Bug 1290812 - Part 26: Implement the 64bit variant of Sub on mips32. r=lth

---
 js/src/jit/MacroAssembler.h                   |  4 ++--
 js/src/jit/mips32/MacroAssembler-mips32-inl.h | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

js/src/jit/MacroAssembler.h

@@ -780,8 +780,8 @@ class MacroAssembler : public MacroAssemblerSpecific
     inline void subPtr(ImmWord imm, Register dest) DEFINED_ON(x64);
     inline void subPtr(const Address& addr, Register dest) DEFINED_ON(mips_shared, arm, arm64, x86, x64);
 
-    inline void sub64(Register64 src, Register64 dest) DEFINED_ON(x86, x64, arm, mips64);
-    inline void sub64(Imm64 imm, Register64 dest) DEFINED_ON(x86, x64, arm, mips64);
+    inline void sub64(Register64 src, Register64 dest) DEFINED_ON(x86, x64, arm, mips32, mips64);
+    inline void sub64(Imm64 imm, Register64 dest) DEFINED_ON(x86, x64, arm, mips32, mips64);
     inline void sub64(const Operand& src, Register64 dest) DEFINED_ON(x64, mips64);
 
     inline void subFloat32(FloatRegister src, FloatRegister dest) PER_SHARED_ARCH;

js/src/jit/mips32/MacroAssembler-mips32-inl.h

@@ -175,6 +175,25 @@ MacroAssembler::subPtr(Imm32 imm, Register dest)
     ma_subu(dest, dest, imm);
 }
 
+void
+MacroAssembler::sub64(Register64 src, Register64 dest)
+{
+    as_sltu(ScratchRegister, dest.low, src.low);
+    as_subu(dest.high, dest.high, ScratchRegister);
+    as_subu(dest.low, dest.low, src.low);
+    as_subu(dest.high, dest.high, src.high);
+}
+
+void
+MacroAssembler::sub64(Imm64 imm, Register64 dest)
+{
+    ma_li(ScratchRegister, imm.low());
+    as_sltu(ScratchRegister, dest.low, ScratchRegister);
+    as_subu(dest.high, dest.high, ScratchRegister);
+    ma_subu(dest.low, dest.low, imm.low());
+    ma_subu(dest.high, dest.high, imm.hi());
+}
+
 void
 MacroAssembler::mul64(Imm64 imm, const Register64& dest)
 {