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Ilya Tocar 9916feeddf cmd/compile/internal/ssa: don't spill register offsets on amd64
Transform (ADDQconst SP) into (LEA SP), because lea is rematerializeable,
so this avoids register spill. We can't mark ADDQconst as rematerializeable,
because it clobbers flags. This makes go binary ~2kb smaller.

For reference here is generated code for function from bug report.
Before:
        CALL    "".g(SB)
        MOVBLZX (SP), AX
        LEAQ    8(SP), DI
        TESTB   AX, AX
        JEQ     15
        MOVQ    "".p(SP), SI
        DUFFCOPY        $196
        MOVQ    $0, (SP)
        PCDATA  $0, $1
        CALL    "".h(SB)
        RET
        MOVQ    DI, ""..autotmp_2-8(SP) // extra spill
        PCDATA  $0, $2
        CALL    "".g(SB)
        MOVQ    ""..autotmp_2-8(SP), DI // extra register fill
        MOVQ    "".p(SP), SI
        DUFFCOPY        $196
        MOVQ    $1, (SP)
        PCDATA  $0, $1
        CALL    "".h(SB)
        JMP     14
        END

After:
        CALL    "".g(SB)
        MOVBLZX (SP), AX
        TESTB   AX, AX
        JEQ     15
        LEAQ    8(SP), DI
        MOVQ    "".p(SP), SI
        DUFFCOPY        $196
        MOVQ    $0, (SP)
        PCDATA  $0, $1
        CALL    "".h(SB)
        RET
        PCDATA  $0, $0  // no spill
        CALL    "".g(SB)
        LEAQ    8(SP), DI // rematerialized instead
        MOVQ    "".p(SP), SI
        DUFFCOPY        $196
        MOVQ    $1, (SP)
        PCDATA  $0, $1
        CALL    "".h(SB)
        JMP     14
        END

Fixes #22947

Change-Id: I8f33b860dc6c8828373477171b172ca2ce30074f
Reviewed-on: https://go-review.googlesource.com/81815
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2018-02-14 20:08:43 +00:00
.github github: add a Pull Request template 2018-02-14 16:13:49 +00:00
api syscall: support Getwd on all BSDs 2018-02-13 15:41:19 +00:00
doc doc/articles/wiki: highlight the use of _ warning 2018-02-14 04:54:37 +00:00
lib/time all: use HTTPS for iana.org links 2018-02-13 18:36:48 +00:00
misc misc/cgo/testcshared: increase sleep in TestUnexportedSymbols 2018-02-14 15:03:29 +00:00
src cmd/compile/internal/ssa: don't spill register offsets on amd64 2018-02-14 20:08:43 +00:00
test cmd/compile: fix constant folding of right shifts 2018-02-14 00:03:36 +00:00
.gitattributes
.gitignore .gitignore: ignore src/cmd/dist/dist 2017-10-28 21:55:49 +00:00
AUTHORS A+C: update late Go 1.10 contributors 2018-01-06 04:52:00 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS A+C: update late Go 1.10 contributors 2018-01-06 04:52:00 +00:00
favicon.ico website: recreate 16px and 32px favicon 2016-08-25 15:43:32 +00:00
LICENSE
PATENTS
README.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
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