[llvm-commits] CVS: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
Chris Lattner
lattner at cs.uiuc.edu
Tue Feb 18 13:58:00 PST 2003
Changes in directory llvm/lib/Transforms/Scalar:
InstructionCombining.cpp updated: 1.68 -> 1.69
---
Log message:
4 new transformations:
* X*C + X --> X * (C+1)
* X + X*C --> X * (C+1)
* X - X*C --> X * (1-C)
* X*C - X --> X * (C-1)
---
Diffs of the changes:
Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.68 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.69
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.68 Tue Feb 18 13:28:33 2003
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp Tue Feb 18 13:57:07 2003
@@ -146,6 +146,16 @@
return Count;
}
+static inline Value *dyn_castFoldableMul(Value *V) {
+ if (V->use_size() == 1 && V->getType()->isInteger())
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ if (I->getOpcode() == Instruction::Mul)
+ if (isa<Constant>(I->getOperand(1)))
+ return I->getOperand(0);
+ return 0;
+}
+
+
Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
bool Changed = SimplifyBinOp(I);
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
@@ -182,6 +192,22 @@
}
}
+ // X*C + X --> X * (C+1)
+ if (dyn_castFoldableMul(LHS) == RHS) {
+ Constant *CP1 = *cast<Constant>(cast<Instruction>(LHS)->getOperand(1)) +
+ *ConstantInt::get(I.getType(), 1);
+ assert(CP1 && "Couldn't constant fold C + 1?");
+ return BinaryOperator::create(Instruction::Mul, RHS, CP1);
+ }
+
+ // X + X*C --> X * (C+1)
+ if (dyn_castFoldableMul(RHS) == LHS) {
+ Constant *CP1 = *cast<Constant>(cast<Instruction>(RHS)->getOperand(1)) +
+ *ConstantInt::get(I.getType(), 1);
+ assert(CP1 && "Couldn't constant fold C + 1?");
+ return BinaryOperator::create(Instruction::Mul, LHS, CP1);
+ }
+
return Changed ? &I : 0;
}
@@ -231,7 +257,23 @@
Instruction *NewNot = BinaryOperator::createNot(OtherOp, "B.not", &I);
return BinaryOperator::create(Instruction::And, Op0, NewNot);
}
+
+ // X - X*C --> X * (1-C)
+ if (dyn_castFoldableMul(Op1I) == Op0) {
+ Constant *CP1 = *ConstantInt::get(I.getType(), 1) -
+ *cast<Constant>(cast<Instruction>(Op1)->getOperand(1));
+ assert(CP1 && "Couldn't constant fold 1-C?");
+ return BinaryOperator::create(Instruction::Mul, Op0, CP1);
+ }
}
+
+ // X*C - X --> X * (C-1)
+ if (dyn_castFoldableMul(Op0) == Op1) {
+ Constant *CP1 = *cast<Constant>(cast<Instruction>(Op0)->getOperand(1)) -
+ *ConstantInt::get(I.getType(), 1);
+ assert(CP1 && "Couldn't constant fold C - 1?");
+ return BinaryOperator::create(Instruction::Mul, Op1, CP1);
+ }
return 0;
}
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