RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-10-19 19:12:56 +02:00
Code Issues Projects Releases Wiki Activity

[DAGcombine] Do not replace truncate node by itself when doing constant folding, this trigger needless extra rounds of combine for nothing. NFC

Browse Source 
llvm-svn: 317926
This commit is contained in:
Amaury Sechet 2017-11-10 20:59:53 +00:00
parent 7497a5ca3a
commit f3e0c5f2ce
1 changed files with 9 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -8360,12 +8360,18 @@ SDValue DAGCombiner::visitTRUNCATE(SDNode *N) {
// noop truncate
if (N0.getValueType() == N->getValueType(0))
return N0;
// fold (truncate c1) -> c1
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::TRUNCATE, SDLoc(N), VT, N0);
// fold (truncate (truncate x)) -> (truncate x)
if (N0.getOpcode() == ISD::TRUNCATE)
return DAG.getNode(ISD::TRUNCATE, SDLoc(N), VT, N0.getOperand(0));
// fold (truncate c1) -> c1
if (DAG.isConstantIntBuildVectorOrConstantInt(N0)) {
SDValue C = DAG.getNode(ISD::TRUNCATE, SDLoc(N), VT, N0);
if (C.getNode() != N)
return C;
}
// fold (truncate (ext x)) -> (ext x) or (truncate x) or x
if (N0.getOpcode() == ISD::ZERO_EXTEND ||
N0.getOpcode() == ISD::SIGN_EXTEND ||