Fix a bug when shifting left by zero. Ensure that the left operand is

writable (non-aliased) so it can be used for the result in the slow
case.

Review URL: http://codereview.chromium.org/118496

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2134 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ia32/codegen-ia32.cc

@@ -1691,6 +1691,8 @@ void CodeGenerator::ConstantSmiBinaryOperation(Token::Value op,
         int shift_value = int_value & 0x1f;
         operand->ToRegister();
         if (shift_value == 0) {
+          // Spill operand so it can be overwritten in the slow case.
+          frame_->Spill(operand->reg());
           DeferredInlineSmiOperation* deferred =
               new DeferredInlineSmiOperation(op,
                                              operand->reg(),

test/mjsunit/smi-ops.js

@@ -585,3 +585,10 @@ function testShiftNonSmis() {
 }
 
 testShiftNonSmis();
+
+
+// Verify that we handle the (optimized) corner case of shifting by
+// zero even for non-smis.
+function shiftByZero(n) { return n << 0; }
+
+assertEquals(3, shiftByZero(3.1415));