cmd/compile: fix a bug in 386 backend

The ADDLmodify/SUBLmodify/ANDLmodify/ORLmodify/XORLmodify should
have clobberFlags set to true.

Change-Id: Ie447d536db51334eddc70c00a722647282186a69
Reviewed-on: https://go-review.googlesource.com/122556
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/ssa/gen/386Ops.go

@@ -346,11 +346,11 @@ func init() {
 		{name: "MOVLstore", argLength: 3, reg: gpstore, asm: "MOVL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, symEffect: "Write"},    // store 4 bytes in arg1 to arg0+auxint+aux. arg2=mem
 
 		// direct binary-op on memory (read-modify-write)
-		{name: "ADDLmodify", argLength: 3, reg: gpstore, asm: "ADDL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, symEffect: "Read,Write"}, // *(arg0+auxint+aux) += arg1, arg2=mem
-		{name: "SUBLmodify", argLength: 3, reg: gpstore, asm: "SUBL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, symEffect: "Read,Write"}, // *(arg0+auxint+aux) -= arg1, arg2=mem
-		{name: "ANDLmodify", argLength: 3, reg: gpstore, asm: "ANDL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, symEffect: "Read,Write"}, // *(arg0+auxint+aux) &= arg1, arg2=mem
-		{name: "ORLmodify", argLength: 3, reg: gpstore, asm: "ORL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, symEffect: "Read,Write"},   // *(arg0+auxint+aux) |= arg1, arg2=mem
-		{name: "XORLmodify", argLength: 3, reg: gpstore, asm: "XORL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, symEffect: "Read,Write"}, // *(arg0+auxint+aux) ^= arg1, arg2=mem
+		{name: "ADDLmodify", argLength: 3, reg: gpstore, asm: "ADDL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, clobberFlags: true, symEffect: "Read,Write"}, // *(arg0+auxint+aux) += arg1, arg2=mem
+		{name: "SUBLmodify", argLength: 3, reg: gpstore, asm: "SUBL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, clobberFlags: true, symEffect: "Read,Write"}, // *(arg0+auxint+aux) -= arg1, arg2=mem
+		{name: "ANDLmodify", argLength: 3, reg: gpstore, asm: "ANDL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, clobberFlags: true, symEffect: "Read,Write"}, // *(arg0+auxint+aux) &= arg1, arg2=mem
+		{name: "ORLmodify", argLength: 3, reg: gpstore, asm: "ORL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, clobberFlags: true, symEffect: "Read,Write"},   // *(arg0+auxint+aux) |= arg1, arg2=mem
+		{name: "XORLmodify", argLength: 3, reg: gpstore, asm: "XORL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true, clobberFlags: true, symEffect: "Read,Write"}, // *(arg0+auxint+aux) ^= arg1, arg2=mem
 
 		// indexed loads/stores
 		{name: "MOVBloadidx1", argLength: 3, reg: gploadidx, commutative: true, asm: "MOVBLZX", aux: "SymOff", symEffect: "Read"}, // load a byte from arg0+arg1+auxint+aux. arg2=mem

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

@@ -4435,6 +4435,7 @@ var opcodeTable = [...]opInfo{
 		name:           "ADDLmodify",
 		auxType:        auxSymOff,
 		argLen:         3,
+		clobberFlags:   true,
 		faultOnNilArg0: true,
 		symEffect:      SymRead | SymWrite,
 		asm:            x86.AADDL,
@@ -4449,6 +4450,7 @@ var opcodeTable = [...]opInfo{
 		name:           "SUBLmodify",
 		auxType:        auxSymOff,
 		argLen:         3,
+		clobberFlags:   true,
 		faultOnNilArg0: true,
 		symEffect:      SymRead | SymWrite,
 		asm:            x86.ASUBL,
@@ -4463,6 +4465,7 @@ var opcodeTable = [...]opInfo{
 		name:           "ANDLmodify",
 		auxType:        auxSymOff,
 		argLen:         3,
+		clobberFlags:   true,
 		faultOnNilArg0: true,
 		symEffect:      SymRead | SymWrite,
 		asm:            x86.AANDL,
@@ -4477,6 +4480,7 @@ var opcodeTable = [...]opInfo{
 		name:           "ORLmodify",
 		auxType:        auxSymOff,
 		argLen:         3,
+		clobberFlags:   true,
 		faultOnNilArg0: true,
 		symEffect:      SymRead | SymWrite,
 		asm:            x86.AORL,
@@ -4491,6 +4495,7 @@ var opcodeTable = [...]opInfo{
 		name:           "XORLmodify",
 		auxType:        auxSymOff,
 		argLen:         3,
+		clobberFlags:   true,
 		faultOnNilArg0: true,
 		symEffect:      SymRead | SymWrite,
 		asm:            x86.AXORL,