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

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>

1 files changed, 14 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/gc/testdata/fp_ssa.go b/src/cmd/compile/internal/gc/testdata/fp_ssa.go
index 6193983e4c..ee3163abb3 100644
--- a/src/cmd/compile/internal/gc/testdata/fp_ssa.go
+++ b/src/cmd/compile/internal/gc/testdata/fp_ssa.go
@@ -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)