MIPS: Optimise Math.floor(x/y) to use integer division for MIPS.

src/mips/lithium-mips.h

Index: src/mips/lithium-mips.h
diff --git a/src/mips/lithium-mips.h b/src/mips/lithium-mips.h
index 50feee0cb7e26477797f7a8e93534ced62bf662f..32db0dd43652096db87b511043463e0854098c6b 100644
--- a/src/mips/lithium-mips.h
+++ b/src/mips/lithium-mips.h
@@ -137,6 +137,7 @@ class LCodeGen;
   V(MathCos)                                    \
   V(MathExp)                                    \
   V(MathFloor)                                  \
+  V(MathFloorOfDiv)                             \
   V(MathLog)                                    \
   V(MathMinMax)                                 \
   V(MathPowHalf)                                \
@@ -623,6 +624,25 @@ class LDivI: public LTemplateInstruction<1, 2, 0> {
 };
 
 
+class LMathFloorOfDiv: public LTemplateInstruction<1, 2, 1> {
+ public:
+  LMathFloorOfDiv(LOperand* left,
+                  LOperand* right,
+                  LOperand* temp = NULL) {
+    inputs_[0] = left;
+    inputs_[1] = right;
+    temps_[0] = temp;
+  }
+
+  LOperand* left() { return inputs_[0]; }
+  LOperand* right() { return inputs_[1]; }
+  LOperand* temp() { return temps_[0]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(MathFloorOfDiv, "math-floor-of-div")
+  DECLARE_HYDROGEN_ACCESSOR(MathFloorOfDiv)
+};
+
+
 class LMulI: public LTemplateInstruction<1, 2, 1> {
  public:
   LMulI(LOperand* left, LOperand* right, LOperand* temp) {
@@ -2642,6 +2662,9 @@ class LChunkBuilder BASE_EMBEDDED {
 
   LInstruction* DoMultiplyAdd(HMul* mul, HValue* addend);
 
+  static bool HasMagicNumberForDivisor(int32_t divisor);
+  static HValue* SimplifiedDivisorForMathFloorOfDiv(HValue* val);
+
   LInstruction* DoMathFloor(HUnaryMathOperation* instr);
   LInstruction* DoMathRound(HUnaryMathOperation* instr);
   LInstruction* DoMathAbs(HUnaryMathOperation* instr);