Bug 1254500 - IonMonkey: MIPS: Implement ma_ctz. r=arai

---
 js/src/jit/mips-shared/MacroAssembler-mips-shared.cpp | 11 +++++++++++
 js/src/jit/mips-shared/MacroAssembler-mips-shared.h   |  2 ++
 2 files changed, 13 insertions(+)

js/src/jit/mips-shared/MacroAssembler-mips-shared.cpp

@@ -184,6 +184,17 @@ MacroAssemblerMIPSShared::ma_xor(Register rd, Register rs, Imm32 imm)
     }
 }
 
+void
+MacroAssemblerMIPSShared::ma_ctz(Register rd, Register rs)
+{
+    ma_negu(ScratchRegister, rs);
+    as_and(rd, ScratchRegister, rs);
+    as_clz(rd, rd);
+    ma_negu(SecondScratchReg, rd);
+    ma_addu(SecondScratchReg, Imm32(0x1f));
+    as_movn(rd, SecondScratchReg, ScratchRegister);
+}
+
 // Arithmetic-based ops.
 
 // Add.

js/src/jit/mips-shared/MacroAssembler-mips-shared.h

@@ -99,6 +99,8 @@ class MacroAssemblerMIPSShared : public Assembler
     void ma_xor(Register rd, Imm32 imm);
     void ma_xor(Register rd, Register rs, Imm32 imm);
 
+    void ma_ctz(Register rd, Register rs);
+
     // load
     void ma_load(Register dest, const BaseIndex& src, LoadStoreSize size = SizeWord,
                  LoadStoreExtension extension = SignExtend);