Bug 1100123 - IonMonkey: Simplify LSimdSelect's regalloc constraints r=bbouvier

js/src/jit/LIR-Common.h

@@ -476,7 +476,7 @@ class LSimdShift : public LInstructionHelper<1, 2, 0>
 
 // SIMD selection of lanes from two int32x4 or float32x4 arguments based on a
 // int32x4 argument.
-class LSimdSelect : public LInstructionHelper<1, 3, 0>
+class LSimdSelect : public LInstructionHelper<1, 3, 1>
 {
   public:
     LIR_HEADER(SimdSelect);
@@ -489,6 +489,9 @@ class LSimdSelect : public LInstructionHelper<1, 3, 0>
     const LAllocation *rhs() {
         return getOperand(2);
     }
+    const LDefinition *temp() {
+        return getTemp(0);
+    }
     MSimdTernaryBitwise::Operation operation() const {
         return mir_->toSimdTernaryBitwise()->operation();
     }

js/src/jit/shared/CodeGenerator-x86-shared.cpp

@@ -2940,11 +2940,17 @@ CodeGeneratorX86Shared::visitSimdSelect(LSimdSelect *ins)
     FloatRegister mask = ToFloatRegister(ins->mask());
     FloatRegister onTrue = ToFloatRegister(ins->lhs());
     FloatRegister onFalse = ToFloatRegister(ins->rhs());
+    FloatRegister output = ToFloatRegister(ins->output());
+    FloatRegister temp = ToFloatRegister(ins->temp());
 
-    MOZ_ASSERT(onTrue == ToFloatRegister(ins->output()));
-    masm.bitwiseAndX4(Operand(mask), onTrue);
-    masm.bitwiseAndNotX4(Operand(onFalse), mask);
-    masm.bitwiseOrX4(Operand(mask), onTrue);
+    if (onTrue != output)
+        masm.movaps(onTrue, output);
+    if (mask != temp)
+        masm.movaps(mask, temp);
+
+    masm.bitwiseAndX4(Operand(mask), output);
+    masm.bitwiseAndNotX4(Operand(onFalse), temp);
+    masm.bitwiseOrX4(Operand(temp), output);
 }
 
 void

js/src/jit/shared/Lowering-x86-shared.cpp

@@ -677,18 +677,16 @@ LIRGeneratorX86Shared::visitSimdTernaryBitwise(MSimdTernaryBitwise *ins)
 
     if (ins->type() == MIRType_Int32x4 || ins->type() == MIRType_Float32x4) {
         LSimdSelect *lins = new(alloc()) LSimdSelect;
+        MDefinition *r0 = ins->getOperand(0);
+        MDefinition *r1 = ins->getOperand(1);
+        MDefinition *r2 = ins->getOperand(2);
 
-        // This must be useRegisterAtStart() because it is destroyed.
-        lins->setOperand(0, useRegisterAtStart(ins->getOperand(0)));
-        // This must be useRegisterAtStart() because it is destroyed.
-        lins->setOperand(1, useRegisterAtStart(ins->getOperand(1)));
-        // This could be useRegister(), but combining it with
-        // useRegisterAtStart() is broken see bug 772830.
-        lins->setOperand(2, useRegisterAtStart(ins->getOperand(2)));
-        // The output is constrained to be in the same register as the second
-        // argument to avoid redundantly copying the result into place. The
-        // register allocator will move the result if necessary.
-        defineReuseInput(lins, ins, 1);
+        lins->setOperand(0, useRegister(r0));
+        lins->setOperand(1, useRegister(r1));
+        lins->setOperand(2, useRegister(r2));
+        lins->setTemp(0, temp(LDefinition::FLOAT32X4));
+
+        define(lins, ins);
     } else {
         MOZ_CRASH("Unknown SIMD kind when doing bitwise operations");
     }