MIPS: Use neg instruction in r6

src/mips/macro-assembler-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #if V8_TARGET_ARCH_MIPS
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
@@ skipping 1897 matching lines @@
     and_(t8, rs, at);
     sll(t8, t8, pos);
     sll(at, at, pos);
     nor(at, at, zero_reg);
     and_(at, rt, at);
     or_(rt, t8, at);
   }
 }
 
 void MacroAssembler::Neg_s(FPURegister fd, FPURegister fs) {
-  Register scratch1 = t8;
-  Register scratch2 = t9;
   if (IsMipsArchVariant(kMips32r2)) {
     Label is_nan, done;
     Register scratch1 = t8;
     Register scratch2 = t9;
     BranchF32(nullptr, &is_nan, eq, fs, fs);
     Branch(USE_DELAY_SLOT, &done);
     // For NaN input, neg_s will return the same NaN value,
     // while the sign has to be changed separately.
     neg_s(fd, fs);  // In delay slot.
-
     bind(&is_nan);
     mfc1(scratch1, fs);
     And(scratch2, scratch1, Operand(~kBinary32SignMask));
     And(scratch1, scratch1, Operand(kBinary32SignMask));
     Xor(scratch1, scratch1, Operand(kBinary32SignMask));
     Or(scratch2, scratch2, scratch1);
     mtc1(scratch2, fd);
     bind(&done);
   } else {
-    mfc1(scratch1, fs);
-    And(scratch2, scratch1, Operand(~kBinary32SignMask));
-    And(scratch1, scratch1, Operand(kBinary32SignMask));
-    Xor(scratch1, scratch1, Operand(kBinary32SignMask));
-    Or(scratch2, scratch2, scratch1);
-    mtc1(scratch2, fd);
+    // r6 neg_s changes the sign for NaN-like operands as well.
+    neg_s(fd, fs);
   }
 }
 
 void MacroAssembler::Neg_d(FPURegister fd, FPURegister fs) {
-  Register scratch1 = t8;
-  Register scratch2 = t9;
   if (IsMipsArchVariant(kMips32r2)) {
     Label is_nan, done;
+    Register scratch1 = t8;
+    Register scratch2 = t9;
     BranchF64(nullptr, &is_nan, eq, fs, fs);
     Branch(USE_DELAY_SLOT, &done);
     // For NaN input, neg_d will return the same NaN value,
     // while the sign has to be changed separately.
     neg_d(fd, fs);  // In delay slot.
-
     bind(&is_nan);
     Mfhc1(scratch1, fs);
     And(scratch2, scratch1, Operand(~HeapNumber::kSignMask));
     And(scratch1, scratch1, Operand(HeapNumber::kSignMask));
     Xor(scratch1, scratch1, Operand(HeapNumber::kSignMask));
     Or(scratch2, scratch2, scratch1);
     Mthc1(scratch2, fd);
     bind(&done);
   } else {
-    Move_d(fd, fs);
-    Mfhc1(scratch1, fs);
-    And(scratch2, scratch1, Operand(~HeapNumber::kSignMask));
-    And(scratch1, scratch1, Operand(HeapNumber::kSignMask));
-    Xor(scratch1, scratch1, Operand(HeapNumber::kSignMask));
-    Or(scratch2, scratch2, scratch1);
-    Mthc1(scratch2, fd);
+    // r6 neg_d changes the sign for NaN-like operands as well.
+    neg_d(fd, fs);
   }
 }
 
 void MacroAssembler::Cvt_d_uw(FPURegister fd, Register rs,
                               FPURegister scratch) {
   // In FP64Mode we do convertion from long.
   if (IsFp64Mode()) {
     mtc1(rs, scratch);
     Mthc1(zero_reg, scratch);
     cvt_d_l(fd, scratch);
@@ skipping 5006 matching lines @@
   if (mag.shift > 0) sra(result, result, mag.shift);
   srl(at, dividend, 31);
   Addu(result, result, Operand(at));
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS