6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-10-20 09:24:58 +00:00
Code Issues Projects Releases Wiki Activity

allow SRL to simplify its operands, as it doesn't demand all bits as input.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36245 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-04-18 03:06:49 +00:00
parent ec06e9a670
commit 61a4c072b9
1 changed files with 7 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -1728,7 +1728,7 @@ SDOperand DAGCombiner::visitSHL(SDNode *N) {
// if (shl x, c) is known to be zero, return 0
if (TLI.MaskedValueIsZero(SDOperand(N, 0), MVT::getIntVTBitMask(VT)))
return DAG.getConstant(0, VT);
if (SimplifyDemandedBits(SDOperand(N, 0)))
if (N1C && SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand(N, 0);
// fold (shl (shl x, c1), c2) -> 0 or (shl x, c1+c2)
if (N1C && N0.getOpcode() == ISD::SHL &&
@ -1907,6 +1907,12 @@ SDOperand DAGCombiner::visitSRL(SDNode *N) {
return DAG.getNode(ISD::XOR, VT, Op, DAG.getConstant(1, VT));
}
}
// fold operands of srl based on knowledge that the low bits are not
// demanded.
if (N1C && SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand(N, 0);
return SDOperand();
}