PPC: Sign-extended result in DoFlooringDivI/DoDivI on 64bit

     result is sign-extended on 64bit for functions
     LCodeGen::DoFlooringDivI and LCodeGen::DoDivI

R=joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2029273002
Cr-Commit-Position: refs/heads/master@{#36661}

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

@@ -1140,6 +1140,10 @@ void LCodeGen::DoDivI(LDivI* instr) {
     }
   }
 
+#if V8_TARGET_ARCH_PPC64
+  __ extsw(result, result);
+#endif
+
   if (!hdiv->CheckFlag(HInstruction::kAllUsesTruncatingToInt32)) {
     // Deoptimize if remainder is not 0.
     Register scratch = scratch0();
@@ -1333,6 +1337,9 @@ void LCodeGen::DoFlooringDivI(LFlooringDivI* instr) {
   // We performed a truncating division. Correct the result.
   __ subi(result, result, Operand(1));
   __ bind(&done);
+#if V8_TARGET_ARCH_PPC64
+  __ extsw(result, result);
+#endif
 }