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| author | Ben Shi <powerman1st@163.com> | 2018-06-19 03:44:28 +0000 |
|---|---|---|
| committer | Ben Shi <powerman1st@163.com> | 2018-08-20 14:05:37 +0000 |
| commit | bd483592a23c5c8964d1af5ca85792db031229ad (patch) | |
| tree | 8371c805b56d3be12e7514109111b2c1efe136a6 /src/cmd/compile/internal/x86 | |
| parent | 5403b8ecebc37da227dae170f01b6004a66bf2e6 (diff) | |
| download | go-bd483592a23c5c8964d1af5ca85792db031229ad.tar.gz go-bd483592a23c5c8964d1af5ca85792db031229ad.zip | |
cmd/compile/internal/x86: simplify 387 with FLDZ and FLZ1
FLD1 pushes +1.0 to the 387 register stack, and FLDZ pushes +0.0
to the 387 regiser stack.
They can be used to simplify MOVSSconst/MOVSDconst when the
constant is +0.0, -0.0, +1.0, -1.0.
The size of the go executable reduces about 62KB and the total size
of pkg/linux_386 reduces about 7KB with this optimization.
Change-Id: Icc8213b58262e0024a277cf1103812a17dd4b05e
Reviewed-on: https://go-review.googlesource.com/119635
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Diffstat (limited to 'src/cmd/compile/internal/x86')
| -rw-r--r-- | src/cmd/compile/internal/x86/387.go | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/src/cmd/compile/internal/x86/387.go b/src/cmd/compile/internal/x86/387.go index 7a3622405c..ab3d30e76c 100644 --- a/src/cmd/compile/internal/x86/387.go +++ b/src/cmd/compile/internal/x86/387.go @@ -22,11 +22,24 @@ func ssaGenValue387(s *gc.SSAGenState, v *ssa.Value) { switch v.Op { case ssa.Op386MOVSSconst, ssa.Op386MOVSDconst: - p := s.Prog(loadPush(v.Type)) - p.From.Type = obj.TYPE_FCONST - p.From.Val = math.Float64frombits(uint64(v.AuxInt)) - p.To.Type = obj.TYPE_REG - p.To.Reg = x86.REG_F0 + iv := uint64(v.AuxInt) + if iv == 0x0000000000000000 { // +0.0 + s.Prog(x86.AFLDZ) + } else if iv == 0x3ff0000000000000 { // +1.0 + s.Prog(x86.AFLD1) + } else if iv == 0x8000000000000000 { // -0.0 + s.Prog(x86.AFLDZ) + s.Prog(x86.AFCHS) + } else if iv == 0xbff0000000000000 { // -1.0 + s.Prog(x86.AFLD1) + s.Prog(x86.AFCHS) + } else { // others + p := s.Prog(loadPush(v.Type)) + p.From.Type = obj.TYPE_FCONST + p.From.Val = math.Float64frombits(iv) + p.To.Type = obj.TYPE_REG + p.To.Reg = x86.REG_F0 + } popAndSave(s, v) case ssa.Op386MOVSSconst2, ssa.Op386MOVSDconst2: |