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authorChris Lattner <sabre@nondot.org>2004-11-13 19:50:12 +0000
committerChris Lattner <sabre@nondot.org>2004-11-13 19:50:12 +0000
commit50af16a97b3983c224a48ae4369d7e9facf8174e (patch)
tree65c919b6cf46be906fc0f562734b82995a9a5497
parent706759e8c99ee78bec9fc90c9ac7efd668b284d3 (diff)
Simplify handling of shifts to be the same as we do for adds. Add support
for (X * C1) + (X * C2) (where * can be mul or shl), allowing us to fold: Y+Y+Y+Y+Y+Y+Y+Y into %tmp.8 = shl long %Y, ubyte 3 ; <long> [#uses=1] instead of %tmp.4 = shl long %Y, ubyte 2 ; <long> [#uses=1] %tmp.12 = shl long %Y, ubyte 2 ; <long> [#uses=1] %tmp.8 = add long %tmp.4, %tmp.12 ; <long> [#uses=1] This implements add.ll:test25 Also add support for (X*C1)-(X*C2) -> X*(C1-C2), implementing sub.ll:test18 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17704 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r--lib/Transforms/Scalar/InstructionCombining.cpp85
1 files changed, 40 insertions, 45 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 3f746a59ee..5af9aee165 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -317,14 +317,23 @@ static inline Value *dyn_castNotVal(Value *V) {
// dyn_castFoldableMul - If this value is a multiply that can be folded into
// other computations (because it has a constant operand), return the
-// non-constant operand of the multiply.
+// non-constant operand of the multiply, and set CST to point to the multiplier.
+// Otherwise, return null.
//
-static inline Value *dyn_castFoldableMul(Value *V) {
+static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
if (V->hasOneUse() && V->getType()->isInteger())
- if (Instruction *I = dyn_cast<Instruction>(V))
+ if (Instruction *I = dyn_cast<Instruction>(V)) {
if (I->getOpcode() == Instruction::Mul)
- if (isa<Constant>(I->getOperand(1)))
+ if (CST = dyn_cast<ConstantInt>(I->getOperand(1)))
+ return I->getOperand(0);
+ if (I->getOpcode() == Instruction::Shl)
+ if (CST = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ // The multiplier is really 1 << CST.
+ Constant *One = ConstantInt::get(V->getType(), 1);
+ CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
return I->getOperand(0);
+ }
+ }
return 0;
}
@@ -595,42 +604,26 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
if (Value *V = dyn_castNegVal(RHS))
return BinaryOperator::createSub(LHS, V);
- // X*C + X --> X * (C+1)
- if (dyn_castFoldableMul(LHS) == RHS) {
- Constant *CP1 =
- ConstantExpr::getAdd(
- cast<Constant>(cast<Instruction>(LHS)->getOperand(1)),
- ConstantInt::get(I.getType(), 1));
- return BinaryOperator::createMul(RHS, CP1);
+ ConstantInt *C2;
+ if (Value *X = dyn_castFoldableMul(LHS, C2)) {
+ if (X == RHS) // X*C + X --> X * (C+1)
+ return BinaryOperator::createMul(RHS, AddOne(C2));
+
+ // X*C1 + X*C2 --> X * (C1+C2)
+ ConstantInt *C1;
+ if (X == dyn_castFoldableMul(RHS, C1))
+ return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
}
// X + X*C --> X * (C+1)
- if (dyn_castFoldableMul(RHS) == LHS) {
- Constant *CP1 =
- ConstantExpr::getAdd(
- cast<Constant>(cast<Instruction>(RHS)->getOperand(1)),
- ConstantInt::get(I.getType(), 1));
- return BinaryOperator::createMul(LHS, CP1);
- }
+ if (dyn_castFoldableMul(RHS, C2) == LHS)
+ return BinaryOperator::createMul(LHS, AddOne(C2));
+
// (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
- ConstantInt *C2;
if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
- // (X + (X << C2)) --> X * ((1 << C2) + 1)
- // ((X << C2) + X) --> X * ((1 << C2) + 1)
- Value *Tmp;
- if ((RHS->hasOneUse() && match(RHS, m_Shl(m_Value(Tmp),
- m_ConstantInt(C2))) && LHS == Tmp)||
- (LHS->hasOneUse() && match(LHS, m_Shl(m_Value(Tmp),
- m_ConstantInt(C2))) && RHS == Tmp)){
- ConstantInt *One = ConstantInt::get(LHS->getType(), 1);
- Constant *NewRHS =
- ConstantExpr::getAdd(ConstantExpr::getShl(One, C2), One);
- return BinaryOperator::createMul(Tmp, NewRHS);
- }
-
if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
Value *X;
if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
@@ -800,24 +793,26 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
ConstantExpr::getNeg(DivRHS));
// X - X*C --> X * (1-C)
- if (dyn_castFoldableMul(Op1I) == Op0) {
- Constant *CP1 =
- ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
- cast<Constant>(cast<Instruction>(Op1)->getOperand(1)));
- assert(CP1 && "Couldn't constant fold 1-C?");
+ ConstantInt *C2;
+ if (dyn_castFoldableMul(Op1I, C2) == Op0) {
+ Constant *CP1 =
+ ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
return BinaryOperator::createMul(Op0, CP1);
}
}
- // X*C - X --> X * (C-1)
- if (dyn_castFoldableMul(Op0) == Op1) {
- Constant *CP1 =
- ConstantExpr::getSub(cast<Constant>(cast<Instruction>(Op0)->getOperand(1)),
- ConstantInt::get(I.getType(), 1));
- assert(CP1 && "Couldn't constant fold C - 1?");
- return BinaryOperator::createMul(Op1, CP1);
- }
+
+ ConstantInt *C1;
+ if (Value *X = dyn_castFoldableMul(Op0, C1)) {
+ if (X == Op1) { // X*C - X --> X * (C-1)
+ Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
+ return BinaryOperator::createMul(Op1, CP1);
+ }
+ ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
+ if (X == dyn_castFoldableMul(Op1, C2))
+ return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
+ }
return 0;
}