6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-06-15 05:24:01 +00:00
Code Issues Projects Releases Wiki Activity

Combine not (not X) -> X

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2493 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2002-05-06 17:03:21 +00:00
parent 9bfed886a8
commit ed3a55005d
1 changed files with 14 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -57,7 +57,7 @@ namespace {
// I - Change was made, I is still valid // I - Change was made, I is still valid
// otherwise - Change was made, replace I with returned instruction // otherwise - Change was made, replace I with returned instruction
// //
Instruction *visitNot(UnaryOperator *I);
Instruction *visitAdd(BinaryOperator *I); Instruction *visitAdd(BinaryOperator *I);
Instruction *visitSub(BinaryOperator *I); Instruction *visitSub(BinaryOperator *I);
Instruction *visitMul(BinaryOperator *I); Instruction *visitMul(BinaryOperator *I);
@ -78,6 +78,19 @@ namespace {
} }
Instruction *InstCombiner::visitNot(UnaryOperator *I) {
if (I->use_empty()) return 0; // Don't fix dead instructions...
// not (not X) = X
if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(0)))
if (Op->getOpcode() == Instruction::Not) {
AddUsesToWorkList(I); // Add all modified instrs to worklist
I->replaceAllUsesWith(Op->getOperand(0));
return I;
}
return 0;
}
// Make sure that this instruction has a constant on the right hand side if it // Make sure that this instruction has a constant on the right hand side if it
// has any constant arguments. If not, fix it an return true. // has any constant arguments. If not, fix it an return true.