maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[DAGCombine] Do not try to deduplicate commutative operations if both operand are the same. 

Summary: It is creating useless work as the commuted nodes is the same as the node we are working on in that case.

Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D33840

llvm-svn: 310832
This commit is contained in:
Amaury Sechet 2017-08-14 11:44:03 +00:00
parent 9b5a89b0e2
commit 9c529b6be3
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -1614,15 +1614,15 @@ SDValue DAGCombiner::combine(SDNode *N) {
}
}
// If N is a commutative binary node, try commuting it to enable more
// sdisel CSE.
// If N is a commutative binary node, try eliminate it if the commuted
// version is already present in the DAG.
if (!RV.getNode() && TLI.isCommutativeBinOp(N->getOpcode()) &&
N->getNumValues() == 1) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
// Constant operands are canonicalized to RHS.
if (isa<ConstantSDNode>(N0) || !isa<ConstantSDNode>(N1)) {
if (N0 != N1 && (isa<ConstantSDNode>(N0) || !isa<ConstantSDNode>(N1))) {
SDValue Ops[] = {N1, N0};
SDNode *CSENode = DAG.getNodeIfExists(N->getOpcode(), N->getVTList(), Ops,
N->getFlags());