From: Michael Munday <mndygolang+git@gmail.com>
Date: Tue, 26 Aug 2025 21:12:29 +0000 (+0100)
Subject: cmd/compile/internal/ssa: make oneBit function generic
X-Git-Tag: go1.26rc1~992
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=84b070bfb1;p=gostls13.git

cmd/compile/internal/ssa: make oneBit function generic

Allows rewrite rules using oneBit to be made more compact.

Change-Id: I986715f77db5b548759d809fe668e1893048f25c
Reviewed-on: https://go-review.googlesource.com/c/go/+/699295
Reviewed-by: Youlin Feng <fengyoulin@live.com>
Commit-Queue: Keith Randall <khr@golang.org>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---

diff --git a/src/cmd/compile/internal/ssa/_gen/generic.rules b/src/cmd/compile/internal/ssa/_gen/generic.rules
index 7ac36c3b3c..da112abbf5 100644
--- a/src/cmd/compile/internal/ssa/_gen/generic.rules
+++ b/src/cmd/compile/internal/ssa/_gen/generic.rules
@@ -1896,22 +1896,10 @@
 (Neq(8|16|32|64) s:(Sub(8|16|32|64) x y) (Const(8|16|32|64) [0])) && s.Uses == 1 => (Neq(8|16|32|64) x y)
 
 // Optimize bitsets
-(Eq8 (And8 <t> x (Const8 <t> [y])) (Const8 <t> [y])) && oneBit8(y)
-  => (Neq8 (And8 <t> x (Const8 <t> [y])) (Const8 <t> [0]))
-(Eq16 (And16 <t> x (Const16 <t> [y])) (Const16 <t> [y])) && oneBit16(y)
-  => (Neq16 (And16 <t> x (Const16 <t> [y])) (Const16 <t> [0]))
-(Eq32 (And32 <t> x (Const32 <t> [y])) (Const32 <t> [y])) && oneBit32(y)
-  => (Neq32 (And32 <t> x (Const32 <t> [y])) (Const32 <t> [0]))
-(Eq64 (And64 <t> x (Const64 <t> [y])) (Const64 <t> [y])) && oneBit64(y)
-  => (Neq64 (And64 <t> x (Const64 <t> [y])) (Const64 <t> [0]))
-(Neq8 (And8 <t> x (Const8 <t> [y])) (Const8 <t> [y])) && oneBit8(y)
-  => (Eq8 (And8 <t> x (Const8 <t> [y])) (Const8 <t> [0]))
-(Neq16 (And16 <t> x (Const16 <t> [y])) (Const16 <t> [y])) && oneBit16(y)
-  => (Eq16 (And16 <t> x (Const16 <t> [y])) (Const16 <t> [0]))
-(Neq32 (And32 <t> x (Const32 <t> [y])) (Const32 <t> [y])) && oneBit32(y)
-  => (Eq32 (And32 <t> x (Const32 <t> [y])) (Const32 <t> [0]))
-(Neq64 (And64 <t> x (Const64 <t> [y])) (Const64 <t> [y])) && oneBit64(y)
-  => (Eq64 (And64 <t> x (Const64 <t> [y])) (Const64 <t> [0]))
+(Eq(8|16|32|64) (And(8|16|32|64) <t> x (Const(8|16|32|64) <t> [y])) (Const(8|16|32|64) <t> [y])) && oneBit(y)
+  => (Neq(8|16|32|64) (And(8|16|32|64) <t> x (Const(8|16|32|64) <t> [y])) (Const(8|16|32|64) <t> [0]))
+(Neq(8|16|32|64) (And(8|16|32|64) <t> x (Const(8|16|32|64) <t> [y])) (Const(8|16|32|64) <t> [y])) && oneBit(y)
+  => (Eq(8|16|32|64) (And(8|16|32|64) <t> x (Const(8|16|32|64) <t> [y])) (Const(8|16|32|64) <t> [0]))
 
 // Reassociate expressions involving
 // constants such that constants come first,
diff --git a/src/cmd/compile/internal/ssa/rewrite.go b/src/cmd/compile/internal/ssa/rewrite.go
index 236a3f885a..6704c7d6e0 100644
--- a/src/cmd/compile/internal/ssa/rewrite.go
+++ b/src/cmd/compile/internal/ssa/rewrite.go
@@ -470,11 +470,10 @@ func ntz32(x int32) int { return bits.TrailingZeros32(uint32(x)) }
 func ntz16(x int16) int { return bits.TrailingZeros16(uint16(x)) }
 func ntz8(x int8) int   { return bits.TrailingZeros8(uint8(x)) }
 
-func oneBit(x int64) bool   { return x&(x-1) == 0 && x != 0 }
-func oneBit8(x int8) bool   { return x&(x-1) == 0 && x != 0 }
-func oneBit16(x int16) bool { return x&(x-1) == 0 && x != 0 }
-func oneBit32(x int32) bool { return x&(x-1) == 0 && x != 0 }
-func oneBit64(x int64) bool { return x&(x-1) == 0 && x != 0 }
+// oneBit reports whether x contains exactly one set bit.
+func oneBit[T int8 | int16 | int32 | int64](x T) bool {
+	return x&(x-1) == 0 && x != 0
+}
 
 // nto returns the number of trailing ones.
 func nto(x int64) int64 {
diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go
index 3af7f40e68..5394747ba5 100644
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@@ -8796,7 +8796,7 @@ func rewriteValuegeneric_OpEq16(v *Value) bool {
 		break
 	}
 	// match: (Eq16 (And16 <t> x (Const16 <t> [y])) (Const16 <t> [y]))
-	// cond: oneBit16(y)
+	// cond: oneBit(y)
 	// result: (Neq16 (And16 <t> x (Const16 <t> [y])) (Const16 <t> [0]))
 	for {
 		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -8813,7 +8813,7 @@ func rewriteValuegeneric_OpEq16(v *Value) bool {
 					continue
 				}
 				y := auxIntToInt16(v_0_1.AuxInt)
-				if v_1.Op != OpConst16 || v_1.Type != t || auxIntToInt16(v_1.AuxInt) != y || !(oneBit16(y)) {
+				if v_1.Op != OpConst16 || v_1.Type != t || auxIntToInt16(v_1.AuxInt) != y || !(oneBit(y)) {
 					continue
 				}
 				v.reset(OpNeq16)
@@ -9660,7 +9660,7 @@ func rewriteValuegeneric_OpEq32(v *Value) bool {
 		break
 	}
 	// match: (Eq32 (And32 <t> x (Const32 <t> [y])) (Const32 <t> [y]))
-	// cond: oneBit32(y)
+	// cond: oneBit(y)
 	// result: (Neq32 (And32 <t> x (Const32 <t> [y])) (Const32 <t> [0]))
 	for {
 		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -9677,7 +9677,7 @@ func rewriteValuegeneric_OpEq32(v *Value) bool {
 					continue
 				}
 				y := auxIntToInt32(v_0_1.AuxInt)
-				if v_1.Op != OpConst32 || v_1.Type != t || auxIntToInt32(v_1.AuxInt) != y || !(oneBit32(y)) {
+				if v_1.Op != OpConst32 || v_1.Type != t || auxIntToInt32(v_1.AuxInt) != y || !(oneBit(y)) {
 					continue
 				}
 				v.reset(OpNeq32)
@@ -10241,7 +10241,7 @@ func rewriteValuegeneric_OpEq64(v *Value) bool {
 		break
 	}
 	// match: (Eq64 (And64 <t> x (Const64 <t> [y])) (Const64 <t> [y]))
-	// cond: oneBit64(y)
+	// cond: oneBit(y)
 	// result: (Neq64 (And64 <t> x (Const64 <t> [y])) (Const64 <t> [0]))
 	for {
 		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -10258,7 +10258,7 @@ func rewriteValuegeneric_OpEq64(v *Value) bool {
 					continue
 				}
 				y := auxIntToInt64(v_0_1.AuxInt)
-				if v_1.Op != OpConst64 || v_1.Type != t || auxIntToInt64(v_1.AuxInt) != y || !(oneBit64(y)) {
+				if v_1.Op != OpConst64 || v_1.Type != t || auxIntToInt64(v_1.AuxInt) != y || !(oneBit(y)) {
 					continue
 				}
 				v.reset(OpNeq64)
@@ -10663,7 +10663,7 @@ func rewriteValuegeneric_OpEq8(v *Value) bool {
 		break
 	}
 	// match: (Eq8 (And8 <t> x (Const8 <t> [y])) (Const8 <t> [y]))
-	// cond: oneBit8(y)
+	// cond: oneBit(y)
 	// result: (Neq8 (And8 <t> x (Const8 <t> [y])) (Const8 <t> [0]))
 	for {
 		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -10680,7 +10680,7 @@ func rewriteValuegeneric_OpEq8(v *Value) bool {
 					continue
 				}
 				y := auxIntToInt8(v_0_1.AuxInt)
-				if v_1.Op != OpConst8 || v_1.Type != t || auxIntToInt8(v_1.AuxInt) != y || !(oneBit8(y)) {
+				if v_1.Op != OpConst8 || v_1.Type != t || auxIntToInt8(v_1.AuxInt) != y || !(oneBit(y)) {
 					continue
 				}
 				v.reset(OpNeq8)
@@ -20309,7 +20309,7 @@ func rewriteValuegeneric_OpNeq16(v *Value) bool {
 		break
 	}
 	// match: (Neq16 (And16 <t> x (Const16 <t> [y])) (Const16 <t> [y]))
-	// cond: oneBit16(y)
+	// cond: oneBit(y)
 	// result: (Eq16 (And16 <t> x (Const16 <t> [y])) (Const16 <t> [0]))
 	for {
 		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -20326,7 +20326,7 @@ func rewriteValuegeneric_OpNeq16(v *Value) bool {
 					continue
 				}
 				y := auxIntToInt16(v_0_1.AuxInt)
-				if v_1.Op != OpConst16 || v_1.Type != t || auxIntToInt16(v_1.AuxInt) != y || !(oneBit16(y)) {
+				if v_1.Op != OpConst16 || v_1.Type != t || auxIntToInt16(v_1.AuxInt) != y || !(oneBit(y)) {
 					continue
 				}
 				v.reset(OpEq16)
@@ -20496,7 +20496,7 @@ func rewriteValuegeneric_OpNeq32(v *Value) bool {
 		break
 	}
 	// match: (Neq32 (And32 <t> x (Const32 <t> [y])) (Const32 <t> [y]))
-	// cond: oneBit32(y)
+	// cond: oneBit(y)
 	// result: (Eq32 (And32 <t> x (Const32 <t> [y])) (Const32 <t> [0]))
 	for {
 		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -20513,7 +20513,7 @@ func rewriteValuegeneric_OpNeq32(v *Value) bool {
 					continue
 				}
 				y := auxIntToInt32(v_0_1.AuxInt)
-				if v_1.Op != OpConst32 || v_1.Type != t || auxIntToInt32(v_1.AuxInt) != y || !(oneBit32(y)) {
+				if v_1.Op != OpConst32 || v_1.Type != t || auxIntToInt32(v_1.AuxInt) != y || !(oneBit(y)) {
 					continue
 				}
 				v.reset(OpEq32)
@@ -20706,7 +20706,7 @@ func rewriteValuegeneric_OpNeq64(v *Value) bool {
 		break
 	}
 	// match: (Neq64 (And64 <t> x (Const64 <t> [y])) (Const64 <t> [y]))
-	// cond: oneBit64(y)
+	// cond: oneBit(y)
 	// result: (Eq64 (And64 <t> x (Const64 <t> [y])) (Const64 <t> [0]))
 	for {
 		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -20723,7 +20723,7 @@ func rewriteValuegeneric_OpNeq64(v *Value) bool {
 					continue
 				}
 				y := auxIntToInt64(v_0_1.AuxInt)
-				if v_1.Op != OpConst64 || v_1.Type != t || auxIntToInt64(v_1.AuxInt) != y || !(oneBit64(y)) {
+				if v_1.Op != OpConst64 || v_1.Type != t || auxIntToInt64(v_1.AuxInt) != y || !(oneBit(y)) {
 					continue
 				}
 				v.reset(OpEq64)
@@ -20916,7 +20916,7 @@ func rewriteValuegeneric_OpNeq8(v *Value) bool {
 		break
 	}
 	// match: (Neq8 (And8 <t> x (Const8 <t> [y])) (Const8 <t> [y]))
-	// cond: oneBit8(y)
+	// cond: oneBit(y)
 	// result: (Eq8 (And8 <t> x (Const8 <t> [y])) (Const8 <t> [0]))
 	for {
 		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -20933,7 +20933,7 @@ func rewriteValuegeneric_OpNeq8(v *Value) bool {
 					continue
 				}
 				y := auxIntToInt8(v_0_1.AuxInt)
-				if v_1.Op != OpConst8 || v_1.Type != t || auxIntToInt8(v_1.AuxInt) != y || !(oneBit8(y)) {
+				if v_1.Op != OpConst8 || v_1.Type != t || auxIntToInt8(v_1.AuxInt) != y || !(oneBit(y)) {
 					continue
 				}
 				v.reset(OpEq8)