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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
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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
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MOVBS and MOVHS are defined as duplicates of MOVB and MOVH,
and perform sign-extension moving.
No change is made to code generation.
Update #1837
R=rsc, bradfitz
CC=golang-dev
https://golang.org/cl/12682043
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This CL introduces a FUNCDATA number for runtime-specific
garbage collection metadata, changes the C and Go compilers
to emit that metadata, and changes the runtime to expect it.
The old pseudo-instructions that carried this information
are gone, as is the linker code to process them.
R=golang-dev, dvyukov, cshapiro
CC=golang-dev
https://golang.org/cl/11406044
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The portable code in cmd/ld already knows how to process it,
we just have to ignore it during code generation.
R=ken2
CC=golang-dev
https://golang.org/cl/11363043
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The type information is (and for years has been) included
as an extra field in the address chunk of an instruction.
Unfortunately, suppose there is a string at a+24(FP) and
we have an instruction reading its length. It will say:
MOVQ x+32(FP), AX
and the type of *that* argument is int (not slice), because
it is the length being read. This confuses the picture seen
by debuggers and now, worse, by the garbage collector.
Instead of attaching the type information to all uses,
emit an explicit list of TYPE instructions with the information.
The TYPE instructions are no-ops whose only role is to
provide an address to attach type information to.
For example, this function:
func f(x, y, z int) (a, b string) {
return
}
now compiles into:
--- prog list "f" ---
0000 (/Users/rsc/x.go:3) TEXT f+0(SB),$0-56
0001 (/Users/rsc/x.go:3) LOCALS ,
0002 (/Users/rsc/x.go:3) TYPE x+0(FP){int},$8
0003 (/Users/rsc/x.go:3) TYPE y+8(FP){int},$8
0004 (/Users/rsc/x.go:3) TYPE z+16(FP){int},$8
0005 (/Users/rsc/x.go:3) TYPE a+24(FP){string},$16
0006 (/Users/rsc/x.go:3) TYPE b+40(FP){string},$16
0007 (/Users/rsc/x.go:3) MOVQ $0,b+40(FP)
0008 (/Users/rsc/x.go:3) MOVQ $0,b+48(FP)
0009 (/Users/rsc/x.go:3) MOVQ $0,a+24(FP)
0010 (/Users/rsc/x.go:3) MOVQ $0,a+32(FP)
0011 (/Users/rsc/x.go:4) RET ,
The { } show the formerly hidden type information.
The { } syntax is used when printing from within the gc compiler.
It is not accepted by the assemblers.
The same type information is now included on global variables:
0055 (/Users/rsc/x.go:15) GLOBL slice+0(SB){[]string},$24(AL*0)
This more accurate type information fixes a bug in the
garbage collector's precise heap collection.
The linker only cares about globals right now, but having the
local information should make things a little nicer for Carl
in the future.
Fixes #4907.
R=ken2
CC=golang-dev
https://golang.org/cl/7395056
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locals information
Previously, the func structure contained an inaccurate value for
the args member and a 0 value for the locals member.
This change populates the func structure with args and locals
values computed by the compiler. The number of args was
already available in the ATEXT instruction. The number of
locals is now passed through in the new ALOCALS instruction.
This change also switches the unit of args and locals to be
bytes, just like the frame member, instead of 32-bit words.
R=golang-dev, bradfitz, cshapiro, dave, rsc
CC=golang-dev
https://golang.org/cl/7399045
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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
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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
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This is an experiment in static analysis of Go programs
to understand which struct fields a program might use.
It is not part of the Go language specification, it must
be enabled explicitly when building the toolchain,
and it may be removed at any time.
After building the toolchain with GOEXPERIMENT=fieldtrack,
a specific field can be marked for tracking by including
`go:"track"` in the field tag:
package pkg
type T struct {
F int `go:"track"`
G int // untracked
}
To simplify usage, only named struct types can have
tracked fields, and only exported fields can be tracked.
The implementation works by making each function begin
with a sequence of no-op USEFIELD instructions declaring
which tracked fields are accessed by a specific function.
After the linker's dead code elimination removes unused
functions, the fields referred to by the remaining
USEFIELD instructions are the ones reported as used by
the binary.
The -k option to the linker specifies the fully qualified
symbol name (such as my/pkg.list) of a string variable that
should be initialized with the field tracking information
for the program. The field tracking string is a sequence
of lines, each terminated by a \n and describing a single
tracked field referred to by the program. Each line is made
up of one or more tab-separated fields. The first field is
the name of the tracked field, fully qualified, as in
"my/pkg.T.F". Subsequent fields give a shortest path of
reverse references from that field to a global variable or
function, corresponding to one way in which the program
might reach that field.
A common source of false positives in field tracking is
types with large method sets, because a reference to the
type descriptor carries with it references to all methods.
To address this problem, the CL also introduces a comment
annotation
//go:nointerface
that marks an upcoming method declaration as unavailable
for use in satisfying interfaces, both statically and
dynamically. Such a method is also invisible to package
reflect.
Again, all of this is disabled by default. It only turns on
if you have GOEXPERIMENT=fieldtrack set during make.bash.
R=iant, ken
CC=golang-dev
https://golang.org/cl/6749064
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Part of issue 3747.
R=dave, lvd, rsc
CC=golang-dev
https://golang.org/cl/6084044
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R=golang-dev, dave, rsc, minux.ma
CC=golang-dev
https://golang.org/cl/6225051
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Supported in ARMv5TE and above.
Also corrected MULA disassembly listing.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6265045
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Supported in ARMv5 and above.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6284043
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On 6l and 8l, this is a real instruction, guaranteed to
cause an 'undefined instruction' exception.
On 5l, we simulate it as BL to address 0.
The plan is to use it as a signal to the linker that this
point in the instruction stream cannot be reached
(hence the changes to nofollow). This will help the
compiler explain that panicindex and friends do not
return without having to put a list of these functions
in the linker.
R=ken2
CC=golang-dev
https://golang.org/cl/6255064
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Part 1 of CL 5601044 (cgo: Linux/ARM support)
Limitation: doesn't support thumb library yet.
R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/5991065
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Supported in ARMv5TE and above, excluding ARMv5TExP.
For CL 5990066.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5999044
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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
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The dynamic ELF sections were pointing to the proper data,
but that data was already owned by the rodata and text sections.
Some ELF references explicitly prohibit multiple sections from
owning the same data, and strip behaves accordingly.
The data for these sections was moved out and their ranges are
now owned by their respective sections. This change makes strip
happy both with and without -s being provided at link time.
A test was added in debug/elf to ensure there are no regressions
on this area in the future.
Fixes #1242.
Fixes #2022.
NOTE: Tested on Linux amd64/386/arm only.
R=rsc
CC=golang-dev
https://golang.org/cl/4808043
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Should fix the arm build.
R=golang-dev, dsymonds, adg
CC=golang-dev
https://golang.org/cl/4777041
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5a/a.h:
. Removed <u.h> and <lib.h>.
. Made definition of EOF conditional.
5a/a.y:
. Added <u.h> and <lib.h>.
5a/lex.c:
. Added <u.h> and <lib.h>.
. Dropped <ctype.h> (now in <u.h>).
5c/peep.c:
. Removed unnecessary "return 0" statement.
5c/reg.c:
. Added compilation condition around unused code.
5c/swt.c:
. Removed unused "thestring" argument from Bprint() calls.
5l/asm.c:
. Added USED() statements as required.
. Adjusted a few format specifications.
. Added compilation condition around unused code.
5l/l.h:
. Dropped directory prefix from <../5l/5.out.h>.
. Added varargck pragma for "I" and "i".
5l/obj.c:
. Cascaded consecutive "if" statements.
. Dropped unnecessary incrementation and assignments.
5l/pass.c:
. Dropped unnecessary assignment.
5l/prof.c:
. #if 0 converted to #ifdef NOTDEF.
5l/span.c:
. Dropped unnecessary incrementation and assignments.
R=golang-dev
CC=golang-dev, rsc
https://golang.org/cl/4752041
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Thumb code and ARM pre-V4 code is unused,
unmaintained, and almost certainly wrong by now.
Every time I try to change 5l I have to sort out
what's dead code and what's not.
30% of lines of code in this directory deleted.
R=ken2
CC=golang-dev
https://golang.org/cl/4601049
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5a: add SQRTF and SQRTD
5l: add ASQRTF and ASQRTD
Use ARMv7 VFP VSQRT instruction to speed up math.Sqrt
R=rsc, dave, m
CC=golang-dev
https://golang.org/cl/4551082
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R=rsc, iant
CC=golang-dev
https://golang.org/cl/4538083
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Add implementation for addr<->reg short moves.
Align large data, for ARM.
R=ken2
CC=golang-dev
https://golang.org/cl/4545050
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R=ken2
CC=golang-dev
https://golang.org/cl/4239041
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R=r
CC=golang-dev
https://golang.org/cl/4000041
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R=rsc
CC=golang-dev
https://golang.org/cl/3053041
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currently, softfloat does not work and
there are some unsigned-to-float conversion errors.
R=rsc
CC=golang-dev
https://golang.org/cl/2886041
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That is, move the pc/ln table and the symbol table
into the read-only data segment. This eliminates
the need for a special load command to map the
symbol table into memory, which makes the
information available on systems that couldn't handle
the magic load to 0x99000000, like NaCl and ARM QEMU
and Linux without config_highmem=y. It also
eliminates an #ifdef and some clumsy code to
find the symbol table on Windows.
The bad news is that the binary appears to be bigger
than it used to be. This is not actually the case, though:
the same amount of data is being mapped into memory
as before, and the tables are still read-only, so they're
still shared across multiple instances of the binary as
they were before. The difference is just that the tables
aren't squirreled away in some section that "size" doesn't
know to look at.
This is a checkpoint.
It probably breaks Windows and breaks NaCl more
than it used to be broken, but those will be fixed.
The logic involving -s needs to be revisited too.
Fixes #871.
R=ken2
CC=golang-dev
https://golang.org/cl/2587041
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Lay out code before data.
R=ken2
CC=golang-dev
https://golang.org/cl/2490043
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R=ken2
CC=golang-dev
https://golang.org/cl/2479043
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Because the SB is only good for 8k and Go programs
tend to have much more data than that, SB doesn't
save very much. A fmt.Printf-based hello world program
has 360 kB text segment. Removing SB makes the text
500 bytes (0.14%) longer.
R=ken2, r2, ken3
CC=golang-dev
https://golang.org/cl/2487042
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Using explicit relocations internally, we can
represent the data for a particular symbol as
an initialized block of memory instead of a
linked list of ADATA instructions. The real
goal here is to be able to hand off some of the
relocations to the dynamic linker when interacting
with system libraries, but a pleasant side effect is
that the memory image is much more compact
than the ADATA list, so the linkers use less memory.
R=ken2
CC=golang-dev
https://golang.org/cl/2512041
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The Plan 9 tools assume that long is 32 bits.
We converted all instances of long to int32 when
importing the code but missed the print formats.
Because int32 is always int on the compilers we use,
it is never correct to use %lux, %ld, etc. Convert to %ux, %d, etc.
(It matters because on 64-bit gcc, long is 64 bits,
so we were printing 32-bit quantities with 64-bit formats.)
R=ken2
CC=golang-dev
https://golang.org/cl/2491041
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* Maintain Sym* list for text with individual
prog lists instead of using one huge list and
overloading p->pcond.
* Comment what each file is for.
* Move some output code from span.c to asm.c.
* Move profiling into prof.c, symbol table into symtab.c.
* Move mkfwd to ld/lib.c.
* Throw away dhog dynamic loading code.
* Throw away Alef become.
* Fix printing of WORD instructions in 5l -a.
Goal here is to be able to handle each piece of text or data
as a separate piece, both to make it easier to load the
occasional .o file and also to make it possible to split the
work across multiple threads.
R=ken2, r, ken3
CC=golang-dev
https://golang.org/cl/2335043
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This is entirely adding and removing tabs.
It looks weird but will make the diffs for the
next change easier to read.
R=ken2
CC=golang-dev
https://golang.org/cl/2490041
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5l, 6l, 8l: change ELF header so that strip doesn't destroy binary
Fixes #261.
R=iant, r
CC=golang-dev
https://golang.org/cl/994044
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R=rsc
APPROVED=rsc
DELTA=30 (30 added, 0 deleted, 0 changed)
OCL=35751
CL=35756
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R=r
DELTA=3214 (904 added, 2260 deleted, 50 changed)
OCL=35425
CL=35427
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R=rsc
APPROVED=rsc
DELTA=4 (0 added, 0 deleted, 4 changed)
OCL=31016
CL=31126
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combination.
R=rsc
APPROVED=rsc
DELTA=69 (68 added, 0 deleted, 1 changed)
OCL=30798
CL=30801
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R=rsc
APPROVED=rsc
DELTA=72 (12 added, 52 deleted, 8 changed)
OCL=30748
CL=30793
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- morestack support for 5l and arm runtime
- argsize support in 5c, 5l, ar and nm. assembly code from 5a
will break in interesting ways unless NOSPLIT is specified
- explicit cond execution constants
- fix 5l output to use %d instead of %ld so that negative
values show.
- added a lot of code to arm/asm.s. runtime entry code almost
working currently aborts at gogo not implemented
R=rsc
APPROVED=rsc
DELTA=305 (125 added, 29 deleted, 151 changed)
OCL=30246
CL=30347
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and expected review latency I needed to combine the CLs.
1. Made the 5* toolpath build using the go build
system. Hooked the subdirectories to clean.bash but added a
separate make5.bash for now. Minor massage to make the code
more similar to the current structure of 6c/6a/6l.
2. Change all references from long to int32 in line with
similar change for the other toolchains.
The end result is that 5c, 5a and 5l can now be compiled and
the executables start up properly. Haven't thrown any input at
them yet.
R=rsc
APPROVED=rsc
DELTA=1052 (392 added, 328 deleted, 332 changed)
OCL=26757
CL=26761
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R=rsc
APPROVED=rsc
DELTA=19042 (19042 added, 0 deleted, 0 changed)
OCL=26268
CL=26270
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