Bug 1258632 - Distinguish signed/unsigned MDiv/MMod in GVN. r=bbouvier

Modify the congruentTo method of MDiv and MMod opcodes to take into
account signedness, which is necessary for correct code generation.

--HG--
extra : rebase_source : 73037989ae280384c9bb2fd21f5e58243f06da4f

js/src/jit-test/tests/asm.js/testExpressions.js

@@ -393,3 +393,4 @@ for (let i = 0; i < 31; i++) {
     assertEq(f(Math.pow(2,i)), (Math.pow(2,i) * 2)|0);
     assertEq(f(Math.pow(2,i+1) - 1), ((Math.pow(2,i+1) - 1) * 2)|0);
 }
+assertEq(asmLink(asmCompile(USE_ASM + "var g=0; function f(x, y) { x = x|0; y = y|0; g = (x>>>0)%(y>>>0)|0; return (x|0)%(y|0)|0; } return f;"))(0xff40001, 0xfff80000), 0x40001);

js/src/jit/MIR.h

@@ -6905,6 +6905,11 @@ class MDiv : public MBinaryArithInstruction
         return specialization_ < MIRType_Object;
     }
 
+    bool congruentTo(const MDefinition* ins) const override {
+        return MBinaryArithInstruction::congruentTo(ins) &&
+               unsigned_ == ins->toDiv()->isUnsigned();
+    }
+
     ALLOW_CLONE(MDiv)
 };
 
@@ -6983,6 +6988,11 @@ class MMod : public MBinaryArithInstruction
     void collectRangeInfoPreTrunc() override;
     TruncateKind operandTruncateKind(size_t index) const override;
 
+    bool congruentTo(const MDefinition* ins) const override {
+        return MBinaryArithInstruction::congruentTo(ins) &&
+               unsigned_ == ins->toMod()->isUnsigned();
+    }
+
     ALLOW_CLONE(MMod)
 };