Commit graph

438 commits

Author SHA1 Message Date
Josh Bleecher Snyder
5abf5f831e cmd/compile: clarify Node.NonNil and Node.Bounded
Node.NonNil and Node.Bounded were a bit muddled. This led to #38496.
This change clarifies and documents them.

It also corrects one misuse.
However, since ssa conversion doesn't make full use of the bounded hint,
this correction doesn't change any generated code.
The next change will fix that.

Passes toolstash-check.

Change-Id: I2bcd487a0a4aef5d7f6090e653974fce0dce3b8e
Reviewed-on: https://go-review.googlesource.com/c/go/+/228787
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2020-04-20 16:35:40 +00:00
Cuong Manh Le
62ccee49d6 cmd/compile: refactor detecting package reflect logic
Passes toolstash-check.

Change-Id: Ie4b1f61528bb183dc66bb6955851a47b2641549c
Reviewed-on: https://go-review.googlesource.com/c/go/+/228859
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2020-04-20 02:39:16 +00:00
Cherry Zhang
a32262d462 cmd/compile: when marking REFLECTMETHOD, check for reflect package itself
reflect.Type.Method (and MethodByName) can be used to obtain a
reference of a method by reflection. The linker needs to know
if reflect.Type.Method is called, and retain all exported methods
accordingly. This is handled by the compiler, which marks the
caller of reflect.Type.Method with REFLECTMETHOD attribute. The
current code failed to handle the reflect package itself, so the
method wrapper reflect.Type.Method is not marked. This CL fixes
it.

Fixes #38515.

Change-Id: I12904d23eda664cf1794bc3676152f3218fb762b
Reviewed-on: https://go-review.googlesource.com/c/go/+/228880
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2020-04-19 03:12:32 +00:00
Josh Bleecher Snyder
80e5c3b8b5 cmd/compile: remove superfluous SetBounded call
The call does nothing when applied to an OLSH node.
It would be unnecessary anyway, since we're shifting by a small constant.

Passes toolstash-check.

Change-Id: If858711f1704f44637fa0f6a4c66cbaad6db24b8
Reviewed-on: https://go-review.googlesource.com/c/go/+/228699
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
2020-04-17 15:33:31 +00:00
Josh Bleecher Snyder
02ab2c040e cmd/compile: make ifaceData accept a position
This lets us provide a better position in its use in swt.go.

Change-Id: I7c0da6bd0adea81acfc9a591e6a01b241a5e0942
Reviewed-on: https://go-review.googlesource.com/c/go/+/228219
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
2020-04-14 17:43:56 +00:00
Cuong Manh Le
34e38ac99f cmd/compile: remove "special return in disguise" case
ascompatee does not generate 'x = x' during return, so we don't have to
check for samelist and disguising special return anymore.

While at it, also remove samelist, as this is the only place it's used.

Passes toolstash-check.

Change-Id: I41c7b077d562aadb5916a61e2ab6229bae3cdef4
Reviewed-on: https://go-review.googlesource.com/c/go/+/227807
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2020-04-14 07:12:17 +00:00
Cuong Manh Le
b78109e80e cmd/compile: correct comment for len check when make slice
CL 226737 optimizes len check when make slice. The comment that cap is
constrainted to [0, 2^31) is not quite true, it's 31 or 63 depends on
whether it's 32/64-bit systems.

Change-Id: I6f54e41827ffe4d0b67a44975da3ce07b2fabbad
Reviewed-on: https://go-review.googlesource.com/c/go/+/227803
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2020-04-11 16:20:57 +00:00
Cuong Manh Le
98b6c6aca6 cmd/compile: do not allocate bucket for non-escaping map
For map with hint larger than BUCKETSIZE, makemap ignore allocated
bucket and allocate buckets itself. So do not allocate bucket in
this case, save us the cost of zeroing+assignment to the bucket.

name                            old time/op    new time/op    delta
NewEmptyMap-12                    3.89ns ± 4%    3.88ns ± 2%    ~     (p=0.939 n=19+20)
NewSmallMap-12                    23.3ns ± 3%    23.1ns ± 2%    ~     (p=0.307 n=18+17)
NewEmptyMapHintLessThan8-12       6.43ns ± 3%    6.31ns ± 2%  -1.72%  (p=0.000 n=19+18)
NewEmptyMapHintGreaterThan8-12     159ns ± 2%     150ns ± 1%  -5.79%  (p=0.000 n=20+18)

Benchmark run with commit ab7c174 reverted, see #38314.

Fixes #20184

Change-Id: Ic021f57454c3a0dd50601d73bbd77b8faf8d93b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/227458
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2020-04-09 03:18:43 +00:00
Josh Bleecher Snyder
b6feb03b24 cmd/compile,runtime: pass only ptr and len to some runtime calls
Some runtime calls accept a slice, but only use ptr and len.
This change modifies most such routines to accept only ptr and len.

After this change, the only runtime calls that accept an unnecessary
cap arg are concatstrings and slicerunetostring.
Neither is particularly common, and both are complicated to modify.

Negligible compiler performance impact. Shrinks binaries a little.
There are only a few regressions; the one I investigated was
due to register allocation fluctuation.

Passes 'go test -race std cmd', modulo #38265 and #38266.
Wow, does that take a long time to run.

Updates #36890

file      before    after     Δ       %       
compile   19655024  19655152  +128    +0.001% 
cover     5244840   5236648   -8192   -0.156% 
dist      3662376   3658280   -4096   -0.112% 
link      6680056   6675960   -4096   -0.061% 
pprof     14789844  14777556  -12288  -0.083% 
test2json 2824744   2820648   -4096   -0.145% 
trace     11647876  11639684  -8192   -0.070% 
vet       8260472   8256376   -4096   -0.050% 
total     115163736 115118808 -44928  -0.039% 

Change-Id: Idb29fa6a81d6a82bfd3b65740b98cf3275ca0a78
Reviewed-on: https://go-review.googlesource.com/c/go/+/227163
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2020-04-08 22:19:53 +00:00
Cuong Manh Le
6edd7971bb cmd/compile: optimize len check when make slice
In CL 226278, we did:

	if len < 0 { panicmakeslicelen }
	if len > cap { panicmakeslicecap }

But due to the fact that cap is constrained to [0,2^31), so it is safe
to do:

	if uint64(len) > cap {
	    if len < 0 { panicmakeslicelen() }
	    panicmakeslicecap()
	}

save us a comparison in common case when len is within range.

Passes toolstash-check.

Change-Id: I0ebd52914ccde4cbb45f16c9e020b0c8f42e0663
Reviewed-on: https://go-review.googlesource.com/c/go/+/226737
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2020-03-31 23:39:12 +00:00
Cuong Manh Le
7b30a2d268 cmd/compile: make isSmallMakeSlice checks slice cap only
If slice cap is not set, it will be equal to slice len. So
isSmallMakeSlice only needs to check whether slice cap is constant.

While at it, also add test to make sure panicmakeslicecap is called
when make slice contains invalid non-constant len.

For this benchmark:

func BenchmarkMakeSliceNonConstantLen(b *testing.B) {
	len := 1
	for i := 0; i < b.N; i++ {
		s := make([]int, len, 2)
		_ = s

	}
}

Result compare with parent:

name                        old time/op  new time/op  delta
MakeSliceNonConstantLen-12  18.4ns ± 1%   0.2ns ± 2%  -98.66%  (p=0.008 n=5+5)

Fixes #37975

Change-Id: I4bc926361bc2ffeab4cfaa888ef0a30cbc3b80e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/226278
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
2020-03-31 21:51:51 +00:00
kadern0
9a2db7c41b cmd/compile: remove unused isIntOrdering method
Fixes #37989

Change-Id: Iabf86529fde3be9a98222b7e8d09ff8301cf8830
Reviewed-on: https://go-review.googlesource.com/c/go/+/224777
Reviewed-by: Michael Munday <mike.munday@ibm.com>
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2020-03-22 11:16:34 +00:00
Diogo Pinela
19ed0d993c cmd/compile: use staticuint64s instead of staticbytes
There are still two places in src/runtime/string.go that use
staticbytes, so we cannot delete it just yet.

There is a new codegen test to verify that the index calculation
is constant-folded, at least on amd64. ppc64, mips[64] and s390x
cannot currently do that.

There is also a new runtime benchmark to ensure that this does not
slow down performance (tested against parent commit):

name                      old time/op  new time/op  delta
ConvT2EByteSized/bool-4   1.07ns ± 1%  1.07ns ± 1%   ~     (p=0.060 n=14+15)
ConvT2EByteSized/uint8-4  1.06ns ± 1%  1.07ns ± 1%   ~     (p=0.095 n=14+15)

Updates #37612

Change-Id: I5ec30738edaa48cda78dfab4a78e24a32fa7fd6a
Reviewed-on: https://go-review.googlesource.com/c/go/+/221957
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
2020-03-04 21:43:01 +00:00
Michael Munday
24343cb886 cmd/compile: remove walkinrange optimization
The walkinrange optimization has been superseded by CL 165998.

Has a small positive impact on binary sizes:

compilecmp master -> HEAD
master (e37cc29863): cmd/compile: optimize integer-in-range checks
HEAD (1a70680a34): cmd/compile: remove walkinrange optimization
platform: linux/amd64

file      before    after     Δ       %
addr2line 4329144   4325048   -4096   -0.095%
api       6060970   6056874   -4096   -0.068%
asm       5196905   5192809   -4096   -0.079%
cgo       4898769   4890577   -8192   -0.167%
compile   20222193  20209713  -12480  -0.062%
cover     5331580   5323388   -8192   -0.154%
dist      3732778   3728682   -4096   -0.110%
doc       4748488   4740296   -8192   -0.173%
link      6707380   6695092   -12288  -0.183%
nm        4278685   4274589   -4096   -0.096%
pack      2305038   2300942   -4096   -0.178%
pprof     14874834  14870738  -4096   -0.028%
test2json 2849221   2845125   -4096   -0.144%
vet       8393173   8384981   -8192   -0.098%
go        15205572  15193284  -12288  -0.081%
total     131812292 131709700 -102592 -0.078%

Updates #30645.

Change-Id: I42d74481652c90fef1a9bc58c70836e42c9b1c4b
Reviewed-on: https://go-review.googlesource.com/c/go/+/221802
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
2020-03-03 19:53:02 +00:00
Josh Bleecher Snyder
eb5cd0fb40 cmd/compile: mark Lsyms as readonly earlier
The SSA backend has rules to read the contents of readonly Lsyms.
However, this rule was failing to trigger for many readonly Lsyms.
This is because the readonly attribute that was set on the Node.Name
was not propagated to its Lsym until the dump globals phase, after SSA runs.

To work around this phase ordering problem, introduce Node.SetReadonly,
which sets Node.Name.Readonly and also configures the Lsym
enough that SSA can use it.

This change also fixes a latent problem in the rewrite rule function,
namely that reads past the end of lsym.P were treated as entirely zero,
instead of merely requiring padding with trailing zeros.

This change also adds an amd64 rule needed to fully optimize
the results of this change. It would be better not to need this,
but the zero extension that should handle this for us
gets optimized away too soon (see #36897 for a similar problem).
I have not investigated whether other platforms also need new
rules to take full advantage of the new optimizations.

Compiled code for (interface{})(true) on amd64 goes from:

LEAQ	type.bool(SB), AX
MOVBLZX	""..stmp_0(SB), BX
LEAQ	runtime.staticbytes(SB), CX
ADDQ	CX, BX

to

LEAQ	type.bool(SB), AX
LEAQ	runtime.staticbytes+1(SB), BX

Prior to this change, the readonly symbol rewrite rules
fired a total of 884 times during make.bash.
Afterwards they fire 1807 times.

file    before    after     Δ       %
cgo     4827832   4823736   -4096   -0.085%
compile 24907768  24895656  -12112  -0.049%
fix     3376952   3368760   -8192   -0.243%
pprof   14751700  14747604  -4096   -0.028%
total   120343528 120315032 -28496  -0.024%

Change-Id: I59ea52138276c37840f69e30fb109fd376d579ec
Reviewed-on: https://go-review.googlesource.com/c/go/+/220499
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2020-02-26 19:30:21 +00:00
Keith Randall
316fd8cc4a cmd/compile: mark ... argument to checkptrArithmetic as not escaping
Fixes #36516

Change-Id: Ibf4f86fb3a25fa30e0cd54e2dd2e12c60ee75ddb
Reviewed-on: https://go-review.googlesource.com/c/go/+/214679
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2020-01-17 17:38:40 +00:00
Cuong Manh Le
bf49905222 cmd/compile: update comments to refer to Order methods
Change-Id: I09090effcc5d814d4e024da3f944e825365588f1
Reviewed-on: https://go-review.googlesource.com/c/go/+/205477
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-11-13 15:52:21 +00:00
Matthew Dempsky
ea0b4e7c7d cmd/compile, runtime: add comparison tracing for libFuzzer
This CL extends cmd/compile's experimental libFuzzer support with
calls to __sanitizer_cov_trace_{,const_}cmp{1,2,4,8}. This allows much
more efficient fuzzing of comparisons.

Only supports amd64 and arm64 for now.

Updates #14565.

Change-Id: Ibf82a8d9658f2bc50d955bdb1ae26723a3f0584d
Reviewed-on: https://go-review.googlesource.com/c/go/+/203887
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-11-05 00:00:43 +00:00
Cuong Manh Le
25f5044e46 cmd/compile: hard fail if n.Opt() is not nil in walkCheckPtrArithmetic
n.Opt() is used in walkCheckPtrArithmetic to prevent infinite loops. The
fact that it's used today because n.Opt() is not used for OCONVNOP
during walk.go. If that changes, then it's not safe to repalce it
anymore. So doing hard fail if that case happens, the author of new
changes will be noticed and must change the usage of n.Opt() inside
walkCheckPtrArithmetic, too.

Change-Id: Ic7094baa1759c647fc10e82457c19026099a0d47
Reviewed-on: https://go-review.googlesource.com/c/go/+/202497
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-10-29 05:39:25 +00:00
Shenghou Ma
449b6abbac cmd/compile/internal/gc: reword "declared and not used" error message
"declared and not used" is technically correct, but might confuse
the user. Switching "and" to "but" will hopefully create the
contrast for the users: they did one thing (declaration), but
not the other --- actually using the variable.

This new message is still not ideal (specifically, declared is not
entirely precise here), but at least it matches the other parsers
and is one step in the right direction.

Change-Id: I725c7c663535f9ab9725c4b0bf35b4fa74b0eb20
Reviewed-on: https://go-review.googlesource.com/c/go/+/203282
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-10-28 23:34:13 +00:00
Dan Scales
be64a19d99 cmd/compile, cmd/link, runtime: make defers low-cost through inline code and extra funcdata
Generate inline code at defer time to save the args of defer calls to unique
(autotmp) stack slots, and generate inline code at exit time to check which defer
calls were made and make the associated function/method/interface calls. We
remember that a particular defer statement was reached by storing in the deferBits
variable (always stored on the stack). At exit time, we check the bits of the
deferBits variable to determine which defer function calls to make (in reverse
order). These low-cost defers are only used for functions where no defers
appear in loops. In addition, we don't do these low-cost defers if there are too
many defer statements or too many exits in a function (to limit code increase).

When a function uses open-coded defers, we produce extra
FUNCDATA_OpenCodedDeferInfo information that specifies the number of defers, and
for each defer, the stack slots where the closure and associated args have been
stored. The funcdata also includes the location of the deferBits variable.
Therefore, for panics, we can use this funcdata to determine exactly which defers
are active, and call the appropriate functions/methods/closures with the correct
arguments for each active defer.

In order to unwind the stack correctly after a recover(), we need to add an extra
code segment to functions with open-coded defers that simply calls deferreturn()
and returns. This segment is not reachable by the normal function, but is returned
to by the runtime during recovery. We set the liveness information of this
deferreturn() to be the same as the liveness at the first function call during the
last defer exit code (so all return values and all stack slots needed by the defer
calls will be live).

I needed to increase the stackguard constant from 880 to 896, because of a small
amount of new code in deferreturn().

The -N flag disables open-coded defers. '-d defer' prints out the kind of defer
being used at each defer statement (heap-allocated, stack-allocated, or
open-coded).

Cost of defer statement  [ go test -run NONE -bench BenchmarkDefer$ runtime ]
  With normal (stack-allocated) defers only:         35.4  ns/op
  With open-coded defers:                             5.6  ns/op
  Cost of function call alone (remove defer keyword): 4.4  ns/op

Text size increase (including funcdata) for go binary without/with open-coded defers:  0.09%

The average size increase (including funcdata) for only the functions that use
open-coded defers is 1.1%.

The cost of a panic followed by a recover got noticeably slower, since panic
processing now requires a scan of the stack for open-coded defer frames. This scan
is required, even if no frames are using open-coded defers:

Cost of panic and recover [ go test -run NONE -bench BenchmarkPanicRecover runtime ]
  Without open-coded defers:        62.0 ns/op
  With open-coded defers:           255  ns/op

A CGO Go-to-C-to-Go benchmark got noticeably faster because of open-coded defers:

CGO Go-to-C-to-Go benchmark [cd misc/cgo/test; go test -run NONE -bench BenchmarkCGoCallback ]
  Without open-coded defers:        443 ns/op
  With open-coded defers:           347 ns/op

Updates #14939 (defer performance)
Updates #34481 (design doc)

Change-Id: I63b1a60d1ebf28126f55ee9fd7ecffe9cb23d1ff
Reviewed-on: https://go-review.googlesource.com/c/go/+/202340
Reviewed-by: Austin Clements <austin@google.com>
2019-10-24 13:54:11 +00:00
Matthew Dempsky
7b58581a23 cmd/compile: recognize (*[Big]T)(ptr)[:n:m] pattern for -d=checkptr
A common idiom for turning an unsafe.Pointer into a slice is to write:

    s := (*[Big]T)(ptr)[:n:m]

This technically violates Go's unsafe pointer rules (rule #1 says T2
can't be bigger than T1), but it's fairly common and not too difficult
to recognize, so might as well allow it for now so we can make
progress on #34972.

This should be revisited if #19367 is accepted.

Updates #22218.
Updates #34972.

Change-Id: Id824e2461904e770910b6e728b4234041d2cc8bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/201839
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-10-21 23:16:27 +00:00
Matthew Dempsky
b282efa022 cmd/compile: recognize reflect.{Slice,String}Header for -d=checkptr
Avoids false positive pointer arithmetic panic.

Fixes #35027.

Change-Id: Idd008caaab25fcf739327ac50a021b835ef13def
Reviewed-on: https://go-review.googlesource.com/c/go/+/202560
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-10-21 20:51:06 +00:00
Matthew Dempsky
46aa8354fa cmd/compile: only escape unsafe.Pointer conversions when -d=checkptr=2
Escaping all unsafe.Pointer conversions for -d=checkptr seems like it
might be a little too aggressive to enable for -race/-msan mode, since
at least some tests are written to expect unsafe.Pointer conversions
to not affect escape analysis.

So instead only enable that functionality behind -d=checkptr=2.

Updates #22218.
Updates #34959.

Change-Id: I2f0a774ea5961dabec29bc5b8ebe387a1b90d27b
Reviewed-on: https://go-review.googlesource.com/c/go/+/201840
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-10-18 23:33:48 +00:00
Matthew Dempsky
f9226454b9 cmd/compile: fix -d=checkptr for named unsafe.Pointer types
We need to explicitly convert pointers to unsafe.Pointer before
passing to the runtime checkptr instrumentation in case the user
declared their own type with underlying type unsafe.Pointer.

Updates #22218.
Fixes #34966.

Change-Id: I3baa2809d77f8257167cd78f57156f819130baa8
Reviewed-on: https://go-review.googlesource.com/c/go/+/201782
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-10-17 21:10:22 +00:00
Matthew Dempsky
b6b984fcff cmd/compile: escape unsafe.Pointer conversions when -d=checkptr
This CL tweaks escape analysis to treat unsafe.Pointer(ptr) as an
escaping operation when -d=checkptr is enabled. This allows better
detection of unsafe pointer arithmetic and conversions, because the
runtime checkptr instrumentation can currently only detect object
boundaries for heap objects, not stack objects.

Updates #22218.
Fixes #34959.

Change-Id: I856812cc23582fe4d0d401592583323e95919f28
Reviewed-on: https://go-review.googlesource.com/c/go/+/201781
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-10-17 20:09:00 +00:00
Matthew Dempsky
dc72a2f95f cmd/compile: detect unsafe conversions from smaller to larger types
This CL extends the runtime instrumentation for (*T)(ptr) to also
check that the first and last bytes of *(*T)(ptr) are part of the same
heap object.

Updates #22218.
Updates #34959.

Change-Id: I2c8063fe1b7fe6e6145e41c5654cb64dd1c9dd41
Reviewed-on: https://go-review.googlesource.com/c/go/+/201778
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-10-17 19:29:20 +00:00
Matthew Dempsky
80a6fedea0 cmd/compile: add -d=checkptr to validate unsafe.Pointer rules
This CL adds -d=checkptr as a compile-time option for adding
instrumentation to check that Go code is following unsafe.Pointer
safety rules dynamically. In particular, it currently checks two
things:

1. When converting unsafe.Pointer to *T, make sure the resulting
pointer is aligned appropriately for T.

2. When performing pointer arithmetic, if the result points to a Go
heap object, make sure we can find an unsafe.Pointer-typed operand
that pointed into the same object.

These checks are currently disabled for the runtime, and can also be
disabled through a new //go:nocheckptr annotation. The latter is
necessary for functions like strings.noescape, which intentionally
violate safety rules to workaround escape analysis limitations.

Fixes #22218.

Change-Id: If5a51273881d93048f74bcff10a3275c9c91da6a
Reviewed-on: https://go-review.googlesource.com/c/go/+/162237
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-10-17 00:40:21 +00:00
Bryan C. Mills
b76e6f8825 Revert "cmd/compile, cmd/link, runtime: make defers low-cost through inline code and extra funcdata"
This reverts CL 190098.

Reason for revert: broke several builders.

Change-Id: I69161352f9ded02537d8815f259c4d391edd9220
Reviewed-on: https://go-review.googlesource.com/c/go/+/201519
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Dan Scales <danscales@google.com>
2019-10-16 20:59:53 +00:00
Dan Scales
dad616375f cmd/compile, cmd/link, runtime: make defers low-cost through inline code and extra funcdata
Generate inline code at defer time to save the args of defer calls to unique
(autotmp) stack slots, and generate inline code at exit time to check which defer
calls were made and make the associated function/method/interface calls. We
remember that a particular defer statement was reached by storing in the deferBits
variable (always stored on the stack). At exit time, we check the bits of the
deferBits variable to determine which defer function calls to make (in reverse
order). These low-cost defers are only used for functions where no defers
appear in loops. In addition, we don't do these low-cost defers if there are too
many defer statements or too many exits in a function (to limit code increase).

When a function uses open-coded defers, we produce extra
FUNCDATA_OpenCodedDeferInfo information that specifies the number of defers, and
for each defer, the stack slots where the closure and associated args have been
stored. The funcdata also includes the location of the deferBits variable.
Therefore, for panics, we can use this funcdata to determine exactly which defers
are active, and call the appropriate functions/methods/closures with the correct
arguments for each active defer.

In order to unwind the stack correctly after a recover(), we need to add an extra
code segment to functions with open-coded defers that simply calls deferreturn()
and returns. This segment is not reachable by the normal function, but is returned
to by the runtime during recovery. We set the liveness information of this
deferreturn() to be the same as the liveness at the first function call during the
last defer exit code (so all return values and all stack slots needed by the defer
calls will be live).

I needed to increase the stackguard constant from 880 to 896, because of a small
amount of new code in deferreturn().

The -N flag disables open-coded defers. '-d defer' prints out the kind of defer
being used at each defer statement (heap-allocated, stack-allocated, or
open-coded).

Cost of defer statement  [ go test -run NONE -bench BenchmarkDefer$ runtime ]
  With normal (stack-allocated) defers only:         35.4  ns/op
  With open-coded defers:                             5.6  ns/op
  Cost of function call alone (remove defer keyword): 4.4  ns/op

Text size increase (including funcdata) for go cmd without/with open-coded defers:  0.09%

The average size increase (including funcdata) for only the functions that use
open-coded defers is 1.1%.

The cost of a panic followed by a recover got noticeably slower, since panic
processing now requires a scan of the stack for open-coded defer frames. This scan
is required, even if no frames are using open-coded defers:

Cost of panic and recover [ go test -run NONE -bench BenchmarkPanicRecover runtime ]
  Without open-coded defers:        62.0 ns/op
  With open-coded defers:           255  ns/op

A CGO Go-to-C-to-Go benchmark got noticeably faster because of open-coded defers:

CGO Go-to-C-to-Go benchmark [cd misc/cgo/test; go test -run NONE -bench BenchmarkCGoCallback ]
  Without open-coded defers:        443 ns/op
  With open-coded defers:           347 ns/op

Updates #14939 (defer performance)
Updates #34481 (design doc)

Change-Id: I51a389860b9676cfa1b84722f5fb84d3c4ee9e28
Reviewed-on: https://go-review.googlesource.com/c/go/+/190098
Reviewed-by: Austin Clements <austin@google.com>
2019-10-16 18:27:16 +00:00
Matthew Dempsky
b649bdc7f3 cmd/compile: remove period from "not allowed in runtime" errors
We don't punctuate compiler diagnostics.

Change-Id: I19e1f30fbf04f0d1bfe6648fae26beaf3a06ee92
Reviewed-on: https://go-review.googlesource.com/c/go/+/201077
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-10-14 19:32:08 +00:00
Matthew Dempsky
06b12e660c cmd/compile: move some ONAME-specific flags from Node to Name
The IsClosureVar, IsOutputParamHeapAddr, Assigned, Addrtaken,
InlFormal, and InlLocal flags are only interesting for ONAME nodes, so
it's better to set these flags on Name.flags instead of Node.flags.

Two caveats though:

1. Previously, we would set Assigned and Addrtaken on the entire
expression tree involved in an assignment or addressing operation.
However, the rest of the compiler only actually cares about knowing
whether the underlying ONAME (if any) was assigned/addressed.

2. This actually requires bumping Name.flags from bitset8 to bitset16,
whereas it doesn't allow shrinking Node.flags any. However, Name has
some trailing padding bytes, so expanding Name.flags doesn't cost any
memory.

Passes toolstash-check.

Change-Id: I7775d713566a38d5b9723360b1659b79391744c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/200898
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-10-14 18:57:11 +00:00
Matthew Dempsky
46be01f4e0 cmd/compile: remove Addable flag
This flag is supposed to indicate whether the expression is
"addressable"; but in practice, we infer this from other
attributes about the expression (e.g., n.Op and n.Class()).

Passes toolstash-check.

Change-Id: I19352ca07ab5646e232d98e8a7c1c9aec822ddd0
Reviewed-on: https://go-review.googlesource.com/c/go/+/200897
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-10-13 01:48:30 +00:00
Cuong Manh Le
ba6aeb6ce8 cmd/compile: simplify OAS2XXX nodes handle in order
Passes toolstash-check.

Updates #23017

Change-Id: I0ae82e28a6e9e732ba2a6aa98f9b35551efcea10
Reviewed-on: https://go-review.googlesource.com/c/go/+/200580
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-10-12 08:00:25 +00:00
Matthew Dempsky
e76b9e8908 cmd/compile: remove pointer temporaries in walkcompare
When comparing two T-typed values t1 and t2 using the T_eq function,
we used to generate:

    pl := &t1
    pr := &t2
    return T_eq(pl, pr, unsafe.Sizeof(T{}))

This CL changes it to simply generate:

    return T_eq(&t1, &t2, unsafe.Sizeof(T{}))

Surprisingly, this does not pass toolstash. For some reason, it seems
like SSA wasn't able to SSA-ify the pl and pr variables in all cases.

Change-Id: I111fbb068a1741fa169c9922cb8cdb6e21579aa4
Reviewed-on: https://go-review.googlesource.com/c/go/+/197601
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-09-30 23:44:36 +00:00
Matthew Dempsky
ecc2d61798 cmd/compile: remove redundant anylit calls in walkcompare
walkcompare already called walkexpr on n.Left and n.Right, which in
turn calls anylit when appropriate.

Passes toolstash-check.

Change-Id: I6912ac5a42b977c04db9d85cb2e7295e275e083d
Reviewed-on: https://go-review.googlesource.com/c/go/+/197600
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-09-30 23:42:51 +00:00
Mohit Verma
c729116332 cmd/compile: use Node.Right for OAS2* nodes (cleanup)
This CL changes cmd/compile to use Node.Right instead of
Node.Rlist for OAS2FUNC/OAS2RECV/OAS2MAPR/OAS2DOTTYPE nodes.
Fixes #32293

Change-Id: I4c9d9100be2d98d15e016797f934f64d385f5faa
Reviewed-on: https://go-review.googlesource.com/c/go/+/197817
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-09-28 05:04:49 +00:00
Cuong Manh Le
e0dde990de cmd/compile: remove n.SetLikely(false) usage
n.SetLikely(false) is probably mean to indicate that the branch is
"unlikely", but it has the real effect of not marking branch as likely.

So invert the test condition, we can use more meaningful n.SetLikely(true).

Before:

	if l2 < 0 {
		panicmakeslicelen()
	}

After:

	if l2 >= 0 {
	} else {
		panicmakeslicelen
	}

Fixes #32486

Change-Id: I156fdba1f9a5d554a178c8903f1a391ed304199d
Reviewed-on: https://go-review.googlesource.com/c/go/+/195197
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-09-25 18:10:51 +00:00
Matthew Dempsky
2fc6366fb5 cmd/compile: remove OCASE and rename OXCASE to OCASE
We used to use OXCASE to represent general, possibly multi-valued
cases, and then desugar these during walk into single-value cases
represented by OCASE.

In CL 194660, we switched to eliminated the desugaring step and
instead handle the multi-valued cases directly, which eliminates the
need for an OCASE Op. Instead, we can simply remove OCASE, and rename
OXCASE to just OCASE.

Passes toolstash-check.

Change-Id: I3cc184340f9081d37453927cca1c059267fdbc12
Reviewed-on: https://go-review.googlesource.com/c/go/+/196117
Reviewed-by: Keith Randall <khr@golang.org>
2019-09-18 02:31:34 +00:00
LE Manh Cuong
ec4e8517cd cmd/compile: support more length types for slice extension optimization
golang.org/cl/109517 optimized the compiler to avoid the allocation for make in
append(x, make([]T, y)...). This was only implemented for the case that y has type int.

This change extends the optimization to trigger for all integer types where the value
is known at compile time to fit into an int.

name             old time/op    new time/op    delta
ExtendInt-12        106ns ± 4%     106ns ± 0%      ~     (p=0.351 n=10+6)
ExtendUint64-12    1.03µs ± 5%    0.10µs ± 4%   -90.01%  (p=0.000 n=9+10)

name             old alloc/op   new alloc/op   delta
ExtendInt-12        0.00B          0.00B           ~     (all equal)
ExtendUint64-12    13.6kB ± 0%     0.0kB       -100.00%  (p=0.000 n=10+10)

name             old allocs/op  new allocs/op  delta
ExtendInt-12         0.00           0.00           ~     (all equal)
ExtendUint64-12      1.00 ± 0%      0.00       -100.00%  (p=0.000 n=10+10)

Updates #29785

Change-Id: Ief7760097c285abd591712da98c5b02bc3961fcd
Reviewed-on: https://go-review.googlesource.com/c/go/+/182559
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-09-17 17:18:17 +00:00
Cuong Manh Le
75da700d0a cmd/compile: consistently use strlit to access constants string values
Passes toolstash-check.

Change-Id: Ieaef20b7649787727b69469f93ffc942022bc079
Reviewed-on: https://go-review.googlesource.com/c/go/+/195198
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-09-16 11:41:20 +00:00
Ainar Garipov
0efbd10157 all: fix typos
Use the following (suboptimal) script to obtain a list of possible
typos:

  #!/usr/bin/env sh

  set -x

  git ls-files |\
    grep -e '\.\(c\|cc\|go\)$' |\
    xargs -n 1\
    awk\
    '/\/\// { gsub(/.*\/\//, ""); print; } /\/\*/, /\*\// { gsub(/.*\/\*/, ""); gsub(/\*\/.*/, ""); }' |\
    hunspell -d en_US -l |\
    grep '^[[:upper:]]\{0,1\}[[:lower:]]\{1,\}$' |\
    grep -v -e '^.\{1,4\}$' -e '^.\{16,\}$' |\
    sort -f |\
    uniq -c |\
    awk '$1 == 1 { print $2; }'

Then, go through the results manually and fix the most obvious typos in
the non-vendored code.

Change-Id: I3cb5830a176850e1a0584b8a40b47bde7b260eae
Reviewed-on: https://go-review.googlesource.com/c/go/+/193848
Reviewed-by: Robert Griesemer <gri@golang.org>
2019-09-08 17:28:20 +00:00
Cuong Manh Le
d535501a8e cmd/compile: remove tempname usages
CL 59610 merged tempname to tempAt, but some of comments and error
message still refer to tempname. So changing to tempAt instead.

Change-Id: I032f3bedc135d17124b0daaf22c97d0d5ada0a6f
Reviewed-on: https://go-review.googlesource.com/c/go/+/193817
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-09-06 16:59:11 +00:00
Agniva De Sarker
8e4399ff77 cmd/compile: refactor zero value size to be a constant
Change-Id: I31dd4fb55d5974cd45de00148039d04f8a7d5cb3
Reviewed-on: https://go-review.googlesource.com/c/go/+/187257
Run-TryBot: Agniva De Sarker <agniva.quicksilver@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
2019-08-29 08:35:32 +00:00
LE Manh Cuong
25ebf015f6 cmd/compile: ensure interface-to-concrete comparison panics when it should
In interface-to-concrete comparisons, we are short circuiting on the interface
value's dynamic type before evaluating the concrete expression for side effects,
causing concrete expression won't panic at runtime, while it should.

To fix it, evaluating the RHS of comparison before we do the short-circuit.

We also want to prioritize panics in the LHS over the RHS, so evaluating
the LHS too.

Fixes #32187

Change-Id: I15b58a523491b7fd1856b8fdb9ba0cba5d11ebb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/178817
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-08-28 19:45:00 +00:00
David Chase
037ac2bd84 cmd/compile: add -smallframes gc flag for GC latency diagnosis
Shrinks the size of things that can be stack allocated from
10M to 128k for declared variables and from 64k to 16k for
implicit allocations (new(T), &T{}, etc).

Usage: "go build -gcflags -smallframes hello.go"

An earlier GOEXPERIMENT version of this caused only one
problem, when a gc-should-detect-oversize-stack test no
longer had an oversized stack to detect.  The change was
converted to a flag to make it easier to access (for
diagnosing "long" GC-related single-thread pauses) and to
remove interference with the test.

Includes test to verify behavior.

Updates #27732.

Change-Id: I1255d484331e77185e07c78389a8b594041204c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/180817
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-06-06 11:38:40 +00:00
Josh Bleecher Snyder
73cb9a1cb3 all: refer to map elements as elements instead of values
The spec carefully and consistently uses "key" and "element"
as map terminology. The implementation, not so much.

This change attempts to make the implementation consistently
hew to the spec's terminology. Beyond consistency, this has
the advantage of avoid some confusion and naming collisions,
since v and value are very generic and commonly used terms.

I believe that I found all everything, but there are a lot of
non-obvious places for these to hide, and grepping for them is hard.
Hopefully this change changes enough of them that we will start using
elem going forward. Any remaining hidden cases can be removed ad hoc
as they are discovered.

The only externally-facing part of this change is in package reflect,
where there is a minor doc change and a function parameter name change.

Updates #27167

Change-Id: I2f2d78f16c360dc39007b9966d5c2046a29d3701
Reviewed-on: https://go-review.googlesource.com/c/go/+/174523
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-04-30 18:18:12 +00:00
Josh Bleecher Snyder
980a57a84b cmd/compile: clean up string/bytes/runes conversion code
Combine the OBYTES2STR and ORUNES2STR cases, as they are identical.

Clean up the construction, commenting, and spacing of the other cases,
and make them all match.

Passes toolstash-check.

Change-Id: I1be8a528927caeb15e49cb12ca0f11c0827dadd9
Reviewed-on: https://go-review.googlesource.com/c/go/+/173322
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-04-23 02:14:40 +00:00
Josh Bleecher Snyder
336f951b07 cmd/compile: add ORESULT, remove OINDREGSP
This change is mostly cosmetic.

OINDREGSP was used only for reading the results of a function call.
In recognition of that fact, rename it to ORESULT.
Along the way, trim down our handling of it to the bare minimum,
and rely on the increased clarity of ORESULT to inline nodarg.

Passes toolstash-check.

Change-Id: I25b177df4ea54a8e94b1698d044c297b7e453c64
Reviewed-on: https://go-review.googlesource.com/c/go/+/170705
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-04-08 21:33:15 +00:00
Josh Bleecher Snyder
23b476a3c8 cmd/compile: port callnew to ssa conversion
This is part of a general effort to shrink walk.
In an ideal world, we'd have an SSA op for allocation,
but we don't yet have a good mechanism for introducing
function calling during SSA compilation.
In the meantime, SSA conversion is a better place for it.

This also makes it easier to introduce new optimizations;
instead of doing the typecheck walk dance,
we can simply write what we want the backend to do.

I introduced a new opcode in this change because:

(a) It avoids a class of bugs involving correctly detecting
    whether this ONEW is a "before walk" ONEW or an "after walk" ONEW.
    It also means that using ONEW or ONEWOBJ in the wrong context
    will generally result in a faster failure.
(b) Opcodes are cheap.
(c) It provides a better place to put documentation.

This change also is also marginally more performant:

name        old alloc/op      new alloc/op      delta
Template         39.1MB ± 0%       39.0MB ± 0%  -0.14%  (p=0.008 n=5+5)
Unicode          28.4MB ± 0%       28.4MB ± 0%    ~     (p=0.421 n=5+5)
GoTypes           132MB ± 0%        132MB ± 0%  -0.23%  (p=0.008 n=5+5)
Compiler          608MB ± 0%        607MB ± 0%  -0.25%  (p=0.008 n=5+5)
SSA              2.04GB ± 0%       2.04GB ± 0%  -0.01%  (p=0.008 n=5+5)
Flate            24.4MB ± 0%       24.3MB ± 0%  -0.13%  (p=0.008 n=5+5)
GoParser         29.3MB ± 0%       29.1MB ± 0%  -0.54%  (p=0.008 n=5+5)
Reflect          84.8MB ± 0%       84.7MB ± 0%  -0.21%  (p=0.008 n=5+5)
Tar              36.7MB ± 0%       36.6MB ± 0%  -0.10%  (p=0.008 n=5+5)
XML              48.7MB ± 0%       48.6MB ± 0%  -0.24%  (p=0.008 n=5+5)
[Geo mean]       85.0MB            84.8MB       -0.19%

name        old allocs/op     new allocs/op     delta
Template           383k ± 0%         382k ± 0%  -0.26%  (p=0.008 n=5+5)
Unicode            341k ± 0%         341k ± 0%    ~     (p=0.579 n=5+5)
GoTypes           1.37M ± 0%        1.36M ± 0%  -0.39%  (p=0.008 n=5+5)
Compiler          5.59M ± 0%        5.56M ± 0%  -0.49%  (p=0.008 n=5+5)
SSA               16.9M ± 0%        16.9M ± 0%  -0.03%  (p=0.008 n=5+5)
Flate              238k ± 0%         238k ± 0%  -0.23%  (p=0.008 n=5+5)
GoParser           306k ± 0%         303k ± 0%  -0.93%  (p=0.008 n=5+5)
Reflect            990k ± 0%         987k ± 0%  -0.33%  (p=0.008 n=5+5)
Tar                356k ± 0%         355k ± 0%  -0.20%  (p=0.008 n=5+5)
XML                444k ± 0%         442k ± 0%  -0.45%  (p=0.008 n=5+5)
[Geo mean]         848k              845k       -0.33%

Change-Id: I2c36003a7cbf71b53857b7de734852b698f49310
Reviewed-on: https://go-review.googlesource.com/c/go/+/167957
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-03-20 19:38:50 +00:00