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to "C ^ 1" is only valid when C is known to be either 0 or 1. Most of the similar foldings in this function only handle "i1" types, but this one appears intentionally written to handle larger integer types. If C has an integer type larger than "i1", this needs to check if the high bits of a boolean are known to be zero. I also changed the comment to describe this folding as "C ^ 1" instead of "~C", since that is what the code does and since the latter would only be valid for "i1" types. The good news is that most LLVM targets use TargetLowering::ZeroOrOneBooleanContent so this change will not disable the optimization; the bad news is that I've been unable to come up with a testcase to demonstrate the problem. I have also removed a "FIXME" comment for folding "select C, X, 0" to "C & X", since the code looks correct to me. It could be made more aggressive by not limiting the type to "i1", but that would then require checking for TargetLowering::ZeroOrNegativeOneBooleanContent. Similar changes could be done for the other SELECT foldings, but it was decided to be not worth the trouble and complexity (see e.g., r44663). llvm-svn: 62790 |
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| .. | ||
| CallingConvLower.cpp | ||
| CMakeLists.txt | ||
| DAGCombiner.cpp | ||
| FastISel.cpp | ||
| LegalizeDAG.cpp | ||
| LegalizeFloatTypes.cpp | ||
| LegalizeIntegerTypes.cpp | ||
| LegalizeTypes.cpp | ||
| LegalizeTypes.h | ||
| LegalizeTypesGeneric.cpp | ||
| LegalizeVectorTypes.cpp | ||
| Makefile | ||
| ScheduleDAGFast.cpp | ||
| ScheduleDAGList.cpp | ||
| ScheduleDAGRRList.cpp | ||
| ScheduleDAGSDNodes.cpp | ||
| ScheduleDAGSDNodesEmit.cpp | ||
| SelectionDAG.cpp | ||
| SelectionDAGBuild.cpp | ||
| SelectionDAGBuild.h | ||
| SelectionDAGISel.cpp | ||
| SelectionDAGPrinter.cpp | ||
| TargetLowering.cpp | ||