Bug 1123064 - IonMonkey: Fold constant numbers in MToInt32, r=h4writer

js/src/jit-test/tests/ion/bug1123064.js

@@ -0,0 +1,30 @@
+
+
+function toint32() {
+
+    // The test case to trigger MToInt32 operation.
+    var ToInteger = getSelfHostedValue("ToInteger");
+
+    // Case1: The input operand is constant int32.
+    var result = ToInteger(1);
+    assertEq(result, 1);
+
+    // Case2: The input operand is constant double.
+    result = ToInteger(0.12);
+    assertEq(result, 0);
+
+    // Case3: The input operand is constant float.
+    result = ToInteger(Math.fround(0.13));
+    assertEq(result, 0);
+
+    // Case4: The input operand is constant boolean.
+    result = ToInteger(true);
+    assertEq(result, 1);
+
+    // Case5: The input operand is null.
+    result = ToInteger(null);
+    assertEq(result, 0);
+}
+
+toint32();
+toint32();

js/src/jit/MIR.cpp

@@ -3044,6 +3044,30 @@ MDefinition *
 MToInt32::foldsTo(TempAllocator &alloc)
 {
     MDefinition *input = getOperand(0);
+
+    // Fold this operation if the input operand is constant.
+    if (input->isConstant()) {
+        Value val = input->toConstant()->value();
+        MacroAssembler::IntConversionInputKind convert = conversion();
+        switch (input->type()) {
+          case MIRType_Null:
+            MOZ_ASSERT(convert == MacroAssembler::IntConversion_Any);
+            return MConstant::New(alloc, Int32Value(0));
+          case MIRType_Boolean:
+            MOZ_ASSERT(convert == MacroAssembler::IntConversion_Any ||
+                       convert == MacroAssembler::IntConversion_NumbersOrBoolsOnly);
+            return MConstant::New(alloc, Int32Value(val.toBoolean()));
+          case MIRType_Int32:
+            return MConstant::New(alloc, Int32Value(val.toInt32()));
+          case MIRType_Float32:
+          case MIRType_Double:
+            int32_t ival;
+            // Only the value within the range of Int32 can be substitued as constant.
+            if (mozilla::NumberEqualsInt32(val.toNumber(), &ival))
+                return MConstant::New(alloc, Int32Value(ival));
+        }
+    }
+
     if (input->type() == MIRType_Int32)
         return input;
     return this;