Fix bug when generating a fast smi loop.

We may encounter an invalid frame after generating code
for the loop body in case the loop body ends in an unconditional
return. Before setting the type information for the loop variable
we need to check for a valid frame.

Review URL: http://codereview.chromium.org/1106002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4182 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ia32/codegen-ia32.cc

@@ -3766,7 +3766,7 @@ void CodeGenerator::VisitForStatement(ForStatement* node) {
 
   // Set the type of the loop variable to smi before compiling the test
   // expression if we are in a fast smi loop condition.
-  if (node->is_fast_smi_loop()) {
+  if (node->is_fast_smi_loop() && has_valid_frame()) {
     // Set number type of the loop variable to smi.
     Slot* slot = node->loop_variable()->slot();
     ASSERT(slot->type() == Slot::LOCAL);

test/mjsunit/compiler/loopcount.js

@@ -75,3 +75,12 @@ function f8() {
   return i;
 }
 assertEquals(0x40000002, f8());
+
+
+function f9() {
+  var i;
+  for (i = 0; i < 42; i++) {
+    return 42;
+  }
+}
+assertEquals(42, f9());