for .LFB3: non-standard register 5 being saved in prolog
                      -- on x86.
                      ++ (if cLdHasNoCompactUnwind == "YES"    &&
                             platformOS   platform == OSDarwin &&
                             platformArch platform `elem` [ArchX86, ArchX86_64]
                          then ["-Wl,-no_compact_unwind"]
                          else [])

                      -- '-Wl,-read_only_relocs,suppress'
                      -- ld gives loads of warnings like:
                      --     ld: warning: text reloc in _base_GHCziArr_unsafeArray_info to _base_GHCziArr_unsafeArray_closure
                      -- when linking any program. We're not sure
                      -- whether this is something we ought to fix, but
                      -- for now this flags silences them.
                      ++ (if platformOS   platform == OSDarwin &&
                             platformArch platform == ArchX86
                          then ["-Wl,-read_only_relocs,suppress"]
                          else [])

                      ++ o_files
                      ++ extra_ld_inputs
                      ++ lib_path_opts
                      ++ extra_ld_opts
                      ++ rc_objs
                      ++ framework_path_opts
                      ++ framework_opts
                      ++ pkg_lib_path_opts
                      ++ extraLinkObj:noteLinkObjs
                      ++ pkg_link_opts
                      ++ pkg_framework_path_opts
                      ++ pkg_framework_opts
                      ++ debug_opts
                      ++ thread_opts
                    ))

    -- parallel only: move binary to another dir -- HWL
    success <- runPhase_MoveBinary dflags output_fn
    if success then return ()
               else ghcError (InstallationError ("cannot move binary"))


exeFileName :: DynFlags -> FilePath
exeFileName dflags
  | Just s <- outputFile dflags =
      if platformOS (targetPlatform dflags) == OSMinGW32
      then if null (takeExtension s)
           then s <.> "exe"
           else s
      else s
  | otherwise =
      if platformOS (targetPlatform dflags) == OSMinGW32
      then "main.exe"
      else "a.out"

maybeCreateManifest
   :: DynFlags
   -> FilePath                          -- filename of executable
   -> IO [FilePath]                     -- extra objects to embed, maybe
maybeCreateManifest dflags exe_filename
 | platformOS (targetPlatform dflags) == OSMinGW32 &&
   dopt Opt_GenManifest dflags
    = do let manifest_filename = exe_filename <.> "manifest"

         writeFile manifest_filename $
             "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\n"++
             "  <assembly xmlns=\"urn:schemas-microsoft-com:asm.v1\" manifestVersion=\"1.0\">\n"++
             "  <assemblyIdentity version=\"1.0.0.0\"\n"++
             "     processorArchitecture=\"X86\"\n"++
             "     name=\"" ++ dropExtension exe_filename ++ "\"\n"++
             "     type=\"win32\"/>\n\n"++
             "  <trustInfo xmlns=\"urn:schemas-microsoft-com:asm.v3\">\n"++
             "    <security>\n"++
             "      <requestedPrivileges>\n"++
             "        <requestedExecutionLevel level=\"asInvoker\" uiAccess=\"false\"/>\n"++
             "        </requestedPrivileges>\n"++
             "       </security>\n"++
             "  </trustInfo>\n"++
             "</assembly>\n"

         -- Windows will find the manifest file if it is named
         -- foo.exe.manifest. However, for extra robustness, and so that
         -- we can move the binary around, we can embed the manifest in
         -- the binary itself using windres:
         if not (dopt Opt_EmbedManifest dflags) then return [] else do

         rc_filename <- newTempName dflags "rc"
         rc_obj_filename <- newTempName dflags (objectSuf dflags)

         writeFile rc_filename $
             "1 24 MOVEABLE PURE " ++ show manifest_filename ++ "\n"
               -- magic numbers :-)
               -- show is a bit hackish above, but we need to escape the
               -- backslashes in the path.

         let wr_opts = getOpts dflags opt_windres
         runWindres dflags $ map SysTools.Option $
               ["--input="++rc_filename,
                "--output="++rc_obj_filename,
                "--output-format=coff"]
               ++ wr_opts
               -- no FileOptions here: windres doesn't like seeing
               -- backslashes, apparently

         removeFile manifest_filename

         return [rc_obj_filename]
 | otherwise = return []


linkDynLib :: DynFlags -> [String] -> [PackageId] -> IO ()
linkDynLib dflags o_files dep_packages = do
    let verbFlags = getVerbFlags dflags
    let o_file = outputFile dflags

    pkgs <- getPreloadPackagesAnd dflags dep_packages

    let pkg_lib_paths = collectLibraryPaths pkgs
    let pkg_lib_path_opts = concatMap get_pkg_lib_path_opts pkg_lib_paths
        get_pkg_lib_path_opts l
         | osElfTarget (platformOS (targetPlatform dflags)) &&
           dynLibLoader dflags == SystemDependent &&
           not opt_Static
            = ["-L" ++ l, "-Wl,-rpath", "-Wl," ++ l]
         | otherwise = ["-L" ++ l]

    let lib_paths = libraryPaths dflags
    let lib_path_opts = map ("-L"++) lib_paths

    -- We don't want to link our dynamic libs against the RTS package,
    -- because the RTS lib comes in several flavours and we want to be
    -- able to pick the flavour when a binary is linked.
    -- On Windows we need to link the RTS import lib as Windows does
    -- not allow undefined symbols.
    -- The RTS library path is still added to the library search path
    -- above in case the RTS is being explicitly linked in (see #3807).
    let pkgs_no_rts = case platformOS (targetPlatform dflags) of
                      OSMinGW32 ->
                          pkgs
                      _ ->
                          filter ((/= rtsPackageId) . packageConfigId) pkgs
    let pkg_link_opts = collectLinkOpts dflags pkgs_no_rts

        -- probably _stub.o files
    extra_ld_inputs <- readIORef v_Ld_inputs

    let extra_ld_opts = getOpts dflags opt_l

#if defined(mingw32_HOST_OS)
    -----------------------------------------------------------------------------
    -- Making a DLL
    -----------------------------------------------------------------------------
    let output_fn = case o_file of { Just s -> s; Nothing -> "HSdll.dll"; }

    SysTools.runLink dflags (
            map SysTools.Option verbFlags
         ++ [ SysTools.Option "-o"
            , SysTools.FileOption "" output_fn
            , SysTools.Option "-shared"
            ] ++
            [ SysTools.FileOption "-Wl,--out-implib=" (output_fn ++ ".a")
            | dopt Opt_SharedImplib dflags
            ]
         ++ map (SysTools.FileOption "") o_files
         ++ map SysTools.Option (

         -- Permit the linker to auto link _symbol to _imp_symbol
         -- This lets us link against DLLs without needing an "import library"
            ["-Wl,--enable-auto-import"]

         ++ extra_ld_inputs
         ++ lib_path_opts
         ++ extra_ld_opts
         ++ pkg_lib_path_opts
         ++ pkg_link_opts
        ))
#elif defined(darwin_TARGET_OS)
    -----------------------------------------------------------------------------
    -- Making a darwin dylib
    -----------------------------------------------------------------------------
    -- About the options used for Darwin:
    -- -dynamiclib
    --   Apple's way of saying -shared
    -- -undefined dynamic_lookup:
    --   Without these options, we'd have to specify the correct dependencies
    --   for each of the dylibs. Note that we could (and should) do without this
    --   for all libraries except the RTS; all we need to do is to pass the
    --   correct HSfoo_dyn.dylib files to the link command.
    --   This feature requires Mac OS X 10.3 or later; there is a similar feature,
    --   -flat_namespace -undefined suppress, which works on earlier versions,
    --   but it has other disadvantages.
    -- -single_module
    --   Build the dynamic library as a single "module", i.e. no dynamic binding
    --   nonsense when referring to symbols from within the library. The NCG
    --   assumes that this option is specified (on i386, at least).
    -- -install_name
    --   Mac OS/X stores the path where a dynamic library is (to be) installed
    --   in the library itself.  It's called the "install name" of the library.
    --   Then any library or executable that links against it before it's
    --   installed will search for it in its ultimate install location.  By
    --   default we set the install name to the absolute path at build time, but
    --   it can be overridden by the -dylib-install-name option passed to ghc.
    --   Cabal does this.
    -----------------------------------------------------------------------------

    let output_fn = case o_file of { Just s -> s; Nothing -> "a.out"; }

    instName <- case dylibInstallName dflags of
        Just n -> return n
        Nothing -> do
            pwd <- getCurrentDirectory
            return $ pwd `combine` output_fn
    SysTools.runLink dflags (
            map SysTools.Option verbFlags
         ++ [ SysTools.Option "-dynamiclib"
            , SysTools.Option "-o"
            , SysTools.FileOption "" output_fn
            ]
         ++ map SysTools.Option (
            o_files
         ++ [ "-undefined", "dynamic_lookup", "-single_module",
#if !defined(x86_64_TARGET_ARCH)
              "-Wl,-read_only_relocs,suppress",
#endif
              "-install_name", instName ]
         ++ extra_ld_inputs
         ++ lib_path_opts
         ++ extra_ld_opts
         ++ pkg_lib_path_opts
         ++ pkg_link_opts
        ))
#else
    -----------------------------------------------------------------------------
    -- Making a DSO
    -----------------------------------------------------------------------------

    let output_fn = case o_file of { Just s -> s; Nothing -> "a.out"; }
    let buildingRts = thisPackage dflags == rtsPackageId
    let bsymbolicFlag = if buildingRts
                        then -- -Bsymbolic breaks the way we implement
                             -- hooks in the RTS
                             []
                        else -- we need symbolic linking to resolve
                             -- non-PIC intra-package-relocations
                             ["-Wl,-Bsymbolic"]

    SysTools.runLink dflags (
            map SysTools.Option verbFlags
         ++ [ SysTools.Option "-o"
            , SysTools.FileOption "" output_fn
            ]
         ++ map SysTools.Option (
            o_files
         ++ [ "-shared" ]
         ++ bsymbolicFlag
            -- Set the library soname. We use -h rather than -soname as
            -- Solaris 10 doesn't support the latter:
         ++ [ "-Wl,-h," ++ takeFileName output_fn ]
         ++ extra_ld_inputs
         ++ lib_path_opts
         ++ extra_ld_opts
         ++ pkg_lib_path_opts
         ++ pkg_link_opts
        ))
#endif
-- -----------------------------------------------------------------------------
-- Running CPP

doCpp :: DynFlags -> Bool -> Bool -> FilePath -> FilePath -> IO ()
doCpp dflags raw include_cc_opts input_fn output_fn = do
    let hscpp_opts = getOpts dflags opt_P
    let cmdline_include_paths = includePaths dflags

    pkg_include_dirs <- getPackageIncludePath dflags []
    let include_paths = foldr (\ x xs -> "-I" : x : xs) []
                          (cmdline_include_paths ++ pkg_include_dirs)

    let verbFlags = getVerbFlags dflags

    let cc_opts
          | include_cc_opts = getOpts dflags opt_c
          | otherwise       = []

    let cpp_prog args | raw       = SysTools.runCpp dflags args
                      | otherwise = SysTools.runCc dflags (SysTools.Option "-E" : args)

    let target_defs =
          [ "-D" ++ HOST_OS     ++ "_BUILD_OS=1",
            "-D" ++ HOST_ARCH   ++ "_BUILD_ARCH=1",
            "-D" ++ TARGET_OS   ++ "_HOST_OS=1",
            "-D" ++ TARGET_ARCH ++ "_HOST_ARCH=1" ]
        -- remember, in code we *compile*, the HOST is the same our TARGET,
        -- and BUILD is the same as our HOST.

    cpp_prog       (   map SysTools.Option verbFlags
                    ++ map SysTools.Option include_paths
                    ++ map SysTools.Option hsSourceCppOpts
                    ++ map SysTools.Option target_defs
                    ++ map SysTools.Option hscpp_opts
                    ++ map SysTools.Option cc_opts
                    ++ [ SysTools.Option     "-x"
                       , SysTools.Option     "c"
                       , SysTools.Option     input_fn
        -- We hackily use Option instead of FileOption here, so that the file
        -- name is not back-slashed on Windows.  cpp is capable of
        -- dealing with / in filenames, so it works fine.  Furthermore
        -- if we put in backslashes, cpp outputs #line directives
        -- with *double* backslashes.   And that in turn means that
        -- our error messages get double backslashes in them.
        -- In due course we should arrange that the lexer deals
        -- with these \\ escapes properly.
                       , SysTools.Option     "-o"
                       , SysTools.FileOption "" output_fn
                       ])

hsSourceCppOpts :: [String]
-- Default CPP defines in Haskell source
hsSourceCppOpts =
        [ "-D__GLASGOW_HASKELL__="++cProjectVersionInt ]

-- ---------------------------------------------------------------------------
-- join object files into a single relocatable object file, using ld -r

joinObjectFiles :: DynFlags -> [FilePath] -> FilePath -> IO ()
joinObjectFiles dflags o_files output_fn = do
  let ld_r args = SysTools.runLink dflags ([
                            SysTools.Option "-nostdlib",
                            SysTools.Option "-nodefaultlibs",
                            SysTools.Option "-Wl,-r"
                            ]
                            -- gcc on sparc sets -Wl,--relax implicitly, but
                            -- -r and --relax are incompatible for ld, so
                            -- disable --relax explicitly.
                         ++ (if platformArch (targetPlatform dflags) == ArchSPARC
                                then [SysTools.Option "-Wl,-no-relax"]
                                else [])
                         ++ [
                            SysTools.Option ld_build_id,
                            -- SysTools.Option ld_x_flag,
                            SysTools.Option "-o",
                            SysTools.FileOption "" output_fn ]
                         ++ args)

      -- Do *not* add the -x flag to ld, because we want to keep those
      -- local symbols around for the benefit of external tools. e.g.
      -- the 'perf report' output is much less useful if all the local
      -- symbols have been stripped out.
      --
      -- ld_x_flag | null cLD_X = ""
      --           | otherwise  = "-Wl,-x"

      -- suppress the generation of the .note.gnu.build-id section,
      -- which we don't need and sometimes causes ld to emit a
      -- warning:
      ld_build_id | cLdHasBuildId == "YES"  = "-Wl,--build-id=none"
                  | otherwise               = ""

  if cLdIsGNULd == "YES"
     then do
          script <- newTempName dflags "ldscript"
          writeFile script $ "INPUT(" ++ unwords o_files ++ ")"
          ld_r [SysTools.FileOption "" script]
     else do
          ld_r (map (SysTools.FileOption "") o_files)

-- -----------------------------------------------------------------------------
-- Misc.

-- | What phase to run after one of the backend code generators has run
hscPostBackendPhase :: DynFlags -> HscSource -> HscTarget -> Phase
hscPostBackendPhase _ HsBootFile _    =  StopLn
hscPostBackendPhase dflags _ hsc_lang =
  case hsc_lang of
        HscC -> HCc
        HscAsm | dopt Opt_SplitObjs dflags -> Splitter
               | otherwise                 -> As
        HscLlvm        -> LlvmOpt
        HscNothing     -> StopLn
        HscInterpreted -> StopLn

touchObjectFile :: DynFlags -> FilePath -> IO ()
touchObjectFile dflags path = do
  createDirectoryIfMissing True $ takeDirectory path
  SysTools.touch dflags "Touching object file" path