PPC/s390: Check for overflow when SubI IntMin

R=joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2639853002
Cr-Commit-Position: refs/heads/master@{#42468}

src/crankshaft/ppc/lithium-codegen-ppc.cc

@@ -1707,12 +1707,15 @@ void LCodeGen::DoSubI(LSubI* instr) {
     } else {
       __ sub(result, left, EmitLoadRegister(right, ip));
     }
-#if V8_TARGET_ARCH_PPC64
     if (can_overflow) {
+#if V8_TARGET_ARCH_PPC64
       __ TestIfInt32(result, r0);
+#else
+      __ TestIfInt32(scratch0(), result, r0);
+#endif
       DeoptimizeIf(ne, instr, DeoptimizeReason::kOverflow);
     }
-#endif
+
   } else {
     if (right->IsConstantOperand()) {
       __ AddAndCheckForOverflow(result, left, -(ToOperand(right).immediate()),

src/crankshaft/s390/lithium-codegen-s390.cc

@@ -1682,10 +1682,17 @@ void LCodeGen::DoSubI(LSubI* instr) {
 #endif
 
   if (right->IsConstantOperand()) {
-    if (!isInteger || !checkOverflow)
+    if (!isInteger || !checkOverflow) {
       __ SubP(ToRegister(result), ToRegister(left), ToOperand(right));
-    else
+    } else {
+      // -(MinInt) will overflow
+      if (ToInteger32(LConstantOperand::cast(right)) == kMinInt) {
+        __ Load(scratch0(), ToOperand(right));
+        __ Sub32(ToRegister(result), ToRegister(left), scratch0());
+      } else {
         __ Sub32(ToRegister(result), ToRegister(left), ToOperand(right));
+      }
+    }
   } else if (right->IsRegister()) {
     if (!isInteger)
       __ SubP(ToRegister(result), ToRegister(left), ToRegister(right));