[release-branch.go1.14] cmd/compile: mark s390x int <-> float convers…

…ions as clobbering flags These conversion instructions set the condition code and so should be marked as clobbering flags. Updates #39651. Fixes #39690. Change-Id: I1e3f2cf33337128d321b52ac72f46d1b8798ebd9 Reviewed-on: https://go-review.googlesource.com/c/go/+/242237 Run-TryBot: Michael Munday <[email protected]> TryBot-Result: Gobot Gobot <[email protected]> Reviewed-by: Cherry Zhang <[email protected]>
golang · Aug 21, 2020 · db4890e · db4890e
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commit db4890e
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diff --git a/src/cmd/compile/internal/ssa/gen/S390XOps.go b/src/cmd/compile/internal/ssa/gen/S390XOps.go
@@ -391,18 +391,20 @@ func init() {
 
 		{name: "MOVDconst", reg: gp01, asm: "MOVD", typ: "UInt64", aux: "Int64", rematerializeable: true}, // auxint
 
-		{name: "LDGR", argLength: 1, reg: gpfp, asm: "LDGR"},     // move int64 to float64 (no conversion)
-		{name: "LGDR", argLength: 1, reg: fpgp, asm: "LGDR"},     // move float64 to int64 (no conversion)
-		{name: "CFDBRA", argLength: 1, reg: fpgp, asm: "CFDBRA"}, // convert float64 to int32
-		{name: "CGDBRA", argLength: 1, reg: fpgp, asm: "CGDBRA"}, // convert float64 to int64
-		{name: "CFEBRA", argLength: 1, reg: fpgp, asm: "CFEBRA"}, // convert float32 to int32
-		{name: "CGEBRA", argLength: 1, reg: fpgp, asm: "CGEBRA"}, // convert float32 to int64
-		{name: "CEFBRA", argLength: 1, reg: gpfp, asm: "CEFBRA"}, // convert int32 to float32
-		{name: "CDFBRA", argLength: 1, reg: gpfp, asm: "CDFBRA"}, // convert int32 to float64
-		{name: "CEGBRA", argLength: 1, reg: gpfp, asm: "CEGBRA"}, // convert int64 to float32
-		{name: "CDGBRA", argLength: 1, reg: gpfp, asm: "CDGBRA"}, // convert int64 to float64
-		{name: "LEDBR", argLength: 1, reg: fp11, asm: "LEDBR"},   // convert float64 to float32
-		{name: "LDEBR", argLength: 1, reg: fp11, asm: "LDEBR"},   // convert float32 to float64
+		{name: "LDGR", argLength: 1, reg: gpfp, asm: "LDGR"}, // move int64 to float64 (no conversion)
+		{name: "LGDR", argLength: 1, reg: fpgp, asm: "LGDR"}, // move float64 to int64 (no conversion)
+
+		{name: "CFDBRA", argLength: 1, reg: fpgp, asm: "CFDBRA", clobberFlags: true}, // convert float64 to int32
+		{name: "CGDBRA", argLength: 1, reg: fpgp, asm: "CGDBRA", clobberFlags: true}, // convert float64 to int64
+		{name: "CFEBRA", argLength: 1, reg: fpgp, asm: "CFEBRA", clobberFlags: true}, // convert float32 to int32
+		{name: "CGEBRA", argLength: 1, reg: fpgp, asm: "CGEBRA", clobberFlags: true}, // convert float32 to int64
+		{name: "CEFBRA", argLength: 1, reg: gpfp, asm: "CEFBRA", clobberFlags: true}, // convert int32 to float32
+		{name: "CDFBRA", argLength: 1, reg: gpfp, asm: "CDFBRA", clobberFlags: true}, // convert int32 to float64
+		{name: "CEGBRA", argLength: 1, reg: gpfp, asm: "CEGBRA", clobberFlags: true}, // convert int64 to float32
+		{name: "CDGBRA", argLength: 1, reg: gpfp, asm: "CDGBRA", clobberFlags: true}, // convert int64 to float64
+
+		{name: "LEDBR", argLength: 1, reg: fp11, asm: "LEDBR"}, // convert float64 to float32
+		{name: "LDEBR", argLength: 1, reg: fp11, asm: "LDEBR"}, // convert float32 to float64
 
 		{name: "MOVDaddr", argLength: 1, reg: addr, aux: "SymOff", rematerializeable: true, symEffect: "Read"}, // arg0 + auxint + offset encoded in aux
 		{name: "MOVDaddridx", argLength: 2, reg: addridx, aux: "SymOff", symEffect: "Read"},                    // arg0 + arg1 + auxint + aux

diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
diff --git a/test/fixedbugs/issue39651.go b/test/fixedbugs/issue39651.go
@@ -0,0 +1,26 @@
+// run
+
+// Copyright 2020 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.
+
+// Test that float -> integer conversion doesn't clobber
+// flags.
+
+package main
+
+//go:noinline
+func f(x, y float64, a, b *bool, r *int64) {
+	*a = x < y    // set flags
+	*r = int64(x) // clobber flags
+	*b = x == y   // use flags
+}
+
+func main() {
+	var a, b bool
+	var r int64
+	f(1, 1, &a, &b, &r)
+	if a || !b {
+		panic("comparison incorrect")
+	}
+}