Preparation for golang.org/s/go13linker work.
This CL does not build by itself. It depends on 35740044
and 35790044 and will be submitted at the same time.
R=iant
CC=golang-dev
https://golang.org/cl/34590045
This change allows the garbage collector to examine stack
slots that are determined as live and containing a pointer
value by the garbage collector. This results in a mean
reduction of 65% in the number of stack slots scanned during
an invocation of "GOGC=1 all.bash".
Unfortunately, this does not yet allow garbage collection to
be precise for the stack slots computed as live. Pointers
confound the determination of what definitions reach a given
instruction. In general, this problem is not solvable without
runtime cost but some advanced cooperation from the compiler
might mitigate common cases.
R=golang-dev, rsc, cshapiro
CC=golang-dev
https://golang.org/cl/14430048
This eliminates ~75% of the nil checks being emitted,
on all architectures. We can do better, but we need
a bit more general support from the compiler, and
I don't want to do that so close to Go 1.2.
What's here is simple but effective and safe.
A few small code generation cleanups were required
to make the analysis consistent on all systems about
which nil checks are omitted, at least in the test.
Fixes#6019.
R=ken2
CC=golang-dev
https://golang.org/cl/13334052
When the new call site-specific frame bitmaps are available,
we can cut the zeroing to just those values that need it due
to scope escaping.
R=cshapiro, cshapiro
CC=golang-dev
https://golang.org/cl/13045043
See golang.org/s/go12nil.
This CL is about getting all the right checks inserted.
A followup CL will add an optimization pass to
remove redundant checks.
R=ken2
CC=golang-dev
https://golang.org/cl/12970043
On entry to a function, zero the results and zero the pointer
section of the local variables.
This is an intermediate step on the way to precise collection
of Go frames.
This can incur a significant (up to 30%) slowdown, but it also ensures
that the garbage collector never looks at a word in a Go frame
and sees a stale pointer value that could cause a space leak.
(C frames and assembly frames are still possibly problematic.)
This CL is required to start making collection of interface values
as precise as collection of pointer values are today.
Since we have to dereference the interface type to understand
whether the value is a pointer, it is critical that the type field be
initialized.
A future CL by Carl will make the garbage collection pointer
bitmaps context-sensitive. At that point it will be possible to
remove most of the zeroing. The only values that will still need
zeroing are values whose addresses escape the block scoping
of the function but do not escape to the heap.
benchmark old ns/op new ns/op delta
BenchmarkBinaryTree17 4420289180 4331060459 -2.02%
BenchmarkFannkuch11 3442469663 3277706251 -4.79%
BenchmarkFmtFprintfEmpty 100 142 +42.00%
BenchmarkFmtFprintfString 262 310 +18.32%
BenchmarkFmtFprintfInt 213 281 +31.92%
BenchmarkFmtFprintfIntInt 355 431 +21.41%
BenchmarkFmtFprintfPrefixedInt 321 383 +19.31%
BenchmarkFmtFprintfFloat 444 533 +20.05%
BenchmarkFmtManyArgs 1380 1559 +12.97%
BenchmarkGobDecode 10240054 11794915 +15.18%
BenchmarkGobEncode 17350274 19970478 +15.10%
BenchmarkGzip 455179460 460699139 +1.21%
BenchmarkGunzip 114271814 119291574 +4.39%
BenchmarkHTTPClientServer 89051 89894 +0.95%
BenchmarkJSONEncode 40486799 52691558 +30.15%
BenchmarkJSONDecode 94193361 112428781 +19.36%
BenchmarkMandelbrot200 4747060 4748043 +0.02%
BenchmarkGoParse 6363798 6675098 +4.89%
BenchmarkRegexpMatchEasy0_32 129 171 +32.56%
BenchmarkRegexpMatchEasy0_1K 365 395 +8.22%
BenchmarkRegexpMatchEasy1_32 106 152 +43.40%
BenchmarkRegexpMatchEasy1_1K 952 1245 +30.78%
BenchmarkRegexpMatchMedium_32 198 283 +42.93%
BenchmarkRegexpMatchMedium_1K 79006 101097 +27.96%
BenchmarkRegexpMatchHard_32 3478 5115 +47.07%
BenchmarkRegexpMatchHard_1K 110245 163582 +48.38%
BenchmarkRevcomp 777384355 793270857 +2.04%
BenchmarkTemplate 136713089 157093609 +14.91%
BenchmarkTimeParse 1511 1761 +16.55%
BenchmarkTimeFormat 535 850 +58.88%
benchmark old MB/s new MB/s speedup
BenchmarkGobDecode 74.95 65.07 0.87x
BenchmarkGobEncode 44.24 38.43 0.87x
BenchmarkGzip 42.63 42.12 0.99x
BenchmarkGunzip 169.81 162.67 0.96x
BenchmarkJSONEncode 47.93 36.83 0.77x
BenchmarkJSONDecode 20.60 17.26 0.84x
BenchmarkGoParse 9.10 8.68 0.95x
BenchmarkRegexpMatchEasy0_32 247.24 186.31 0.75x
BenchmarkRegexpMatchEasy0_1K 2799.20 2591.93 0.93x
BenchmarkRegexpMatchEasy1_32 299.31 210.44 0.70x
BenchmarkRegexpMatchEasy1_1K 1074.71 822.45 0.77x
BenchmarkRegexpMatchMedium_32 5.04 3.53 0.70x
BenchmarkRegexpMatchMedium_1K 12.96 10.13 0.78x
BenchmarkRegexpMatchHard_32 9.20 6.26 0.68x
BenchmarkRegexpMatchHard_1K 9.29 6.26 0.67x
BenchmarkRevcomp 326.95 320.40 0.98x
BenchmarkTemplate 14.19 12.35 0.87x
R=cshapiro
CC=golang-dev
https://golang.org/cl/12616045
This is required to properly unwind reflect.methodValueCall/makeFuncStub.
Fixes#5954.
Stats for 'go install std':
61849 total INSTCALL
24655 currently have ArgSize metadata
27278 have ArgSize metadata with this change
godoc size before: 11351888, after: 11364288
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12163043
clearfat (used to zero initialize structures) will use AX for x86 block ops. If we write to AX while calculating the dest pointer, we will fill the structure with incorrect values.
Since 64-bit arithmetic uses AX to synthesize a 64-bit register, getting an adress by indexing with 64-bit ops can clobber the register.
Fixes#5820.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/11383043
If calling a function in package runtime, emit argument size
information around the call in case the call is to a variadic C function.
R=ken2
CC=golang-dev
https://golang.org/cl/11371043
Deferred functions are not run by a call instruction. They are run by
the runtime editing registers to make the call start with a caller PC
returning to a
CALL deferreturn
instruction.
That instruction has always had the line number of the function's
closing brace, but that instruction's line number is irrelevant.
Stack traces show the line number of the instruction before the
return PC, because normally that's what started the call. Not so here.
The instruction before the CALL deferreturn could be almost anywhere
in the function; it's unrelated and its line number is incorrect to show.
Fix the line number by inserting a true hardware no-op with the right
line number before the returned-to CALL instruction. That is, the deferred
calls now appear to start with a caller PC returning to the second instruction
in this sequence:
NOP
CALL deferreturn
The traceback will show the line number of the NOP, which we've set
to be the line number of the function's closing brace.
The NOP here is not the usual pseudo-instruction, which would be
elided by the linker. Instead it is the real hardware instruction:
XCHG AX, AX on 386 and amd64, and AND.EQ R0, R0, R0 on ARM.
Fixes#5856.
R=ken2, ken
CC=golang-dev
https://golang.org/cl/11223043
Keeping the string "compactframe" because that's what
I always search for to find this code. But point to the real place too.
TBR=iant
CC=golang-dev
https://golang.org/cl/10676047
Requires adding new linker instruction
RET f(SB)
meaning return but then immediately call f.
This is what you'd use to implement a tail call after
fiddling with the arguments, but the compiler only
uses it in genwrapper.
This CL eliminates the copy-and-paste genembedtramp
functions from 5g/8g/6g and makes the code run on ARM
for the first time. It removes a small special case for function
generation, which should help Carl a bit, but at the same time
it does not bother to implement general tail call optimization,
which we do not want anyway.
Fixes#5627.
R=ken2
CC=golang-dev
https://golang.org/cl/10057044
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
Change ARM context register to R7, to get out of the way
of the register allocator during the compilation of the
prologue statements (it wants to use R0 as a temporary).
Step 2 of http://golang.org/s/go11func.
R=ken2
CC=golang-dev
https://golang.org/cl/7369048
runtime: add context argument to gogocall
Too many other things use AX, and at least one
(stack zeroing) cannot be moved onto a different
register. Use the less special DX instead.
Preparation for step 2 of http://golang.org/s/go11func.
Nothing interesting here, just split out so that we can
see it's correct before moving on.
R=ken2
CC=golang-dev
https://golang.org/cl/7395050
A new environment variable GO386 is introduced to choose between
code generation targeting 387 or SSE2. No auto-detection is
performed and the setting defaults to 387 to preserve previous
behaviour.
The patch is a reorganization of CL6549052 by rsc.
Fixes#3912.
R=minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6962043
Change suggested by iant. The compiler generates
special code for a/b when a is -0x80...0 and b = -1.
A single instruction can cover the case where b is -1,
so only one comparison is needed.
Fixes#3551.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6922049
This allows 5g and 8g to benefit from the rewrite as shifts
or magic multiplies. The 64-bit arithmetic is not handled there,
and left in 6g.
Update #2230.
R=golang-dev, dave, mtj, iant, rsc
CC=golang-dev
https://golang.org/cl/6819123
In two cases, registers were allocated too early resulting
in exhausting of available registers when nesting these
operations.
The case of method calls was due to missing cases in igen,
which only makes calls but doesn't allocate a register for
the result.
The case of 8-bit multiplication was due to a wrong order
in register allocation when Ullman numbers were bigger on the
RHS.
Fixes#3907.
Fixes#4156.
R=rsc
CC=golang-dev, remy
https://golang.org/cl/6560054
It is enough to load directly the data word and the itab word
from memory, so we save a LEA instruction for each method call,
and allow elimination of some extra temporaries.
Update #1914.
R=daniel.morsing, rsc
CC=golang-dev, remy
https://golang.org/cl/6501110
Drop expecttaken function in favor of extra argument
to gbranch and bgen. Mark loop condition as likely to
be true, so that loops are generated inline.
The main benefit here is contiguous code when trying
to read the generated assembly. It has only minor effects
on the timing, and they mostly cancel the minor effects
that aligning function entry points had. One exception:
both changes made Fannkuch faster.
Compared to before CL 6244066 (before aligned functions)
benchmark old ns/op new ns/op delta
BenchmarkBinaryTree17 4222117400 4201958800 -0.48%
BenchmarkFannkuch11 3462631800 3215908600 -7.13%
BenchmarkGobDecode 20887622 20899164 +0.06%
BenchmarkGobEncode 9548772 9439083 -1.15%
BenchmarkGzip 151687 152060 +0.25%
BenchmarkGunzip 8742 8711 -0.35%
BenchmarkJSONEncode 62730560 62686700 -0.07%
BenchmarkJSONDecode 252569180 252368960 -0.08%
BenchmarkMandelbrot200 5267599 5252531 -0.29%
BenchmarkRevcomp25M 980813500 985248400 +0.45%
BenchmarkTemplate 361259100 357414680 -1.06%
Compared to tip (aligned functions):
benchmark old ns/op new ns/op delta
BenchmarkBinaryTree17 4140739800 4201958800 +1.48%
BenchmarkFannkuch11 3259914400 3215908600 -1.35%
BenchmarkGobDecode 20620222 20899164 +1.35%
BenchmarkGobEncode 9384886 9439083 +0.58%
BenchmarkGzip 150333 152060 +1.15%
BenchmarkGunzip 8741 8711 -0.34%
BenchmarkJSONEncode 65210990 62686700 -3.87%
BenchmarkJSONDecode 249394860 252368960 +1.19%
BenchmarkMandelbrot200 5273394 5252531 -0.40%
BenchmarkRevcomp25M 996013800 985248400 -1.08%
BenchmarkTemplate 360620840 357414680 -0.89%
R=ken2
CC=golang-dev
https://golang.org/cl/6245069
The old code generated for a bounds check was
CMP
JLT ok
CALL panicindex
ok:
...
The new code is (once the linker finishes with it):
CMP
JGE panic
...
panic:
CALL panicindex
which moves the calls out of line, putting more useful
code in each cache line. This matters especially in tight
loops, such as in Fannkuch. The benefit is more modest
elsewhere, but real.
From test/bench/go1, amd64:
benchmark old ns/op new ns/op delta
BenchmarkBinaryTree17 6096092000 6088808000 -0.12%
BenchmarkFannkuch11 6151404000 4020463000 -34.64%
BenchmarkGobDecode 28990050 28894630 -0.33%
BenchmarkGobEncode 12406310 12136730 -2.17%
BenchmarkGzip 179923 179903 -0.01%
BenchmarkGunzip 11219 11130 -0.79%
BenchmarkJSONEncode 86429350 86515900 +0.10%
BenchmarkJSONDecode 334593800 315728400 -5.64%
BenchmarkRevcomp25M 1219763000 1180767000 -3.20%
BenchmarkTemplate 492947600 483646800 -1.89%
And 386:
benchmark old ns/op new ns/op delta
BenchmarkBinaryTree17 6354902000 6243000000 -1.76%
BenchmarkFannkuch11 8043769000 7326965000 -8.91%
BenchmarkGobDecode 19010800 18941230 -0.37%
BenchmarkGobEncode 14077500 13792460 -2.02%
BenchmarkGzip 194087 193619 -0.24%
BenchmarkGunzip 12495 12457 -0.30%
BenchmarkJSONEncode 125636400 125451400 -0.15%
BenchmarkJSONDecode 696648600 685032800 -1.67%
BenchmarkRevcomp25M 2058088000 2052545000 -0.27%
BenchmarkTemplate 602140000 589876800 -2.04%
To implement this, two new instruction forms:
JLT target // same as always
JLT $0, target // branch expected not taken
JLT $1, target // branch expected taken
The linker could also emit the prediction prefixes, but it
does not: expected taken branches are reversed so that the
expected case is not taken (as in example above), and
the default expectaton for such a jump is not taken
already.
R=golang-dev, gri, r, dave
CC=golang-dev
https://golang.org/cl/6248049
* Eliminate bounds check on known small shifts.
* Rewrite x<<s | x>>(32-s) as a rotate (constant s).
* More aggressive (but still minimal) range analysis.
R=ken, dave, iant
CC=golang-dev
https://golang.org/cl/6209077
Such variables would be put at 0(SP), leading to serious
corruptions at zero initialization.
Fixes#3084.
R=golang-dev, r
CC=golang-dev, remy
https://golang.org/cl/5683052
8g/cgen.c:
8g/gobj.c
. dropped unnecessary assignments;
8g/gg.h
. added varargckk pragmas;
8g/ggen.c
. dropped duplicate assignment;
8g/gsubr.c
. adjusted format in print statement;
. dropped unnecessary assignment;
. replaced GCC's _builtin_return_address(0) with Plan 9's
getcallerpc(&n) which is defined as a macro in <u.h>;
8g/list.c
. adjusted format in snprint statement;
8g/opt.h
. added varargck pragma (Adr*) that is specific for the invoking
modules;
8g/peep.c
. dropped unnecessary incrementation;
R=rsc
CC=golang-dev
https://golang.org/cl/4974044
#include "go.h" (or "gg.h")
becomes
#include <u.h>
#include <libc.h>
#include "go.h"
so that go.y can #include <stdio.h>
after <u.h> but before "go.h".
This is necessary on Plan 9.
R=ken2
CC=golang-dev
https://golang.org/cl/4971041
Required moving some parts of gc/pgen.c to ?g/ggen.c
on linux tests pass for all 3 architectures, and
frames are actually compacted (diagnostic code for
that has been removed from the CL).
R=rsc
CC=golang-dev
https://golang.org/cl/4571071
The recent linker changes broke NaCl support
a month ago, and there are no known users of it.
The NaCl code can always be recovered from the
repository history.
R=adg, r
CC=golang-dev
https://golang.org/cl/3671042
No semantic changes here, but working
toward being able to align structs based
on the maximum alignment of the fields
inside instead of having a fixed alignment
for all structs (issue 482).
R=ken2
CC=golang-dev
https://golang.org/cl/3617041
