go/src/cmd
Cherry Zhang b08a9b7ecc all: use new softfloat on GOARM=5
Use the new softfloat support in the compiler, originally added
for softfloat on MIPS. This support is portable, so we can just
use it for softfloat on ARM.

In the old softfloat support on ARM, the compiler generates
floating point instructions, then the assembler inserts calls
to _sfloat before FP instructions. _sfloat decodes the following
FP instructions and simulates them.

In the new scheme, the compiler generates runtime calls to do FP
operations at a higher level. It doesn't generate FP instructions,
and therefore the assembler won't insert _sfloat calls, i.e. the
old mechanism is automatically suppressed.

The old method may be still be triggered with assembly code
using FP instructions. In the standard library, the only
occurance is math/sqrt_arm.s, which is rewritten to call to the
Go implementation instead.

Some significant speedups for code using floating points:

name                     old time/op    new time/op     delta
BinaryTree17-4              37.1s ± 2%      37.3s ± 1%     ~     (p=0.105 n=10+10)
Fannkuch11-4                13.0s ± 0%      13.1s ± 0%   +0.46%  (p=0.000 n=10+10)
FmtFprintfEmpty-4           700ns ± 4%      734ns ± 6%   +4.84%  (p=0.009 n=10+10)
FmtFprintfString-4         1.22µs ± 3%     1.22µs ± 4%     ~     (p=0.897 n=10+10)
FmtFprintfInt-4            1.27µs ± 2%     1.30µs ± 1%   +1.91%  (p=0.001 n=10+9)
FmtFprintfIntInt-4         1.83µs ± 2%     1.81µs ± 3%     ~     (p=0.149 n=10+10)
FmtFprintfPrefixedInt-4    1.80µs ± 3%     1.81µs ± 2%     ~     (p=0.421 n=10+8)
FmtFprintfFloat-4          6.89µs ± 3%     3.59µs ± 2%  -47.93%  (p=0.000 n=10+10)
FmtManyArgs-4              6.39µs ± 1%     6.09µs ± 1%   -4.61%  (p=0.000 n=10+9)
GobDecode-4                 109ms ± 2%       81ms ± 2%  -25.99%  (p=0.000 n=9+10)
GobEncode-4                 109ms ± 2%       76ms ± 2%  -29.88%  (p=0.000 n=10+9)
Gzip-4                      3.61s ± 1%      3.59s ± 1%     ~     (p=0.247 n=10+10)
Gunzip-4                    449ms ± 4%      450ms ± 1%     ~     (p=0.230 n=10+7)
HTTPClientServer-4         1.55ms ± 3%     1.53ms ± 2%     ~     (p=0.400 n=9+10)
JSONEncode-4                356ms ± 1%      183ms ± 1%  -48.73%  (p=0.000 n=10+10)
JSONDecode-4                1.12s ± 2%      0.87s ± 1%  -21.88%  (p=0.000 n=10+10)
Mandelbrot200-4             5.49s ± 1%      2.55s ± 1%  -53.45%  (p=0.000 n=9+10)
GoParse-4                  49.6ms ± 2%     47.5ms ± 1%   -4.08%  (p=0.000 n=10+9)
RegexpMatchEasy0_32-4      1.13µs ± 4%     1.20µs ± 4%   +6.42%  (p=0.000 n=10+10)
RegexpMatchEasy0_1K-4      4.41µs ± 2%     4.44µs ± 2%     ~     (p=0.128 n=10+10)
RegexpMatchEasy1_32-4      1.15µs ± 5%     1.20µs ± 5%   +4.85%  (p=0.002 n=10+10)
RegexpMatchEasy1_1K-4      6.21µs ± 2%     6.37µs ± 4%   +2.62%  (p=0.001 n=9+10)
RegexpMatchMedium_32-4     1.58µs ± 5%     1.65µs ± 3%   +4.85%  (p=0.000 n=10+10)
RegexpMatchMedium_1K-4      341µs ± 3%      351µs ± 7%     ~     (p=0.573 n=8+10)
RegexpMatchHard_32-4       21.4µs ± 3%     21.5µs ± 5%     ~     (p=0.931 n=9+9)
RegexpMatchHard_1K-4        626µs ± 2%      626µs ± 1%     ~     (p=0.645 n=8+8)
Revcomp-4                  46.4ms ± 2%     47.4ms ± 2%   +2.07%  (p=0.000 n=10+10)
Template-4                  1.31s ± 3%      1.23s ± 4%   -6.13%  (p=0.000 n=10+10)
TimeParse-4                4.49µs ± 1%     4.41µs ± 2%   -1.81%  (p=0.000 n=10+9)
TimeFormat-4               9.31µs ± 1%     9.32µs ± 2%     ~     (p=0.561 n=9+9)

Change-Id: Iaeeff6c9a09c1b2c064d06e09dd88101dc02bfa4
Reviewed-on: https://go-review.googlesource.com/106735
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2018-04-13 16:39:39 +00:00
..
addr2line
api cmd/api: don’t rely on hardcoded go versions 2017-12-11 22:28:37 +00:00
asm cmd/internal/obj/arm64: fix the bug of incorrect handling negative offset of LDP/STP/LDPW/STPW 2018-04-13 15:37:21 +00:00
buildid cmd/buildid: fix rewrite algorithm 2018-01-04 16:56:51 +00:00
cgo cmd/cgo: add support for GOARCH=sparc64 2018-03-26 18:58:51 +00:00
compile all: use new softfloat on GOARM=5 2018-04-13 16:39:39 +00:00
cover all: use strings.Builder instead of bytes.Buffer where appropriate 2018-03-26 23:05:53 +00:00
dist go/build, go/types, cmd/dist: add js/wasm architecture 2018-03-30 21:34:18 +00:00
doc go/printer, gofmt: tuned table alignment for better results 2018-04-04 13:39:34 -07:00
fix all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
go cmd/go: fix typo in test inputs descriptor 2018-04-11 19:59:53 +00:00
gofmt
internal cmd/internal/obj/arm64: fix the bug of incorrect handling negative offset of LDP/STP/LDPW/STPW 2018-04-13 15:37:21 +00:00
link cmd/link: do not pass -no-pie to host linker when -linkshared is passed 2018-04-12 10:21:35 +00:00
nm cmd/internal/goobj: accept int64 in readInt 2017-11-01 18:23:58 +00:00
objdump cmd/objdump: pass the correct execution mode to x86asm.Decode in disasm_x86 on 386 2017-11-10 20:11:20 +00:00
pack cmd: remove some unused parameters 2018-04-02 15:51:31 +00:00
pprof go/printer, gofmt: tuned table alignment for better results 2018-04-04 13:39:34 -07:00
test2json cmd/test2json: document missing "skip" action 2018-03-24 18:37:22 +00:00
trace cmd/trace: change span id computation for trace view use 2018-04-13 16:18:30 +00:00
vendor cmd/vendor/.../pprof: update to 0f7d9ba1 2018-04-06 23:03:41 +00:00
vet cmd: some semi-automated cleanups 2018-04-06 13:59:29 +00:00