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3445 Commits

Author SHA1 Message Date
Matthew Dempsky
85fc765341 cmd/compile: optimize switch on strings
When compiling expression switches, we try to optimize runs of
constants into binary searches. The ordering used isn't visible to the
application, so it's unimportant as long as we're consistent between
sorting and searching.

For strings, it's much cheaper to compare string lengths than strings
themselves, so instead of ordering strings by "si <= sj", we currently
order them by "len(si) < len(sj) || len(si) == len(sj) && si <= sj"
(i.e., the lexicographical ordering on the 2-tuple (len(s), s)).

However, it's also somewhat cheaper to compare strings for equality
(i.e., ==) than for ordering (i.e., <=). And if there were two or
three string constants of the same length in a switch statement, we
might unnecessarily emit ordering comparisons.

For example, given:

    switch s {
    case "", "1", "2", "3": // ordered by length then content
        goto L
    }

we currently compile this as:

    if len(s) < 1 || len(s) == 1 && s <= "1" {
        if s == "" { goto L }
        else if s == "1" { goto L }
    } else {
        if s == "2" { goto L }
        else if s == "3" { goto L }
    }

This CL switches to using a 2-level binary search---first on len(s),
then on s itself---so that string ordering comparisons are only needed
when there are 4 or more strings of the same length. (4 being the
cut-off for when using binary search is actually worthwhile.)

So the above switch instead now compiles to:

    if len(s) == 0 {
        if s == "" { goto L }
    } else if len(s) == 1 {
        if s == "1" { goto L }
        else if s == "2" { goto L }
        else if s == "3" { goto L }
    }

which is better optimized by walk and SSA. (Notably, because there are
only two distinct lengths and no more than three strings of any
particular length, this example ends up falling back to simply using
linear search.)

Test case by khr@ from CL 195138.

Fixes #33934.

Change-Id: I8eeebcaf7e26343223be5f443d6a97a0daf84f07
Reviewed-on: https://go-review.googlesource.com/c/go/+/195340
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-09-18 05:33:05 +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
Matthew Dempsky
115e4c9c14 test: add test coverage for type-switch hash collisions
This CL expands the test for #29612 to check that type switches also
work correctly when type hashes collide.

Change-Id: Ia153743e6ea0736c1a33191acfe4d8ba890be527
Reviewed-on: https://go-review.googlesource.com/c/go/+/195782
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-09-16 22:14:49 +00:00
Matthew Dempsky
7f907b9cee cmd/compile: require -lang=go1.14 for overlapping interfaces
Support for overlapping interfaces is a new (proposed) Go language
feature to be supported in Go 1.14, so it shouldn't be supported under
-lang=go1.13 or earlier.

Fixes #34329.

Change-Id: I5fea5716b7d135476980bc40b4f6e8c611b67735
Reviewed-on: https://go-review.googlesource.com/c/go/+/195678
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
2019-09-16 19:43:54 +00:00
Alberto Donizetti
c2facbe937 Revert "test/codegen: document -all_codegen option in README"
This reverts CL 192101.

Reason for revert: The same paragraph was added 2 weeks ago
(look a few lines above)

Change-Id: I05efb2631d7b4966f66493f178f2a649c715a3cc
Reviewed-on: https://go-review.googlesource.com/c/go/+/195637
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-09-16 17:31:37 +00:00
Matthew Dempsky
606019cb4b cmd/compile: trim function name prefix from escape diagnostics
This information is redundant with the position information already
provided. Also, no other -m diagnostics print out function name.

While here, report parameter leak diagnostics against the parameter
declaration position rather than the function, and use Warnl for
"moved to heap" messages.

Test cases updated programmatically by removing the first word from
every "no match for" error emitted by run.go:

go run run.go |& \
  sed -E -n 's/^(.*):(.*): no match for `([^ ]* (.*))` in:$/\1!\2!\3!\4/p' | \
  while IFS='!' read -r fn line before after; do
    before=$(echo "$before" | sed 's/[.[\*^$()+?{|]/\\&/g')
    after=$(echo "$after" | sed -E 's/(\&|\\)/\\&/g')
    fn=$(find . -name "${fn}" | head -1)
    sed -i -E -e "${line}s/\"${before}\"/\"${after}\"/" "${fn}"
  done

Passes toolstash-check.

Change-Id: I6e02486b1409e4a8dbb2b9b816d22095835426b5
Reviewed-on: https://go-review.googlesource.com/c/go/+/195040
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-09-16 15:30:51 +00:00
Cherry Zhang
d9b8ffa51c test/codegen: document -all_codegen option in README
It is useful to know about the -all_codegen option for running
codegen tests for all platforms. I was puzzling that some codegen
test was not failing on my local machine or on trybot, until I
found this option.

Change-Id: I062cf4d73f6a6c9ebc2258195779d2dab21bc36d
Reviewed-on: https://go-review.googlesource.com/c/go/+/192101
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-09-16 11:53:57 +00:00
Ruixin Bao
98aa97806b cmd/compile: add math/bits.Mul64 intrinsic on s390x
This change adds an intrinsic for Mul64 on s390x. To achieve that,
a new assembly instruction, MLGR, is introduced in s390x/asmz.go. This assembly
instruction directly uses an existing instruction on Z and supports multiplication
of two 64 bit unsigned integer and stores the result in two separate registers.

In this case, we require the multiplcand to be stored in register R3 and
the output result (the high and low 64 bit of the product) to be stored in
R2 and R3 respectively.

A test case is also added.

Benchmark:
name      old time/op  new time/op  delta
Mul-18    11.1ns ± 0%   1.4ns ± 0%  -87.39%  (p=0.002 n=8+10)
Mul32-18  2.07ns ± 0%  2.07ns ± 0%     ~     (all equal)
Mul64-18  11.1ns ± 1%   1.4ns ± 0%  -87.42%  (p=0.000 n=10+10)

Change-Id: Ieca6ad1f61fff9a48a31d50bbd3f3c6d9e6675c1
Reviewed-on: https://go-review.googlesource.com/c/go/+/194572
Reviewed-by: Michael Munday <mike.munday@ibm.com>
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-09-13 09:04:48 +00:00
Cuong Manh Le
55c0ad4b62 cmd/compile: allow iota inside function in a ConstSpec
Fixes #22344

Change-Id: I7c400d9d4ebcab279d08a8c190508d82cbd20899
Reviewed-on: https://go-review.googlesource.com/c/go/+/194717
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-09-12 06:46:57 +00:00
Matthew Dempsky
0b739fd4df cmd/compile: move duplicate type-case checking into typecheck
Part of the general trend of moving yyerror calls out of walk and into
typecheck.

Notably, this requires splitting test/typeswitch2.go into two files,
because now some of the errors are reported during typecheck and
others are still reported during walk; and if there were any errors
during typecheck, then cmd/compile exits without invoking walk.

Passes toolstash-check.

Change-Id: I05ee0c00b99af659ee1eef098d342d0d736cf31e
Reviewed-on: https://go-review.googlesource.com/c/go/+/194659
Reviewed-by: Robert Griesemer <gri@golang.org>
2019-09-11 23:33:11 +00:00
Matthew Dempsky
b9704872d1 cmd/compile: better integrate parameter tagging with escape.go
This CL moves parameter tagging to before escape analysis is complete,
so we still have access to EscLocation. This will be useful once
EscLocation starts tracking higher-fidelity escape details.

Notably, this CL stops using n.Esc to record parameter escape analysis
details. Now escape analysis only ever sets n.Esc to EscNone or
EscHeap. (It still defaults to EscUnknown, and is set to EscNever in
some places though.)

Passes toolstash-check.

Updates #33981.

Change-Id: I50a91ea1e38c442092de6cd14e20b211f8f818c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/193178
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-09-10 23:01:30 +00:00
Michael Munday
5c5f217b63 cmd/compile: improve s390x sign/zero extension removal
This CL gets rid of the MOVDreg and MOVDnop SSA operations on
s390x. They were originally inserted to help avoid situations
where a sign/zero extension was elided but a spill invalidated
the optimization. It's not really clear we need to do this though
(amd64 doesn't have these ops for example) so long as we are
careful when removing sign/zero extensions. Also, the MOVDreg
technique doesn't work if the register is spilled before the
MOVDreg op (I haven't seen that in practice).

Removing these ops reduces the complexity of the rules and also
allows us to unblock optimizations. For example, the compiler can
now merge the loads in binary.{Big,Little}Endian.PutUint16 which
it wasn't able to do before. This CL reduces the size of the .text
section in the go tool by about 4.7KB (0.09%).

Change-Id: Icaddae7f2e4f9b2debb6fabae845adb3f73b41db
Reviewed-on: https://go-review.googlesource.com/c/go/+/173897
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-09-10 13:17:24 +00:00
Matthew Dempsky
e710a1fb2e cmd/compile: report more precise errors about untyped constants
Previously, we used a single "untyped number" type for all untyped
numeric constants. This led to vague error messages like "string(1.0)"
reporting that "1 (type untyped number)" can't be converted to string,
even though "string(1)" is valid.

This CL makes cmd/compile more like go/types by utilizing
types.Ideal{int,rune,float,complex} instead of types.Types[TIDEAL],
and keeping n.Type in sync with n.Val().Ctype() during constant
folding.

Thanks to K Heller for looking into this issue, and for the included
test case.

Fixes #21979.

Change-Id: Ibfea88c05704bc3c0a502a455d018a375589754d
Reviewed-on: https://go-review.googlesource.com/c/go/+/194019
Reviewed-by: Robert Griesemer <gri@golang.org>
2019-09-09 22:12:15 +00:00
Martin Möhrmann
5bb59b6d16 Revert "compile: prefer an AND instead of SHR+SHL instructions"
This reverts commit 9ec7074a94.

Reason for revert: broke s390x (copysign, abs) and arm64 (bitfield) tests.

Change-Id: I16c1b389c062e8c4aa5de079f1d46c9b25b0db52
Reviewed-on: https://go-review.googlesource.com/c/go/+/193850
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Agniva De Sarker <agniva.quicksilver@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-09-09 07:33:25 +00:00
Martin Möhrmann
9ec7074a94 compile: prefer an AND instead of SHR+SHL instructions
On modern 64bit CPUs a SHR, SHL or AND instruction take 1 cycle to execute.
A pair of shifts that operate on the same register will take 2 cycles
and needs to wait for the input register value to be available.

Large constants used to mask the high bits of a register with an AND
instruction can not be encoded as an immediate in the AND instruction
on amd64 and therefore need to be loaded into a register with a MOV
instruction.

However that MOV instruction is not dependent on the output register and
on many CPUs does not compete with the AND or shift instructions for
execution ports.

Using a pair of shifts to mask high bits instead of an AND to mask high
bits of a register has a shorter encoding and uses one less general
purpose register but is slower due to taking one clock cycle longer
if there is no register pressure that would make the AND variant need to
generate a spill.

For example the instructions emitted for (x & 1 << 63) before this CL are:
48c1ea3f                SHRQ $0x3f, DX
48c1e23f                SHLQ $0x3f, DX

after this CL the instructions are the same as GCC and LLVM use:
48b80000000000000080    MOVQ $0x8000000000000000, AX
4821d0                  ANDQ DX, AX

Some platforms such as arm64 already have SSA optimization rules to fuse
two shift instructions back into an AND.

Removing the general rule to rewrite AND to SHR+SHL speeds up this benchmark:

var GlobalU uint

func BenchmarkAndHighBits(b *testing.B) {
	x := uint(0)
	for i := 0; i < b.N; i++ {
		x &= 1 << 63
	}
	GlobalU = x
}

amd64/darwin on Intel(R) Core(TM) i7-3520M CPU @ 2.90GHz:
name           old time/op  new time/op  delta
AndHighBits-4  0.61ns ± 6%  0.42ns ± 6%  -31.42%  (p=0.000 n=25+25):

Updates #33826
Updates #32781

Change-Id: I862d3587446410c447b9a7265196b57f85358633
Reviewed-on: https://go-review.googlesource.com/c/go/+/191780
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-09-09 06:49:17 +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
Matthew Dempsky
581526ce96 cmd/compile: rewrite untyped constant conversion logic
This CL detangles the hairy mess that was convlit+defaultlit. In
particular, it makes the following changes:

1. convlit1 now follows the standard typecheck behavior of setting
"n.Type = nil" if there's an error. Notably, this means for a lot of
test cases, we now avoid reporting useless follow-on error messages.
For example, after reporting that "1 << s + 1.0" has an invalid shift,
we no longer also report that it can't be assigned to string.

2. Previously, assignconvfn had some extra logic for trying to
suppress errors from convlit/defaultlit so that it could provide its
own errors with better context information. Instead, this extra
context information is now passed down into convlit1 directly.

3. Relatedly, this CL also removes redundant calls to defaultlit prior
to assignconv. As a consequence, when an expression doesn't make sense
for a particular assignment (e.g., assigning an untyped string to an
integer), the error messages now say "untyped string" instead of just
"string". This is more consistent with go/types behavior.

4. defaultlit2 is now smarter about only trying to convert pairs of
untyped constants when it's likely to succeed. This allows us to
report better error messages for things like 3+"x"; instead of "cannot
convert 3 to string" we now report "mismatched types untyped number
and untyped string".

Passes toolstash-check.

Change-Id: I26822a02dc35855bd0ac774907b1cf5737e91882
Reviewed-on: https://go-review.googlesource.com/c/go/+/187657
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
2019-09-06 23:15:48 +00:00
Matthew Dempsky
e6ba19f913 Revert "cmd/compile: improve errors for invalid conversions of consts"
This reverts commit 2da9c3e0f9.

Reason for revert: while the new error messages are more informative,
they're not strictly correct. This CL also conflicts with CL 187657.

Change-Id: I1c36cf7e86c2f35ee83a4f98918ee38aa1f59965
Reviewed-on: https://go-review.googlesource.com/c/go/+/193977
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
2019-09-06 22:44:48 +00:00
K. "pestophagous" Heller
2da9c3e0f9 cmd/compile: improve errors for invalid conversions of consts
Follow-up to Change-Id: If6e52c59eab438599d641ecf6f110ebafca740a9

This addresses the remaining tech debt on issue 21979.

The aforementioned previous CL silenced one of two mostly redundant
compiler errors. However, the silenced error was the more expressive
error. This CL now imbues the surviving error with the same level
of expressiveness as the old semi-redundant error.

Fixes #21979

Change-Id: I3273d48c88bbab073fabe53421d801df621ce321
Reviewed-on: https://go-review.googlesource.com/c/go/+/191079
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
2019-09-06 18:03:49 +00:00
Than McIntosh
d4a6a2661c test: add test that failed with gccgo
Test with some code that triggered a compilation error bug in gccgo.

Updates #33866.

Change-Id: Ib2f226bbbebbfae33b41037438fe34dc5f2ad034
Reviewed-on: https://go-review.googlesource.com/c/go/+/193261
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-09-06 12:11:17 +00:00
Cuong Manh Le
1406ece446 cmd/compile: preserve loop depth when evaluating block
Add block method to preserve loop depth when evaluating statements in a
block, so escape analysis can handle looping label more precisely.

Updates #22438

Change-Id: I39b306544a6c0ee3fcbebbe0d0ee735cb71773e6
Reviewed-on: https://go-review.googlesource.com/c/go/+/193517
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 01:35:46 +00:00
Keith Randall
36f30ba289 cmd/compile,runtime: generate hash functions only for types which are map keys
Right now we generate hash functions for all types, just in case they
are used as map keys. That's a lot of wasted effort and binary size
for types which will never be used as a map key. Instead, generate
hash functions only for types that we know are map keys.

Just doing that is a bit too simple, since maps with an interface type
as a key might have to hash any concrete key type that implements that
interface. So for that case, implement hashing of such types at
runtime (instead of with generated code). It will be slower, but only
for maps with interface types as keys, and maybe only a bit slower as
the aeshash time probably dominates the dispatch time.

Reorg where we keep the equals and hash functions. Move the hash function
from the key type to the map type, saving a field in every non-map type.
That leaves only one function in the alg structure, so get rid of that and
just keep the equal function in the type descriptor itself.

cmd/go now has 10 generated hash functions, instead of 504. Makes
cmd/go 1.0% smaller. Update #6853.

Speed on non-interface keys is unchanged. Speed on interface keys
is ~20% slower:

name                  old time/op  new time/op  delta
MapInterfaceString-8  23.0ns ±21%  27.6ns ±14%  +20.01%  (p=0.002 n=10+10)
MapInterfacePtr-8     19.4ns ±16%  23.7ns ± 7%  +22.48%   (p=0.000 n=10+8)

Change-Id: I7c2e42292a46b5d4e288aaec4029bdbb01089263
Reviewed-on: https://go-review.googlesource.com/c/go/+/191198
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
2019-09-03 20:41:29 +00:00
Cuong Manh Le
d2f958d8d1 cmd/compile: extend ssa.go to handle 1-element array and 1-field struct
Assinging to 1-element array/1-field struct variable is considered clobbering
the whole variable. By emitting OpVarDef in this case, liveness analysis
can now know the variable is redefined.

Also, the isfat is not necessary anymore, and will be removed in follow up CL.

Fixes #33916

Change-Id: Iece0d90b05273f333d59d6ee5b12ee7dc71908c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/192979
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-09-03 19:33:04 +00:00
Matthew Dempsky
9f89edcd96 cmd/compile: silence esc diagnostics about directiface OCONVIFACEs
In general, a conversion to interface type may require values to be
boxed, which in turn necessitates escape analysis to determine whether
the boxed representation can be stack allocated.

However, esc.go used to unconditionally print escape analysis
decisions about OCONVIFACE, even for conversions that don't require
boxing (e.g., pointers, channels, maps, functions).

For test compatibility with esc.go, escape.go similarly printed these
useless diagnostics. This CL removes the diagnostics, and updates test
expectations accordingly.

Change-Id: I97c57a4a08e44d265bba516c78426ff4f2bf1e12
Reviewed-on: https://go-review.googlesource.com/c/go/+/192697
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-09-03 17:52:06 +00:00
Matthew Dempsky
380ef6b759 cmd/compile: simplify {defer,resume}checkwidth logic
This CL extends {defer,resume}checkwidth to support nesting, which
simplifies usage.

Updates #33658.

Change-Id: Ib3ffb8a7cabfae2cbeba74e21748c228436f4726
Reviewed-on: https://go-review.googlesource.com/c/go/+/192721
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
2019-09-03 17:38:32 +00:00
Alberto Donizetti
e6d2544d20 test/codegen: mention -all_codegen in the README
For performance reasons (avoiding costly cross-compilations) CL 177577
changed the codegen test harness to only run the tests for the
machine's GOARCH by default.

This change updates the codegen README accordingly, explaining what
all.bash does run by default and how to perform the tests for all
architectures.

Fixes #33924

Change-Id: I43328d878c3e449ebfda46f7e69963a44a511d40
Reviewed-on: https://go-review.googlesource.com/c/go/+/192619
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
2019-09-01 15:37:13 +00:00
Brian Kessler
b003afe4fe cmd/compile: intrinsify RotateLeft32 on wasm
wasm has 32-bit versions of all integer operations. This change
lowers RotateLeft32 to i32.rotl on wasm and intrinsifies the math/bits
call.  Benchmarking on amd64 under node.js this is ~25% faster.

node v10.15.3/amd64
name          old time/op  new time/op  delta
RotateLeft    8.37ns ± 1%  8.28ns ± 0%   -1.05%  (p=0.029 n=4+4)
RotateLeft8   11.9ns ± 1%  11.8ns ± 0%     ~     (p=0.167 n=5+5)
RotateLeft16  11.8ns ± 0%  11.8ns ± 0%     ~     (all equal)
RotateLeft32  11.9ns ± 1%   8.7ns ± 0%  -26.32%  (p=0.008 n=5+5)
RotateLeft64  8.31ns ± 1%  8.43ns ± 2%     ~     (p=0.063 n=5+5)

Updates #31265

Change-Id: I5b8e155978faeea536c4f6427ac9564d2f096a46
Reviewed-on: https://go-review.googlesource.com/c/go/+/182359
Run-TryBot: Brian Kessler <brian.m.kessler@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Richard Musiol <neelance@gmail.com>
2019-08-31 17:03:04 +00:00
Ben Shi
1786ecd502 cmd/compile: eliminate WASM's redundant extension & wrapping
This CL eliminates unnecessary pairs of I32WrapI64 and
I64ExtendI32U generated by the WASM backend for IF
statements. And it makes the total size of pkg/js_wasm/
decreases about 490KB.

Change-Id: I16b0abb686c4e30d5624323166ec2d0ec57dbe2d
Reviewed-on: https://go-review.googlesource.com/c/go/+/191758
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Richard Musiol <neelance@gmail.com>
2019-08-30 21:20:03 +00:00
Ben Shi
8d5197d818 cmd/compile: optimize 386's math.bits.TrailingZeros16
This CL reverts CL 192097 and fixes the issue in CL 189277.

Change-Id: Icd271262e1f5019a8e01c91f91c12c1261eeb02b
Reviewed-on: https://go-review.googlesource.com/c/go/+/192519
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-08-30 17:37:00 +00:00
Keith Randall
579c69ac1c internal/fmtsort: don't out-of-bounds panic if there's a race condition
Raising an out-of-bounds panic is confusing. There's no indication
that the underlying problem is a race.

The runtime already does a pretty good job of detecting this kind of
race (modification while iterating). We might as well just reorganize
a bit to avoid the out-of-bounds panic.

Fixes #33275

Change-Id: Icdd337ad2eb3c84f999db0850ec1d2ff2c146b6e
Reviewed-on: https://go-review.googlesource.com/c/go/+/191197
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
2019-08-30 05:41:23 +00:00
Robert Griesemer
5411953df5 cmd/compile: avoid follow-on errors for literals with syntax errors
- only convert literal strings if there were no syntax errors
  (some of the conversion routines exit if there is an error)
- mark nodes for literals with syntax errors to avoid follow-on
  errors
- don't attempt to import packages whose path had syntax errors

Fixes #32133.

Change-Id: I1803ad48c65abfecf6f48ddff1e27eded5e282c5
Reviewed-on: https://go-review.googlesource.com/c/go/+/192437
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-08-29 23:37:07 +00:00
Josh Bleecher Snyder
b8cbcacabe cmd/compile: optimize more pointer comparisons
The existing pointer comparison optimizations
don't include pointer arithmetic. Add them.

These rules trigger a few times in std cmd, while compiling:

time.Duration.String
cmd/go/internal/tlog.NodeHash
crypto/tls.ticketKeyFromBytes (3 times)
crypto/elliptic.(*p256Point).p256ScalarMult (15 times!)
crypto/elliptic.initTable

These weird comparisons occur when using the copy builtin,
which does a pointer comparison between src and dst.

This also happens to fix #32454, by optimizing enough
early on that all values can be eliminated.

Fixes #32454

Change-Id: I799d45743350bddd15a295dc1e12f8d03c11d1c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/180940
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-08-29 19:35:18 +00:00
Cuong Manh Le
97bc039c9c cmd/compile: emit error message for broken type
The original report in #5172 was that cmd/compile was generating bogus
follow-on error messages when typechecking a struct failed. Instead of
fixing those follow-on error messages, golang.org/cl/9614044 suppress all
follow-on error messages after struct typecheck fails. We should
continue emitting error messages instead.

While at it, also add the test case for original report.

Fixes #33947

Change-Id: I4a5c6878977128abccd704350a12df743631c7bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/191944
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-08-29 19:08:00 +00:00
LE Manh Cuong
24c6dd9823 cmd/compile: fix internal error on complex comparison
Complex type is the only TIDEAL that lack of support for all comparison
operators. When rewriting constant comparison into literal node, that
missing cause compiler raise an internal error.

Checking the operator is available for complex type before that fix the
problem.

We can make this check works more generally if there's more type lack of
supporting all comparison operators added, but it does not seem to be
happened, so just check explicitly for complex only.

Fixes #32723

Change-Id: I4938b1bdcbcdae9a9d87436024984bd2ab12995e
Reviewed-on: https://go-review.googlesource.com/c/go/+/183459
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-08-29 18:24:31 +00:00
Josh Bleecher Snyder
2393d16147 cmd/compile: handle infinite loops in shortcircuit pass
The newly upgraded shortcircuit pass attempted to remove infinite loops.
Stop doing that.

Fixes #33903

Change-Id: I0fc9c1b5f2427e54ce650806602ef5e3ad65aca5
Reviewed-on: https://go-review.googlesource.com/c/go/+/192144
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-08-29 17:41:49 +00:00
LE Manh Cuong
e87fe0f1f5 cmd/compile: make typecheck set n.Type.Nod when returning OTYPE
typecheck only set n.Type.Nod for declared type, and leave it nil for
anonymous types, type alias. It leads to compiler crashes, because
n.Type.Nod is nil at the time dowidth was called.

Fixing it by set n.Type.Nod right after n.Type initialization if n.Op is
OTYPE.

When embedding interface cycles involve in type alias, it also helps
pointing the error message to the position of the type alias
declaration, instead of position of embedding interface.

Fixes #31872

Change-Id: Ia18391e987036a91f42ba0c08b5506f52d07f683
Reviewed-on: https://go-review.googlesource.com/c/go/+/191540
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-08-29 16:43:07 +00:00
Than McIntosh
35ac194557 test: new testcase for gollvm bug
Testcase for a gollvm bug (assert in Llvm_backend::materializeComposite).

Updates golang/go#33020.

Change-Id: Icdf5b4b2b6eb55a5b48a31a61c41215b1ae4cf01
Reviewed-on: https://go-review.googlesource.com/c/go/+/191743
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2019-08-29 15:21:31 +00:00
Cherry Zhang
9859f6bedb test/codegen: fix ARM32 RotateLeft32 test
The syntax of a shifted operation does not have a "$" sign for
the shift amount. Remove it.

Change-Id: I50782fe942b640076f48c2fafea4d3175be8ff99
Reviewed-on: https://go-review.googlesource.com/c/go/+/192100
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-08-28 20:42:48 +00:00
Matthew Dempsky
777304a5d3 Revert "cmd/compile: make isfat handle 1-element array, 1-field struct"
This reverts commit 5322776215.

Reason for revert: broke js-wasm builder.

Change-Id: If22762317c4a9e00f5060eb84377a4a52d601fca
Reviewed-on: https://go-review.googlesource.com/c/go/+/192157
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
2019-08-28 20:28:13 +00:00
LE Manh Cuong
5322776215 cmd/compile: make isfat handle 1-element array, 1-field struct
This will improve liveness analysis slightly, the same logic as
isdirectiface curently does. In:

	type T struct {
	    m map[int]int
	}

        v := T{}
        v.m = make(map[int]int)

T is considered "fat", now it is not. So assigning to v.m is considered
to clobber the entire v.

This is follow up of CL 179057.

Change-Id: Id6b4807b8e8521ef5d8bcb14fedb6dceb9dbf18c
Reviewed-on: https://go-review.googlesource.com/c/go/+/179578
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 19:48:31 +00:00
Cholerae Hu
52cff70100 cmd/compile: truncate constant arithmetic result with typed complex numbers
Fixes #33285

Change-Id: Idd125e3342058051216be3f105330aef987320c3
Reviewed-on: https://go-review.googlesource.com/c/go/+/187697
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2019-08-28 19:45:44 +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
Matthew Dempsky
501b786e5c test: remove -newescape from regress tests
Prep for subsequent CLs to remove old escape analysis pass.

This CL removes -newescape=true from tests that use it, and deletes
tests that use -newescape=false. (For history, see CL 170447.)

Notably, this removes escape_because.go without any replacement, but
this is being tracked by #31489.

Change-Id: I6f6058d58fff2c5d210cb1d2713200cc9f501ca7
Reviewed-on: https://go-review.googlesource.com/c/go/+/187617
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
2019-08-28 19:27:20 +00:00
Ian Lance Taylor
4757518737 test: add test that failed with gccgo
Updates #33739

Change-Id: Ib7ce4bc51972fe49998f37f6e27baa6a2a036d5e
Reviewed-on: https://go-review.googlesource.com/c/go/+/191001
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-08-28 18:35:32 +00:00
Ben Shi
3cfd003a8a cmd/compile: optimize ARM's math.bits.RotateLeft32
This CL optimizes math.bits.RotateLeft32 to inline
"MOVW Rx@>Ry, Rd" on ARM.

The benchmark results of math/bits show some improvements.
name               old time/op  new time/op  delta
RotateLeft-4       9.42ns ± 0%  6.91ns ± 0%  -26.66%  (p=0.000 n=40+33)
RotateLeft8-4      8.79ns ± 0%  8.79ns ± 0%   -0.04%  (p=0.000 n=40+31)
RotateLeft16-4     8.79ns ± 0%  8.79ns ± 0%   -0.04%  (p=0.000 n=40+32)
RotateLeft32-4     8.16ns ± 0%  7.54ns ± 0%   -7.68%  (p=0.000 n=40+40)
RotateLeft64-4     15.7ns ± 0%  15.7ns ± 0%     ~     (all equal)

updates #31265

Change-Id: I77bc1c2c702d5323fc7cad5264a8e2d5666bf712
Reviewed-on: https://go-review.googlesource.com/c/go/+/188697
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-08-28 15:41:58 +00:00
Ben Shi
c683ab8128 cmd/compile: optimize ARM's math.Abs
This CL optimizes math.Abs to an inline ABSD instruction on ARM.

The benchmark results of src/math/ show big improvements.
name                   old time/op  new time/op  delta
Acos-4                  181ns ± 0%   182ns ± 0%   +0.30%  (p=0.000 n=40+40)
Acosh-4                 202ns ± 0%   202ns ± 0%     ~     (all equal)
Asin-4                  163ns ± 0%   163ns ± 0%     ~     (all equal)
Asinh-4                 242ns ± 0%   242ns ± 0%     ~     (all equal)
Atan-4                  120ns ± 0%   121ns ± 0%   +0.83%  (p=0.000 n=40+40)
Atanh-4                 202ns ± 0%   202ns ± 0%     ~     (all equal)
Atan2-4                 173ns ± 0%   173ns ± 0%     ~     (all equal)
Cbrt-4                 1.06µs ± 0%  1.06µs ± 0%   +0.09%  (p=0.000 n=39+37)
Ceil-4                 72.9ns ± 0%  72.8ns ± 0%     ~     (p=0.237 n=40+40)
Copysign-4             13.2ns ± 0%  13.2ns ± 0%     ~     (all equal)
Cos-4                   193ns ± 0%   183ns ± 0%   -5.18%  (p=0.000 n=40+40)
Cosh-4                  254ns ± 0%   239ns ± 0%   -5.91%  (p=0.000 n=40+40)
Erf-4                   112ns ± 0%   112ns ± 0%     ~     (all equal)
Erfc-4                  117ns ± 0%   117ns ± 0%     ~     (all equal)
Erfinv-4                127ns ± 0%   127ns ± 1%     ~     (p=0.492 n=40+40)
Erfcinv-4               128ns ± 0%   128ns ± 0%     ~     (all equal)
Exp-4                   212ns ± 0%   206ns ± 0%   -3.05%  (p=0.000 n=40+40)
ExpGo-4                 216ns ± 0%   209ns ± 0%   -3.24%  (p=0.000 n=40+40)
Expm1-4                 142ns ± 0%   142ns ± 0%     ~     (all equal)
Exp2-4                  191ns ± 0%   184ns ± 0%   -3.45%  (p=0.000 n=40+40)
Exp2Go-4                194ns ± 0%   187ns ± 0%   -3.61%  (p=0.000 n=40+40)
Abs-4                  14.4ns ± 0%   6.3ns ± 0%  -56.39%  (p=0.000 n=38+39)
Dim-4                  12.6ns ± 0%  12.6ns ± 0%     ~     (all equal)
Floor-4                49.6ns ± 0%  49.6ns ± 0%     ~     (all equal)
Max-4                  27.6ns ± 0%  27.6ns ± 0%     ~     (all equal)
Min-4                  27.0ns ± 0%  27.0ns ± 0%     ~     (all equal)
Mod-4                   349ns ± 0%   305ns ± 1%  -12.55%  (p=0.000 n=33+40)
Frexp-4                54.0ns ± 0%  47.1ns ± 0%  -12.78%  (p=0.000 n=38+38)
Gamma-4                 242ns ± 0%   234ns ± 0%   -3.16%  (p=0.000 n=36+40)
Hypot-4                84.8ns ± 0%  67.8ns ± 0%  -20.05%  (p=0.000 n=31+35)
HypotGo-4              88.5ns ± 0%  71.6ns ± 0%  -19.12%  (p=0.000 n=40+38)
Ilogb-4                45.8ns ± 0%  38.9ns ± 0%  -15.12%  (p=0.000 n=40+32)
J0-4                    821ns ± 0%   802ns ± 0%   -2.33%  (p=0.000 n=33+40)
J1-4                    816ns ± 0%   807ns ± 0%   -1.05%  (p=0.000 n=40+29)
Jn-4                   1.67µs ± 0%  1.65µs ± 0%   -1.45%  (p=0.000 n=40+39)
Ldexp-4                61.5ns ± 0%  54.6ns ± 0%  -11.27%  (p=0.000 n=40+32)
Lgamma-4                188ns ± 0%   188ns ± 0%     ~     (all equal)
Log-4                   154ns ± 0%   147ns ± 0%   -4.78%  (p=0.000 n=40+40)
Logb-4                 50.9ns ± 0%  42.7ns ± 0%  -16.11%  (p=0.000 n=34+39)
Log1p-4                 160ns ± 0%   159ns ± 0%     ~     (p=0.828 n=40+40)
Log10-4                 173ns ± 0%   166ns ± 0%   -4.05%  (p=0.000 n=40+40)
Log2-4                 65.3ns ± 0%  58.4ns ± 0%  -10.57%  (p=0.000 n=37+37)
Modf-4                 36.4ns ± 0%  36.4ns ± 0%     ~     (all equal)
Nextafter32-4          36.4ns ± 0%  36.4ns ± 0%     ~     (all equal)
Nextafter64-4          32.7ns ± 0%  32.6ns ± 0%     ~     (p=0.375 n=40+40)
PowInt-4                300ns ± 0%   277ns ± 0%   -7.78%  (p=0.000 n=40+40)
PowFrac-4               676ns ± 0%   635ns ± 0%   -6.00%  (p=0.000 n=40+35)
Pow10Pos-4             17.6ns ± 0%  17.6ns ± 0%     ~     (all equal)
Pow10Neg-4             22.0ns ± 0%  22.0ns ± 0%     ~     (all equal)
Round-4                30.1ns ± 0%  30.1ns ± 0%     ~     (all equal)
RoundToEven-4          38.9ns ± 0%  38.9ns ± 0%     ~     (all equal)
Remainder-4             291ns ± 0%   263ns ± 0%   -9.62%  (p=0.000 n=40+40)
Signbit-4              11.3ns ± 0%  11.3ns ± 0%     ~     (all equal)
Sin-4                   185ns ± 0%   185ns ± 0%     ~     (all equal)
Sincos-4                230ns ± 0%   230ns ± 0%     ~     (all equal)
Sinh-4                  253ns ± 0%   246ns ± 0%   -2.77%  (p=0.000 n=39+39)
SqrtIndirect-4         41.4ns ± 0%  41.4ns ± 0%     ~     (all equal)
SqrtLatency-4          13.8ns ± 0%  13.8ns ± 0%     ~     (all equal)
SqrtIndirectLatency-4  37.0ns ± 0%  37.0ns ± 0%     ~     (p=0.632 n=40+40)
SqrtGoLatency-4         911ns ± 0%   911ns ± 0%   +0.08%  (p=0.000 n=40+40)
SqrtPrime-4            13.2µs ± 0%  13.2µs ± 0%   +0.01%  (p=0.038 n=38+40)
Tan-4                   205ns ± 0%   205ns ± 0%     ~     (all equal)
Tanh-4                  264ns ± 0%   247ns ± 0%   -6.44%  (p=0.000 n=39+32)
Trunc-4                45.2ns ± 0%  45.2ns ± 0%     ~     (all equal)
Y0-4                    796ns ± 0%   792ns ± 0%   -0.55%  (p=0.000 n=35+40)
Y1-4                    804ns ± 0%   797ns ± 0%   -0.82%  (p=0.000 n=24+40)
Yn-4                   1.64µs ± 0%  1.62µs ± 0%   -1.27%  (p=0.000 n=40+39)
Float64bits-4          8.16ns ± 0%  8.16ns ± 0%   +0.04%  (p=0.000 n=35+40)
Float64frombits-4      10.7ns ± 0%  10.7ns ± 0%     ~     (all equal)
Float32bits-4          7.53ns ± 0%  7.53ns ± 0%     ~     (p=0.760 n=40+40)
Float32frombits-4      6.91ns ± 0%  6.91ns ± 0%   -0.04%  (p=0.002 n=32+38)
[Geo mean]              111ns        106ns        -3.98%

Change-Id: I54f4fd7f5160db020b430b556bde59cc0fdb996d
Reviewed-on: https://go-review.googlesource.com/c/go/+/188678
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-08-28 15:41:28 +00:00
Bryan C. Mills
372b0eed17 Revert "cmd/compile: optimize 386's math.bits.TrailingZeros16"
This reverts CL 189277.

Reason for revert: broke 32-bit builders.

Updates #33902

Change-Id: Ie5f180d0371a90e5057ed578c334372e5fc3a286
Reviewed-on: https://go-review.googlesource.com/c/go/+/192097
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
2019-08-28 12:57:59 +00:00
Agniva De Sarker
7be97af2ff cmd/compile: apply optimization for readonly globals on wasm
Extend the optimization introduced in CL 141118 to the wasm architecture.

And for reference, the rules trigger 212 times while building std and cmd

$GOOS=js GOARCH=wasm gotip build std cmd
$grep -E "Wasm.rules:44(1|2|3|4)" rulelog | wc -l
212

Updates #26498

Change-Id: I153684a2b98589ae812b42268da08b65679e09d1
Reviewed-on: https://go-review.googlesource.com/c/go/+/185477
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Reviewed-by: Richard Musiol <neelance@gmail.com>
2019-08-28 05:55:52 +00:00
Agniva De Sarker
8fedb2d338 cmd/compile: optimize bounded shifts on wasm
Use the shiftIsBounded function to generate more efficient
Shift instructions.

Updates #25167

Change-Id: Id350f8462dc3a7ed3bfed0bcbea2860b8f40048a
Reviewed-on: https://go-review.googlesource.com/c/go/+/182558
Run-TryBot: Agniva De Sarker <agniva.quicksilver@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Richard Musiol <neelance@gmail.com>
2019-08-28 04:44:21 +00:00
Ben Shi
22355d6cd2 cmd/compile: optimize 386's math.bits.TrailingZeros16
This CL optimizes math.bits.TrailingZeros16 on 386 with
a pair of BSFL and ORL instrcutions.

The case TrailingZeros16-4 of the benchmark test in
math/bits shows big improvement.
name               old time/op  new time/op  delta
TrailingZeros16-4  1.55ns ± 1%  0.87ns ± 1%  -43.87%  (p=0.000 n=50+49)

Change-Id: Ia899975b0e46f45dcd20223b713ed632bc32740b
Reviewed-on: https://go-review.googlesource.com/c/go/+/189277
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2019-08-28 02:29:54 +00:00