Allow uint32 value on optimized frames if they are consumed by safe operations.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 8ab9531a7a51a0133e188467bfafd929087131e5..d4eade6992c9ab214b04ee610a4a082da8d8a3be 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -510,7 +510,8 @@ void LCodeGen::WriteTranslation(LEnvironment* environment,
         translation->MarkDuplicate();
         AddToTranslation(translation,
                          environment->spilled_registers()[value->index()],
-                         environment->HasTaggedValueAt(i));
+                         environment->HasTaggedValueAt(i),
+                         environment->HasUint32ValueAt(i));
       } else if (
           value->IsDoubleRegister() &&
           environment->spilled_double_registers()[value->index()] != NULL) {
@@ -518,18 +519,23 @@ void LCodeGen::WriteTranslation(LEnvironment* environment,
         AddToTranslation(
             translation,
             environment->spilled_double_registers()[value->index()],
+            false,
             false);
       }
     }
 
-    AddToTranslation(translation, value, environment->HasTaggedValueAt(i));
+    AddToTranslation(translation,
+                     value,
+                     environment->HasTaggedValueAt(i),
+                     environment->HasUint32ValueAt(i));
   }
 }
 
 
 void LCodeGen::AddToTranslation(Translation* translation,
                                 LOperand* op,
-                                bool is_tagged) {
+                                bool is_tagged,
+                                bool is_uint32) {
   if (op == NULL) {
     // TODO(twuerthinger): Introduce marker operands to indicate that this value
     // is not present and must be reconstructed from the deoptimizer. Currently
@@ -538,6 +544,8 @@ void LCodeGen::AddToTranslation(Translation* translation,
   } else if (op->IsStackSlot()) {
     if (is_tagged) {
       translation->StoreStackSlot(op->index());
+    } else if (is_uint32) {
+      translation->StoreUint32StackSlot(op->index());
     } else {
       translation->StoreInt32StackSlot(op->index());
     }
@@ -551,6 +559,8 @@ void LCodeGen::AddToTranslation(Translation* translation,
     Register reg = ToRegister(op);
     if (is_tagged) {
       translation->StoreRegister(reg);
+    } else if (is_uint32) {
+      translation->StoreUint32Register(reg);
     } else {
       translation->StoreInt32Register(reg);
     }
@@ -3020,11 +3030,10 @@ void LCodeGen::DoLoadKeyedSpecializedArrayElement(
         break;
       case EXTERNAL_UNSIGNED_INT_ELEMENTS:
         __ ldr(result, mem_operand);
-        __ cmp(result, Operand(0x80000000));
-        // TODO(danno): we could be more clever here, perhaps having a special
-        // version of the stub that detects if the overflow case actually
-        // happens, and generate code that returns a double rather than int.
-        DeoptimizeIf(cs, instr->environment());
+        if (!instr->hydrogen()->CheckFlag(HInstruction::kUint32)) {
+          __ cmp(result, Operand(0x80000000));
+          DeoptimizeIf(cs, instr->environment());
+        }
         break;
       case EXTERNAL_FLOAT_ELEMENTS:
       case EXTERNAL_DOUBLE_ELEMENTS:
@@ -4262,12 +4271,24 @@ void LCodeGen::DoInteger32ToDouble(LInteger32ToDouble* instr) {
 }
 
 
+void LCodeGen::DoUint32ToDouble(LUint32ToDouble* instr) {
+  LOperand* input = instr->InputAt(0);
+  LOperand* output = instr->result();
+
+  SwVfpRegister flt_scratch = double_scratch0().low();
+  __ vmov(flt_scratch, ToRegister(input));
+  __ vcvt_f64_u32(ToDoubleRegister(output), flt_scratch);
+}
+
+
 void LCodeGen::DoNumberTagI(LNumberTagI* instr) {
   class DeferredNumberTagI: public LDeferredCode {
    public:
     DeferredNumberTagI(LCodeGen* codegen, LNumberTagI* instr)
         : LDeferredCode(codegen), instr_(instr) { }
-    virtual void Generate() { codegen()->DoDeferredNumberTagI(instr_); }
+    virtual void Generate() {
+      codegen()->DoDeferredNumberTagI(instr_, SIGNED_INT32);
+    }
     virtual LInstruction* instr() { return instr_; }
    private:
     LNumberTagI* instr_;
@@ -4283,7 +4304,33 @@ void LCodeGen::DoNumberTagI(LNumberTagI* instr) {
 }
 
 
-void LCodeGen::DoDeferredNumberTagI(LNumberTagI* instr) {
+void LCodeGen::DoNumberTagU(LNumberTagU* instr) {
+  class DeferredNumberTagU: public LDeferredCode {
+   public:
+    DeferredNumberTagU(LCodeGen* codegen, LNumberTagU* instr)
+        : LDeferredCode(codegen), instr_(instr) { }
+    virtual void Generate() {
+      codegen()->DoDeferredNumberTagI(instr_, UNSIGNED_INT32);
+    }
+    virtual LInstruction* instr() { return instr_; }
+   private:
+    LNumberTagU* instr_;
+  };
+
+  LOperand* input = instr->InputAt(0);
+  ASSERT(input->IsRegister() && input->Equals(instr->result()));
+  Register reg = ToRegister(input);
+
+  DeferredNumberTagU* deferred = new(zone()) DeferredNumberTagU(this, instr);
+  __ cmp(reg, Operand(Smi::kMaxValue));
+  __ b(hi, deferred->entry());
+  __ SmiTag(reg, reg);
+  __ bind(deferred->exit());
+}
+
+
+void LCodeGen::DoDeferredNumberTagI(LInstruction* instr,
+                                    IntegerSignedness signedness) {
   Label slow;
   Register src = ToRegister(instr->InputAt(0));
   Register dst = ToRegister(instr->result());
@@ -4293,16 +4340,22 @@ void LCodeGen::DoDeferredNumberTagI(LNumberTagI* instr) {
   // Preserve the value of all registers.
   PushSafepointRegistersScope scope(this, Safepoint::kWithRegisters);
 
-  // There was overflow, so bits 30 and 31 of the original integer
-  // disagree. Try to allocate a heap number in new space and store
-  // the value in there. If that fails, call the runtime system.
   Label done;
-  if (dst.is(src)) {
-    __ SmiUntag(src, dst);
-    __ eor(src, src, Operand(0x80000000));
+  if (signedness == SIGNED_INT32) {
+    // There was overflow, so bits 30 and 31 of the original integer
+    // disagree. Try to allocate a heap number in new space and store
+    // the value in there. If that fails, call the runtime system.
+    if (dst.is(src)) {
+      __ SmiUntag(src, dst);
+      __ eor(src, src, Operand(0x80000000));
+    }
+    __ vmov(flt_scratch, src);
+    __ vcvt_f64_s32(dbl_scratch, flt_scratch);
+  } else {
+    __ vmov(flt_scratch, src);
+    __ vcvt_f64_u32(dbl_scratch, flt_scratch);
   }
-  __ vmov(flt_scratch, src);
-  __ vcvt_f64_s32(dbl_scratch, flt_scratch);
+
   if (FLAG_inline_new) {
     __ LoadRoot(r6, Heap::kHeapNumberMapRootIndex);
     __ AllocateHeapNumber(r5, r3, r4, r6, &slow);