cmd/compile: use CMPWU for 32-bit or smaller unsigned Geq on ppc64{,le}

Fixes #18808.

Change-Id: I49b266380b9d6804c9f6563ebac9c7c0e05f37f6
Reviewed-on: https://go-review.googlesource.com/35890
Run-TryBot: Michael Munday <munday@ca.ibm.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/compile/internal/ssa/gen/PPC64.rules

@@ -338,9 +338,9 @@
 (Geq32F x y) -> (FGreaterEqual (FCMPU x y))
 (Geq64F x y) -> (FGreaterEqual (FCMPU x y))
 
-(Geq8U x y)  -> (GreaterEqual (CMPU (ZeroExt8to32 x) (ZeroExt8to32 y)))
+(Geq8U x y)  -> (GreaterEqual (CMPWU (ZeroExt8to32 x) (ZeroExt8to32 y)))
-(Geq16U x y) -> (GreaterEqual (CMPU (ZeroExt16to32 x) (ZeroExt16to32 y)))
+(Geq16U x y) -> (GreaterEqual (CMPWU (ZeroExt16to32 x) (ZeroExt16to32 y)))
-(Geq32U x y) -> (GreaterEqual (CMPU x y))
+(Geq32U x y) -> (GreaterEqual (CMPWU x y))
 (Geq64U x y) -> (GreaterEqual (CMPU x y))
 
 // Absorb pseudo-ops into blocks.

src/cmd/compile/internal/ssa/rewritePPC64.go

@@ -1543,12 +1543,12 @@ func rewriteValuePPC64_OpGeq16U(v *Value, config *Config) bool {
 	_ = b
 	// match: (Geq16U x y)
 	// cond:
-	// result: (GreaterEqual (CMPU (ZeroExt16to32 x) (ZeroExt16to32 y)))
+	// result: (GreaterEqual (CMPWU (ZeroExt16to32 x) (ZeroExt16to32 y)))
 	for {
 		x := v.Args[0]
 		y := v.Args[1]
 		v.reset(OpPPC64GreaterEqual)
-		v0 := b.NewValue0(v.Line, OpPPC64CMPU, TypeFlags)
+		v0 := b.NewValue0(v.Line, OpPPC64CMPWU, TypeFlags)
 		v1 := b.NewValue0(v.Line, OpZeroExt16to32, config.fe.TypeUInt32())
 		v1.AddArg(x)
 		v0.AddArg(v1)
@@ -1598,12 +1598,12 @@ func rewriteValuePPC64_OpGeq32U(v *Value, config *Config) bool {
 	_ = b
 	// match: (Geq32U x y)
 	// cond:
-	// result: (GreaterEqual (CMPU x y))
+	// result: (GreaterEqual (CMPWU x y))
 	for {
 		x := v.Args[0]
 		y := v.Args[1]
 		v.reset(OpPPC64GreaterEqual)
-		v0 := b.NewValue0(v.Line, OpPPC64CMPU, TypeFlags)
+		v0 := b.NewValue0(v.Line, OpPPC64CMPWU, TypeFlags)
 		v0.AddArg(x)
 		v0.AddArg(y)
 		v.AddArg(v0)
@@ -1687,12 +1687,12 @@ func rewriteValuePPC64_OpGeq8U(v *Value, config *Config) bool {
 	_ = b
 	// match: (Geq8U x y)
 	// cond:
-	// result: (GreaterEqual (CMPU (ZeroExt8to32 x) (ZeroExt8to32 y)))
+	// result: (GreaterEqual (CMPWU (ZeroExt8to32 x) (ZeroExt8to32 y)))
 	for {
 		x := v.Args[0]
 		y := v.Args[1]
 		v.reset(OpPPC64GreaterEqual)
-		v0 := b.NewValue0(v.Line, OpPPC64CMPU, TypeFlags)
+		v0 := b.NewValue0(v.Line, OpPPC64CMPWU, TypeFlags)
 		v1 := b.NewValue0(v.Line, OpZeroExt8to32, config.fe.TypeUInt32())
 		v1.AddArg(x)
 		v0.AddArg(v1)

test/fixedbugs/issue18808.go

@@ -0,0 +1,63 @@
+// run
+
+// Copyright 2017 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
+
+const lim = 0x80000000
+
+//go:noinline
+func eq(x uint32) {
+	if x == lim {
+		return
+	}
+	panic("x == lim returned false")
+}
+
+//go:noinline
+func neq(x uint32) {
+	if x != lim {
+		panic("x != lim returned true")
+	}
+}
+
+//go:noinline
+func gt(x uint32) {
+	if x > lim {
+		return
+	}
+	panic("x > lim returned false")
+}
+
+//go:noinline
+func gte(x uint32) {
+	if x >= lim {
+		return
+	}
+	panic("x >= lim returned false")
+}
+
+//go:noinline
+func lt(x uint32) {
+	if x < lim {
+		panic("x < lim returned true")
+	}
+}
+
+//go:noinline
+func lte(x uint32) {
+	if x <= lim {
+		panic("x <= lim returned true")
+	}
+}
+
+func main() {
+	eq(lim)
+	neq(lim)
+	gt(lim+1)
+	gte(lim+1)
+	lt(lim+1)
+	lte(lim+1)
+}