MIPS: Improve TruncateNumberToI implementation after DoubleToIStub usage (r16461).

src/mips/macro-assembler-mips.cc

Index: src/mips/macro-assembler-mips.cc
diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index cd1d38ee34bab0dfaaa5b155f46d7eecf61a324e..a85b0d803441b655e287e14ff66abe16e4b4712d 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -1298,60 +1298,6 @@ void MacroAssembler::Clz(Register rd, Register rs) {
 }
 
 
-// Tries to get a signed int32 out of a double precision floating point heap
-// number. Rounds towards 0. Branch to 'not_int32' if the double is out of the
-// 32bits signed integer range.
-// This method implementation differs from the ARM version for performance
-// reasons.
-void MacroAssembler::ConvertToInt32(Register source,
-                                    Register dest,
-                                    Register scratch,
-                                    Register scratch2,
-                                    FPURegister double_scratch,
-                                    Label *not_int32) {
-  Label right_exponent, done;
-  // Get exponent word (ENDIAN issues).
-  lw(scratch, FieldMemOperand(source, HeapNumber::kExponentOffset));
-  // Get exponent alone in scratch2.
-  And(scratch2, scratch, Operand(HeapNumber::kExponentMask));
-  // Load dest with zero.  We use this either for the final shift or
-  // for the answer.
-  mov(dest, zero_reg);
-  // Check whether the exponent matches a 32 bit signed int that is not a Smi.
-  // A non-Smi integer is 1.xxx * 2^30 so the exponent is 30 (biased).  This is
-  // the exponent that we are fastest at and also the highest exponent we can
-  // handle here.
-  const uint32_t non_smi_exponent =
-      (HeapNumber::kExponentBias + 30) << HeapNumber::kExponentShift;
-  // If we have a match of the int32-but-not-Smi exponent then skip some logic.
-  Branch(&right_exponent, eq, scratch2, Operand(non_smi_exponent));
-  // If the exponent is higher than that then go to not_int32 case.  This
-  // catches numbers that don't fit in a signed int32, infinities and NaNs.
-  Branch(not_int32, gt, scratch2, Operand(non_smi_exponent));
-
-  // We know the exponent is smaller than 30 (biased).  If it is less than
-  // 0 (biased) then the number is smaller in magnitude than 1.0 * 2^0, i.e.
-  // it rounds to zero.
-  const uint32_t zero_exponent =
-      (HeapNumber::kExponentBias + 0) << HeapNumber::kExponentShift;
-  Subu(scratch2, scratch2, Operand(zero_exponent));
-  // Dest already has a Smi zero.
-  Branch(&done, lt, scratch2, Operand(zero_reg));
-  bind(&right_exponent);
-
-  // MIPS FPU instructions implementing double precision to integer
-  // conversion using round to zero. Since the FP value was qualified
-  // above, the resulting integer should be a legal int32.
-  // The original 'Exponent' word is still in scratch.
-  lwc1(double_scratch, FieldMemOperand(source, HeapNumber::kMantissaOffset));
-  mtc1(scratch, FPURegister::from_code(double_scratch.code() + 1));
-  trunc_w_d(double_scratch, double_scratch);
-  mfc1(dest, double_scratch);
-
-  bind(&done);
-}
-
-
 void MacroAssembler::EmitFPUTruncate(FPURoundingMode rounding_mode,
                                      Register result,
                                      DoubleRegister double_input,
@@ -1416,88 +1362,6 @@ void MacroAssembler::EmitFPUTruncate(FPURoundingMode rounding_mode,
 }
 
 
-void MacroAssembler::EmitOutOfInt32RangeTruncate(Register result,
-                                                 Register input_high,
-                                                 Register input_low,
-                                                 Register scratch) {
-  Label done, normal_exponent, restore_sign;
-  // Extract the biased exponent in result.
-  Ext(result,
-      input_high,
-      HeapNumber::kExponentShift,
-      HeapNumber::kExponentBits);
-
-  // Check for Infinity and NaNs, which should return 0.
-  Subu(scratch, result, HeapNumber::kExponentMask);
-  Movz(result, zero_reg, scratch);
-  Branch(&done, eq, scratch, Operand(zero_reg));
-
-  // Express exponent as delta to (number of mantissa bits + 31).
-  Subu(result,
-       result,
-       Operand(HeapNumber::kExponentBias + HeapNumber::kMantissaBits + 31));
-
-  // If the delta is strictly positive, all bits would be shifted away,
-  // which means that we can return 0.
-  Branch(&normal_exponent, le, result, Operand(zero_reg));
-  mov(result, zero_reg);
-  Branch(&done);
-
-  bind(&normal_exponent);
-  const int kShiftBase = HeapNumber::kNonMantissaBitsInTopWord - 1;
-  // Calculate shift.
-  Addu(scratch, result, Operand(kShiftBase + HeapNumber::kMantissaBits));
-
-  // Save the sign.
-  Register sign = result;
-  result = no_reg;
-  And(sign, input_high, Operand(HeapNumber::kSignMask));
-
-  // On ARM shifts > 31 bits are valid and will result in zero. On MIPS we need
-  // to check for this specific case.
-  Label high_shift_needed, high_shift_done;
-  Branch(&high_shift_needed, lt, scratch, Operand(32));
-  mov(input_high, zero_reg);
-  Branch(&high_shift_done);
-  bind(&high_shift_needed);
-
-  // Set the implicit 1 before the mantissa part in input_high.
-  Or(input_high,
-     input_high,
-     Operand(1 << HeapNumber::kMantissaBitsInTopWord));
-  // Shift the mantissa bits to the correct position.
-  // We don't need to clear non-mantissa bits as they will be shifted away.
-  // If they weren't, it would mean that the answer is in the 32bit range.
-  sllv(input_high, input_high, scratch);
-
-  bind(&high_shift_done);
-
-  // Replace the shifted bits with bits from the lower mantissa word.
-  Label pos_shift, shift_done;
-  li(at, 32);
-  subu(scratch, at, scratch);
-  Branch(&pos_shift, ge, scratch, Operand(zero_reg));
-
-  // Negate scratch.
-  Subu(scratch, zero_reg, scratch);
-  sllv(input_low, input_low, scratch);
-  Branch(&shift_done);
-
-  bind(&pos_shift);
-  srlv(input_low, input_low, scratch);
-
-  bind(&shift_done);
-  Or(input_high, input_high, Operand(input_low));
-  // Restore sign if necessary.
-  mov(scratch, sign);
-  result = sign;
-  sign = no_reg;
-  Subu(result, zero_reg, input_high);
-  Movz(result, input_high, scratch);
-  bind(&done);
-}
-
-
 void MacroAssembler::TryInlineTruncateDoubleToI(Register result,
                                                 DoubleRegister double_input,
                                                 Label* done) {
@@ -1570,31 +1434,14 @@ void MacroAssembler::TruncateHeapNumberToI(Register result, Register object) {
 void MacroAssembler::TruncateNumberToI(Register object,
                                        Register result,
                                        Register heap_number_map,
-                                       Register scratch1,
-                                       Register scratch2,
-                                       Register scratch3,
+                                       Register scratch,
                                        Label* not_number) {
   Label done;
-  Label not_in_int32_range;
-  DoubleRegister double_scratch = f12;
+  ASSERT(!result.is(object));
 
   UntagAndJumpIfSmi(result, object, &done);
-  JumpIfNotHeapNumber(object, heap_number_map, scratch1, not_number);
-  ConvertToInt32(object,
-                 result,
-                 scratch1,
-                 scratch2,
-                 double_scratch,
-                 &not_in_int32_range);
-  jmp(&done);
-
-  bind(&not_in_int32_range);
-  lw(scratch1, FieldMemOperand(object, HeapNumber::kExponentOffset));
-  lw(scratch2, FieldMemOperand(object, HeapNumber::kMantissaOffset));
-  EmitOutOfInt32RangeTruncate(result,
-                              scratch1,
-                              scratch2,
-                              scratch3);
+  JumpIfNotHeapNumber(object, heap_number_map, scratch, not_number);
+  TruncateHeapNumberToI(result, object);
 
   bind(&done);
 }