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cmd/compile: use unsigned power-of-two detector for unsigned mod

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Same as CL 689815, but for modulus instead of division.

Updates #74485

Change-Id: I73000231c886a987a1093669ff207fd9117a8160
Reviewed-on: https://go-review.googlesource.com/c/go/+/689895
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Cuong Manh Le 2025-07-23 23:51:16 +07:00 • committed by Gopher Robot
parent f3582fc80e
commit bd94ae8903
3 changed files with 32 additions and 27 deletions
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9
src/cmd/compile/internal/ssa/_gen/generic.rules
View file

@ -1293,11 +1293,10 @@
(Const64 <typ.UInt64> [63]))) (Const64 <typ.UInt64> [63])))
// Unsigned mod by power of 2 constant. // Unsigned mod by power of 2 constant.
(Mod8u <t> n (Const8 [c])) && isPowerOfTwo(c) => (And8 n (Const8 <t> [c-1])) (Mod8u <t> n (Const8 [c])) && isUnsignedPowerOfTwo(uint8(c)) => (And8 n (Const8 <t> [c-1]))
(Mod16u <t> n (Const16 [c])) && isPowerOfTwo(c) => (And16 n (Const16 <t> [c-1])) (Mod16u <t> n (Const16 [c])) && isUnsignedPowerOfTwo(uint16(c)) => (And16 n (Const16 <t> [c-1]))
(Mod32u <t> n (Const32 [c])) && isPowerOfTwo(c) => (And32 n (Const32 <t> [c-1])) (Mod32u <t> n (Const32 [c])) && isUnsignedPowerOfTwo(uint32(c)) => (And32 n (Const32 <t> [c-1]))
(Mod64u <t> n (Const64 [c])) && isPowerOfTwo(c) => (And64 n (Const64 <t> [c-1])) (Mod64u <t> n (Const64 [c])) && isUnsignedPowerOfTwo(uint64(c)) => (And64 n (Const64 <t> [c-1]))
(Mod64u <t> n (Const64 [-1<<63])) => (And64 n (Const64 <t> [1<<63-1]))
// Signed non-negative mod by power of 2 constant. // Signed non-negative mod by power of 2 constant.
(Mod8 <t> n (Const8 [c])) && isNonNegative(n) && isPowerOfTwo(c) => (And8 n (Const8 <t> [c-1])) (Mod8 <t> n (Const8 [c])) && isNonNegative(n) && isPowerOfTwo(c) => (And8 n (Const8 <t> [c-1]))

30
src/cmd/compile/internal/ssa/rewritegeneric.go
View file

@ -16906,7 +16906,7 @@ func rewriteValuegeneric_OpMod16u(v *Value) bool {
return true return true
} }
// match: (Mod16u <t> n (Const16 [c])) // match: (Mod16u <t> n (Const16 [c]))
// cond: isPowerOfTwo(c) // cond: isUnsignedPowerOfTwo(uint16(c))
// result: (And16 n (Const16 <t> [c-1])) // result: (And16 n (Const16 <t> [c-1]))
for { for {
t := v.Type t := v.Type
@ -16915,7 +16915,7 @@ func rewriteValuegeneric_OpMod16u(v *Value) bool {
break break
} }
c := auxIntToInt16(v_1.AuxInt) c := auxIntToInt16(v_1.AuxInt)
if !(isPowerOfTwo(c)) { if !(isUnsignedPowerOfTwo(uint16(c))) {
break break
} }
v.reset(OpAnd16) v.reset(OpAnd16)
@ -17060,7 +17060,7 @@ func rewriteValuegeneric_OpMod32u(v *Value) bool {
return true return true
} }
// match: (Mod32u <t> n (Const32 [c])) // match: (Mod32u <t> n (Const32 [c]))
// cond: isPowerOfTwo(c) // cond: isUnsignedPowerOfTwo(uint32(c))
// result: (And32 n (Const32 <t> [c-1])) // result: (And32 n (Const32 <t> [c-1]))
for { for {
t := v.Type t := v.Type
@ -17069,7 +17069,7 @@ func rewriteValuegeneric_OpMod32u(v *Value) bool {
break break
} }
c := auxIntToInt32(v_1.AuxInt) c := auxIntToInt32(v_1.AuxInt)
if !(isPowerOfTwo(c)) { if !(isUnsignedPowerOfTwo(uint32(c))) {
break break
} }
v.reset(OpAnd32) v.reset(OpAnd32)
@ -17225,7 +17225,7 @@ func rewriteValuegeneric_OpMod64u(v *Value) bool {
return true return true
} }
// match: (Mod64u <t> n (Const64 [c])) // match: (Mod64u <t> n (Const64 [c]))
// cond: isPowerOfTwo(c) // cond: isUnsignedPowerOfTwo(uint64(c))
// result: (And64 n (Const64 <t> [c-1])) // result: (And64 n (Const64 <t> [c-1]))
for { for {
t := v.Type t := v.Type
@ -17234,7 +17234,7 @@ func rewriteValuegeneric_OpMod64u(v *Value) bool {
break break
} }
c := auxIntToInt64(v_1.AuxInt) c := auxIntToInt64(v_1.AuxInt)
if !(isPowerOfTwo(c)) { if !(isUnsignedPowerOfTwo(uint64(c))) {
break break
} }
v.reset(OpAnd64) v.reset(OpAnd64)
@ -17243,20 +17243,6 @@ func rewriteValuegeneric_OpMod64u(v *Value) bool {
v.AddArg2(n, v0) v.AddArg2(n, v0)
return true return true
} }
// match: (Mod64u <t> n (Const64 [-1<<63]))
// result: (And64 n (Const64 <t> [1<<63-1]))
for {
t := v.Type
n := v_0
if v_1.Op != OpConst64 || auxIntToInt64(v_1.AuxInt) != -1<<63 {
break
}
v.reset(OpAnd64)
v0 := b.NewValue0(v.Pos, OpConst64, t)
v0.AuxInt = int64ToAuxInt(1<<63 - 1)
v.AddArg2(n, v0)
return true
}
// match: (Mod64u <t> x (Const64 [c])) // match: (Mod64u <t> x (Const64 [c]))
// cond: x.Op != OpConst64 && c > 0 && umagicOK64(c) // cond: x.Op != OpConst64 && c > 0 && umagicOK64(c)
// result: (Sub64 x (Mul64 <t> (Div64u <t> x (Const64 <t> [c])) (Const64 <t> [c]))) // result: (Sub64 x (Mul64 <t> (Div64u <t> x (Const64 <t> [c])) (Const64 <t> [c])))
@ -17393,7 +17379,7 @@ func rewriteValuegeneric_OpMod8u(v *Value) bool {
return true return true
} }
// match: (Mod8u <t> n (Const8 [c])) // match: (Mod8u <t> n (Const8 [c]))
// cond: isPowerOfTwo(c) // cond: isUnsignedPowerOfTwo(uint8(c))
// result: (And8 n (Const8 <t> [c-1])) // result: (And8 n (Const8 <t> [c-1]))
for { for {
t := v.Type t := v.Type
@ -17402,7 +17388,7 @@ func rewriteValuegeneric_OpMod8u(v *Value) bool {
break break
} }
c := auxIntToInt8(v_1.AuxInt) c := auxIntToInt8(v_1.AuxInt)
if !(isPowerOfTwo(c)) { if !(isUnsignedPowerOfTwo(uint8(c))) {
break break
} }
v.reset(OpAnd8) v.reset(OpAnd8)

20
test/codegen/issue74485.go
View file

@ -25,3 +25,23 @@ func divUint8(b uint8) uint8 {
// amd64:"SHRB [$]7, AL" // amd64:"SHRB [$]7, AL"
return b / 128 return b / 128
} }
func modUint64(b uint64) uint64 {
// amd64:"BTRQ [$]63, AX"
return b % 9223372036854775808
}
func modUint32(b uint32) uint32 {
// amd64:"ANDL [$]2147483647, AX"
return b % 2147483648
}
func modUint16(b uint16) uint16 {
// amd64:"ANDL [$]32767, AX"
return b % 32768
}
func modUint8(b uint8) uint8 {
// amd64:"ANDL [$]127, AX"
return b % 128
}