6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-08-18 12:29:21 +00:00
Code Issues Projects Releases Wiki Activity

Fold (X|C1)^C2 -> X^(C1|C2) when possible. This implements

Browse Source 
InstCombine/or.ll:test23.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26385 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-02-26 19:57:54 +00:00
parent 80e2065565
commit 02bd1b3e94
1 changed files with 14 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -2846,6 +2846,20 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
ConstantInt::get(I.getType(), 1)),
Op0I->getOperand(0));
}
} else if (Op0I->getOpcode() == Instruction::Or) {
// (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getZExtValue())) {
Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
// Anything in both C1 and C2 is known to be zero, remove it from
// NewRHS.
Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS);
NewRHS = ConstantExpr::getAnd(NewRHS,
ConstantExpr::getNot(CommonBits));
WorkList.push_back(Op0I);
I.setOperand(0, Op0I->getOperand(0));
I.setOperand(1, NewRHS);
return &I;
}
}
}