On Dec 28, 2007, at 10:26 PM, Chris Lattner wrote: > Author: lattner > Date: Sat Dec 29 00:26:16 2007 > New Revision: 45398 > > URL: http://llvm.org/viewvc/llvm-project?rev=45398&view=rev > Log: > Delete a store whose input is a load from the same pointer: > x = load p > store x -> p
This is unsafe for volatile. I don't see a check? > > Modified: > llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp > > Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp > URL: > http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=45398&r1=45397&r2=45398&view=diff > > = > = > = > = > = > = > = > = > ====================================================================== > --- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original) > +++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Sat Dec 29 > 00:26:16 2007 > @@ -4223,7 +4223,7 @@ > if (CombineToPreIndexedLoadStore(N) || > CombineToPostIndexedLoadStore(N)) > return SDOperand(N, 0); > > - // FIXME: is there such a think as a truncating indexed store? > + // FIXME: is there such a thing as a truncating indexed store? > if (ST->isTruncatingStore() && ST->getAddressingMode() == > ISD::UNINDEXED && > MVT::isInteger(Value.getValueType())) { > // See if we can simplify the input to this truncstore with > knowledge that > @@ -4243,6 +4243,17 @@ > return SDOperand(N, 0); > } > > + // If this is a load followed by a store to the same location, > then the store > + // is dead/noop. > + if (LoadSDNode *Ld = dyn_cast<LoadSDNode>(Value)) { > + if (Chain.Val == Ld && Ld->getBasePtr() == Ptr && > + ST->getAddressingMode() == ISD::UNINDEXED && > + ST->getStoredVT() == Ld->getLoadedVT()) { > + // The store is dead, remove it. > + return Chain; > + } > + } > + > return SDOperand(); > } > > > > _______________________________________________ > llvm-commits mailing list > llvm-commits@cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
