Move some those Xor simplifications which don't require creating new
instructions out of InstCombine and into InstructionSimplify. While
there, introduce an m_AllOnes pattern to simplify matching with integers
and vectors with all bits equal to one.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119536 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 5ad842b..7848d50 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -276,23 +276,13 @@
if (Op0 == Op1)
return Op0;
- // X & <0,0> = <0,0>
- if (isa<ConstantAggregateZero>(Op1))
+ // X & 0 = 0
+ if (match(Op1, m_Zero()))
return Op1;
- // X & <-1,-1> = X
- if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1))
- if (CP->isAllOnesValue())
- return Op0;
-
- if (ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1)) {
- // X & 0 = 0
- if (Op1CI->isZero())
- return Op1CI;
- // X & -1 = X
- if (Op1CI->isAllOnesValue())
- return Op0;
- }
+ // X & -1 = X
+ if (match(Op1, m_AllOnes()))
+ return Op0;
// A & ~A = ~A & A = 0
Value *A, *B;
@@ -365,23 +355,13 @@
if (Op0 == Op1)
return Op0;
- // X | <0,0> = X
- if (isa<ConstantAggregateZero>(Op1))
+ // X | 0 = X
+ if (match(Op1, m_Zero()))
return Op0;
- // X | <-1,-1> = <-1,-1>
- if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1))
- if (CP->isAllOnesValue())
- return Op1;
-
- if (ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1)) {
- // X | 0 = X
- if (Op1CI->isZero())
- return Op0;
- // X | -1 = -1
- if (Op1CI->isAllOnesValue())
- return Op1CI;
- }
+ // X | -1 = -1
+ if (match(Op1, m_AllOnes()))
+ return Op1;
// A | ~A = ~A | A = -1
Value *A, *B;
@@ -431,6 +411,71 @@
return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
}
+/// SimplifyXorInst - Given operands for a Xor, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+ if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { CLHS, CRHS };
+ return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
+ Ops, 2, TD);
+ }
+
+ // Canonicalize the constant to the RHS.
+ std::swap(Op0, Op1);
+ }
+
+ // A ^ undef -> undef
+ if (isa<UndefValue>(Op1))
+ return UndefValue::get(Op0->getType());
+
+ // A ^ 0 = A
+ if (match(Op1, m_Zero()))
+ return Op0;
+
+ // A ^ A = 0
+ if (Op0 == Op1)
+ return Constant::getNullValue(Op0->getType());
+
+ // A ^ ~A = ~A ^ A = -1
+ Value *A, *B;
+ if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
+ (match(Op1, m_Not(m_Value(A))) && A == Op0))
+ return Constant::getAllOnesValue(Op0->getType());
+
+ // (A ^ B) ^ A = B
+ if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
+ (A == Op1 || B == Op1))
+ return A == Op1 ? B : A;
+
+ // A ^ (A ^ B) = B
+ if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0))
+ return A == Op0 ? B : A;
+
+ // If the operation is with the result of a select instruction, check whether
+ // operating on either branch of the select always yields the same value.
+ if (MaxRecurse && (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)))
+ if (Value *V = ThreadBinOpOverSelect(Instruction::Xor, Op0, Op1, TD, DT,
+ MaxRecurse-1))
+ return V;
+
+ // If the operation is with the result of a phi instruction, check whether
+ // operating on all incoming values of the phi always yields the same value.
+ if (MaxRecurse && (isa<PHINode>(Op0) || isa<PHINode>(Op1)))
+ if (Value *V = ThreadBinOpOverPHI(Instruction::Xor, Op0, Op1, TD, DT,
+ MaxRecurse-1))
+ return V;
+
+ return 0;
+}
+
+Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
static const Type *GetCompareTy(Value *Op) {
return CmpInst::makeCmpResultType(Op->getType());
}
@@ -774,6 +819,9 @@
case Instruction::Or:
Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
+ case Instruction::Xor:
+ Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
case Instruction::ICmp:
Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD, DT);