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Change-Id: Ic66243674ac1dbf829c7523005e33611cc89ac83
Reviewed-on: https://go-review.googlesource.com/6362
Reviewed-by: Rob Pike <r@golang.org>
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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>
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Liblink is still needed for the linker (for a bit longer) but mostly not.
Delete the unused parts.
Change-Id: Ie63a7c1520dee52b17425b384943cd16262d36e3
Reviewed-on: https://go-review.googlesource.com/6110
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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The point of GOOBJ=2 was to have an active test of the cmd/internal/obj code.
Now we have end-to-end tests of the assembler, and soon the compiler,
so we don't need this halfway test on by default anymore.
(It's still possible to enable during debugging with the
environment variable.)
The problem it causes on the builders is that this particular testing
mode ends up with both the C process and the Go objwriter subprocess
having the same very large Prog list in memory simultaneously,
which causes basically a 2x memory blowup. In large programs
(such as the one generated by test/rotate.go) this is significant.
Disabling GOOBJ=2 should help with the current dev.cc builder
failures.
Change-Id: I1b11e4f29ea575659f02d2234242a904f7c867e4
Reviewed-on: https://go-review.googlesource.com/4832
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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cmd/internal/obj reconverted using rsc.io/c2go rev 2a95256.
- Brings in new, more regular Prog, Addr definitions
- Add Prog* argument to oclass in liblink/asm[68].c, for c2go conversion.
- Update objwriter for change in TEXT size encoding.
- Merge 5a, 6a, 8a, 9a changes into new5a, new6a, new8a, new9a (by hand).
- Add +build ignore to cmd/asm/internal/{addr,arch,asm}, cmd/asm.
They need to be updated for the changes.
- Reenable verifyAsm in cmd/go.
- Reenable GOOBJ=2 mode by default in liblink.
All architectures build successfully again.
Change-Id: I2c845c5d365aa484b570476898171bee657b626d
Reviewed-on: https://go-review.googlesource.com/3963
Reviewed-by: Rob Pike <r@golang.org>
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Change-Id: I2aa1d0b0c4cf7632a54e843810959b468e3812ab
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The upcoming merge is going to break the synchrony.
Will restore separately.
Change-Id: I90946119a0901e24063b190d1a074594af7654c7
Reviewed-on: https://go-review.googlesource.com/3888
Reviewed-by: Russ Cox <rsc@golang.org>
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This makes names like ANOP, ATEXT, AGLOBL, ACALL, AJMP, ARET
available for use by architecture-independent processing passes.
On arm and ppc64, the alternate names are now aliases for the
official ones (ABL for ACALL, AB or ABR for AJMP, ARETURN for ARET).
Change-Id: Id027771243795af2b3745199c645b6e1bedd7d18
Reviewed-on: https://go-review.googlesource.com/3577
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Reviewed-by: Austin Clements <austin@google.com>
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Before, amd64 and 386 stored the flags in p->from.scale
and arm and ppc64 stored the flags in p->reg.
Both caused special cases in printing and in handling of the
addresses.
To avoid possible conflicts with the real meaning of p->from
and to avoid storing a non-register value in a reg field,
use from3 to hold a TYPE_CONST value giving the flags.
There is still a special case for printing, because the flags
are specified without a $, and normally a TYPE_CONST prints
with a $. But that's much less special than what came before.
This allows us to remove the textflag and settextflag methods
from LinkArch. They are no longer architecture-specific.
Change-Id: I931da8e1ecd92e127cd9aa44ef5a73c42e730110
Reviewed-on: https://go-review.googlesource.com/3572
Reviewed-by: Austin Clements <austin@google.com>
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Change-Id: Ia6f8badca56565b9df80c8dbe28c47f6cf7e653f
Reviewed-on: https://go-review.googlesource.com/3515
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
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Pointers change from run to run, making it hard to use
the debug output to identify the reason for a changed
object file.
Change-Id: I0c954da0943092c48686afc99ecf75eba516de6a
Reviewed-on: https://go-review.googlesource.com/3352
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Reviewed-by: Rob Pike <r@golang.org>
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This CL enables moving the bulk of the object writing code
out of liblink and into translated Go libraries in cmd/internal/obj,
but it does not do the move.
This CL introduces two new environment variables,
$GOOBJ and $GOOBJWRITER, but both will be deleted along with
the rest of the liblink C code.
The default behavior of a build is unchanged by this CL:
the C version of liblink uses the C object layout and writing code.
If $GOOBJ=1, liblink invokes go tool objwriter instead.
If $GOOBJ=2, liblink does its own layout and then invokes
go tool objwriter, which checks that it gets the same answer.
That is, in $GOOBJ=2 mode, both the C and the Go version of
the code run, and the operation fails if the two produce different
answers. This provides a very strong check that the translation
is working correctly.
Change-Id: I56ab49b07ccb2c7b81085f1d6950131047c6aa3c
Reviewed-on: https://go-review.googlesource.com/3048
Reviewed-by: Ian Lance Taylor <iant@golang.org>
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Executing 'clean -i std' removes installed Go programs,
including the toolchain binaries we need for building.
It's not clear why the 'clean -i std' is here in the first place.
cmd/dist just removed the entire pkg tree, so everything is new.
The only reason for 'clean -i std' would be if you don't trust
that dist compiled the packages properly. If that's true for
some reason, we can fix cmd/dist, or add -a to the install
commands that follow. Perhaps clean -i std should not
remove tools, or perhaps std should not expand to any tools.
Not sure.
Also remove banner from make.bat and make.rc that was
already removed from make.bash. cmd/dist prints it now.
Also fix array size error in liblink/objfile.c.
Fixes dev.cc build.
Change-Id: I60855e001a682efce55ad9aa307a8f3ee47f7366
Reviewed-on: https://go-review.googlesource.com/3100
Reviewed-by: Russ Cox <rsc@golang.org>
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This doesn't actually use objwriter for any real work.
It's just to check that objwriter is available.
The real work will be moved once the bootstrapping
mechanisms are working.
Change-Id: I5f41c8910c4b11b9d80cb0b0847ff9cb582fc2be
Reviewed-on: https://go-review.googlesource.com/3045
Reviewed-by: Ian Lance Taylor <iant@golang.org>
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This reverts commit ab0535ae3fb45ba734d47542cc4845f27f708d1b.
I think it will remain useful to distinguish code that must
run on a system stack from code that can run on either stack,
even if that distinction is no
longer based on the implementation language.
That is, I expect to add a //go:systemstack comment that,
in terms of the old implementation, tells the compiler,
to pretend this function was written in C.
Change-Id: I33d2ebb2f99ae12496484c6ec8ed07233d693275
Reviewed-on: https://go-review.googlesource.com/2275
Reviewed-by: Russ Cox <rsc@golang.org>
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Now that we've removed all the C code in runtime and the C compilers,
there is no need to have a separate stackguard field to check for C
code on Go stack.
Remove field g.stackguard1 and rename g.stackguard0 to g.stackguard.
Adjust liblink and cmd/ld as necessary.
Change-Id: I54e75db5a93d783e86af5ff1a6cd497d669d8d33
Reviewed-on: https://go-review.googlesource.com/2144
Reviewed-by: Keith Randall <khr@golang.org>
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This is to reduce the delta between dev.cc and dev.garbage to just garbage collector changes.
These are the files that had merge conflicts and have been edited by hand:
malloc.go
mem_linux.go
mgc.go
os1_linux.go
proc1.go
panic1.go
runtime1.go
LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/174180043
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If the linker finds the same name given a BSS and a non-BSS
symbol, the assumption is that the non-BSS symbol is the
true one, and the BSS symbol is just the best Go can do toward
an "extern" declaration. This has always been the case,
as long as the object files were read in the right order.
The old code worked when the BSS symbol is found before
the non-BSS symbol. This CL adds equivalent logic for when
the non-BSS symbol is found before the BSS symbol.
This comes up when Go must refer to symbols defined in
host object files.
LGTM=r
R=r
CC=austin, golang-codereviews, iant, khr
https://golang.org/cl/171480043
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This brings dev.power64 up-to-date with the current tip of
default. go_bootstrap is still panicking with a bad defer
when initializing the runtime (even on amd64).
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/152570049
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LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/160200044
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This fixes the test/linkx.go test, which does not run by default.
(Issue 4139 is about fixing that.)
Fixes #8806.
LGTM=r
R=golang-codereviews, r
CC=bradfitz, golang-codereviews, iant
https://golang.org/cl/145420043
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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 #909.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/149770043
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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://golang.org/cl/143160045
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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 #8753.
LGTM=khr, iant
R=golang-codereviews, iant, khr, bradfitz
CC=golang-codereviews, r, rlh
https://golang.org/cl/142150043
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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://golang.org/cl/137520043
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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://golang.org/cl/135170044
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show rel addend in hex for RISC arches
LGTM=rsc
R=rsc, iant
CC=golang-codereviews
https://golang.org/cl/127770043
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Rather than switch on thechar.
LGTM=rsc, dave
R=rsc, iant, dave
CC=golang-codereviews
https://golang.org/cl/119330043
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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 #6931.
Fixes #7623.
LGTM=iant
R=golang-codereviews, iant, ality
CC=golang-codereviews, r
https://golang.org/cl/88190043
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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://golang.org/cl/88210045
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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 #7338.
Fixes #7347.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/88550043
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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 #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*3ⁿ to the hash, where n is the length of the name.
A collision would need x*3ⁿ ≡ y*3ⁿ (mod 2²⁴ mod 100003),
or equivalently x*3ⁿ ≡ x*3ⁿ + (y-x)*3ⁿ (mod 2²⁴ mod 100003),
so collisions will actually be periodic: versions x and y collide
when d = y-x satisfies d*3ⁿ ≡ 0 (mod 2²⁴ 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://golang.org/cl/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://golang.org/cl/87910047
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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 #7164.
LGTM=iant
R=iant, aram, minux.ma, dave
CC=golang-codereviews
https://golang.org/cl/87920043
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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://golang.org/cl/87670044
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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://golang.org/cl/87670043
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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
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This makes the linker's -X flag work again.
R=iant
CC=bradfitz, golang-codereviews, golang-dev
https://golang.org/cl/44360043
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Overloading size leads to problems if clients
try to set up an LSym by hand.
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/44140043
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Address several warnings generated by clang -fsanitize=undefined
R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/43050043
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At least three Go tests rely on that (log, runtime/{pprof,debug}).
Fixes #6972.
Fixes #6974.
Fixes #6975.
R=alex.brainman, mattn.jp, rsc
CC=golang-dev
https://golang.org/cl/43150043
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- new object file reader/writer (liblink/objfile.c)
- remove old object file writing routines
- add pcdata iterator
- remove all trace of "line number stack" and "path fragments" from
object files, linker (!!!)
- dwarf now writes a single "compilation unit" instead of one per package
This CL disables the check for chains of no-split functions that
could overflow the stack red zone. A future CL will attack the problem
of reenabling that check (issue 6931).
This CL is just the liblink and cmd/ld changes.
There are minor associated adjustments in CL 37030045.
Each depends on the other.
R=golang-dev, dave, iant
CC=golang-dev
https://golang.org/cl/39680043
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