MIPS: Use neg instruction in r6

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 dba1fae9759f0e323e72a23a443192cca9d9f6f9..95a0064f62715cbc55c0d3e01473297bfbec56ba 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -1915,8 +1915,6 @@ void MacroAssembler::Ins(Register rt,
 }
 
 void MacroAssembler::Neg_s(FPURegister fd, FPURegister fs) {
-  Register scratch1 = t8;
-  Register scratch2 = t9;
   if (IsMipsArchVariant(kMips32r2)) {
     Label is_nan, done;
     Register scratch1 = t8;
@@ -1926,7 +1924,6 @@ void MacroAssembler::Neg_s(FPURegister fd, FPURegister fs) {
     // 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));
@@ -1936,26 +1933,21 @@ void MacroAssembler::Neg_s(FPURegister fd, FPURegister fs) {
     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));
@@ -1965,13 +1957,8 @@ void MacroAssembler::Neg_d(FPURegister fd, FPURegister fs) {
     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);
   }
 }