Bug 895465 - IonMonkey: Optimize codegen for test(and(x, y)). r=mrosenberg

js/src/ion/LIR-Common.h

@@ -1677,6 +1677,33 @@ class LCompareVM : public LCallInstructionHelper<1, 2 * BOX_PIECES, 0>
     }
 };
 
+class LBitAndAndBranch : public LControlInstructionHelper<2, 2, 0>
+{
+  public:
+    LIR_HEADER(BitAndAndBranch)
+    LBitAndAndBranch(MBasicBlock *ifTrue, MBasicBlock *ifFalse)
+    {
+        setSuccessor(0, ifTrue);
+        setSuccessor(1, ifFalse);
+    }
+
+    MBasicBlock *ifTrue() const {
+        return getSuccessor(0);
+    }
+    MBasicBlock *ifFalse() const {
+        return getSuccessor(1);
+    }
+    const LAllocation *left() {
+        return getOperand(0);
+    }
+    const LAllocation *right() {
+        return getOperand(1);
+    }
+    MCompare *mir() {
+        return mir_->toCompare();
+    }
+};
+
 class LIsNullOrLikeUndefined : public LInstructionHelper<1, BOX_PIECES, 2>
 {
   public:

js/src/ion/LOpcodes.h

@@ -81,6 +81,7 @@
     _(CompareV)                     \
     _(CompareVAndBranch)            \
     _(CompareVM)                    \
+    _(BitAndAndBranch)              \
     _(IsNullOrLikeUndefined)        \
     _(IsNullOrLikeUndefinedAndBranch)\
     _(EmulatesUndefined)            \

js/src/ion/Lowering.cpp

@@ -520,6 +520,27 @@ ReorderComparison(JSOp op, MDefinition **lhsp, MDefinition **rhsp)
     return op;
 }
 
+static void
+ReorderCommutative(MDefinition **lhsp, MDefinition **rhsp)
+{
+    MDefinition *lhs = *lhsp;
+    MDefinition *rhs = *rhsp;
+
+    // Ensure that if there is a constant, then it is in rhs.
+    // In addition, since clobbering binary operations clobber the left
+    // operand, prefer a non-constant lhs operand with no further uses.
+
+    if (rhs->isConstant())
+        return;
+
+    if (lhs->isConstant() ||
+        (rhs->defUseCount() == 1 && lhs->defUseCount() > 1))
+    {
+        *rhsp = lhs;
+        *lhsp = rhs;
+    }
+}
+
 bool
 LIRGenerator::visitTest(MTest *test)
 {
@@ -674,6 +695,15 @@ LIRGenerator::visitTest(MTest *test)
         }
     }
 
+    // Check if the operand for this test is a bitand operation. If it is, we want
+    // to emit an LBitAndAndBranch rather than an LTest*AndBranch.
+    if (opd->isBitAnd() && opd->isEmittedAtUses()) {
+        MDefinition *lhs = opd->getOperand(0);
+        MDefinition *rhs = opd->getOperand(1);
+        ReorderCommutative(&lhs, &rhs);
+        return lowerForBitAndAndBranch(new LBitAndAndBranch(ifTrue, ifFalse), test, lhs, rhs);
+    }
+
     if (opd->type() == MIRType_Double)
         return add(new LTestDAndBranch(useRegister(opd), ifTrue, ifFalse));
 
@@ -848,27 +878,6 @@ LIRGenerator::visitCompare(MCompare *comp)
     MOZ_ASSUME_UNREACHABLE("Unrecognized compare type.");
 }
 
-static void
-ReorderCommutative(MDefinition **lhsp, MDefinition **rhsp)
-{
-    MDefinition *lhs = *lhsp;
-    MDefinition *rhs = *rhsp;
-
-    // Ensure that if there is a constant, then it is in rhs.
-    // In addition, since clobbering binary operations clobber the left
-    // operand, prefer a non-constant lhs operand with no further uses.
-
-    if (rhs->isConstant())
-        return;
-
-    if (lhs->isConstant() ||
-        (rhs->defUseCount() == 1 && lhs->defUseCount() > 1))
-    {
-        *rhsp = lhs;
-        *lhsp = rhs;
-    }
-}
-
 bool
 LIRGenerator::lowerBitOp(JSOp op, MInstruction *ins)
 {
@@ -928,9 +937,33 @@ LIRGenerator::visitBitNot(MBitNot *ins)
     return assignSafepoint(lir, ins);
 }
 
+static bool
+CanEmitBitAndAtUses(MInstruction *ins)
+{
+    if (!ins->canEmitAtUses())
+        return false;
+
+    MUseDefIterator iter(ins);
+    if (!iter)
+        return false;
+
+    if (!iter.def()->isTest())
+        return false;
+
+    iter++;
+    return !iter;
+}
+
 bool
 LIRGenerator::visitBitAnd(MBitAnd *ins)
 {
+    // Sniff out if the output of this bitand is used only for a branching.
+    // If it is, then we will emit an LBitAndAndBranch instruction in place
+    // of this bitand and any test that uses this bitand. Thus, we can
+    // ignore this BitAnd.
+    if (CanEmitBitAndAtUses(ins))
+        return emitAtUses(ins);
+
     return lowerBitOp(JSOP_BITAND, ins);
 }
 

js/src/ion/arm/CodeGenerator-arm.cpp

@@ -1449,6 +1449,17 @@ CodeGeneratorARM::visitCompareVAndBranch(LCompareVAndBranch *lir)
     return true;
 }
 
+bool
+CodeGeneratorARM::visitBitAndAndBranch(LBitAndAndBranch *baab)
+{
+    if (baab->right()->isConstant())
+        masm.ma_tst(ToRegister(baab->left()), Imm32(ToInt32(baab->right())));
+    else
+        masm.ma_tst(ToRegister(baab->left()), ToRegister(baab->right()));
+    emitBranch(Assembler::NonZero, baab->ifTrue(), baab->ifFalse());
+    return true;
+}
+
 bool
 CodeGeneratorARM::visitUInt32ToDouble(LUInt32ToDouble *lir)
 {

js/src/ion/arm/CodeGenerator-arm.h

@@ -95,6 +95,7 @@ class CodeGeneratorARM : public CodeGeneratorShared
     virtual bool visitCompareBAndBranch(LCompareBAndBranch *lir);
     virtual bool visitCompareV(LCompareV *lir);
     virtual bool visitCompareVAndBranch(LCompareVAndBranch *lir);
+    virtual bool visitBitAndAndBranch(LBitAndAndBranch *baab);
     virtual bool visitUInt32ToDouble(LUInt32ToDouble *lir);
     virtual bool visitNotI(LNotI *ins);
     virtual bool visitNotD(LNotD *ins);

js/src/ion/arm/Lowering-arm.cpp

@@ -185,6 +185,15 @@ LIRGeneratorARM::lowerForFPU(LInstructionHelper<1, 2, 0> *ins, MDefinition *mir,
                   LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::DEFAULT));
 }
 
+bool
+LIRGeneratorARM::lowerForBitAndAndBranch(LBitAndAndBranch *baab, MInstruction *mir,
+                                         MDefinition *lhs, MDefinition *rhs)
+{
+    baab->setOperand(0, useRegister(lhs));
+    baab->setOperand(1, useRegisterOrConstant(rhs));
+    return add(baab, mir);
+}
+
 bool
 LIRGeneratorARM::defineUntypedPhi(MPhi *phi, size_t lirIndex)
 {

js/src/ion/arm/Lowering-arm.h

@@ -45,6 +45,8 @@ class LIRGeneratorARM : public LIRGeneratorShared
                      MDefinition *src);
     bool lowerForFPU(LInstructionHelper<1, 2, 0> *ins, MDefinition *mir,
                      MDefinition *lhs, MDefinition *rhs);
+    bool lowerForBitAndAndBranch(LBitAndAndBranch *baab, MInstruction *mir,
+                                 MDefinition *lhs, MDefinition *rhs);
 
     bool lowerTruncateDToInt32(MTruncateToInt32 *ins);
 

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

@@ -128,6 +128,17 @@ CodeGeneratorX86Shared::visitTestDAndBranch(LTestDAndBranch *test)
     return true;
 }
 
+bool
+CodeGeneratorX86Shared::visitBitAndAndBranch(LBitAndAndBranch *baab)
+{
+    if (baab->right()->isConstant())
+        masm.testl(ToRegister(baab->left()), Imm32(ToInt32(baab->right())));
+    else
+        masm.testl(ToRegister(baab->left()), ToRegister(baab->right()));
+    emitBranch(Assembler::NonZero, baab->ifTrue(), baab->ifFalse());
+    return true;
+}
+
 void
 CodeGeneratorX86Shared::emitCompare(MCompare::CompareType type, const LAllocation *left, const LAllocation *right)
 {

js/src/ion/shared/CodeGenerator-x86-shared.h

@@ -98,6 +98,7 @@ class CodeGeneratorX86Shared : public CodeGeneratorShared
     virtual bool visitCompareAndBranch(LCompareAndBranch *comp);
     virtual bool visitCompareD(LCompareD *comp);
     virtual bool visitCompareDAndBranch(LCompareDAndBranch *comp);
+    virtual bool visitBitAndAndBranch(LBitAndAndBranch *baab);
     virtual bool visitNotI(LNotI *comp);
     virtual bool visitNotD(LNotD *comp);
     virtual bool visitMathD(LMathD *math);

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

@@ -116,6 +116,15 @@ LIRGeneratorX86Shared::lowerForFPU(LInstructionHelper<1, 2, 0> *ins, MDefinition
     return defineReuseInput(ins, mir, 0);
 }
 
+bool
+LIRGeneratorX86Shared::lowerForBitAndAndBranch(LBitAndAndBranch *baab, MInstruction *mir,
+                                               MDefinition *lhs, MDefinition *rhs)
+{
+    baab->setOperand(0, useRegister(lhs));
+    baab->setOperand(1, useRegisterOrConstant(rhs));
+    return add(baab, mir);
+}
+
 bool
 LIRGeneratorX86Shared::lowerMulI(MMul *mul, MDefinition *lhs, MDefinition *rhs)
 {

js/src/ion/shared/Lowering-x86-shared.h

@@ -34,6 +34,8 @@ class LIRGeneratorX86Shared : public LIRGeneratorShared
                      MDefinition *rhs);
     bool lowerForFPU(LInstructionHelper<1, 2, 0> *ins, MDefinition *mir, MDefinition *lhs,
                      MDefinition *rhs);
+    bool lowerForBitAndAndBranch(LBitAndAndBranch *baab, MInstruction *mir,
+                                 MDefinition *lhs, MDefinition *rhs);
     bool visitConstant(MConstant *ins);
     bool visitAsmJSNeg(MAsmJSNeg *ins);
     bool visitAsmJSUDiv(MAsmJSUDiv *ins);