testsuite: introduce 'static_stats' tests

They are a particular type of perf tests. This patch introduces a
'stats_files_dir' configuration field in the testsuite driver where all
haddock timing files (and possibly others in the future) are assumed to live.
We also change both the Make and Hadrian build systems to pass respectively
$(TOP)/testsuite/tests/perf/haddock/ and
<build root>/stage1/haddock-timing-files/ as the value of that new
configuration field, and to generate the timing files in those directories
in the first place while generating documentation with haddock.

This new test type can be seen as one dedicated to examining stats files that
are generated while building a GHC distribution. This also lets us get rid of
the 'extra_files' directives in the all.T entries for haddock.base,
haddock.Cabal and haddock.compiler.

10 files changed, 62 insertions, 22 deletions

diff --git a/hadrian/src/Context.hs b/hadrian/src/Context.hs
index 7c7bb124ff..0676743ee5 100644
--- a/hadrian/src/Context.hs
+++ b/hadrian/src/Context.hs
@@ -8,7 +8,8 @@ module Context (
     -- * Paths
     contextDir, buildPath, buildDir, pkgInplaceConfig, pkgSetupConfigFile,
     pkgHaddockFile, pkgRegisteredLibraryFile, pkgLibraryFile, pkgGhciLibraryFile,
-    pkgConfFile, objectPath, contextPath, getContextPath, libPath, distDir
+    pkgConfFile, objectPath, contextPath, getContextPath, libPath, distDir,
+    haddockStatsFilesDir
     ) where
 
 import Base
diff --git a/hadrian/src/Context/Path.hs b/hadrian/src/Context/Path.hs
index 4bc9d9be34..e5a82710ab 100644
--- a/hadrian/src/Context/Path.hs
+++ b/hadrian/src/Context/Path.hs
@@ -41,3 +41,8 @@ buildPath context = buildRoot <&> (-/- buildDir context)
 -- | The expression that evaluates to the build path of the current 'Context'.
 getBuildPath :: Expr Context b FilePath
 getBuildPath = expr . buildPath =<< getContext
+
+-- | Path to the directory containing haddock timing files, used by
+--   the haddock perf tests.
+haddockStatsFilesDir :: Action FilePath
+haddockStatsFilesDir = (-/- "stage1" -/- "haddock-timing-files") <$> buildRoot
diff --git a/hadrian/src/Rules/Documentation.hs b/hadrian/src/Rules/Documentation.hs
index a70b4d5c9d..9991f01708 100644
--- a/hadrian/src/Rules/Documentation.hs
+++ b/hadrian/src/Rules/Documentation.hs
@@ -205,7 +205,12 @@ buildPackageDocumentation = do
         -- TODO: Pass the correct way from Rules via Context.
         dynamicPrograms <- dynamicGhcPrograms =<< flavour
         let haddockWay = if dynamicPrograms then dynamic else vanilla
+        statsFilesDir <- haddockStatsFilesDir
+        createDirectory statsFilesDir
         build $ target (context {way = haddockWay}) (Haddock BuildPackage) srcs [file]
+        produces [
+          statsFilesDir </> pkgName (Context.package context) <.> "t"
+          ]
 
 data PkgDocTarget = DotHaddock PackageName | HaddockPrologue PackageName
   deriving (Eq, Show)
diff --git a/hadrian/src/Settings/Builders/Haddock.hs b/hadrian/src/Settings/Builders/Haddock.hs
index 65c703160c..b01b8a2459 100644
--- a/hadrian/src/Settings/Builders/Haddock.hs
+++ b/hadrian/src/Settings/Builders/Haddock.hs
@@ -35,13 +35,13 @@ haddockBuilderArgs = mconcat
         output   <- getOutput
         pkg      <- getPackage
         root     <- getBuildRoot
-        path     <- getBuildPath
         context  <- getContext
         version  <- expr $ pkgVersion  pkg
         synopsis <- expr $ pkgSynopsis pkg
         deps     <- getContextData depNames
         haddocks <- expr $ haddockDependencies context
         hVersion <- expr $ pkgVersion haddock
+        statsDir <- expr $ haddockStatsFilesDir
         ghcOpts  <- haddockGhcArgs
         mconcat
             [ arg "--verbosity=0"
@@ -66,6 +66,6 @@ haddockBuilderArgs = mconcat
             , pure [ "--optghc=" ++ opt | opt <- ghcOpts, not ("--package-db" `isInfixOf` opt) ]
             , getInputs
             , arg "+RTS"
-            , arg $ "-t" ++ path -/- "haddock.t"
+            , arg $ "-t" ++ (statsDir -/- pkgName pkg ++ ".t")
             , arg "--machine-readable"
             , arg "-RTS" ] ]
diff --git a/hadrian/src/Settings/Builders/RunTest.hs b/hadrian/src/Settings/Builders/RunTest.hs
index 6cc11f8aef..63e3dfd6c9 100644
--- a/hadrian/src/Settings/Builders/RunTest.hs
+++ b/hadrian/src/Settings/Builders/RunTest.hs
@@ -85,11 +85,14 @@ runTestBuilderArgs = builder RunTest ? do
     wordsize    <- getTestSetting TestWORDSIZE
     top         <- expr $ topDirectory
     ghcFlags    <- expr runTestGhcFlags
-    timeoutProg <- expr buildRoot <&> (-/- timeoutPath)
     cmdrootdirs <- expr (testRootDirs <$> userSetting defaultTestArgs)
     let defaultRootdirs = ("testsuite" -/- "tests") : libTests
         rootdirs | null cmdrootdirs = defaultRootdirs
                  | otherwise        = cmdrootdirs
+    root        <- expr buildRoot
+    let timeoutProg = root -/- timeoutPath
+    statsFilesDir <- expr haddockStatsFilesDir
+
     -- See #16087
     let ghcBuiltByLlvm = False -- TODO: Implement this check
 
@@ -134,6 +137,7 @@ runTestBuilderArgs = builder RunTest ? do
 
             , arg "--config", arg $ "gs=gs"                           -- Use the default value as in test.mk
             , arg "--config", arg $ "timeout_prog=" ++ show (top -/- timeoutProg)
+            , arg "--config", arg $ "stats_files_dir=" ++ statsFilesDir
             , arg $ "--threads=" ++ show threads
             , getTestArgs -- User-provided arguments from command line.
             ]
diff --git a/rules/haddock.mk b/rules/haddock.mk
index f0d686194f..a0e4f1724a 100644
--- a/rules/haddock.mk
+++ b/rules/haddock.mk
@@ -76,7 +76,7 @@ endif
 		$$($1_$2_HS_SRCS) \
 		$$($1_$2_EXTRA_HADDOCK_SRCS) \
 		$$(EXTRA_HADDOCK_OPTS) \
-		+RTS -t"$1/$2/haddock.t" --machine-readable
+		+RTS -t"$$(TOP)/testsuite/tests/perf/haddock/$$($1_PACKAGE).t" --machine-readable
 
 # --no-tmp-comp-dir above is important: it saves a few minutes in a
 # validate.  This flag lets Haddock use the pre-compiled object files
diff --git a/testsuite/driver/testglobals.py b/testsuite/driver/testglobals.py
index b28477c769..ababefba19 100644
--- a/testsuite/driver/testglobals.py
+++ b/testsuite/driver/testglobals.py
@@ -139,6 +139,11 @@ class TestConfig:
         # terminal supports colors
         self.supports_colors = False
 
+        # Where to look up runtime stats produced by haddock, needed for
+        # the haddock perf tests in testsuite/tests/perf/haddock/.
+        # See Note [Haddock runtime stats files] at the bottom of this file.
+        self.stats_files_dir = '/please_set_stats_files_dir'
+
 global config
 config = TestConfig()
 
diff --git a/testsuite/driver/testlib.py b/testsuite/driver/testlib.py
index dc8b1b85f1..d0bd98015d 100644
--- a/testsuite/driver/testlib.py
+++ b/testsuite/driver/testlib.py
@@ -67,7 +67,6 @@ def isStatsTest():
     opts = getTestOpts()
     return opts.is_stats_test
 
-
 # This can be called at the top of a file of tests, to set default test options
 # for the following tests.
 def setTestOpts( f ):
@@ -1211,7 +1210,11 @@ def multi_compile_and_run( name, way, top_mod, extra_mods, extra_hc_opts ):
 
 def stats( name, way, stats_file ):
     opts = getTestOpts()
-    return check_stats(name, way, stats_file, opts.stats_range_fields)
+    return check_stats(name, way, in_testdir(stats_file), opts.stats_range_fields)
+
+def static_stats( name, way, stats_file ):
+    opts = getTestOpts()
+    return check_stats(name, way, in_statsdir(stats_file), opts.stats_range_fields)
 
 def metric_dict(name, way, metric, value):
     return Perf.PerfStat(
@@ -1234,7 +1237,7 @@ def check_stats(name, way, stats_file, range_fields):
     result = passed()
     if range_fields:
         try:
-            f = open(in_testdir(stats_file))
+            f = open(stats_file)
         except IOError as e:
             return failBecause(str(e))
         stats_file_contents = f.read()
@@ -1357,7 +1360,7 @@ def simple_build(name, way, extra_hc_opts, should_fail, top_mod, link, addsuf, b
     # ToDo: if the sub-shell was killed by ^C, then exit
 
     if isCompilerStatsTest():
-        statsResult = check_stats(name, way, stats_file, opts.stats_range_fields)
+        statsResult = check_stats(name, way, in_testdir(stats_file), opts.stats_range_fields)
         if badResult(statsResult):
             return statsResult
 
@@ -1442,7 +1445,7 @@ def simple_run(name, way, prog, extra_run_opts):
     if check_prof and not check_prof_ok(name, way):
         return failBecause('bad profile')
 
-    return check_stats(name, way, stats_file, opts.stats_range_fields)
+    return check_stats(name, way, in_testdir(stats_file), opts.stats_range_fields)
 
 def rts_flags(way):
     args = config.way_rts_flags.get(way, [])
@@ -2103,6 +2106,9 @@ def in_testdir(name, suffix=''):
 def in_srcdir(name, suffix=''):
     return os.path.join(getTestOpts().srcdir, add_suffix(name, suffix))
 
+def in_statsdir(name, suffix=''):
+    return os.path.join(config.stats_files_dir, add_suffix(name, suffix))
+
 # Finding the sample output.  The filename is of the form
 #
 #   <test>.stdout[-ws-<wordsize>][-<platform>|-<os>]
diff --git a/testsuite/mk/test.mk b/testsuite/mk/test.mk
index b1d716fd77..6860974c54 100644
--- a/testsuite/mk/test.mk
+++ b/testsuite/mk/test.mk
@@ -278,6 +278,8 @@ RUNTEST_OPTS +=  \
 	--config 'gs=$(call quote_path,$(GS))' \
 	--config 'timeout_prog=$(call quote_path,$(TIMEOUT_PROGRAM))'
 
+RUNTEST_OPTS += --config 'stats_files_dir=$(TOP)/tests/perf/haddock'
+
 RUNTEST_OPTS += -e "config.stage=$(GhcStage)"
 
 ifneq "$(METRICS_FILE)" ""
diff --git a/testsuite/tests/perf/haddock/all.T b/testsuite/tests/perf/haddock/all.T
index fca30366f9..929a7fd972 100644
--- a/testsuite/tests/perf/haddock/all.T
+++ b/testsuite/tests/perf/haddock/all.T
@@ -1,27 +1,39 @@
+# Note [Haddock runtime stats files]
+#
+# When one of the build systems builds a complete GHC distribution,
+# haddock gets built and then used to generate .haddock files for each
+# library. For that last step, both build systems pass an extra
+# `+RTS -t<some path>.t` to record runtime statistics to the given path.
+#
+# Those .t files are then used by a few haddock perf tests (which all live
+# under testsuite/tests/perf/haddock/). Since each build system needs to produce
+# those files in different places, the testsuite driver takes the directory
+# under which those files are placed as a configuration parameter,
+# `config.stats_files_dir`. Each individual test then specifies the name of
+# the (runtime statistics) file against which some checks are to be performed,
+# in addition to declaring the test's type to be `static_stats`.
+
 # We do not add peak_megabytes_allocated and max_bytes_used to these tests, as
 # they are somewhat unreliable, and it is harder to re-run these numbers to
 # detect outliers, as described in Note [residency]. See #9556.
 
 test('haddock.base',
-     [extra_files(['../../../../libraries/base/dist-install/haddock.t']),
-      unless(in_tree_compiler(), skip), req_haddock
+     [unless(in_tree_compiler(), skip), req_haddock
      ,collect_stats('bytes allocated',5)
       ],
-     stats,
-     ['haddock.t'])
+     static_stats,
+     ['base.t'])
 
 test('haddock.Cabal',
-     [extra_files(['../../../../libraries/Cabal/Cabal/dist-install/haddock.t']),
-      unless(in_tree_compiler(), skip), req_haddock
+     [unless(in_tree_compiler(), skip), req_haddock
      ,collect_stats('bytes allocated',5)
       ],
-     stats,
-     ['haddock.t'])
+     static_stats,
+     ['Cabal.t'])
 
 test('haddock.compiler',
-     [extra_files(['../../../../compiler/stage2/haddock.t']),
-      unless(in_tree_compiler(), skip), req_haddock
+     [unless(in_tree_compiler(), skip), req_haddock
      ,collect_stats('bytes allocated',10)
       ],
-     stats,
-     ['haddock.t'])
+     static_stats,
+     ['ghc.t'])