Generate a custom OSR entrypoint for OSR compiles on all platforms, and transition to optimized cod…

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index ef3761e51e7a8a5d53c59b26966f43f29273e2e6..515eb5de7717ac07efe466e1baf55269991b6ff4 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -35,6 +35,7 @@
 #include "deoptimizer.h"
 #include "stub-cache.h"
 #include "codegen.h"
+#include "hydrogen-osr.h"
 
 namespace v8 {
 namespace internal {
@@ -327,6 +328,28 @@ bool LCodeGen::GeneratePrologue() {
 }
 
 
+void LCodeGen::GenerateOsrPrologue() {
+  // Generate the OSR entry prologue at the first unknown OSR value, or if there
+  // are none, at the OSR entrypoint instruction.
+  if (osr_pc_offset_ >= 0) return;
+
+  osr_pc_offset_ = masm()->pc_offset();
+
+  // Save the first local, which is overwritten by the alignment state.
+  Operand alignment_loc = MemOperand(ebp, -3 * kPointerSize);
+  __ push(alignment_loc);
+
+  // Set the dynamic frame alignment state to "not aligned".
+  __ mov(alignment_loc, Immediate(kNoAlignmentPadding));
+
+  // Adjust the frame size, subsuming the unoptimized frame into the
+  // optimized frame.
+  int slots = GetStackSlotCount() - graph()->osr()->UnoptimizedFrameSlots();
+  ASSERT(slots >= 1);
+  __ sub(esp, Immediate((slots - 1) * kPointerSize));
+}
+
+
 bool LCodeGen::GenerateBody() {
   ASSERT(is_generating());
   bool emit_instructions = true;
@@ -1250,8 +1273,7 @@ void LCodeGen::DoCallStub(LCallStub* instr) {
 
 
 void LCodeGen::DoUnknownOSRValue(LUnknownOSRValue* instr) {
-  // Record the address of the first unknown OSR value as the place to enter.
-  if (osr_pc_offset_ == -1) osr_pc_offset_ = masm()->pc_offset();
+  GenerateOsrPrologue();
 }
 
 
@@ -6438,9 +6460,7 @@ void LCodeGen::DoOsrEntry(LOsrEntry* instr) {
   ASSERT(!environment->HasBeenRegistered());
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
 
-  // Normally we record the first unknown OSR value as the entrypoint to the OSR
-  // code, but if there were none, record the entrypoint here.
-  if (osr_pc_offset_ == -1) osr_pc_offset_ = masm()->pc_offset();
+  GenerateOsrPrologue();
 }