From: Keith Randall <khr@golang.org>
Date: Mon, 7 Apr 2025 17:33:31 +0000 (-0700)
Subject: cmd/compile: add additional flag constant folding rules
X-Git-Tag: go1.25rc1~523
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=af278bfb1f07b9f8f84d325a84b3891a3ab0dbf1;p=gostls13.git

cmd/compile: add additional flag constant folding rules

Fixes #73200

Change-Id: I77518d37acd838acf79ed113194bac5e2c30897f
Reviewed-on: https://go-review.googlesource.com/c/go/+/663535
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
---

diff --git a/src/cmd/compile/internal/ssa/_gen/ARM64.rules b/src/cmd/compile/internal/ssa/_gen/ARM64.rules
index 3962cd7a2d..7040046711 100644
--- a/src/cmd/compile/internal/ssa/_gen/ARM64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/ARM64.rules
@@ -1385,16 +1385,18 @@
 (CSNEG [cc] x y (InvertFlags cmp)) => (CSNEG [arm64Invert(cc)] x y cmp)
 
 // absorb flag constants into boolean values
-(Equal         (FlagConstant [fc])) => (MOVDconst [b2i(fc.eq())])
-(NotEqual      (FlagConstant [fc])) => (MOVDconst [b2i(fc.ne())])
-(LessThan      (FlagConstant [fc])) => (MOVDconst [b2i(fc.lt())])
-(LessThanU     (FlagConstant [fc])) => (MOVDconst [b2i(fc.ult())])
-(LessEqual     (FlagConstant [fc])) => (MOVDconst [b2i(fc.le())])
-(LessEqualU    (FlagConstant [fc])) => (MOVDconst [b2i(fc.ule())])
-(GreaterThan   (FlagConstant [fc])) => (MOVDconst [b2i(fc.gt())])
-(GreaterThanU  (FlagConstant [fc])) => (MOVDconst [b2i(fc.ugt())])
-(GreaterEqual  (FlagConstant [fc])) => (MOVDconst [b2i(fc.ge())])
-(GreaterEqualU (FlagConstant [fc])) => (MOVDconst [b2i(fc.uge())])
+(Equal             (FlagConstant [fc])) => (MOVDconst [b2i(fc.eq())])
+(NotEqual          (FlagConstant [fc])) => (MOVDconst [b2i(fc.ne())])
+(LessThan          (FlagConstant [fc])) => (MOVDconst [b2i(fc.lt())])
+(LessThanU         (FlagConstant [fc])) => (MOVDconst [b2i(fc.ult())])
+(LessEqual         (FlagConstant [fc])) => (MOVDconst [b2i(fc.le())])
+(LessEqualU        (FlagConstant [fc])) => (MOVDconst [b2i(fc.ule())])
+(GreaterThan       (FlagConstant [fc])) => (MOVDconst [b2i(fc.gt())])
+(GreaterThanU      (FlagConstant [fc])) => (MOVDconst [b2i(fc.ugt())])
+(GreaterEqual      (FlagConstant [fc])) => (MOVDconst [b2i(fc.ge())])
+(GreaterEqualU     (FlagConstant [fc])) => (MOVDconst [b2i(fc.uge())])
+(LessThanNoov      (FlagConstant [fc])) => (MOVDconst [b2i(fc.ltNoov())])
+(GreaterEqualNoov  (FlagConstant [fc])) => (MOVDconst [b2i(fc.geNoov())])
 
 // absorb InvertFlags into boolean values
 (Equal            (InvertFlags x)) => (Equal x)
diff --git a/src/cmd/compile/internal/ssa/rewriteARM64.go b/src/cmd/compile/internal/ssa/rewriteARM64.go
index cabc3760df..7f2feabbf7 100644
--- a/src/cmd/compile/internal/ssa/rewriteARM64.go
+++ b/src/cmd/compile/internal/ssa/rewriteARM64.go
@@ -6182,6 +6182,17 @@ func rewriteValueARM64_OpARM64GreaterEqualNoov(v *Value) bool {
 	v_0 := v.Args[0]
 	b := v.Block
 	typ := &b.Func.Config.Types
+	// match: (GreaterEqualNoov (FlagConstant [fc]))
+	// result: (MOVDconst [b2i(fc.geNoov())])
+	for {
+		if v_0.Op != OpARM64FlagConstant {
+			break
+		}
+		fc := auxIntToFlagConstant(v_0.AuxInt)
+		v.reset(OpARM64MOVDconst)
+		v.AuxInt = int64ToAuxInt(b2i(fc.geNoov()))
+		return true
+	}
 	// match: (GreaterEqualNoov (InvertFlags x))
 	// result: (CSINC [OpARM64NotEqual] (LessThanNoov <typ.Bool> x) (MOVDconst [0]) x)
 	for {
@@ -6918,6 +6929,17 @@ func rewriteValueARM64_OpARM64LessThanNoov(v *Value) bool {
 	v_0 := v.Args[0]
 	b := v.Block
 	typ := &b.Func.Config.Types
+	// match: (LessThanNoov (FlagConstant [fc]))
+	// result: (MOVDconst [b2i(fc.ltNoov())])
+	for {
+		if v_0.Op != OpARM64FlagConstant {
+			break
+		}
+		fc := auxIntToFlagConstant(v_0.AuxInt)
+		v.reset(OpARM64MOVDconst)
+		v.AuxInt = int64ToAuxInt(b2i(fc.ltNoov()))
+		return true
+	}
 	// match: (LessThanNoov (InvertFlags x))
 	// result: (CSEL0 [OpARM64NotEqual] (GreaterEqualNoov <typ.Bool> x) x)
 	for {
diff --git a/test/fixedbugs/issue73200.go b/test/fixedbugs/issue73200.go
new file mode 100644
index 0000000000..060f794565
--- /dev/null
+++ b/test/fixedbugs/issue73200.go
@@ -0,0 +1,36 @@
+// build
+
+// Copyright 2025 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+var g bool
+
+func main() {
+	l_4 := uint32(0x6E54EE87)
+	v4 := int8(-Int64FromInt64(1))
+	g = int32(v4) >= safe_mod_func_int32_t_s_s(BoolInt32(l_4 >= 1), 7)
+}
+
+func safe_mod_func_int32_t_s_s(si1 int32, si2 int32) (r int32) {
+	var v1 int32
+	if si2 == 0 {
+		v1 = si1
+	} else {
+		v1 = si1 % si2
+	}
+	return v1
+}
+
+func Int64FromInt64(n int64) int64 {
+	return n
+}
+
+func BoolInt32(b bool) int32 {
+	if b {
+		return 1
+	}
+	return 0
+}