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2015-03-01cmd/5l etc: replace C code with Go codeRuss Cox
mv cmd/new5l cmd/5l and so on. Minimal changes to cmd/dist and cmd/go to keep things building. More can be deleted in followup CLs. Change-Id: I1449eca7654ce2580d1f413a56dc4a75f3d4618b Reviewed-on: https://go-review.googlesource.com/6361 Reviewed-by: Rob Pike <r@golang.org>
2015-03-01cmd/ld: clean for c2goRuss Cox
Change-Id: Iaab2be9a1919f2fa9dbc61a5b7fbf99bcd0712a9 Reviewed-on: https://go-review.googlesource.com/6332 Reviewed-by: Rob Pike <r@golang.org> Reviewed-by: Minux Ma <minux@golang.org>
2015-02-13cmd/ld: make cmd/ld a real libraryRuss Cox
Make cmd/ld a real library invoked by the individual linkers. There are no reverse symbol references anymore (symbols referred to in cmd/ld but defined in cmd/5l etc). This means that in principle we could do an automatic conversion of these to Go, as a stopgap until cmd/link is done or as a replacement for cmd/link. Change-Id: I4a94570257a3a7acc31601bfe0fad9dea0aea054 Reviewed-on: https://go-review.googlesource.com/4649 Reviewed-by: Rob Pike <r@golang.org>
2014-10-22[dev.power64] build: merge default into dev.power64Austin Clements
LGTM=rsc R=rsc CC=golang-codereviews https://golang.org/cl/160200044
2014-08-27cmd/{ld,link,objdump}, runtime, debug/gosym: move linker-defined symbols ↵Matthew Dempsky
into runtime package Fixes #8092. LGTM=rsc R=iant, rsc CC=golang-codereviews https://golang.org/cl/126790043
2014-08-07[dev.power64] cmd/ld: update for power64Shenghou Ma
LGTM=rsc R=rsc, iant CC=golang-codereviews https://golang.org/cl/121380043
2014-07-03cmd/go, cmd/ld, runtime, os/user: TLS emulation for androidDavid Crawshaw
Based on cl/69170045 by Elias Naur. There are currently several schemes for acquiring a TLS slot to save the g register. None of them appear to work for android. The closest are linux and darwin. Linux uses a linker TLS relocation. This is not supported by the android linker. Darwin uses a fixed offset, and calls pthread_key_create until it gets the slot it wants. As the runtime loads late in the android process lifecycle, after an arbitrary number of other libraries, we cannot rely on any particular slot being available. So we call pthread_key_create, take the first slot we are given, and put it in runtime.tlsg, which we turn into a regular variable in cmd/ld. Makes android/arm cgo binaries work. LGTM=minux R=elias.naur, minux, dave, josharian CC=golang-codereviews https://golang.org/cl/106380043
2014-06-26all: remove 'extern register M *m' from runtimeRuss Cox
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 µs) 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://golang.org/cl/109050043
2014-04-03cmd/cc: emit gc bitmaps in read-only memoryRuss Cox
Cuts hello world by 70kB, because we don't write those names into the symbol table. Update #6853 LGTM=khr R=khr CC=golang-codereviews https://golang.org/cl/80370045
2014-04-02cmd/gc, cmd/ld, runtime: compact liveness bitmapsRuss Cox
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 #6929. Fixes #7568. LGTM=khr R=khr CC=golang-codereviews https://golang.org/cl/83630044
2014-03-21cmd/ld: fix warnings on Plan 9David du Colombier
warning: src/cmd/ld/macho.c:595 sign-extended character constant warning: src/cmd/ld/macho.c:595 sign-extended character constant warning: src/cmd/ld/symtab.c:63 sign-extended character constant warning: src/cmd/ld/symtab.c:63 sign-extended character constant LGTM=iant R=golang-codereviews, iant CC=golang-codereviews https://golang.org/cl/76580046
2014-03-14cmd/gc: replace '·' as '.' in ELF/Mach-O symbol tablesShenghou Ma
Old versions of DTrace (as those shipped in OS X and FreeBSD) don't support unicode characters in symbol names. Replace '·' to '.' to make DTrace happy. Fixes #7493 LGTM=aram, rsc R=aram, rsc, gobot, iant CC=golang-codereviews https://golang.org/cl/72280043
2014-02-23cmd/ld: don't emit unreachable dynimport symbols in ELF symtab.Shenghou Ma
Fix build for Dragonfly BSD. Fixes #7318. Fixes #7367. LGTM=jsing, iant R=jsing, iant, mikioh.mikioh CC=golang-codereviews https://golang.org/cl/64340043
2014-02-19cmd/ld: drop gcargs, gclocals symbols from symbol tableRuss Cox
Update #6853 Every function now has a gcargs and gclocals symbol holding associated garbage collection information. Put them all in the same meta-symbol as the go.func data and then drop individual entries from symbol table. Removing gcargs and gclocals reduces the size of a typical binary by 10%. LGTM=r R=r CC=golang-codereviews https://golang.org/cl/65870044
2014-02-18cmd/ld: remove Plan 9 symbol tableRuss Cox
Update #6853 Nothing reads the Plan 9 symbol table anymore. The last holdout was 'go tool nm', but since being rewritten in Go it uses the standard symbol table for the binary format (ELF, Mach-O, PE) instead. Removing the Plan 9 symbol table saves ~15% disk space on most binaries. Two supporting changes included in this CL: debug/gosym: use Go 1.2 pclntab to synthesize func-only symbol table when there is no Plan 9 symbol table debug/elf, debug/macho, debug/pe: ignore final EOF from ReadAt LGTM=r R=r, bradfitz CC=golang-codereviews https://golang.org/cl/65740045
2014-02-11cmd/ld, cmd/6l: part 2 of solaris/amd64 linker changes.Shenghou Ma
Second part of the solaris/amd64 linker changes: relocation and symbol table. LGTM=iant R=golang-codereviews, iant CC=golang-codereviews https://golang.org/cl/61330043
2013-12-08liblink: create new library based on linker codeRuss Cox
There is an enormous amount of code moving around in this CL, but the code is the same, and it is invoked in the same ways. This CL is preparation for the new linker structure, not the new structure itself. The new library's definition is in include/link.h. The main change is the use of a Link structure to hold all the linker-relevant state, replacing the smattering of global variables. The Link structure should both make it clearer which state must be carried around and make it possible to parallelize more easily later. The main body of the linker has moved into the architecture-independent cmd/ld directory. That includes the list of known header types, so the distinction between Hplan9x32 and Hplan9x64 is removed (no other header type distinguished 32- and 64-bit formats), and code for unused formats such as ipaq kernels has been deleted. The code being deleted from 5l, 6l, and 8l reappears in liblink or in ld. Because multiple files are being merged in the liblink directory, it is not possible to show the diffs nicely in hg. The Prog and Addr structures have been unified into an architecture-independent form and moved to link.h, where they will be shared by all tools: the assemblers, the compilers, and the linkers. The unification makes it possible to write architecture-independent traversal of Prog lists, among other benefits. The Sym structures cannot be unified: they are too fundamentally different between the linker and the compilers. Instead, liblink defines an LSym - a linker Sym - to be used in the Prog and Addr structures, and the linker now refers exclusively to LSyms. The compilers will keep using their own syms but will fill out the corresponding LSyms in the Prog and Addr structures. Although code from 5l, 6l, and 8l is now in a single library, the code has been arranged so that only one architecture needs to be linked into a particular program: 5l will not contain the code needed for x86 instruction layout, for example. The object file writing code in liblink/obj.c is from cmd/gc/obj.c. Preparation for golang.org/s/go13linker work. This CL does not build by itself. It depends on 35740044 and will be submitted at the same time. R=iant CC=golang-dev https://golang.org/cl/35790044
2013-08-14runtime.cmd/ld: Add ARM external linking and implement -shared in terms of ↵Elias Naur
external linking This CL is an aggregate of 10271047, 10499043, 9733044. Descriptions of each follow: 10499043 runtime,cmd/ld: Merge TLS symbols and teach 5l about ARM TLS This CL prepares for external linking support to ARM. The pseudo-symbols runtime.g and runtime.m are merged into a single runtime.tlsgm symbol. When external linking, the offset of a thread local variable is stored at a memory location instead of being embedded into a offset of a ldr instruction. With a single runtime.tlsgm symbol for both g and m, only one such offset is needed. The larger part of this CL moves TLS code from gcc compiled to internally compiled. The TLS code now uses the modern MRC instruction, and 5l is taught about TLS fallbacks in case the instruction is not available or appropriate. 10271047 This CL adds support for -linkmode external to 5l. For 5l itself, use addrel to allow for D_CALL relocations to be handled by the host linker. Of the cases listed in rsc's comment in issue 4069, only case 5 and 63 needed an update. One of the TODO: addrel cases was since replaced, and the rest of the cases are either covered by indirection through addpool (cases with LTO or LFROM flags) or stubs (case 74). The addpool cases are covered because addpool emits AWORD instructions, which in turn are handled by case 11. In the runtime, change the argv argument in the rt0* functions slightly to be a pointer to the argv list, instead of relying on a particular location of argv. 9733044 The -shared flag to 6l outputs a shared library, implemented in Go and callable from non-Go programs such as C. The main part of this CL change the thread local storage model. Go uses the fastest and least general mode, local exec. TLS data in shared libraries normally requires at least the local dynamic mode, however, this CL instead opts for using the initial exec mode. Initial exec mode is faster than local dynamic mode and can be used in linux since the linker has reserved a limited amount of TLS space for performance sensitive TLS code. Initial exec mode requires an extra load from the GOT table to determine the TLS offset. This penalty will not be paid if ld is not in -shared mode, since TLS accesses will be reduced to local exec. The elf sections .init_array and .rela.init_array are added to register the Go runtime entry with cgo at library load time. The "hidden" attribute is added to Cgo functions called from Go, since Go does not generate call through the GOT table, and adding non-GOT relocations for a global function is not supported by gcc. Cgo symbols don't need to be global and avoiding the GOT table is also faster. The changes to 8l are only removes code relevant to the old -shared mode where internal linking was used. This CL only address the low level linker work. It can be submitted by itself, but to be useful, the runtime changes in CL 9738047 is also needed. Design discussion at https://groups.google.com/forum/?fromgroups#!topic/golang-nuts/zmjXkGrEx6Q Fixes #5590. R=rsc CC=golang-dev https://golang.org/cl/12871044
2013-07-18cmd/ld, runtime: use new contiguous pcln tableRuss Cox
R=golang-dev, r, dave CC=golang-dev https://golang.org/cl/11494043
2013-07-16cmd/ld, runtime: new in-memory symbol table formatRuss Cox
Design at http://golang.org/s/go12symtab. This enables some cleanup of the garbage collector metadata that will be done in future CLs. This CL does not move the old symtab and pclntab back into an unmapped section of the file. That's a bit tricky and will be done separately. Fixes #4020. R=golang-dev, dave, cshapiro, iant, r CC=golang-dev, nigeltao https://golang.org/cl/11085043
2013-06-04cmd/ld: fix gcdata and gcbss symbolsAnthony Martin
These two symbols don't show up in the Go symbol table since they're defined in dodata which is called sometime after symtab. They do, however, show up in the ELF symbol table. This regression was introduced in changeset 01c40d533367. Also, remove the corresponding strings from the ELF strtab section now that they're unused. R=golang-dev, iant CC=golang-dev https://golang.org/cl/8650043
2013-04-30cmd/ld: emit relocs for DWARF info when doing an external linkIan Lance Taylor
I would like opinions on whether this is a good idea for 1.1. On the one hand it's a moderately important issue. On the other hand this introduces at least the possibility of external linker errors due to the additional relocations and it may be better to wait. I'm fairly confident that the behaviour is unchanged when not using an external linker. Update #5221 This CL is tested lightly on 386 and amd64 and fixes the cases I tested. I have not tested it on Darwin or Windows. R=golang-dev, dave, daniel.morsing, rsc CC=golang-dev https://golang.org/cl/8858047
2013-04-10cmd/ld: fix scope of static objects in symbol tableAnthony Martin
All symbols are currently marked with global scope. The correct behavior was lost when the symbol table format was changed. R=golang-dev, iant, r CC=golang-dev https://golang.org/cl/8625043
2013-03-27cmd/ld: fix OpenBSD (third try)Ian Lance Taylor
On OpenBSD don't mark runtime.{g,m} as STT_TLS symbols. R=golang-dev, dave CC=golang-dev https://golang.org/cl/7867046
2013-03-27cmd/ld: emit TLS relocations during external linkingIan Lance Taylor
This CL was written by rsc. I just tweaked 8l. This CL adds TLS relocation to the ELF .o file we write during external linking, so that the host linker (gcc) can decide the final location of m and g. Similar relocations are not necessary on OS X because we use an alternate program start-time mechanism to acquire thread-local storage. Similar relocations are not necessary on ARM or Plan 9 or Windows because external linking mode is not yet supported on those systems. On almost all ELF systems, the references we use are like %fs:-0x4 or %gs:-0x4, which we write in 6a/8a as -0x4(FS) or -0x4(GS). On Linux/ELF, however, Xen's lack of support for this mode forced us long ago to use a two-instruction sequence: first we load %gs:0x0 into a register r, and then we use -0x4(r). (The ELF program loader arranges that %gs:0x0 contains a regular pointer to that same memory location.) In order to relocate those -0x4(r) references, the linker must know where they are. This CL adds the equivalent notation -0x4(r)(GS*1) for this purpose: it assembles to the same encoding as -0x4(r) but the (GS*1) indicates to the linker that this is one of those thread-local references that needs relocation. Thanks to Elias Naur for reminding me about this missing piece and also for writing the test. R=r CC=golang-dev https://golang.org/cl/7891047
2013-03-20cmd/ld: remove remaining occurrence of isobj.Rémy Oudompheng
Fixes cgo builds. R=golang-dev, minux.ma CC=golang-dev https://golang.org/cl/7784044
2013-03-08cmd/ld: external linking fixes for linux/386Russ Cox
The sticking point on 386 has been the "PC relative" relocations used to point the garbage collection metadata at the type info. These aren't in the code segment, and I don't trust that the linker isn't doing something special that would be okay in code but not when interpreting the pointers as data (for example, a PLT jump table would be terrible). Solve the problem in two steps: 1. Handle "PC relative" relocations within a section internally, so that the external linker never sees them. 2. Move the gcdata and gcbss tables into the rodata section, where the type information lives, so that the relocations can be handled internally. (To answer the obvious question, we make the gc->type references relative so that they need not be relocated individually when generating a shared object file.) R=golang-dev, iant CC=golang-dev https://golang.org/cl/7629043
2013-03-07cmd/ld: host linking support for linux/amd64Russ Cox
Still to do: non-linux and non-amd64. It may work on other ELF-based amd64 systems too, but untested. "go test -ldflags -hostobj $GOROOT/misc/cgo/test" passes. Much may yet change, but this seems a reasonable checkpoint. R=iant CC=golang-dev https://golang.org/cl/7369057
2013-03-01cmd/cgo, cmd/ld: new cgo object file sectionRuss Cox
Switch to new pragma names, but leave old ones available for now. Merge the three cgo-related sections in the .6 files into a single cgo section. R=golang-dev, iant, ality CC=golang-dev https://golang.org/cl/7424048
2013-02-26cmd/ld, runtime: adjust symbol table representationRuss Cox
This CL changes the encoding used for the Go symbol table, stored in the binary and used at run time. It does not change any of the semantics or structure: the bits are just packed a little differently. The comment at the top of runtime/symtab.c describes the new format. Compared to the Go 1.0 format, the main changes are: * Store symbol addresses as full-pointer-sized host-endian values. (For 6g, this means addresses are 64-bit little-endian.) * Store other values (frame sizes and so on) varint-encoded. The second change more than compensates for the first: for the godoc binary on OS X/amd64, the new symbol table is 8% smaller than the old symbol table (1,425,668 down from 1,546,276). This is a required step for allowing the host linker (gcc) to write the final Go binary, since it will have to fill in the symbol address slots (so the slots must be host-endian) and on 64-bit systems it may choose addresses above 4 GB. R=golang-dev, iant CC=golang-dev https://golang.org/cl/7403054
2013-01-31cmd/ld: support for linking with host linkerRuss Cox
A step toward a fix for issue 4069. To allow linking with arbitrary host object files, add a linker mode that can generate a host object file instead of an executable. Then the host linker can be invoked to generate the final executable. This CL adds a new -hostobj flag that instructs the linker to write a host object file instead of an executable. That is, this works: go tool 6g x.go go tool 6l -hostobj -o x.o x.6 ld -e _rt0_amd64_linux x.o ./a.out as does: go tool 8g x.go go tool 8l -hostld ignored -o x.o x.8 ld -m elf_i386 -e _rt0_386_linux x.o ./a.out Because 5l was never updated to use the standard relocation scheme, it will take more work to get this working on ARM. This is a checkpoint of the basic functionality. It does not work with cgo yet, and cgo is the main reason for the change. The command-line interface will likely change too. The gc linker has other information that needs to be returned to the caller for use when invoking the host linker besides the single object file. R=iant, iant CC=golang-dev https://golang.org/cl/7060044
2013-01-306l/5l: PIC and shared library support for the linkers.Elias Naur
Added the -shared flag to 5l/6l to output a PIC executable with the required dynamic relocations and RIP-relative addressing in machine code. Added dummy support to 8l to avoid compilation errors See also: https://golang.org/cl/6822078 https://golang.org/cl/7064048 and https://groups.google.com/d/topic/golang-nuts/P05BDjLcQ5k/discussion R=rsc, iant CC=golang-dev https://golang.org/cl/6926049
2013-01-28cmd/ld: avoid a segfault when dumping the symbol tableCarl Shapiro
The dumping routine incorrectly assumed that all incoming symbols would be non-nil and load through it to retrieve the symbol name. Instead of using the symbol to retrieve a name, use the name provided by the caller. R=golang-dev, rsc CC=golang-dev https://golang.org/cl/7224043
2013-01-06cmd/ld: move symtab, ELF generation to portable codeRuss Cox
More cleanup in preparation for fixing issue 4069. This CL replaces the three nearly identical copies of the asmb ELF code with a single asmbelf function in elf.c. In addition to the ELF code movement, remove the elfstr array in favor of a simpler lookup, and identify sections by name throughout instead of computing fragile indices. The CL also replaces the three nearly identical copies of the genasmsym code with a single genasmsym function in lib.c. The ARM linker still compiles and generates binaries, but I haven't tested the binaries. They may not work. R=ken2 CC=golang-dev https://golang.org/cl/7062047
2013-01-04cmd/ld: use native-endian symbol values in symbol tableRuss Cox
The Plan 9 symbol table format defines big-endian symbol values for portability, but we want to be able to generate an ELF object file and let the host linker link it, as part of the solution to issue 4069. The symbol table itself, since it is loaded into memory at run time, must be filled in by the final host linker, using relocation directives to set the symbol values. On a little-endian machine, the linker will only fill in little-endian values during relocation, so we are forced to use little-endian symbol values. To preserve most of the original portability of the symbol table format, we make the table itself say whether it uses big- or little-endian values. If the table begins with the magic sequence fe ff ff ff 00 00 then the actual table begins after those six bytes and contains little-endian symbol values. Otherwise, the table is in the original format and contains big-endian symbol values. The magic sequence looks like an "end of table" entry (the fifth byte is zero), so legacy readers will see a little-endian table as an empty table. All the gc architectures are little-endian today, so the practical effect of this CL is to make all the generated tables little-endian, but if a big-endian system comes along, ld will not generate the magic sequence, and the various readers will fall back to the original big-endian interpretation. R=ken2 CC=golang-dev https://golang.org/cl/7066043
2012-11-13reflect: add ArrayOf, ChanOf, MapOf, SliceOfRuss Cox
In order to add these, we need to be able to find references to such types that already exist in the binary. To do that, introduce a new linker section holding a list of the types corresponding to arrays, chans, maps, and slices. To offset the storage cost of this list, and to simplify the code, remove the interface{} header from the representation of a runtime type. It was used in early versions of the code but was made obsolete by the kind field: a switch on kind is more efficient than a type switch. In the godoc binary, removing the interface{} header cuts two words from each of about 10,000 types. Adding back the list of pointers to array, chan, map, and slice types reintroduces one word for each of about 500 types. On a 64-bit machine, then, this CL *removes* a net 156 kB of read-only data from the binary. This CL does not include the needed support for precise garbage collection. I have created issue 4375 to track that. This CL also does not set the 'algorithm' - specifically the equality and copy functions - for a new array correctly, so I have unexported ArrayOf for now. That is also part of issue 4375. Fixes #2339. R=r, remyoudompheng, mirtchovski, iant CC=golang-dev https://golang.org/cl/6572043
2012-09-13ld: add .gcdata and .gcbss sectionsJan Ziak
R=rsc CC=golang-dev https://golang.org/cl/6281048
2012-05-29cmd/6l: Fixes for 64-bit Plan 9Akshat Kumar
Plan 9 versions for amd64 have 2 megabyte pages. This also fixes the logic for 32-bit vs 64-bit Plan 9, making 64-bit the default, and adds logic to generate a symbols table. R=golang-dev, rsc, rminnich, ality, 0intro CC=golang-dev, john https://golang.org/cl/6218046
2012-05-23cmd/ld, cmd/6l, cmd/8l, cmd/5l: fix hidden/local symbol import for ELF systemsShenghou Ma
Introduce a newsym() to cmd/lib.c to add a symbol but don't add them to hash table. Introduce a new bit flag SHIDDEN and bit mask SMASK to handle hidden and/or local symbols in ELF symbol tables. Though we still need to order the symbol table entries correctly. Fix for issue 3261 comment #9. For CL 5822049. R=iant, rsc CC=golang-dev https://golang.org/cl/5823055
2012-02-22ld: get symbol table letters rightRuss Cox
Have to assign them before we create the symbol table. ARM debugging. TBR=r CC=golang-dev https://golang.org/cl/5689067
2012-02-21ld: add NOPTRBSS for large, pointer-free uninitialized dataRuss Cox
cc: add #pragma textflag to set it runtime: mark mheap to go into noptr-bss. remove special case in garbage collector Remove the ARM from.flag field created by CL 5687044. The DUPOK flag was already in p->reg, so keep using that. Otherwise test/nilptr.go creates a very large binary. Should fix the arm build. Diagnosed by minux.ma; replacement for CL 5690044. R=golang-dev, minux.ma, r CC=golang-dev https://golang.org/cl/5686060
2012-02-19gc, ld: tag data as no-pointers and allocate in separate sectionRuss Cox
The garbage collector can avoid scanning this section, with reduces collection time as well as the number of false positives. Helps a little bit with issue 909, but certainly does not solve it. R=ken2 CC=golang-dev https://golang.org/cl/5671099
2011-08-22ld: remove duplicate bss definitionsRuss Cox
The EXTERN lines in elf.h already define these. That's not a problem for most C compilers, but apparently it is for some copies of the OS X linker. Fixes #2167. R=golang-dev, iant CC=golang-dev https://golang.org/cl/4936044
2011-06-28ld: fix ELF strip by removing overlap of sectionsGustavo Niemeyer
The gosymtab and gopclntab sections were pointing to the proper data, but that data was already owned by the rodata section. Some ELF references explicitly prohibit multiple sections from owning the same data, and strip behaves accordingly. The data for these sections was moved to after rodata, and the gosymtab and gopclntab sections now own their respective ranges. This change makes strip happy both with and without -s being provided at link time. Note that it won't remove these sections because they are still allocated, and that's by design since they are necessary at runtime for generating proper backtraces and similar introspection operations. Unlike the previous behavior, -s will now maintain zero-sized gosymtab and gopclntab sections. This makes the implementation slightly cleaner. Fixes #1242. NOTE: Tested on Linux amd64/386/arm only. R=ality, rsc CC=golang-dev https://golang.org/cl/4639077
2011-06-27ld: elide the Go symbol table when using -sAnthony Martin
R=rsc, n13m3y3r, gustavo CC=golang-dev https://golang.org/cl/4661050
2011-06-218l: more fixes for Plan 9Lucio De Re
Once these changes are effected, it is possible to construct "8l" native on a (386?) Plan 9 system, albeit with assistance from modules such as mkfiles that are not (yet) included in any public patches. 8l/asm.c: . Corrected some format qualifiers. 8l/list.c: . Cast a print() argument to (int) to match the given format. It may be possible to change the format (%R), but I have not looked into it. 8l/obj.c: . Removed some unused code. 8l/span.c: . Removed unnecessary incrementation on "bp". . Corrected some format qualifiers. ld/data.c: . Corrected some format qualifiers. . Cast print argument to (int): used as field size. . Use braces to suppress warning about empty if() statements. ld/dwarf.c: . Trivial spelling mistake in comment. ld/ldelf.c: . Added USED() statements to silence warnings. . Dropped redundant address (&) operators. . corrected some format qualifiers. . Cast to (int) for switch selection variable. ld/macho.c: . Added USED() statements to silence warnings. ld/ldpe.c: . Added USED() statements to silence warnings. . More careful use of "sect" variable. . Corrected some format qualifiers. . Removed redundant assignments. . Minor fix dropped as it was submitted separately. ld/pe.c: . Dropped <time.h> which is now in <u.h>. . Dropped redundant address (&) operators. . Added a missing variable initialisation. ld/symtab.c: . Added USED() statements to silence warnings. . Removed redundant incrementation. . Corrected some format qualifiers. All the above have been tested against a (very) recent release and do not seem to trigger any regressions. All review suggestions have been incorporated. R=rsc CC=golang-dev https://golang.org/cl/4633043
2011-06-07ld: fix and simplify ELF symbol generationAnthony Martin
I started looking at this code because the nm in GNU binutils was ignoring the first symbol in the .symtab section. Apparently, the System V ABI reserves the first entry and requires all fields inside to be set to zero. The list of changes is as follows: · reserve the first symbol entry (as noted above) · fix the section indices for .data and .bss symbols · factor out common code for Elf32 and Elf64 · remove the special case for elfsymo in [568]l/asm.c:/^asmb · add the "etext" symbol in 6l · add static symbols R=rsc CC=golang-dev https://golang.org/cl/4524075
2011-04-23ld: fix Plan 9 symbol tableAnthony Martin
Static symbols were not being marked as such. I also made the 'z' symbols use the first byte of the name instead of an explicit NUL so that if the symbol table format is ever changed, the only place that would need updating is addhist(). R=rsc CC=golang-dev https://golang.org/cl/4366047
2011-04-09ld: 25% fasterRuss Cox
The ld time was dominated by symbol table processing, so * increase hash table size * emit fewer symbols in gc (just 1 per string, 1 per type) * add read-only lookup to avoid creating spurious symbols * add linked list to speed whole-table traversals Breaks dwarf generator (no idea why), so disable dwarf. Reduces time for 6l to link godoc by 25%. R=ken2 CC=golang-dev https://golang.org/cl/4383047
2011-03-085l, 6l, 8l: omit symbols for type, string, go.stringRuss Cox
Much of the bulk of Go binaries is the symbol tables, which give a name to every C string, Go string, and reflection type symbol. These names are not worth much other than seeing what's where in a binary. This CL deletes all those names from the symbol table, instead aggregating the symbols into contiguous blocks and giving them the names "string.*", "go.string.*", and "type.*". Before: $ 6nm $(which godoc.old) | sort | grep ' string\.' | tail -10 59eda4 D string."aa87ca22be8b05378eb1c71... 59ee08 D string."b3312fa7e23ee7e4988e056... 59ee6c D string."func(*token.FileSet, st... 59eed0 D string."func(io.Writer, []uint8... 59ef34 D string."func(*tls.Config, *tls.... 59ef98 D string."func(*bool, **template.... 59effc D string."method(p *printer.print... 59f060 D string."method(S *scanner.Scann... 59f12c D string."func(*struct { begin in... 59f194 D string."method(ka *tls.ecdheRSA... $ After: $ 6nm $(which godoc) | sort | grep ' string\.' | tail -10 5e6a30 D string.* $ Those names in the "Before" are truncated for the CL. In the real binary they are the complete string, up to a certain length, or else a unique identifier. The same applies to the type and go.string symbols. Removing the names cuts godoc by more than half: -rwxr-xr-x 1 rsc rsc 9153405 2011-03-07 23:19 godoc.old -rwxr-xr-x 1 rsc rsc 4290071 2011-03-07 23:19 godoc For what it's worth, only 80% of what's left gets loaded into memory; the other 20% is dwarf debugging information only ever accessed by gdb: -rwxr-xr-x 1 rsc rsc 3397787 2011-03-07 23:19 godoc.nodwarf R=r, cw CC=golang-dev https://golang.org/cl/4245072