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 3962cd7a2d76c438dbab6f5811106726032853a1..70400467111472c25793bf608b7e6c0f17c6c346 100644 (file)
--- 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 cabc3760dfbf001c0d681365d46867cbe616983d..7f2feabbf77b13bb29c6eafaedf209f90498a301 100644 (file)
--- 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 (file)
index 0000000..060f794
--- /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
+}