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cmd/compile: don't depend on arch-dependent conversions in the compiler

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Leave those constant foldings for runtime, similar to how we do it
for NaN generation.

These are the only instances I could find in cmd/compile/..., using

objdump -d ../pkg/tool/darwin_arm64/compile| egrep "(fcvtz|>:)" | grep -B1 fcvt

(There are instances in other places, like runtime and reflect, but I don't
think those places would affect compiler output.)

Change-Id: I4113fe4570115e4765825cf442cb1fde97cf2f27
Reviewed-on: https://go-review.googlesource.com/c/go/+/711281
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@google.com>
This commit is contained in:
Keith Randall 2025-10-13 09:39:06 -07:00
parent 0e64ee1286
commit 9b8742f2e7
3 changed files with 65 additions and 4 deletions
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8
src/cmd/compile/internal/ssa/_gen/generic.rules
View file

@ -50,10 +50,10 @@
(Cvt32to64F (Const32 [c])) => (Const64F [float64(c)])
(Cvt64to32F (Const64 [c])) => (Const32F [float32(c)])
(Cvt64to64F (Const64 [c])) => (Const64F [float64(c)])
(Cvt32Fto32 (Const32F [c])) => (Const32 [int32(c)])
(Cvt32Fto64 (Const32F [c])) => (Const64 [int64(c)])
(Cvt64Fto32 (Const64F [c])) => (Const32 [int32(c)])
(Cvt64Fto64 (Const64F [c])) => (Const64 [int64(c)])
(Cvt32Fto32 (Const32F [c])) && c >= -1<<31 && c < 1<<31 => (Const32 [int32(c)])
(Cvt32Fto64 (Const32F [c])) && c >= -1<<63 && c < 1<<63 => (Const64 [int64(c)])
(Cvt64Fto32 (Const64F [c])) && c >= -1<<31 && c < 1<<31 => (Const32 [int32(c)])
(Cvt64Fto64 (Const64F [c])) && c >= -1<<63 && c < 1<<63 => (Const64 [int64(c)])
(Round32F x:(Const32F)) => x
(Round64F x:(Const64F)) => x
(CvtBoolToUint8 (ConstBool [false])) => (Const8 [0])

16
src/cmd/compile/internal/ssa/rewritegeneric.go
View file

@ -6607,12 +6607,16 @@ func rewriteValuegeneric_OpCtz8(v *Value) bool {
func rewriteValuegeneric_OpCvt32Fto32(v *Value) bool {
v_0 := v.Args[0]
// match: (Cvt32Fto32 (Const32F [c]))
// cond: c >= -1<<31 && c < 1<<31
// result: (Const32 [int32(c)])
for {
if v_0.Op != OpConst32F {
break
}
c := auxIntToFloat32(v_0.AuxInt)
if !(c >= -1<<31 && c < 1<<31) {
break
}
v.reset(OpConst32)
v.AuxInt = int32ToAuxInt(int32(c))
return true
@ -6622,12 +6626,16 @@ func rewriteValuegeneric_OpCvt32Fto32(v *Value) bool {
func rewriteValuegeneric_OpCvt32Fto64(v *Value) bool {
v_0 := v.Args[0]
// match: (Cvt32Fto64 (Const32F [c]))
// cond: c >= -1<<63 && c < 1<<63
// result: (Const64 [int64(c)])
for {
if v_0.Op != OpConst32F {
break
}
c := auxIntToFloat32(v_0.AuxInt)
if !(c >= -1<<63 && c < 1<<63) {
break
}
v.reset(OpConst64)
v.AuxInt = int64ToAuxInt(int64(c))
return true
@ -6682,12 +6690,16 @@ func rewriteValuegeneric_OpCvt32to64F(v *Value) bool {
func rewriteValuegeneric_OpCvt64Fto32(v *Value) bool {
v_0 := v.Args[0]
// match: (Cvt64Fto32 (Const64F [c]))
// cond: c >= -1<<31 && c < 1<<31
// result: (Const32 [int32(c)])
for {
if v_0.Op != OpConst64F {
break
}
c := auxIntToFloat64(v_0.AuxInt)
if !(c >= -1<<31 && c < 1<<31) {
break
}
v.reset(OpConst32)
v.AuxInt = int32ToAuxInt(int32(c))
return true
@ -6732,12 +6744,16 @@ func rewriteValuegeneric_OpCvt64Fto32F(v *Value) bool {
func rewriteValuegeneric_OpCvt64Fto64(v *Value) bool {
v_0 := v.Args[0]
// match: (Cvt64Fto64 (Const64F [c]))
// cond: c >= -1<<63 && c < 1<<63
// result: (Const64 [int64(c)])
for {
if v_0.Op != OpConst64F {
break
}
c := auxIntToFloat64(v_0.AuxInt)
if !(c >= -1<<63 && c < 1<<63) {
break
}
v.reset(OpConst64)
v.AuxInt = int64ToAuxInt(int64(c))
return true

45
test/codegen/math.go
View file

@ -330,3 +330,48 @@ func nanGenerate32() float32 {
// amd64/v3:"VFMADD231SS"
return z0 + z1
}
func outOfBoundsConv(i32 *[2]int32, u32 *[2]uint32, i64 *[2]int64, u64 *[2]uint64) {
// arm64: "FCVTZSDW"
// amd64: "CVTTSD2SL", "CVTSD2SS"
i32[0] = int32(two40())
// arm64: "FCVTZSDW"
// amd64: "CVTTSD2SL", "CVTSD2SS"
i32[1] = int32(-two40())
// arm64: "FCVTZSDW"
// amd64: "CVTTSD2SL", "CVTSD2SS"
u32[0] = uint32(two41())
// on arm64, this uses an explicit <0 comparison, so it constant folds.
// on amd64, this uses an explicit <0 comparison, so it constant folds.
// amd64: "MOVL\t[$]0,"
u32[1] = uint32(minus1())
// arm64: "FCVTZSD"
// amd64: "CVTTSD2SQ"
i64[0] = int64(two80())
// arm64: "FCVTZSD"
// amd64: "CVTTSD2SQ"
i64[1] = int64(-two80())
// arm64: "FCVTZUD"
// amd64: "CVTTSD2SQ"
u64[0] = uint64(two81())
// arm64: "FCVTZUD"
// on amd64, this uses an explicit <0 comparison, so it constant folds.
// amd64: "MOVQ\t[$]0,"
u64[1] = uint64(minus1())
}
func two40() float64 {
return 1 << 40
}
func two41() float64 {
return 1 << 41
}
func two80() float64 {
return 1 << 80
}
func two81() float64 {
return 1 << 81
}
func minus1() float64 {
return -1
}