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* liblink: require DATA lines to be ordered by offset, with no overlapRuss Cox2014-10-141-0/+2
| | | | | | | | | | | | The assembler could give a better error, but this one is good enough for now. Fixes issue 8880. LGTM=r R=r CC=golang-codereviews https://codereview.appspot.com/153610043
* liblink: generate MRC replacement in liblink, not tls_armDave Cheney2014-09-301-2/+18
| | | | | | | | | | | Fixes issue 8690. This CL moves the save of LR around BL runtime.read_tls_fallback to liblink as it is not needed when MRC is not replaced. LGTM=rsc, minux R=rsc, khr, minux CC=golang-codereviews https://codereview.appspot.com/147310043
* liblink: fix cmd/ld -X flagRuss Cox2014-09-261-0/+2
| | | | | | | | | | | | This fixes the test/linkx.go test, which does not run by default. (Issue 4139 is about fixing that.) Fixes issue 8806. LGTM=r R=golang-codereviews, r CC=bradfitz, golang-codereviews, iant https://codereview.appspot.com/145420043
* cmd/cc, cmd/ld, runtime: disallow conservative data/bss objectsRuss Cox2014-09-241-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In linker, refuse to write conservative (array of pointers) as the garbage collection type for any variable in the data/bss GC program. In the linker, attach the Go type to an already-read C declaration during dedup. This gives us Go types for C globals for free as long as the cmd/dist-generated Go code contains the declaration. (Most runtime C declarations have a corresponding Go declaration. Both are bss declarations and so the linker dedups them.) In cmd/dist, add a few more C files to the auto-Go-declaration list in order to get Go type information for the C declarations into the linker. In C compiler, mark all non-pointer-containing global declarations and all string data as NOPTR. This allows them to exist in C files without any corresponding Go declaration. Count C function pointers as "non-pointer-containing", since we have no heap-allocated C functions. In runtime, add NOPTR to the remaining pointer-containing declarations, none of which refer to Go heap objects. In runtime, also move os.Args and syscall.envs data into runtime-owned variables. Otherwise, in programs that do not import os or syscall, the runtime variables named os.Args and syscall.envs will be missing type information. I believe that this CL eliminates the final source of conservative GC scanning in non-SWIG Go programs, and therefore... Fixes issue 909. LGTM=iant R=iant CC=golang-codereviews https://codereview.appspot.com/149770043
* liblink, sync/atomic: fix arm buildRuss Cox2014-09-162-1/+7
| | | | | | | | | | | | | The liblink code to insert the FUNCDATA for a stack map from the Go prototype was not correct for ARM (different data structure layout). Also, sync/atomic was missing some Go prototypes for ARM-specific functions. TBR=r CC=golang-codereviews https://codereview.appspot.com/143160045
* liblink: make GO_ARGS the default for functions beginning with ?Russ Cox2014-09-161-1/+22
| | | | | | | | | | | | | | | | | If there is a leading ?, assume there is a Go prototype and attach the Go prototype information to the function. If the function is not called from Go and does not need a Go prototype, it can be made file-local instead (using name<>(SB)). This fixes the current BSD build failures, by giving functions like sync/atomic.StoreUint32 argument stack map information. Fixes issue 8753. LGTM=khr, iant R=golang-codereviews, iant, khr, bradfitz CC=golang-codereviews, r, rlh https://codereview.appspot.com/142150043
* cmd/gc: turn Go prototypes into ptr liveness maps for assembly functionsRuss Cox2014-09-121-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The goal here is to allow assembly functions to appear in the middle of a Go stack (having called other code) and still record enough information about their pointers so that stack copying and garbage collection can handle them precisely. Today, these frames are handled only conservatively. If you write func myfunc(x *float64) (y *int) (with no body, an 'extern' declaration), then the Go compiler now emits a liveness bitmap for use from the assembly definition of myfunc. The bitmap symbol is myfunc.args_stackmap and it contains two bitmaps. The first bitmap, in effect at function entry, marks all inputs as live. The second bitmap, not in effect at function entry, marks the outputs live as well. In funcdata.h, define new assembly macros: GO_ARGS opts in to using the Go compiler-generated liveness bitmap for the current function. GO_RESULTS_INITIALIZED indicates that the results have been initialized and need to be kept live for the remainder of the function; it causes a switch to the second generated bitmap for the assembly code that follows. NO_LOCAL_POINTERS indicates that there are no pointers in the local variables being stored in the function's stack frame. LGTM=khr R=khr CC=golang-codereviews https://codereview.appspot.com/137520043
* runtime: assume precisestack, copystack, StackCopyAlways, ScanStackByFramesRuss Cox2014-09-093-229/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit to stack copying for stack growth. We're carrying around a surprising amount of cruft from older schemes. I am confident that precise stack scans and stack copying are here to stay. Delete fallback code for when precise stack info is disabled. Delete fallback code for when copying stacks is disabled. Delete fallback code for when StackCopyAlways is disabled. Delete Stktop chain - there is only one stack segment now. Delete M.moreargp, M.moreargsize, M.moreframesize, M.cret. Delete G.writenbuf (unrelated, just dead). Delete runtime.lessstack, runtime.oldstack. Delete many amd64 morestack variants. Delete initialization of morestack frame/arg sizes (shortens split prologue!). Replace G's stackguard/stackbase/stack0/stacksize/ syscallstack/syscallguard/forkstackguard with simple stack bounds (lo, hi). Update liblink, runtime/cgo for adjustments to G. LGTM=khr R=khr, bradfitz CC=golang-codereviews, iant, r https://codereview.appspot.com/137410043
* liblink, runtime: diagnose and fix C code running on Go stackRuss Cox2014-09-083-2/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This CL contains compiler+runtime changes that detect C code running on Go (not g0, not gsignal) stacks, and it contains corrections for what it detected. The detection works by changing the C prologue to use a different stack guard word in the G than Go prologue does. On the g0 and gsignal stacks, that stack guard word is set to the usual stack guard value. But on ordinary Go stacks, that stack guard word is set to ^0, which will make any stack split check fail. The C prologue then calls morestackc instead of morestack, and morestackc aborts the program with a message about running C code on a Go stack. This check catches all C code running on the Go stack except NOSPLIT code. The NOSPLIT code is allowed, so the check is complete. Since it is a dynamic check, the code must execute to be caught. But unlike the static checks we've been using in cmd/ld, the dynamic check works with function pointers and other indirect calls. For example it caught sigpanic being pushed onto Go stacks in the signal handlers. Fixes issue 8667. LGTM=khr, iant R=golang-codereviews, khr, iant CC=golang-codereviews, r https://codereview.appspot.com/133700043
* build: adjustments for move from src/pkg to srcRuss Cox2014-09-087-7/+7
| | | | | | | | | | | | | | | | | | | This CL adjusts code referring to src/pkg to refer to src. Immediately after submitting this CL, I will submit a change doing 'hg mv src/pkg/* src'. That change will be too large to review with Rietveld but will contain only the 'hg mv'. This CL will break the build. The followup 'hg mv' will fix it. For more about the move, see golang.org/s/go14nopkg. LGTM=r R=r CC=golang-codereviews https://codereview.appspot.com/134570043
* liblink: fix arm wrapper prologueRuss Cox2014-09-071-1/+1
| | | | | | | | Fixes arm build. TBR=khr CC=golang-codereviews https://codereview.appspot.com/132700043
* runtime: fix nacl/amd64p32 buildRuss Cox2014-09-071-0/+22
| | | | | | | | | Update issue 8675 Fixes nacl/amd64p32 build. TBR=khr CC=golang-codereviews https://codereview.appspot.com/141140045
* liblink: fix arm build errorsRuss Cox2014-09-062-10/+8
| | | | | | | | | | This was supposed to be in CL 135490044 but got lost in a transfer from machine to machine. TBR=khr R=khr CC=golang-codereviews https://codereview.appspot.com/135560043
* runtime: fix panic/wrapper/recover mathRuss Cox2014-09-063-90/+189
| | | | | | | | | | | | | | | | | | The gp->panicwrap adjustment is just fatally flawed. Now that there is a Panic.argp field, update that instead. That can be done on entry only, so that unwinding doesn't need to worry about undoing anything. The wrappers emit a few more instructions in the prologue but everything else in the system gets much simpler. It also fixes (without trying) a broken test I never checked in. Fixes issue 7491. LGTM=khr R=khr CC=dvyukov, golang-codereviews, iant, r https://codereview.appspot.com/135490044
* cmd/ld: diagnose Go calling CRuss Cox2014-08-311-4/+14
| | | | | | | | | | For example: go build -ldflags -C cmd/go 2>&1 | awk '{print $NF}' | sort | uniq -c | sort -nr LGTM=khr R=khr, josharian CC=golang-codereviews https://codereview.appspot.com/135170044
* liblink: introduce way to avoid pc-relative addressingRuss Cox2014-08-251-4/+31
| | | | | | | | | For Solaris. Sigh. LGTM=dave R=aram, iant, dave CC=golang-codereviews https://codereview.appspot.com/129540043
* liblink: fix encoding of ASETPC in 6a, 8aJosh Bleecher Snyder2014-08-182-2/+2
| | | | | | | | | It was incorrectly encoded as ASETLS. LGTM=ruiu, rsc R=rsc, ruiu CC=golang-codereviews https://codereview.appspot.com/126400043
* liblink: use pc-relative addressing for all memory references in amd64 codeRuss Cox2014-08-181-21/+8
| | | | | | | LGTM=rminnich, iant R=golang-codereviews, rminnich, iant CC=golang-codereviews, r https://codereview.appspot.com/125140043
* liblink: encode MOVBQZX as MOVZBL instead of MOVZBQRui Ueyama2014-08-051-1/+1
| | | | | | | LGTM=rsc R=golang-codereviews, gobot, rsc CC=golang-codereviews https://codereview.appspot.com/118480046
* liblink, cmd/dist, cmd/5l: introduce %^ and move C_* constants.Shenghou Ma2014-08-062-48/+19
| | | | | | | | | The helps certain diagnostics and also removed duplicated enums as a side effect. LGTM=dave, rsc R=rsc, dave CC=golang-codereviews https://codereview.appspot.com/115060044
* liblink: support big-endian properlyShenghou Ma2014-08-065-9/+28
| | | | | | | LGTM=rsc R=rsc, iant CC=golang-codereviews https://codereview.appspot.com/115300044
* liblink: use LinkArch.textflag() to get text and dataflagShenghou Ma2014-08-061-10/+2
| | | | | | | | | Rather than switch on thechar. LGTM=rsc, dave R=rsc, iant, dave CC=golang-codereviews https://codereview.appspot.com/119330043
* liblink: shorter encoding for zeroing registerRui Ueyama2014-08-051-0/+1
| | | | | | | | | | | | Encode MOV $0, %ax as XOR %eax, %eax instead of XOR %rax, %rax. If an operand register does not need REX.w bit (i.e. not one of R8-R15), it is encoded in 2 bytes instead of 3 bytes. LGTM=rsc R=golang-codereviews, gobot, rsc CC=golang-codereviews https://codereview.appspot.com/115580044
* liblink: warn about TLS base MRC instruction that does not write into R0.Shenghou Ma2014-07-261-13/+21
| | | | | | | | | While we're here, make it lookup the tlsfallback symbol only once. LGTM=crawshaw R=golang-codereviews, crawshaw, dave CC=golang-codereviews https://codereview.appspot.com/107430044
* liblink: more precise literal word comparison on armRuss Cox2014-07-231-2/+5
| | | | | | | | | | | | | | | | | | | | There are fields in the Addr that do not matter for the purpose of deciding that the same word is already in the current literal pool. Copy only the fields that do matter. This came up when comparing against the Go version because the way it is invoked doesn't copy a few fields (like node) that are never directly used by liblink itself. Also remove a stray print that is not well-defined in the new liblink. (Cannot use %D outside of %P, because %D needs the outer Prog*.) LGTM=minux R=minux CC=golang-codereviews https://codereview.appspot.com/119000043
* liblink: remove some gotos + other fixesRuss Cox2014-07-217-99/+110
| | | | | | | | | | | | Rewrite gotos that violate Go's stricter rules. Use uchar* instead of char* in a few places that aren't strings. Remove dead opcross code from asm5.c. Declare regstr (in both list6 and list8) static. LGTM=minux, dave R=minux, dave CC=golang-codereviews https://codereview.appspot.com/113230043
* liblink: fix precedence bug in pcdata comparisonRuss Cox2014-07-161-1/+1
| | | | | | | | | | | | As written, the ! applies before the &1. This would crash writing out missing pcdata tables if we ever used non-contiguous IDs in a function. We don't, but fix anyway. LGTM=iant, minux R=minux, iant CC=golang-codereviews https://codereview.appspot.com/117810047
* liblink: fix warnings on Plan 9David du Colombier2014-07-111-5/+2
| | | | | | | | | | warning: /usr/go/src/liblink/asm5.c:720 set and not used: m warning: /usr/go/src/liblink/asm5.c:807 set and not used: c LGTM=minux R=minux CC=golang-codereviews https://codereview.appspot.com/108570043
* cmd/5c, cmd/5g, cmd/5l, liblink: nacl/arm supportShenghou Ma2014-07-102-32/+356
| | | | | | | LGTM=dave, rsc R=rsc, iant, dave CC=golang-codereviews https://codereview.appspot.com/108360043
* build: annotations and modifications for c2goRuss Cox2014-07-027-1384/+1331
| | | | | | | | | | | | | | | | | | | | | | | The main changes fall into a few patterns: 1. Replace #define with enum. 2. Add /*c2go */ comment giving effect of #define. This is necessary for function-like #defines and non-enum-able #defined constants. (Not all compilers handle negative or large enums.) 3. Add extra braces in struct initializer. (c2go does not implement the full rules.) This is enough to let c2go typecheck the source tree. There may be more changes once it is doing other semantic analyses. LGTM=minux, iant R=minux, dave, iant CC=golang-codereviews https://codereview.appspot.com/106860045
* liblink, runtime: preliminary support for plan9/amd64Aram H?v?rneanu2014-07-025-9/+23
| | | | | | | | | | | | | | | | | | | | | | | | | A TLS slot is reserved by _rt0_.*_plan9 as an automatic and its address (which is static on Plan 9) is saved in the global _privates symbol. The startup linkage now is exactly like that from Plan 9 libc, and the way we access g is exactly as if we'd have used privalloc(2). Aside from making the code more standard, this change drastically simplifies it, both for 386 and for amd64, and makes the Plan 9 code in liblink common for both 386 and amd64. The amd64 runtime code was cleared of nxm assumptions, and now runs on the standard Plan 9 kernel. Note handling fixes will follow in a separate CL. LGTM=rsc R=golang-codereviews, rsc, bradfitz, dave CC=0intro, ality, golang-codereviews, jas, minux.ma, mischief https://codereview.appspot.com/101510049 Committer: Dave Cheney <dave@cheney.net>
* all: add GOOS=androidDavid Crawshaw2014-07-011-0/+1
| | | | | | | | | | | | | | | | As android and linux have significant overlap, and because build tags are a poor way to represent an OS target, this CL introduces an exception into go/build: linux is treated as a synonym for android when matching files. http://golang.org/s/go14android https://groups.google.com/forum/#!topic/golang-dev/P1ATVp1mun0 LGTM=rsc, minux R=golang-codereviews, mikioh.mikioh, dave, aram, minux, gobot, rsc, aram.h, elias.naur, iant CC=golang-codereviews, rsc https://codereview.appspot.com/105270043
* all: remove 'extern register M *m' from runtimeRuss Cox2014-06-263-12/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The runtime has historically held two dedicated values g (current goroutine) and m (current thread) in 'extern register' slots (TLS on x86, real registers backed by TLS on ARM). This CL removes the extern register m; code now uses g->m. On ARM, this frees up the register that formerly held m (R9). This is important for NaCl, because NaCl ARM code cannot use R9 at all. The Go 1 macrobenchmarks (those with per-op times >= 10 ?s) are unaffected: BenchmarkBinaryTree17 5491374955 5471024381 -0.37% BenchmarkFannkuch11 4357101311 4275174828 -1.88% BenchmarkGobDecode 11029957 11364184 +3.03% BenchmarkGobEncode 6852205 6784822 -0.98% BenchmarkGzip 650795967 650152275 -0.10% BenchmarkGunzip 140962363 141041670 +0.06% BenchmarkHTTPClientServer 71581 73081 +2.10% BenchmarkJSONEncode 31928079 31913356 -0.05% BenchmarkJSONDecode 117470065 113689916 -3.22% BenchmarkMandelbrot200 6008923 5998712 -0.17% BenchmarkGoParse 6310917 6327487 +0.26% BenchmarkRegexpMatchMedium_1K 114568 114763 +0.17% BenchmarkRegexpMatchHard_1K 168977 169244 +0.16% BenchmarkRevcomp 935294971 914060918 -2.27% BenchmarkTemplate 145917123 148186096 +1.55% Minux previous reported larger variations, but these were caused by run-to-run noise, not repeatable slowdowns. Actual code changes by Minux. I only did the docs and the benchmarking. LGTM=dvyukov, iant, minux R=minux, josharian, iant, dave, bradfitz, dvyukov CC=golang-codereviews https://codereview.appspot.com/109050043
* liblink: fix field trackingRuss Cox2014-05-202-0/+20
| | | | | | | | | | | | | The USEFIELD instructions no longer make it to the linker, so we have to do something else to pin the references they were pinning. Emit a 0-length relocation of type R_USEFIELD. Fixes issue 7486. LGTM=iant R=golang-codereviews, iant CC=golang-codereviews, r https://codereview.appspot.com/95530043
* cmd/gc: record line number for auto-generated wrappers as <autogenerated>:1Russ Cox2014-05-121-1/+1
| | | | | | | | | | | | Before we used line 1 of the first source file. This should be clearer. Fixes issue 4388. LGTM=iant R=golang-codereviews, iant CC=golang-codereviews https://codereview.appspot.com/92250044
* runtime: use duff zero and copy to initialize memoryKeith Randall2014-05-072-1/+11
| | | | | | | | | | | | | | | | | | | | | | | benchmark old ns/op new ns/op delta BenchmarkCopyFat512 1307 329 -74.83% BenchmarkCopyFat256 666 169 -74.62% BenchmarkCopyFat1024 2617 671 -74.36% BenchmarkCopyFat128 343 89.0 -74.05% BenchmarkCopyFat64 182 48.9 -73.13% BenchmarkCopyFat32 103 28.8 -72.04% BenchmarkClearFat128 102 46.6 -54.31% BenchmarkClearFat512 344 167 -51.45% BenchmarkClearFat64 50.5 26.5 -47.52% BenchmarkClearFat256 147 87.2 -40.68% BenchmarkClearFat32 22.7 16.4 -27.75% BenchmarkClearFat1024 511 662 +29.55% Fixes issue 7624 LGTM=rsc R=golang-codereviews, khr, bradfitz, josharian, dave, rsc CC=golang-codereviews https://codereview.appspot.com/92760044
* liblink, cmd/ld: reenable nosplit checking and testRuss Cox2014-04-166-15/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The new code is adapted from the Go 1.2 nosplit code, but it does not have the bug reported in issue 7623: g% go run nosplit.go g% go1.2 run nosplit.go BUG rejected incorrectly: main 0 call f; f 120 linker output: # _/tmp/go-test-nosplit021064539 main.main: nosplit stack overflow 120 guaranteed after split check in main.main 112 on entry to main.f -8 after main.f uses 120 g% Fixes issue 6931. Fixes issue 7623. LGTM=iant R=golang-codereviews, iant, ality CC=golang-codereviews, r https://codereview.appspot.com/88190043
* liblink, cmd/gc, cmd/{5,6,8}{a,c}: rename linkwriteobj to writeobjIan Lance Taylor2014-04-161-1/+4
| | | | | | | | | | | | | The name linkwriteobj is misleading because it implies that the function has something to do with the linker, which it does not. The name is historical: the function performs an operation that was previously performed by the linker, but no longer is. LGTM=rsc R=rsc, minux.ma CC=golang-codereviews https://codereview.appspot.com/88210045
* liblink: add leaf bit to object file formatRuss Cox2014-04-161-1/+7
| | | | | | | | | | | | | | Without the leaf bit, the linker cannot record the correct frame size in the symbol table, and then stack traces get mangled. (Only for ARM.) Fixes issue 7338. Fixes issue 7347. LGTM=iant R=iant CC=golang-codereviews https://codereview.appspot.com/88550043
* liblink: fix incorrect hash collision in lookupRuss Cox2014-04-162-7/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | linklookup uses hash(name, v) as the hash table index but then only compares name to find a symbol to return. If hash(name, v1) == hash(name, v2) for v1 != v2, the lookup for v2 will return the symbol with v1. The input routines assume that each symbol is found only once, and then each symbol is added to a linked list, with the list header in the symbol. Adding a symbol to such a list multiple times short-circuits the list the second time it is added, causing symbols to be dropped. The liblink rewrite introduced an elegant, if inefficient, handling of duplicated symbols by creating a dummy symbol to read the duplicate into. The dummy symbols are named .dup with sequential version numbers. With many .dup symbols, eventually there will be a conflict, causing a duplicate list add, causing elided symbols, causing a crash when calling one of the elided symbols. The bug is old (2011) but could not have manifested until the liblink rewrite introduced this heavily duplicated symbol .dup. (See History section below.) 1. Correct the lookup function. 2. Since we want all the .dup symbols to be different, there's no point in inserting them into the table. Call linknewsym directly, avoiding the lookup function entirely. 3. Since nothing can refer to the .dup symbols, do not bother adding them to the list of functions (textp) at all. 4. In lieu of a unit test, introduce additional consistency checks to detect adding a symbol to a list multiple times. This would have caught the short-circuit more directly, and it will detect a variety of double-use bugs, including the one arising from the bad lookup. Fixes issue 7749. History On April 9, 2011, I submitted CL 4383047, making ld 25% faster. Much of the focus was on the hash table lookup function, and one of the changes was to remove the s->version == v comparison [1]. I don't know if this was a simple editing error or if I reasoned that same name but different v would yield a different hash slot and so the name test alone sufficed. It is tempting to claim the former, but it was probably the latter. Because the hash is an iterated multiply+add, the version ends up adding v*3? to the hash, where n is the length of the name. A collision would need x*3? ? y*3? (mod 2?? mod 100003), or equivalently x*3? ? x*3? + (y-x)*3? (mod 2?? mod 100003), so collisions will actually be periodic: versions x and y collide when d = y-x satisfies d*3? ? 0 (mod 2?? mod 100003). Since we allocate version numbers sequentially, this is actually about the best case one could imagine: the collision rate is much lower than if the hash were more random. http://play.golang.org/p/TScD41c_hA computes the collision period for various name lengths. The most common symbol in the new linker is .dup, and for n=4 the period is maximized: the 100004th symbol is the first collision. Unfortunately, there are programs with more duplicated symbols than that. In Go 1.2 and before, duplicate symbols were handled without creating a dummy symbol, so this particular case for generating many duplicate symbols could not happen. Go does not use versioned symbols. Only C does; each input file gives a different version to its static declarations. There just aren't enough C files for this to come up in that context. So the bug is old but the realization of the bug is new. [1] https://codereview.appspot.com/4383047/diff/5001/src/cmd/ld/lib.c LGTM=minux.ma, iant, dave R=golang-codereviews, minux.ma, bradfitz, iant, dave CC=golang-codereviews, r https://codereview.appspot.com/87910047
* build: remove tmp dir names from objects, support GOROOT_FINAL againRuss Cox2014-04-152-1/+49
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If we compile a generated file stored in a temporary directory - let's say /tmp/12345/work/x.c - then by default 6c stores the full path and then the pcln table in the final binary includes the full path. This makes repeated builds (using different temporary directories) produce different binaries, even if the inputs are the same. In the old 'go tool pack', the P flag specified a prefix to remove from all stored paths (if present), and cmd/go invoked 'go tool pack grcP $WORK' to remove references to the temporary work directory. We've changed the build to avoid pack as much as possible, under the theory that instead of making pack convert from .6 to .a, the tools should just write the .a directly and save a round of I/O. Instead of going back to invoking pack always, define a common flag -trimpath in the assemblers, C compilers, and Go compilers, implemented in liblink, and arrange for cmd/go to use the flag. Then the object files being written out have the shortened paths from the start. While we are here, reimplement pcln support for GOROOT_FINAL. A build in /tmp/go uses GOROOT=/tmp/go, but if GOROOT_FINAL=/usr/local/go is set, then a source file named /tmp/go/x.go is recorded instead as /usr/local/go/x.go. We use this so that we can prepare distributions to be installed in /usr/local/go without actually working in that directory. The conversion to liblink deleted all the old file name handling code, including the GOROOT_FINAL translation. Bring the GOROOT_FINAL translation back. Before this CL, using GOROOT_FINAL=/goroot make.bash: g% strings $(which go) | grep -c $TMPDIR 6 g% strings $(which go) | grep -c $GOROOT 793 g% After this CL: g% strings $(which go) | grep -c $TMPDIR 0 g% strings $(which go) | grep -c $GOROOT 0 g% (The references to $TMPDIR tend to be cgo-generated source files.) Adding the -trimpath flag to the assemblers required converting them to the new Go-semantics flag parser. The text in go1.3.html is copied and adjusted from go1.1.html, which is when we applied that conversion to the compilers and linkers. Fixes issue 6989. LGTM=iant R=r, iant CC=golang-codereviews https://codereview.appspot.com/88300045
* cmd/ld: use TLS relocations on ELF systems in external linking modeRuss Cox2014-04-152-51/+20
| | | | | | | | | Fixes issue 7719. LGTM=iant R=iant CC=golang-codereviews https://codereview.appspot.com/87760050
* liblink: introduce TLS register on 386 and amd64Russ Cox2014-04-158-255/+413
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When I did the original 386 ports on Linux and OS X, I chose to define GS-relative expressions like 4(GS) as relative to the actual thread-local storage base, which was usually GS but might not be (it might be FS, or it might be a different constant offset from GS or FS). The original scope was limited but since then the rewrites have gotten out of control. Sometimes GS is rewritten, sometimes FS. Some ports do other rewrites to enable shared libraries and other linking. At no point in the code is it clear whether you are looking at the real GS/FS or some synthesized thing that will be rewritten. The code manipulating all these is duplicated in many places. The first step to fixing issue 7719 is to make the code intelligible again. This CL adds an explicit TLS pseudo-register to the 386 and amd64. As a register, TLS refers to the thread-local storage base, and it can only be loaded into another register: MOVQ TLS, AX An offset from the thread-local storage base is written off(reg)(TLS*1). Semantically it is off(reg), but the (TLS*1) annotation marks this as indexing from the loaded TLS base. This emits a relocation so that if the linker needs to adjust the offset, it can. For example: MOVQ TLS, AX MOVQ 8(AX)(TLS*1), CX // load m into CX On systems that support direct access to the TLS memory, this pair of instructions can be reduced to a direct TLS memory reference: MOVQ 8(TLS), CX // load m into CX The 2-instruction and 1-instruction forms correspond roughly to ELF TLS initial exec mode and ELF TLS local exec mode, respectively. Liblink applies this rewrite on systems that support the 1-instruction form. The decision is made using only the operating system (and probably the -shared flag, eventually), not the link mode. If some link modes on a particular operating system require the 2-instruction form, then all builds for that operating system will use the 2-instruction form, so that the link mode decision can be delayed to link time. Obviously it is late to be making changes like this, but I despair of correcting issue 7719 and issue 7164 without it. To make sure I am not changing existing behavior, I built a "hello world" program for every GOOS/GOARCH combination we have and then worked to make sure that the rewrite generates exactly the same binaries, byte for byte. There are a handful of TODOs in the code marking kludges to get the byte-for-byte property, but at least now I can explain exactly how each binary is handled. The targets I tested this way are: darwin-386 darwin-amd64 dragonfly-386 dragonfly-amd64 freebsd-386 freebsd-amd64 freebsd-arm linux-386 linux-amd64 linux-arm nacl-386 nacl-amd64p32 netbsd-386 netbsd-amd64 openbsd-386 openbsd-amd64 plan9-386 plan9-amd64 solaris-amd64 windows-386 windows-amd64 There were four exceptions to the byte-for-byte goal: windows-386 and windows-amd64 have a time stamp at bytes 137 and 138 of the header. darwin-386 and plan9-386 have five or six modified bytes in the middle of the Go symbol table, caused by editing comments in runtime/sys_{darwin,plan9}_386.s. Fixes issue 7164. LGTM=iant R=iant, aram, minux.ma, dave CC=golang-codereviews https://codereview.appspot.com/87920043
* liblink: remove arch-specific constants from file formatRuss Cox2014-04-148-39/+39
| | | | | | | | | | | | | | | | The relocation and automatic variable types were using arch-specific numbers. Introduce portable enumerations instead. To the best of my knowledge, these are the only arch-specific bits left in the new object file format. Remove now, before Go 1.3, because file formats are forever. LGTM=iant R=iant CC=golang-codereviews https://codereview.appspot.com/87670044
* liblink, cmd/link: add version number to object fileRuss Cox2014-04-141-1/+5
| | | | | | | | | | There are changes we know we want to make, but not before Go 1.3 Add a version number so that we can make them more easily later. LGTM=iant R=iant CC=golang-codereviews https://codereview.appspot.com/87670043
* liblink: remove code that is never executedIan Lance Taylor2014-04-072-37/+0
| | | | | | | | | | | | This code tests linkmode == LinkExternal but is only invoked by the compiler/assembler, not the linker. Update issue 7164 LGTM=rsc R=rsc, dave CC=golang-codereviews https://codereview.appspot.com/85080043
* cmd/gc, cmd/ld, runtime: compact liveness bitmapsRuss Cox2014-04-021-2/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Reduce footprint of liveness bitmaps by about 5x. 1. Mark all liveness bitmap symbols as 4-byte aligned (they were aligned to a larger size by default). 2. The bitmap data is a bitmap count n followed by n bitmaps. Each bitmap begins with its own count m giving the number of bits. All the m's are the same for the n bitmaps. Emit this bitmap length once instead of n times. 3. Many bitmaps within a function have the same bit values, but each call site was given a distinct bitmap. Merge duplicate bitmaps so that no bitmap is written more than once. 4. Many functions end up with the same aggregate bitmap data. We used to name the bitmap data funcname.gcargs and funcname.gclocals. Instead, name it gclocals.<md5 of data> and mark it dupok so that the linker coalesces duplicate sets. This cut the bitmap data remaining after step 3 by 40%; I was not expecting it to be quite so dramatic. Applied to "go build -ldflags -w code.google.com/p/go.tools/cmd/godoc": bitmaps pclntab binary on disk before this CL 1326600 1985854 12738268 4-byte align 1154288 (0.87x) 1985854 (1.00x) 12566236 (0.99x) one bitmap len 782528 (0.54x) 1985854 (1.00x) 12193500 (0.96x) dedup bitmap 414748 (0.31x) 1948478 (0.98x) 11787996 (0.93x) dedup bitmap set 245580 (0.19x) 1948478 (0.98x) 11620060 (0.91x) While here, remove various dead blocks of code from plive.c. Fixes issue 6929. Fixes issue 7568. LGTM=khr R=khr CC=golang-codereviews https://codereview.appspot.com/83630044
* runtime: get rid of most uses of REP for copying/zeroing.Keith Randall2014-04-012-0/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | REP MOVSQ and REP STOSQ have a really high startup overhead. Use a Duff's device to do the repetition instead. benchmark old ns/op new ns/op delta BenchmarkClearFat32 7.20 1.60 -77.78% BenchmarkCopyFat32 6.88 2.38 -65.41% BenchmarkClearFat64 7.15 3.20 -55.24% BenchmarkCopyFat64 6.88 3.44 -50.00% BenchmarkClearFat128 9.53 5.34 -43.97% BenchmarkCopyFat128 9.27 5.56 -40.02% BenchmarkClearFat256 13.8 9.53 -30.94% BenchmarkCopyFat256 13.5 10.3 -23.70% BenchmarkClearFat512 22.3 18.0 -19.28% BenchmarkCopyFat512 22.0 19.7 -10.45% BenchmarkCopyFat1024 36.5 38.4 +5.21% BenchmarkClearFat1024 35.1 35.0 -0.28% TODO: use for stack frame zeroing TODO: REP prefixes are still used for "reverse" copying when src/dst regions overlap. Might be worth fixing. LGTM=rsc R=golang-codereviews, rsc CC=golang-codereviews, r https://codereview.appspot.com/81370046
* liblink, runtime: make nacl/386 binaries valid.R?my Oudompheng2014-03-141-2/+11
| | | | | | | | | | They were rejected by NaCl due to AES instructions and accesses to %gs:0x8, caused by wrong tlsoffset value. LGTM=iant R=rsc, dave, iant CC=golang-codereviews https://codereview.appspot.com/76050044
* liblink: fix bad code generated for MOVFD/MOVDF when reg > 7Josh Bleecher Snyder2014-03-111-1/+2
| | | | | | | | | | | | The byte that r is or'd into is already 0x7, so the failure to zero r only impacts the generated machine code if the register is > 7. Fixes issue 7044. LGTM=dave, minux.ma, rsc R=dave, minux.ma, bradfitz, rsc CC=golang-codereviews https://codereview.appspot.com/73730043
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