Truncate rather than round to nearest when performing float-to-integer...

src/arm/ic-arm.cc

Index: src/arm/ic-arm.cc
===================================================================
--- src/arm/ic-arm.cc	(revision 6336)
+++ src/arm/ic-arm.cc	(working copy)
@@ -1369,275 +1369,6 @@
 }
 
 
-void KeyedLoadIC::GenerateExternalArray(MacroAssembler* masm,
-                                        ExternalArrayType array_type) {
-  // ---------- S t a t e --------------
-  //  -- lr     : return address
-  //  -- r0     : key
-  //  -- r1     : receiver
-  // -----------------------------------
-  Label slow, failed_allocation;
-
-  Register key = r0;
-  Register receiver = r1;
-
-  // Check that the object isn't a smi
-  __ BranchOnSmi(receiver, &slow);
-
-  // Check that the key is a smi.
-  __ BranchOnNotSmi(key, &slow);
-
-  // Check that the object is a JS object. Load map into r2.
-  __ CompareObjectType(receiver, r2, r3, FIRST_JS_OBJECT_TYPE);
-  __ b(lt, &slow);
-
-  // Check that the receiver does not require access checks.  We need
-  // to check this explicitly since this generic stub does not perform
-  // map checks.
-  __ ldrb(r3, FieldMemOperand(r2, Map::kBitFieldOffset));
-  __ tst(r3, Operand(1 << Map::kIsAccessCheckNeeded));
-  __ b(ne, &slow);
-
-  // Check that the elements array is the appropriate type of
-  // ExternalArray.
-  __ ldr(r3, FieldMemOperand(receiver, JSObject::kElementsOffset));
-  __ ldr(r2, FieldMemOperand(r3, HeapObject::kMapOffset));
-  __ LoadRoot(ip, Heap::RootIndexForExternalArrayType(array_type));
-  __ cmp(r2, ip);
-  __ b(ne, &slow);
-
-  // Check that the index is in range.
-  __ ldr(ip, FieldMemOperand(r3, ExternalArray::kLengthOffset));
-  __ cmp(ip, Operand(key, ASR, kSmiTagSize));
-  // Unsigned comparison catches both negative and too-large values.
-  __ b(lo, &slow);
-
-  // r3: elements array
-  __ ldr(r3, FieldMemOperand(r3, ExternalArray::kExternalPointerOffset));
-  // r3: base pointer of external storage
-
-  // We are not untagging smi key and instead work with it
-  // as if it was premultiplied by 2.
-  ASSERT((kSmiTag == 0) && (kSmiTagSize == 1));
-
-  Register value = r2;
-  switch (array_type) {
-    case kExternalByteArray:
-      __ ldrsb(value, MemOperand(r3, key, LSR, 1));
-      break;
-    case kExternalUnsignedByteArray:
-      __ ldrb(value, MemOperand(r3, key, LSR, 1));
-      break;
-    case kExternalShortArray:
-      __ ldrsh(value, MemOperand(r3, key, LSL, 0));
-      break;
-    case kExternalUnsignedShortArray:
-      __ ldrh(value, MemOperand(r3, key, LSL, 0));
-      break;
-    case kExternalIntArray:
-    case kExternalUnsignedIntArray:
-      __ ldr(value, MemOperand(r3, key, LSL, 1));
-      break;
-    case kExternalFloatArray:
-      if (CpuFeatures::IsSupported(VFP3)) {
-        CpuFeatures::Scope scope(VFP3);
-        __ add(r2, r3, Operand(key, LSL, 1));
-        __ vldr(s0, r2, 0);
-      } else {
-        __ ldr(value, MemOperand(r3, key, LSL, 1));
-      }
-      break;
-    default:
-      UNREACHABLE();
-      break;
-  }
-
-  // For integer array types:
-  // r2: value
-  // For floating-point array type
-  // s0: value (if VFP3 is supported)
-  // r2: value (if VFP3 is not supported)
-
-  if (array_type == kExternalIntArray) {
-    // For the Int and UnsignedInt array types, we need to see whether
-    // the value can be represented in a Smi. If not, we need to convert
-    // it to a HeapNumber.
-    Label box_int;
-    __ cmp(value, Operand(0xC0000000));
-    __ b(mi, &box_int);
-    // Tag integer as smi and return it.
-    __ mov(r0, Operand(value, LSL, kSmiTagSize));
-    __ Ret();
-
-    __ bind(&box_int);
-    // Allocate a HeapNumber for the result and perform int-to-double
-    // conversion.  Don't touch r0 or r1 as they are needed if allocation
-    // fails.
-    __ LoadRoot(r6, Heap::kHeapNumberMapRootIndex);
-    __ AllocateHeapNumber(r5, r3, r4, r6, &slow);
-    // Now we can use r0 for the result as key is not needed any more.
-    __ mov(r0, r5);
-
-    if (CpuFeatures::IsSupported(VFP3)) {
-      CpuFeatures::Scope scope(VFP3);
-      __ vmov(s0, value);
-      __ vcvt_f64_s32(d0, s0);
-      __ sub(r3, r0, Operand(kHeapObjectTag));
-      __ vstr(d0, r3, HeapNumber::kValueOffset);
-      __ Ret();
-    } else {
-      WriteInt32ToHeapNumberStub stub(value, r0, r3);
-      __ TailCallStub(&stub);
-    }
-  } else if (array_type == kExternalUnsignedIntArray) {
-    // The test is different for unsigned int values. Since we need
-    // the value to be in the range of a positive smi, we can't
-    // handle either of the top two bits being set in the value.
-    if (CpuFeatures::IsSupported(VFP3)) {
-      CpuFeatures::Scope scope(VFP3);
-      Label box_int, done;
-      __ tst(value, Operand(0xC0000000));
-      __ b(ne, &box_int);
-      // Tag integer as smi and return it.
-      __ mov(r0, Operand(value, LSL, kSmiTagSize));
-      __ Ret();
-
-      __ bind(&box_int);
-      __ vmov(s0, value);
-      // Allocate a HeapNumber for the result and perform int-to-double
-      // conversion. Don't use r0 and r1 as AllocateHeapNumber clobbers all
-      // registers - also when jumping due to exhausted young space.
-      __ LoadRoot(r6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(r2, r3, r4, r6, &slow);
-
-      __ vcvt_f64_u32(d0, s0);
-      __ sub(r1, r2, Operand(kHeapObjectTag));
-      __ vstr(d0, r1, HeapNumber::kValueOffset);
-
-      __ mov(r0, r2);
-      __ Ret();
-    } else {
-      // Check whether unsigned integer fits into smi.
-      Label box_int_0, box_int_1, done;
-      __ tst(value, Operand(0x80000000));
-      __ b(ne, &box_int_0);
-      __ tst(value, Operand(0x40000000));
-      __ b(ne, &box_int_1);
-      // Tag integer as smi and return it.
-      __ mov(r0, Operand(value, LSL, kSmiTagSize));
-      __ Ret();
-
-      Register hiword = value;  // r2.
-      Register loword = r3;
-
-      __ bind(&box_int_0);
-      // Integer does not have leading zeros.
-      GenerateUInt2Double(masm, hiword, loword, r4, 0);
-      __ b(&done);
-
-      __ bind(&box_int_1);
-      // Integer has one leading zero.
-      GenerateUInt2Double(masm, hiword, loword, r4, 1);
-
-
-      __ bind(&done);
-      // Integer was converted to double in registers hiword:loword.
-      // Wrap it into a HeapNumber. Don't use r0 and r1 as AllocateHeapNumber
-      // clobbers all registers - also when jumping due to exhausted young
-      // space.
-      __ LoadRoot(r6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(r4, r5, r7, r6, &slow);
-
-      __ str(hiword, FieldMemOperand(r4, HeapNumber::kExponentOffset));
-      __ str(loword, FieldMemOperand(r4, HeapNumber::kMantissaOffset));
-
-      __ mov(r0, r4);
-      __ Ret();
-    }
-  } else if (array_type == kExternalFloatArray) {
-    // For the floating-point array type, we need to always allocate a
-    // HeapNumber.
-    if (CpuFeatures::IsSupported(VFP3)) {
-      CpuFeatures::Scope scope(VFP3);
-      // Allocate a HeapNumber for the result. Don't use r0 and r1 as
-      // AllocateHeapNumber clobbers all registers - also when jumping due to
-      // exhausted young space.
-      __ LoadRoot(r6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(r2, r3, r4, r6, &slow);
-      __ vcvt_f64_f32(d0, s0);
-      __ sub(r1, r2, Operand(kHeapObjectTag));
-      __ vstr(d0, r1, HeapNumber::kValueOffset);
-
-      __ mov(r0, r2);
-      __ Ret();
-    } else {
-      // Allocate a HeapNumber for the result. Don't use r0 and r1 as
-      // AllocateHeapNumber clobbers all registers - also when jumping due to
-      // exhausted young space.
-      __ LoadRoot(r6, Heap::kHeapNumberMapRootIndex);
-      __ AllocateHeapNumber(r3, r4, r5, r6, &slow);
-      // VFP is not available, do manual single to double conversion.
-
-      // r2: floating point value (binary32)
-      // r3: heap number for result
-
-      // Extract mantissa to r0. OK to clobber r0 now as there are no jumps to
-      // the slow case from here.
-      __ and_(r0, value, Operand(kBinary32MantissaMask));
-
-      // Extract exponent to r1. OK to clobber r1 now as there are no jumps to
-      // the slow case from here.
-      __ mov(r1, Operand(value, LSR, kBinary32MantissaBits));
-      __ and_(r1, r1, Operand(kBinary32ExponentMask >> kBinary32MantissaBits));
-
-      Label exponent_rebiased;
-      __ teq(r1, Operand(0x00, RelocInfo::NONE));
-      __ b(eq, &exponent_rebiased);
-
-      __ teq(r1, Operand(0xff));
-      __ mov(r1, Operand(0x7ff), LeaveCC, eq);
-      __ b(eq, &exponent_rebiased);
-
-      // Rebias exponent.
-      __ add(r1,
-             r1,
-             Operand(-kBinary32ExponentBias + HeapNumber::kExponentBias));
-
-      __ bind(&exponent_rebiased);
-      __ and_(r2, value, Operand(kBinary32SignMask));
-      value = no_reg;
-      __ orr(r2, r2, Operand(r1, LSL, HeapNumber::kMantissaBitsInTopWord));
-
-      // Shift mantissa.
-      static const int kMantissaShiftForHiWord =
-          kBinary32MantissaBits - HeapNumber::kMantissaBitsInTopWord;
-
-      static const int kMantissaShiftForLoWord =
-          kBitsPerInt - kMantissaShiftForHiWord;
-
-      __ orr(r2, r2, Operand(r0, LSR, kMantissaShiftForHiWord));
-      __ mov(r0, Operand(r0, LSL, kMantissaShiftForLoWord));
-
-      __ str(r2, FieldMemOperand(r3, HeapNumber::kExponentOffset));
-      __ str(r0, FieldMemOperand(r3, HeapNumber::kMantissaOffset));
-
-      __ mov(r0, r3);
-      __ Ret();
-    }
-
-  } else {
-    // Tag integer as smi and return it.
-    __ mov(r0, Operand(value, LSL, kSmiTagSize));
-    __ Ret();
-  }
-
-  // Slow case, key and receiver still in r0 and r1.
-  __ bind(&slow);
-  __ IncrementCounter(&Counters::keyed_load_external_array_slow, 1, r2, r3);
-  GenerateRuntimeGetProperty(masm);
-}
-
-
 void KeyedLoadIC::GenerateIndexedInterceptor(MacroAssembler* masm) {
   // ---------- S t a t e --------------
   //  -- lr     : return address
@@ -1904,314 +1635,6 @@
 }
 
 
-static bool IsElementTypeSigned(ExternalArrayType array_type) {
-  switch (array_type) {
-    case kExternalByteArray:
-    case kExternalShortArray:
-    case kExternalIntArray:
-      return true;
-
-    case kExternalUnsignedByteArray:
-    case kExternalUnsignedShortArray:
-    case kExternalUnsignedIntArray:
-      return false;
-
-    default:
-      UNREACHABLE();
-      return false;
-  }
-}
-
-
-void KeyedStoreIC::GenerateExternalArray(MacroAssembler* masm,
-                                         ExternalArrayType array_type) {
-  // ---------- S t a t e --------------
-  //  -- r0     : value
-  //  -- r1     : key
-  //  -- r2     : receiver
-  //  -- lr     : return address
-  // -----------------------------------
-  Label slow, check_heap_number;
-
-  // Register usage.
-  Register value = r0;
-  Register key = r1;
-  Register receiver = r2;
-  // r3 mostly holds the elements array or the destination external array.
-
-  // Check that the object isn't a smi.
-  __ BranchOnSmi(receiver, &slow);
-
-  // Check that the object is a JS object. Load map into r3.
-  __ CompareObjectType(receiver, r3, r4, FIRST_JS_OBJECT_TYPE);
-  __ b(le, &slow);
-
-  // Check that the receiver does not require access checks.  We need
-  // to do this because this generic stub does not perform map checks.
-  __ ldrb(ip, FieldMemOperand(r3, Map::kBitFieldOffset));
-  __ tst(ip, Operand(1 << Map::kIsAccessCheckNeeded));
-  __ b(ne, &slow);
-
-  // Check that the key is a smi.
-  __ BranchOnNotSmi(key, &slow);
-
-  // Check that the elements array is the appropriate type of ExternalArray.
-  __ ldr(r3, FieldMemOperand(receiver, JSObject::kElementsOffset));
-  __ ldr(r4, FieldMemOperand(r3, HeapObject::kMapOffset));
-  __ LoadRoot(ip, Heap::RootIndexForExternalArrayType(array_type));
-  __ cmp(r4, ip);
-  __ b(ne, &slow);
-
-  // Check that the index is in range.
-  __ mov(r4, Operand(key, ASR, kSmiTagSize));  // Untag the index.
-  __ ldr(ip, FieldMemOperand(r3, ExternalArray::kLengthOffset));
-  __ cmp(r4, ip);
-  // Unsigned comparison catches both negative and too-large values.
-  __ b(hs, &slow);
-
-  // Handle both smis and HeapNumbers in the fast path. Go to the
-  // runtime for all other kinds of values.
-  // r3: external array.
-  // r4: key (integer).
-  __ BranchOnNotSmi(value, &check_heap_number);
-  __ mov(r5, Operand(value, ASR, kSmiTagSize));  // Untag the value.
-  __ ldr(r3, FieldMemOperand(r3, ExternalArray::kExternalPointerOffset));
-
-  // r3: base pointer of external storage.
-  // r4: key (integer).
-  // r5: value (integer).
-  switch (array_type) {
-    case kExternalByteArray:
-    case kExternalUnsignedByteArray:
-      __ strb(r5, MemOperand(r3, r4, LSL, 0));
-      break;
-    case kExternalShortArray:
-    case kExternalUnsignedShortArray:
-      __ strh(r5, MemOperand(r3, r4, LSL, 1));
-      break;
-    case kExternalIntArray:
-    case kExternalUnsignedIntArray:
-      __ str(r5, MemOperand(r3, r4, LSL, 2));
-      break;
-    case kExternalFloatArray:
-      // Perform int-to-float conversion and store to memory.
-      StoreIntAsFloat(masm, r3, r4, r5, r6, r7, r9);
-      break;
-    default:
-      UNREACHABLE();
-      break;
-  }
-
-  // Entry registers are intact, r0 holds the value which is the return value.
-  __ Ret();
-
-
-  // r3: external array.
-  // r4: index (integer).
-  __ bind(&check_heap_number);
-  __ CompareObjectType(value, r5, r6, HEAP_NUMBER_TYPE);
-  __ b(ne, &slow);
-
-  __ ldr(r3, FieldMemOperand(r3, ExternalArray::kExternalPointerOffset));
-
-  // r3: base pointer of external storage.
-  // r4: key (integer).
-
-  // The WebGL specification leaves the behavior of storing NaN and
-  // +/-Infinity into integer arrays basically undefined. For more
-  // reproducible behavior, convert these to zero.
-  if (CpuFeatures::IsSupported(VFP3)) {
-    CpuFeatures::Scope scope(VFP3);
-
-
-    if (array_type == kExternalFloatArray) {
-      // vldr requires offset to be a multiple of 4 so we can not
-      // include -kHeapObjectTag into it.
-      __ sub(r5, r0, Operand(kHeapObjectTag));
-      __ vldr(d0, r5, HeapNumber::kValueOffset);
-      __ add(r5, r3, Operand(r4, LSL, 2));
-      __ vcvt_f32_f64(s0, d0);
-      __ vstr(s0, r5, 0);
-    } else {
-      // Need to perform float-to-int conversion.
-      // Test for NaN or infinity (both give zero).
-      __ ldr(r6, FieldMemOperand(r5, HeapNumber::kExponentOffset));
-
-      // Hoisted load.  vldr requires offset to be a multiple of 4 so we can not
-      // include -kHeapObjectTag into it.
-      __ sub(r5, r0, Operand(kHeapObjectTag));
-      __ vldr(d0, r5, HeapNumber::kValueOffset);
-
-      __ Sbfx(r6, r6, HeapNumber::kExponentShift, HeapNumber::kExponentBits);
-      // NaNs and Infinities have all-one exponents so they sign extend to -1.
-      __ cmp(r6, Operand(-1));
-      __ mov(r5, Operand(Smi::FromInt(0)), LeaveCC, eq);
-
-      // Not infinity or NaN simply convert to int.
-      if (IsElementTypeSigned(array_type)) {
-        __ vcvt_s32_f64(s0, d0, Assembler::RoundToZero, ne);
-      } else {
-        __ vcvt_u32_f64(s0, d0, Assembler::RoundToZero, ne);
-      }
-      __ vmov(r5, s0, ne);
-
-      switch (array_type) {
-        case kExternalByteArray:
-        case kExternalUnsignedByteArray:
-          __ strb(r5, MemOperand(r3, r4, LSL, 0));
-          break;
-        case kExternalShortArray:
-        case kExternalUnsignedShortArray:
-          __ strh(r5, MemOperand(r3, r4, LSL, 1));
-          break;
-        case kExternalIntArray:
-        case kExternalUnsignedIntArray:
-          __ str(r5, MemOperand(r3, r4, LSL, 2));
-          break;
-        default:
-          UNREACHABLE();
-          break;
-      }
-    }
-
-    // Entry registers are intact, r0 holds the value which is the return value.
-    __ Ret();
-  } else {
-    // VFP3 is not available do manual conversions.
-    __ ldr(r5, FieldMemOperand(value, HeapNumber::kExponentOffset));
-    __ ldr(r6, FieldMemOperand(value, HeapNumber::kMantissaOffset));
-
-    if (array_type == kExternalFloatArray) {
-      Label done, nan_or_infinity_or_zero;
-      static const int kMantissaInHiWordShift =
-          kBinary32MantissaBits - HeapNumber::kMantissaBitsInTopWord;
-
-      static const int kMantissaInLoWordShift =
-          kBitsPerInt - kMantissaInHiWordShift;
-
-      // Test for all special exponent values: zeros, subnormal numbers, NaNs
-      // and infinities. All these should be converted to 0.
-      __ mov(r7, Operand(HeapNumber::kExponentMask));
-      __ and_(r9, r5, Operand(r7), SetCC);
-      __ b(eq, &nan_or_infinity_or_zero);
-
-      __ teq(r9, Operand(r7));
-      __ mov(r9, Operand(kBinary32ExponentMask), LeaveCC, eq);
-      __ b(eq, &nan_or_infinity_or_zero);
-
-      // Rebias exponent.
-      __ mov(r9, Operand(r9, LSR, HeapNumber::kExponentShift));
-      __ add(r9,
-             r9,
-             Operand(kBinary32ExponentBias - HeapNumber::kExponentBias));
-
-      __ cmp(r9, Operand(kBinary32MaxExponent));
-      __ and_(r5, r5, Operand(HeapNumber::kSignMask), LeaveCC, gt);
-      __ orr(r5, r5, Operand(kBinary32ExponentMask), LeaveCC, gt);
-      __ b(gt, &done);
-
-      __ cmp(r9, Operand(kBinary32MinExponent));
-      __ and_(r5, r5, Operand(HeapNumber::kSignMask), LeaveCC, lt);
-      __ b(lt, &done);
-
-      __ and_(r7, r5, Operand(HeapNumber::kSignMask));
-      __ and_(r5, r5, Operand(HeapNumber::kMantissaMask));
-      __ orr(r7, r7, Operand(r5, LSL, kMantissaInHiWordShift));
-      __ orr(r7, r7, Operand(r6, LSR, kMantissaInLoWordShift));
-      __ orr(r5, r7, Operand(r9, LSL, kBinary32ExponentShift));
-
-      __ bind(&done);
-      __ str(r5, MemOperand(r3, r4, LSL, 2));
-      // Entry registers are intact, r0 holds the value which is the return
-      // value.
-      __ Ret();
-
-      __ bind(&nan_or_infinity_or_zero);
-      __ and_(r7, r5, Operand(HeapNumber::kSignMask));
-      __ and_(r5, r5, Operand(HeapNumber::kMantissaMask));
-      __ orr(r9, r9, r7);
-      __ orr(r9, r9, Operand(r5, LSL, kMantissaInHiWordShift));
-      __ orr(r5, r9, Operand(r6, LSR, kMantissaInLoWordShift));
-      __ b(&done);
-    } else {
-      bool is_signed_type = IsElementTypeSigned(array_type);
-      int meaningfull_bits = is_signed_type ? (kBitsPerInt - 1) : kBitsPerInt;
-      int32_t min_value = is_signed_type ? 0x80000000 : 0x00000000;
-
-      Label done, sign;
-
-      // Test for all special exponent values: zeros, subnormal numbers, NaNs
-      // and infinities. All these should be converted to 0.
-      __ mov(r7, Operand(HeapNumber::kExponentMask));
-      __ and_(r9, r5, Operand(r7), SetCC);
-      __ mov(r5, Operand(0, RelocInfo::NONE), LeaveCC, eq);
-      __ b(eq, &done);
-
-      __ teq(r9, Operand(r7));
-      __ mov(r5, Operand(0, RelocInfo::NONE), LeaveCC, eq);
-      __ b(eq, &done);
-
-      // Unbias exponent.
-      __ mov(r9, Operand(r9, LSR, HeapNumber::kExponentShift));
-      __ sub(r9, r9, Operand(HeapNumber::kExponentBias), SetCC);
-      // If exponent is negative than result is 0.
-      __ mov(r5, Operand(0, RelocInfo::NONE), LeaveCC, mi);
-      __ b(mi, &done);
-
-      // If exponent is too big than result is minimal value.
-      __ cmp(r9, Operand(meaningfull_bits - 1));
-      __ mov(r5, Operand(min_value), LeaveCC, ge);
-      __ b(ge, &done);
-
-      __ and_(r7, r5, Operand(HeapNumber::kSignMask), SetCC);
-      __ and_(r5, r5, Operand(HeapNumber::kMantissaMask));
-      __ orr(r5, r5, Operand(1u << HeapNumber::kMantissaBitsInTopWord));
-
-      __ rsb(r9, r9, Operand(HeapNumber::kMantissaBitsInTopWord), SetCC);
-      __ mov(r5, Operand(r5, LSR, r9), LeaveCC, pl);
-      __ b(pl, &sign);
-
-      __ rsb(r9, r9, Operand(0, RelocInfo::NONE));
-      __ mov(r5, Operand(r5, LSL, r9));
-      __ rsb(r9, r9, Operand(meaningfull_bits));
-      __ orr(r5, r5, Operand(r6, LSR, r9));
-
-      __ bind(&sign);
-      __ teq(r7, Operand(0, RelocInfo::NONE));
-      __ rsb(r5, r5, Operand(0, RelocInfo::NONE), LeaveCC, ne);
-
-      __ bind(&done);
-      switch (array_type) {
-        case kExternalByteArray:
-        case kExternalUnsignedByteArray:
-          __ strb(r5, MemOperand(r3, r4, LSL, 0));
-          break;
-        case kExternalShortArray:
-        case kExternalUnsignedShortArray:
-          __ strh(r5, MemOperand(r3, r4, LSL, 1));
-          break;
-        case kExternalIntArray:
-        case kExternalUnsignedIntArray:
-          __ str(r5, MemOperand(r3, r4, LSL, 2));
-          break;
-        default:
-          UNREACHABLE();
-          break;
-      }
-    }
-  }
-
-  // Slow case: call runtime.
-  __ bind(&slow);
-
-  // Entry registers are intact.
-  // r0: value
-  // r1: key
-  // r2: receiver
-  GenerateRuntimeSetProperty(masm);
-}
-
-
 void StoreIC::GenerateMegamorphic(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- r0    : value