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

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index 132e1a60e83b3d46c325ea33cfe01bc656e299ac..9695072ac1ac847c90f4fa550a3d818f84d9fec4 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -30,6 +30,7 @@
 #include "lithium-allocator-inl.h"
 #include "arm/lithium-arm.h"
 #include "arm/lithium-codegen-arm.h"
+#include "hydrogen-osr.h"
 
 namespace v8 {
 namespace internal {
@@ -433,6 +434,15 @@ LPlatformChunk* LChunkBuilder::Build() {
   chunk_ = new(zone()) LPlatformChunk(info(), graph());
   LPhase phase("L_Building chunk", chunk_);
   status_ = BUILDING;
+
+  // If compiling for OSR, reserve space for the unoptimized frame,
+  // which will be subsumed into this frame.
+  if (graph()->has_osr()) {
+    for (int i = graph()->osr()->UnoptimizedFrameSlots(); i > 0; i--) {
+      chunk_->GetNextSpillIndex(false);
+    }
+  }
+
   const ZoneList<HBasicBlock*>* blocks = graph()->blocks();
   for (int i = 0; i < blocks->length(); i++) {
     HBasicBlock* next = NULL;
@@ -2439,10 +2449,18 @@ LInstruction* LChunkBuilder::DoParameter(HParameter* instr) {
 
 
 LInstruction* LChunkBuilder::DoUnknownOSRValue(HUnknownOSRValue* instr) {
-  int spill_index = chunk()->GetNextSpillIndex(false);  // Not double-width.
-  if (spill_index > LUnallocated::kMaxFixedSlotIndex) {
-    Abort(kTooManySpillSlotsNeededForOSR);
-    spill_index = 0;
+  // Use an index that corresponds to the location in the unoptimized frame,
+  // which the optimized frame will subsume.
+  int env_index = instr->index();
+  int spill_index = 0;
+  if (instr->environment()->is_parameter_index(env_index)) {
+    spill_index = chunk()->GetParameterStackSlot(env_index);
+  } else {
+    spill_index = env_index - instr->environment()->first_local_index();
+    if (spill_index > LUnallocated::kMaxFixedSlotIndex) {
+      Abort(kTooManySpillSlotsNeededForOSR);
+      spill_index = 0;
+    }
   }
   return DefineAsSpilled(new(zone()) LUnknownOSRValue, spill_index);
 }