[release-branch.go1.10] cmd/compile: mark LAA and LAAG as clobbering flags on s390x

The atomic add instructions modify the condition code and so need to
be marked as clobbering flags.

Fixes #24449.

Change-Id: Ic69c8d775fbdbfb2a56c5e0cfca7a49c0d7f6897
Reviewed-on: https://go-review.googlesource.com/101455
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-on: https://go-review.googlesource.com/102788
Run-TryBot: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Michael Munday <mike.munday@ibm.com>

diff --git a/src/cmd/compile/internal/ssa/gen/S390XOps.go b/src/cmd/compile/internal/ssa/gen/S390XOps.go
index d12dfe78bb405937e3fb5de7ccd4acea8dafa345..e458e08a1a7c5febd35713b73a226d1636438c98 100644 (file)
--- a/src/cmd/compile/internal/ssa/gen/S390XOps.go
+++ b/src/cmd/compile/internal/ssa/gen/S390XOps.go
@@ -485,8 +485,8 @@ func init() {
                // Atomic adds.
                // *(arg0+auxint+aux) += arg1.  arg2=mem.
                // Returns a tuple of <old contents of *(arg0+auxint+aux), memory>.
-               {name: "LAA", argLength: 3, reg: gpstorelaa, asm: "LAA", typ: "(UInt32,Mem)", aux: "SymOff", faultOnNilArg0: true, hasSideEffects: true, symEffect: "RdWr"},
-               {name: "LAAG", argLength: 3, reg: gpstorelaa, asm: "LAAG", typ: "(UInt64,Mem)", aux: "SymOff", faultOnNilArg0: true, hasSideEffects: true, symEffect: "RdWr"},
+               {name: "LAA", argLength: 3, reg: gpstorelaa, asm: "LAA", typ: "(UInt32,Mem)", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true, symEffect: "RdWr"},
+               {name: "LAAG", argLength: 3, reg: gpstorelaa, asm: "LAAG", typ: "(UInt64,Mem)", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true, symEffect: "RdWr"},
                {name: "AddTupleFirst32", argLength: 2}, // arg1=tuple <x,y>.  Returns <x+arg0,y>.
                {name: "AddTupleFirst64", argLength: 2}, // arg1=tuple <x,y>.  Returns <x+arg0,y>.
 

diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
index 0beabb0b842339de94f4ccbd06062009370bee21..d50561cdf08edc5a3a51a1891b2e01e14366ecfc 100644 (file)
--- a/src/cmd/compile/internal/ssa/opGen.go
+++ b/src/cmd/compile/internal/ssa/opGen.go
@@ -22080,6 +22080,7 @@ var opcodeTable = [...]opInfo{
                name:           "LAA",
                auxType:        auxSymOff,
                argLen:         3,
+               clobberFlags:   true,
                faultOnNilArg0: true,
                hasSideEffects: true,
                symEffect:      SymRdWr,
@@ -22098,6 +22099,7 @@ var opcodeTable = [...]opInfo{
                name:           "LAAG",
                auxType:        auxSymOff,
                argLen:         3,
+               clobberFlags:   true,
                faultOnNilArg0: true,
                hasSideEffects: true,
                symEffect:      SymRdWr,

diff --git a/test/fixedbugs/issue24449.go b/test/fixedbugs/issue24449.go
new file mode 100644 (file)
index 0000000..b236645
--- /dev/null
+++ b/test/fixedbugs/issue24449.go
@@ -0,0 +1,62 @@
+// run
+
+// Copyright 2018 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
+
+import (
+       "sync/atomic"
+)
+
+var cnt32 int32
+
+//go:noinline
+func test32(a, b []int) bool {
+       // Try to generate flag value, issue atomic
+       // adds and then re-use the flag value to see if
+       // the atomic add has clobbered them.
+       atomic.AddInt32(&cnt32, 1)
+       if len(a) == len(b) {
+               atomic.AddInt32(&cnt32, 2)
+       }
+       atomic.AddInt32(&cnt32, 4)
+       if len(a) >= len(b) {
+               atomic.AddInt32(&cnt32, 8)
+       }
+       if len(a) <= len(b) {
+               atomic.AddInt32(&cnt32, 16)
+       }
+       return atomic.LoadInt32(&cnt32) == 31
+}
+
+var cnt64 int64
+
+//go:noinline
+func test64(a, b []int) bool {
+       // Try to generate flag value, issue atomic
+       // adds and then re-use the flag value to see if
+       // the atomic add has clobbered them.
+       atomic.AddInt64(&cnt64, 1)
+       if len(a) == len(b) {
+               atomic.AddInt64(&cnt64, 2)
+       }
+       atomic.AddInt64(&cnt64, 4)
+       if len(a) >= len(b) {
+               atomic.AddInt64(&cnt64, 8)
+       }
+       if len(a) <= len(b) {
+               atomic.AddInt64(&cnt64, 16)
+       }
+       return atomic.LoadInt64(&cnt64) == 31
+}
+
+func main() {
+       if !test32([]int{}, []int{}) {
+               panic("test32")
+       }
+       if !test64([]int{}, []int{}) {
+               panic("test64")
+       }
+}