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[dev.ssa] cmd/compile: fix liblink rewrite of -0.0

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liblink was rewriting xor by a negative zero (used by SSA
for negation) as XORPS reg,reg.

Fixes strconv.

Change-Id: I627a0a7366618e6b07ba8f0ad0db0e102340c5e3
Reviewed-on: https://go-review.googlesource.com/14200
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Todd Neal 2015-09-01 21:25:24 -05:00
parent 634b50c6e1
commit 5cb352edeb
2 changed files with 18 additions and 2 deletions
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14
src/cmd/compile/internal/gc/testdata/fp_ssa.go vendored
View File

@ -105,6 +105,12 @@ func div64_ssa(a, b float64) float64 {
return a / b
}
func neg64_ssa(a, b float64) float64 {
switch {
}
return -a + -1*b
}
func add32_ssa(a, b float32) float32 {
switch {
}
@ -128,6 +134,12 @@ func div32_ssa(a, b float32) float32 {
return a / b
}
func neg32_ssa(a, b float32) float32 {
switch {
}
return -a + -1*b
}
func conv2Float64_ssa(a int8, b uint8, c int16, d uint16,
e int32, f uint32, g int64, h uint64, i float32) (aa, bb, cc, dd, ee, ff, gg, hh, ii float64) {
switch {
@ -1548,11 +1560,13 @@ func main() {
fails += fail64("*", mul64_ssa, a, b, 12.0)
fails += fail64("-", sub64_ssa, a, b, -1.0)
fails += fail64("/", div64_ssa, a, b, 0.75)
fails += fail64("neg", neg64_ssa, a, b, -7)
fails += fail32("+", add32_ssa, c, d, 7.0)
fails += fail32("*", mul32_ssa, c, d, 12.0)
fails += fail32("-", sub32_ssa, c, d, -1.0)
fails += fail32("/", div32_ssa, c, d, 0.75)
fails += fail32("neg", neg32_ssa, c, d, -7)
// denorm-squared should underflow to zero.
fails += fail32("*", mul32_ssa, tiny, tiny, 0)

6
src/cmd/internal/obj/x86/obj6.go
View File

@ -221,7 +221,8 @@ func progedit(ctxt *obj.Link, p *obj.Prog) {
// Convert AMOVSS $(0), Xx to AXORPS Xx, Xx
case AMOVSS:
if p.From.Type == obj.TYPE_FCONST {
if p.From.Val.(float64) == 0 {
// f == 0 can't be used here due to -0, so use Float64bits
if f := p.From.Val.(float64); math.Float64bits(f) == 0 {
if p.To.Type == obj.TYPE_REG && REG_X0 <= p.To.Reg && p.To.Reg <= REG_X15 {
p.As = AXORPS
p.From = p.To
@ -261,7 +262,8 @@ func progedit(ctxt *obj.Link, p *obj.Prog) {
case AMOVSD:
// Convert AMOVSD $(0), Xx to AXORPS Xx, Xx
if p.From.Type == obj.TYPE_FCONST {
if p.From.Val.(float64) == 0 {
// f == 0 can't be used here due to -0, so use Float64bits
if f := p.From.Val.(float64); math.Float64bits(f) == 0 {
if p.To.Type == obj.TYPE_REG && REG_X0 <= p.To.Reg && p.To.Reg <= REG_X15 {
p.As = AXORPS
p.From = p.To