cmd/compile: fix bounds check report

For constant-index, variable length situations.

Inadvertant shadowing of the yVal variable. Oops.

Fixes #75327

Change-Id: I3403066fc39b7664222a3098cf0f22b5761ea66a
Reviewed-on: https://go-review.googlesource.com/c/go/+/702015
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/compile/internal/amd64/ssa.go

@@ -1306,7 +1306,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.OpAMD64LoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - x86.REG_AX)
+			yVal = int(v.Args[0].Reg() - x86.REG_AX)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

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

@@ -777,7 +777,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.OpARMLoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - arm.REG_R0)
+			yVal = int(v.Args[0].Reg() - arm.REG_R0)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

src/cmd/compile/internal/arm64/ssa.go

@@ -1319,7 +1319,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.OpARM64LoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - arm64.REG_R0)
+			yVal = int(v.Args[0].Reg() - arm64.REG_R0)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

src/cmd/compile/internal/loong64/ssa.go

@@ -811,7 +811,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.OpLOONG64LoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - loong64.REG_R4)
+			yVal = int(v.Args[0].Reg() - loong64.REG_R4)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

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

@@ -551,7 +551,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.OpMIPSLoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - mips.REG_R1)
+			yVal = int(v.Args[0].Reg() - mips.REG_R1)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

src/cmd/compile/internal/mips64/ssa.go

@@ -542,7 +542,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.OpMIPS64LoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - mips.REG_R1)
+			yVal = int(v.Args[0].Reg() - mips.REG_R1)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

src/cmd/compile/internal/ppc64/ssa.go

@@ -1947,7 +1947,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.OpPPC64LoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - ppc64.REG_R3)
+			yVal = int(v.Args[0].Reg() - ppc64.REG_R3)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

src/cmd/compile/internal/riscv64/ssa.go

@@ -544,7 +544,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.OpRISCV64LoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - riscv.REG_X5)
+			yVal = int(v.Args[0].Reg() - riscv.REG_X5)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

src/cmd/compile/internal/s390x/ssa.go

@@ -608,7 +608,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.OpS390XLoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - s390x.REG_R0)
+			yVal = int(v.Args[0].Reg() - s390x.REG_R0)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

src/cmd/compile/internal/x86/ssa.go

@@ -804,7 +804,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 			}
 		case ssa.Op386LoweredPanicBoundsCR:
 			yIsReg = true
-			yVal := int(v.Args[0].Reg() - x86.REG_AX)
+			yVal = int(v.Args[0].Reg() - x86.REG_AX)
 			c := v.Aux.(ssa.PanicBoundsC).C
 			if c >= 0 && c <= abi.BoundsMaxConst {
 				xVal = int(c)

test/fixedbugs/issue75327.go

@@ -0,0 +1,33 @@
+// run
+
+package main
+
+import (
+	"fmt"
+	"strings"
+)
+
+func main() {
+	defer func() {
+		err := recover()
+		txt := fmt.Sprintf("%s", err)
+		if !strings.HasSuffix(txt, "with length 1") {
+			panic("bad error: " + txt)
+		}
+	}()
+	foo([]uint64{0})
+}
+
+//go:noinline
+func foo(haystack []uint64) {
+	for n := range len(haystack) {
+		_ = n
+		_ = haystack[1]
+	}
+
+	xxx := haystack[0:len(haystack)]
+	sink(xxx)
+}
+
+//go:noinline
+func sink([]uint64) {}