ARM: Improve register allocation and constraints....

src/arm/lithium-codegen-arm.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 855 matching lines @@
 
 
 void LCodeGen::DoUnknownOSRValue(LUnknownOSRValue* instr) {
   // Nothing to do.
 }
 
 
 void LCodeGen::DoModI(LModI* instr) {
   if (instr->hydrogen()->HasPowerOf2Divisor()) {
     Register dividend = ToRegister(instr->InputAt(0));
+    Register result = ToRegister(instr->result());
 
     int32_t divisor =
         HConstant::cast(instr->hydrogen()->right())->Integer32Value();
 
     if (divisor < 0) divisor = -divisor;
 
     Label positive_dividend, done;
     __ cmp(dividend, Operand(0));
     __ b(pl, &positive_dividend);
-    __ rsb(dividend, dividend, Operand(0));
-    __ and_(dividend, dividend, Operand(divisor - 1));
-    __ rsb(dividend, dividend, Operand(0), SetCC);
+    __ rsb(result, dividend, Operand(0));
+    __ and_(dividend, result, Operand(divisor - 1), SetCC);
     if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
-      __ b(ne, &done);
-      DeoptimizeIf(al, instr->environment());
-    } else {
-      __ b(&done);
+      DeoptimizeIf(eq, instr->environment());
     }
+    __ rsb(result, dividend, Operand(0));
+    __ b(&done);
     __ bind(&positive_dividend);
-    __ and_(dividend, dividend, Operand(divisor - 1));
+    __ and_(result, dividend, Operand(divisor - 1));
     __ bind(&done);
     return;
   }
 
   // These registers hold untagged 32 bit values.
   Register left = ToRegister(instr->InputAt(0));
   Register right = ToRegister(instr->InputAt(1));
   Register result = ToRegister(instr->result());
 
   Register scratch = scratch0();
   Register scratch2 = ToRegister(instr->TempAt(0));
   DwVfpRegister dividend = ToDoubleRegister(instr->TempAt(1));
   DwVfpRegister divisor = ToDoubleRegister(instr->TempAt(2));
   DwVfpRegister quotient = double_scratch0();
 
-  ASSERT(result.is(left));
-
   ASSERT(!dividend.is(divisor));
   ASSERT(!dividend.is(quotient));
   ASSERT(!divisor.is(quotient));
   ASSERT(!scratch.is(left));
   ASSERT(!scratch.is(right));
   ASSERT(!scratch.is(result));
 
   Label done, vfp_modulo, both_positive, right_negative;
 
   // Check for x % 0.
   if (instr->hydrogen()->CheckFlag(HValue::kCanBeDivByZero)) {
     __ cmp(right, Operand(0));
     DeoptimizeIf(eq, instr->environment());
   }
 
+  __ Move(result, left);
+
   // (0 % x) must yield 0 (if x is finite, which is the case here).
   __ cmp(left, Operand(0));
   __ b(eq, &done);
   // Preload right in a vfp register.
   __ vmov(divisor.low(), right);
   __ b(lt, &vfp_modulo);
 
   __ cmp(left, Operand(right));
   __ b(lt, &done);
 
@@ skipping 175 matching lines @@
   __ CallStub(&stub);
   RecordSafepointWithRegistersAndDoubles(instr->pointer_map(),
                                          0,
                                          Safepoint::kNoDeoptimizationIndex);
   // Overwrite the stored value of r0 with the result of the stub.
   __ StoreToSafepointRegistersAndDoublesSlot(r0, r0);
 }
 
 
 void LCodeGen::DoMulI(LMulI* instr) {
-  ASSERT(instr->result()->Equals(instr->InputAt(0)));
   Register scratch = scratch0();
   Register result = ToRegister(instr->result());
+  // Note that result may alias left.
   Register left = ToRegister(instr->InputAt(0));
   LOperand* right_op = instr->InputAt(1);
 
   bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
   bool bailout_on_minus_zero =
     instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero);
 
   if (right_op->IsConstantOperand() && !can_overflow) {
     // Use optimized code for specific constants.
     int32_t constant = ToInteger32(LConstantOperand::cast(right_op));
@@ skipping 12 matching lines @@
       case 0:
         if (bailout_on_minus_zero) {
           // If left is strictly negative and the constant is null, the
           // result is -0. Deoptimize if required, otherwise return 0.
           __ cmp(left, Operand(0));
           DeoptimizeIf(mi, instr->environment());
         }
         __ mov(result, Operand(0));
         break;
       case 1:
-        // Nothing to do.
+        __ Move(result, left);
         break;
       default:
         // Multiplying by powers of two and powers of two plus or minus
         // one can be done faster with shifted operands.
         // For other constants we emit standard code.
         int32_t mask = constant >> 31;
         uint32_t constant_abs = (constant + mask) ^ mask;
 
         if (IsPowerOf2(constant_abs) ||
             IsPowerOf2(constant_abs - 1) ||
@@ skipping 41 matching lines @@
       __ b(ne, &done);
       __ cmp(ToRegister(instr->TempAt(0)), Operand(0));
       DeoptimizeIf(mi, instr->environment());
       __ bind(&done);
     }
   }
 }
 
 
 void LCodeGen::DoBitI(LBitI* instr) {
-  LOperand* left = instr->InputAt(0);
-  LOperand* right = instr->InputAt(1);
-  ASSERT(left->Equals(instr->result()));
-  ASSERT(left->IsRegister());
-  Register result = ToRegister(left);
-  Operand right_operand(no_reg);
+  LOperand* left_op = instr->InputAt(0);
+  LOperand* right_op = instr->InputAt(1);
+  ASSERT(left_op->IsRegister());
+  Register left = ToRegister(left_op);
+  Register result = ToRegister(instr->result());
+  Operand right(no_reg);
 
-  if (right->IsStackSlot() || right->IsArgument()) {
-    Register right_reg = EmitLoadRegister(right, ip);
-    right_operand = Operand(right_reg);
+  if (right_op->IsStackSlot() || right_op->IsArgument()) {
+    right = Operand(EmitLoadRegister(right_op, ip));
   } else {
-    ASSERT(right->IsRegister() || right->IsConstantOperand());
-    right_operand = ToOperand(right);
+    ASSERT(right_op->IsRegister() || right_op->IsConstantOperand());
+    right = ToOperand(right_op);
   }
 
   switch (instr->op()) {
     case Token::BIT_AND:
-      __ and_(result, ToRegister(left), right_operand);
+      __ and_(result, left, right);
       break;
     case Token::BIT_OR:
-      __ orr(result, ToRegister(left), right_operand);
+      __ orr(result, left, right);
       break;
     case Token::BIT_XOR:
-      __ eor(result, ToRegister(left), right_operand);
+      __ eor(result, left, right);
       break;
     default:
       UNREACHABLE();
       break;
   }
 }
 
 
 void LCodeGen::DoShiftI(LShiftI* instr) {
+  // Both 'left' and 'right' are "used at start" (see LCodeGen::DoShift), so
+  // result may alias either of them.
+  LOperand* right_op = instr->InputAt(1);
+  Register left = ToRegister(instr->InputAt(0));
+  Register result = ToRegister(instr->result());
   Register scratch = scratch0();
-  LOperand* left = instr->InputAt(0);
-  LOperand* right = instr->InputAt(1);
-  ASSERT(left->Equals(instr->result()));
-  ASSERT(left->IsRegister());
-  Register result = ToRegister(left);
-  if (right->IsRegister()) {
-    // Mask the right operand.
-    __ and_(scratch, ToRegister(right), Operand(0x1F));
+  if (right_op->IsRegister()) {
+    // Mask the right_op operand.
+    __ and_(scratch, ToRegister(right_op), Operand(0x1F));
     switch (instr->op()) {
       case Token::SAR:
-        __ mov(result, Operand(result, ASR, scratch));
+        __ mov(result, Operand(left, ASR, scratch));
         break;
       case Token::SHR:
         if (instr->can_deopt()) {
-          __ mov(result, Operand(result, LSR, scratch), SetCC);
+          __ mov(result, Operand(left, LSR, scratch), SetCC);
           DeoptimizeIf(mi, instr->environment());
         } else {
-          __ mov(result, Operand(result, LSR, scratch));
+          __ mov(result, Operand(left, LSR, scratch));
         }
         break;
       case Token::SHL:
-        __ mov(result, Operand(result, LSL, scratch));
+        __ mov(result, Operand(left, LSL, scratch));
         break;
       default:
         UNREACHABLE();
         break;
     }
   } else {
-    int value = ToInteger32(LConstantOperand::cast(right));
+    // Mask the right_op operand.
+    int value = ToInteger32(LConstantOperand::cast(right_op));
     uint8_t shift_count = static_cast<uint8_t>(value & 0x1F);
     switch (instr->op()) {
       case Token::SAR:
         if (shift_count != 0) {
-          __ mov(result, Operand(result, ASR, shift_count));
+          __ mov(result, Operand(left, ASR, shift_count));
+        } else {
+          __ Move(result, left);
         }
         break;
       case Token::SHR:
-        if (shift_count == 0 && instr->can_deopt()) {
-          __ tst(result, Operand(0x80000000));
-          DeoptimizeIf(ne, instr->environment());
+        if (shift_count != 0) {
+          __ mov(result, Operand(left, LSR, shift_count));
         } else {
-          __ mov(result, Operand(result, LSR, shift_count));
+          if (instr->can_deopt()) {
+            __ tst(left, Operand(0x80000000));
+            DeoptimizeIf(ne, instr->environment());
+          }
+          __ Move(result, left);
         }
         break;
       case Token::SHL:
         if (shift_count != 0) {
-          __ mov(result, Operand(result, LSL, shift_count));
+          __ mov(result, Operand(left, LSL, shift_count));
+        } else {
+          __ Move(result, left);
         }
         break;
       default:
         UNREACHABLE();
         break;
     }
   }
 }
 
 
 void LCodeGen::DoSubI(LSubI* instr) {
   LOperand* left = instr->InputAt(0);
   LOperand* right = instr->InputAt(1);
-  ASSERT(left->Equals(instr->result()));
+  LOperand* result = instr->result();
   bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
   SBit set_cond = can_overflow ? SetCC : LeaveCC;
 
   if (right->IsStackSlot() || right->IsArgument()) {
     Register right_reg = EmitLoadRegister(right, ip);
-    __ sub(ToRegister(left), ToRegister(left), Operand(right_reg), set_cond);
+    __ sub(ToRegister(result), ToRegister(left), Operand(right_reg), set_cond);
   } else {
     ASSERT(right->IsRegister() || right->IsConstantOperand());
-    __ sub(ToRegister(left), ToRegister(left), ToOperand(right), set_cond);
+    __ sub(ToRegister(result), ToRegister(left), ToOperand(right), set_cond);
   }
 
   if (can_overflow) {
     DeoptimizeIf(vs, instr->environment());
   }
 }
 
 
 void LCodeGen::DoConstantI(LConstantI* instr) {
   ASSERT(instr->result()->IsRegister());
   __ mov(ToRegister(instr->result()), Operand(instr->value()));
 }
 
 
 void LCodeGen::DoConstantD(LConstantD* instr) {
   ASSERT(instr->result()->IsDoubleRegister());
   DwVfpRegister result = ToDoubleRegister(instr->result());
   double v = instr->value();
-  __ vmov(result, v);
+  __ Vmov(result, v);
 }
 
 
 void LCodeGen::DoConstantT(LConstantT* instr) {
   ASSERT(instr->result()->IsRegister());
   __ mov(ToRegister(instr->result()), Operand(instr->value()));
 }
 
 
 void LCodeGen::DoJSArrayLength(LJSArrayLength* instr) {
@@ skipping 28 matching lines @@
   __ ldr(result, FieldMemOperand(result, Map::kBitField2Offset));
   // Retrieve elements_kind from bit field 2.
   __ ubfx(result, result, Map::kElementsKindShift, Map::kElementsKindBitCount);
 }
 
 
 void LCodeGen::DoValueOf(LValueOf* instr) {
   Register input = ToRegister(instr->InputAt(0));
   Register result = ToRegister(instr->result());
   Register map = ToRegister(instr->TempAt(0));
-  ASSERT(input.is(result));
   Label done;
 
   // If the object is a smi return the object.
-  __ JumpIfSmi(input, &done);
+  __ tst(input, Operand(kSmiTagMask));
+  __ Move(result, input, eq);
+  __ b(eq, &done);
 
   // If the object is not a value type, return the object.
   __ CompareObjectType(input, map, map, JS_VALUE_TYPE);
+  __ Move(result, input, ne);
   __ b(ne, &done);
   __ ldr(result, FieldMemOperand(input, JSValue::kValueOffset));
 
   __ bind(&done);
 }
 
 
 void LCodeGen::DoBitNotI(LBitNotI* instr) {
-  LOperand* input = instr->InputAt(0);
-  ASSERT(input->Equals(instr->result()));
-  __ mvn(ToRegister(input), Operand(ToRegister(input)));
+  Register input = ToRegister(instr->InputAt(0));
+  Register result = ToRegister(instr->result());
+  __ mvn(result, Operand(input));
 }
 
 
 void LCodeGen::DoThrow(LThrow* instr) {
   Register input_reg = EmitLoadRegister(instr->InputAt(0), ip);
   __ push(input_reg);
   CallRuntime(Runtime::kThrow, 1, instr);
 
   if (FLAG_debug_code) {
     __ stop("Unreachable code.");
   }
 }
 
 
 void LCodeGen::DoAddI(LAddI* instr) {
   LOperand* left = instr->InputAt(0);
   LOperand* right = instr->InputAt(1);
-  ASSERT(left->Equals(instr->result()));
+  LOperand* result = instr->result();
   bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
   SBit set_cond = can_overflow ? SetCC : LeaveCC;
 
   if (right->IsStackSlot() || right->IsArgument()) {
     Register right_reg = EmitLoadRegister(right, ip);
-    __ add(ToRegister(left), ToRegister(left), Operand(right_reg), set_cond);
+    __ add(ToRegister(result), ToRegister(left), Operand(right_reg), set_cond);
   } else {
     ASSERT(right->IsRegister() || right->IsConstantOperand());
-    __ add(ToRegister(left), ToRegister(left), ToOperand(right), set_cond);
+    __ add(ToRegister(result), ToRegister(left), ToOperand(right), set_cond);
   }
 
   if (can_overflow) {
     DeoptimizeIf(vs, instr->environment());
   }
 }
 
 
 void LCodeGen::DoArithmeticD(LArithmeticD* instr) {
   DoubleRegister left = ToDoubleRegister(instr->InputAt(0));
   DoubleRegister right = ToDoubleRegister(instr->InputAt(1));
+  DoubleRegister result = ToDoubleRegister(instr->result());
   switch (instr->op()) {
     case Token::ADD:
-      __ vadd(left, left, right);
+      __ vadd(result, left, right);
       break;
     case Token::SUB:
-      __ vsub(left, left, right);
+      __ vsub(result, left, right);
       break;
     case Token::MUL:
-      __ vmul(left, left, right);
+      __ vmul(result, left, right);
       break;
     case Token::DIV:
-      __ vdiv(left, left, right);
+      __ vdiv(result, left, right);
       break;
     case Token::MOD: {
       // Save r0-r3 on the stack.
       __ stm(db_w, sp, r0.bit() | r1.bit() | r2.bit() | r3.bit());
 
       __ PrepareCallCFunction(0, 2, scratch0());
       __ SetCallCDoubleArguments(left, right);
       __ CallCFunction(
           ExternalReference::double_fp_operation(Token::MOD, isolate()),
           0, 2);
       // Move the result in the double result register.
-      __ GetCFunctionDoubleResult(ToDoubleRegister(instr->result()));
+      __ GetCFunctionDoubleResult(result);
 
       // Restore r0-r3.
       __ ldm(ia_w, sp, r0.bit() | r1.bit() | r2.bit() | r3.bit());
       break;
     }
     default:
       UNREACHABLE();
       break;
   }
 }
@@ skipping 72 matching lines @@
       __ b(eq, true_label);
       __ LoadRoot(ip, Heap::kFalseValueRootIndex);
       __ cmp(reg, ip);
       __ b(eq, false_label);
       __ cmp(reg, Operand(0));
       __ b(eq, false_label);
       __ JumpIfSmi(reg, true_label);
 
       // Test double values. Zero and NaN are false.
       Label call_stub;
-      DoubleRegister dbl_scratch = d0;
+      DoubleRegister dbl_scratch = double_scratch0();
       Register scratch = scratch0();
       __ ldr(scratch, FieldMemOperand(reg, HeapObject::kMapOffset));
       __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
       __ cmp(scratch, Operand(ip));
       __ b(ne, &call_stub);
       __ sub(ip, reg, Operand(kHeapObjectTag));
       __ vldr(dbl_scratch, ip, HeapNumber::kValueOffset);
       __ VFPCompareAndLoadFlags(dbl_scratch, 0.0, scratch);
       __ tst(scratch, Operand(kVFPZConditionFlagBit | kVFPVConditionFlagBit));
       __ b(ne, false_label);
@@ skipping 1025 matching lines @@
   __ add(length, length, Operand(1));
   __ ldr(result, MemOperand(arguments, length, LSL, kPointerSizeLog2));
 }
 
 
 void LCodeGen::DoLoadKeyedFastElement(LLoadKeyedFastElement* instr) {
   Register elements = ToRegister(instr->elements());
   Register key = EmitLoadRegister(instr->key(), scratch0());
   Register result = ToRegister(instr->result());
   Register scratch = scratch0();
-  ASSERT(result.is(elements));
 
   // Load the result.
   __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2));
   __ ldr(result, FieldMemOperand(scratch, FixedArray::kHeaderSize));
 
   // Check for the hole value.
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ LoadRoot(scratch, Heap::kTheHoleValueRootIndex);
     __ cmp(result, scratch);
     DeoptimizeIf(eq, instr->environment());
@@ skipping 299 matching lines @@
   ASSERT(ToRegister(instr->result()).is(r0));
   __ mov(r1, Operand(instr->function()));
   CallKnownFunction(instr->function(),
                     instr->arity(),
                     instr,
                     CALL_AS_METHOD);
 }
 
 
 void LCodeGen::DoDeferredMathAbsTaggedHeapNumber(LUnaryMathOperation* instr) {
-  ASSERT(instr->InputAt(0)->Equals(instr->result()));
   Register input = ToRegister(instr->InputAt(0));
+  Register result = ToRegister(instr->result());
   Register scratch = scratch0();
 
   // Deoptimize if not a heap number.
   __ ldr(scratch, FieldMemOperand(input, HeapObject::kMapOffset));
   __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
   __ cmp(scratch, Operand(ip));
   DeoptimizeIf(ne, instr->environment());
 
   Label done;
   Register exponent = scratch0();
   scratch = no_reg;
   __ ldr(exponent, FieldMemOperand(input, HeapNumber::kExponentOffset));
   // Check the sign of the argument. If the argument is positive, just
-  // return it. We do not need to patch the stack since |input| and
-  // |result| are the same register and |input| would be restored
-  // unchanged by popping safepoint registers.
+  // return it.
   __ tst(exponent, Operand(HeapNumber::kSignMask));
+  // Move the input to the result if necessary.
+  __ Move(result, input);
   __ b(eq, &done);
 
   // Input is negative. Reverse its sign.
   // Preserve the value of all registers.
   {
     PushSafepointRegistersScope scope(this, Safepoint::kWithRegisters);
 
     // Registers were saved at the safepoint, so we can use
     // many scratch registers.
     Register tmp1 = input.is(r1) ? r0 : r1;
@@ skipping 19 matching lines @@
     __ ldr(exponent, FieldMemOperand(input, HeapNumber::kExponentOffset));
 
     __ bind(&allocated);
     // exponent: floating point exponent value.
     // tmp1: allocated heap number.
     __ bic(exponent, exponent, Operand(HeapNumber::kSignMask));
     __ str(exponent, FieldMemOperand(tmp1, HeapNumber::kExponentOffset));
     __ ldr(tmp2, FieldMemOperand(input, HeapNumber::kMantissaOffset));
     __ str(tmp2, FieldMemOperand(tmp1, HeapNumber::kMantissaOffset));
 
-    __ StoreToSafepointRegisterSlot(tmp1, input);
+    __ StoreToSafepointRegisterSlot(tmp1, result);
   }
 
   __ bind(&done);
 }
 
 
 void LCodeGen::EmitIntegerMathAbs(LUnaryMathOperation* instr) {
   Register input = ToRegister(instr->InputAt(0));
+  Register result = ToRegister(instr->result());
   __ cmp(input, Operand(0));
+  __ Move(result, input, pl);
   // We can make rsb conditional because the previous cmp instruction
   // will clear the V (overflow) flag and rsb won't set this flag
   // if input is positive.
-  __ rsb(input, input, Operand(0), SetCC, mi);
+  __ rsb(result, input, Operand(0), SetCC, mi);
   // Deoptimize on overflow.
   DeoptimizeIf(vs, instr->environment());
 }
 
 
 void LCodeGen::DoMathAbs(LUnaryMathOperation* instr) {
   // Class for deferred case.
   class DeferredMathAbsTaggedHeapNumber: public LDeferredCode {
    public:
     DeferredMathAbsTaggedHeapNumber(LCodeGen* codegen,
                                     LUnaryMathOperation* instr)
         : LDeferredCode(codegen), instr_(instr) { }
     virtual void Generate() {
       codegen()->DoDeferredMathAbsTaggedHeapNumber(instr_);
     }
    private:
     LUnaryMathOperation* instr_;
   };
 
-  ASSERT(instr->InputAt(0)->Equals(instr->result()));
   Representation r = instr->hydrogen()->value()->representation();
   if (r.IsDouble()) {
     DwVfpRegister input = ToDoubleRegister(instr->InputAt(0));
-    __ vabs(input, input);
+    DwVfpRegister result = ToDoubleRegister(instr->result());
+    __ vabs(result, input);
   } else if (r.IsInteger32()) {
     EmitIntegerMathAbs(instr);
   } else {
     // Representation is tagged.
     DeferredMathAbsTaggedHeapNumber* deferred =
         new DeferredMathAbsTaggedHeapNumber(this, instr);
     Register input = ToRegister(instr->InputAt(0));
     // Smi check.
     __ JumpIfNotSmi(input, deferred->entry());
     // If smi, handle it directly.
@@ skipping 57 matching lines @@
   }
 
   // The following conversion will not work with numbers
   // outside of ]-2^32, 2^32[.
   __ cmp(scratch2, Operand(HeapNumber::kExponentBias + 32));
   DeoptimizeIf(ge, instr->environment());
 
   // Save the original sign for later comparison.
   __ and_(scratch2, scratch1, Operand(HeapNumber::kSignMask));
 
-  __ vmov(double_scratch0(), 0.5);
+  __ Vmov(double_scratch0(), 0.5);
   __ vadd(input, input, double_scratch0());
 
   // Check sign of the result: if the sign changed, the input
   // value was in ]0.5, 0[ and the result should be -0.
   __ vmov(scratch1, input.high());
   __ eor(scratch1, scratch1, Operand(scratch2), SetCC);
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     DeoptimizeIf(mi, instr->environment());
   } else {
     __ mov(result, Operand(0), LeaveCC, mi);
@@ skipping 16 matching lines @@
     __ vmov(scratch1, input.high());
     __ tst(scratch1, Operand(HeapNumber::kSignMask));
     DeoptimizeIf(ne, instr->environment());
   }
   __ bind(&done);
 }
 
 
 void LCodeGen::DoMathSqrt(LUnaryMathOperation* instr) {
   DoubleRegister input = ToDoubleRegister(instr->InputAt(0));
-  ASSERT(ToDoubleRegister(instr->result()).is(input));
-  __ vsqrt(input, input);
+  DoubleRegister result = ToDoubleRegister(instr->result());
+  __ vsqrt(result, input);
 }
 
 
 void LCodeGen::DoMathPowHalf(LUnaryMathOperation* instr) {
   DoubleRegister input = ToDoubleRegister(instr->InputAt(0));
-  Register scratch = scratch0();
-  SwVfpRegister single_scratch = double_scratch0().low();
-  DoubleRegister double_scratch = double_scratch0();
-  ASSERT(ToDoubleRegister(instr->result()).is(input));
-
+  DoubleRegister result = ToDoubleRegister(instr->result());
   // Add +0 to convert -0 to +0.
-  __ mov(scratch, Operand(0));
-  __ vmov(single_scratch, scratch);
-  __ vcvt_f64_s32(double_scratch, single_scratch);
-  __ vadd(input, input, double_scratch);
-  __ vsqrt(input, input);
+  __ vadd(result, input, kDoubleRegZero);
+  __ vsqrt(result, result);
 }
 
 
 void LCodeGen::DoPower(LPower* instr) {
   LOperand* left = instr->InputAt(0);
   LOperand* right = instr->InputAt(1);
   Register scratch = scratch0();
   DoubleRegister result_reg = ToDoubleRegister(instr->result());
   Representation exponent_type = instr->hydrogen()->right()->representation();
   if (exponent_type.IsDouble()) {
@@ skipping 578 matching lines @@
   DeferredNumberTagI* deferred = new DeferredNumberTagI(this, instr);
   __ SmiTag(reg, SetCC);
   __ b(vs, deferred->entry());
   __ bind(deferred->exit());
 }
 
 
 void LCodeGen::DoDeferredNumberTagI(LNumberTagI* instr) {
   Label slow;
   Register reg = ToRegister(instr->InputAt(0));
-  DoubleRegister dbl_scratch = d0;
-  SwVfpRegister flt_scratch = s0;
+  DoubleRegister dbl_scratch = double_scratch0();
+  SwVfpRegister flt_scratch = dbl_scratch.low();
 
   // 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;
   __ SmiUntag(reg);
   __ eor(reg, reg, Operand(0x80000000));
@@ skipping 88 matching lines @@
     __ SmiUntag(ToRegister(input));
   }
 }
 
 
 void LCodeGen::EmitNumberUntagD(Register input_reg,
                                 DoubleRegister result_reg,
                                 bool deoptimize_on_undefined,
                                 LEnvironment* env) {
   Register scratch = scratch0();
-  SwVfpRegister flt_scratch = s0;
-  ASSERT(!result_reg.is(d0));
+  SwVfpRegister flt_scratch = double_scratch0().low();
+  ASSERT(!result_reg.is(double_scratch0()));
 
   Label load_smi, heap_number, done;
 
   // Smi check.
   __ JumpIfSmi(input_reg, &load_smi);
 
   // Heap number map check.
   __ ldr(scratch, FieldMemOperand(input_reg, HeapObject::kMapOffset));
   __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
   __ cmp(scratch, Operand(ip));
@@ skipping 724 matching lines @@
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 
 
 
 #undef __
 
 } }  // namespace v8::internal