search for: visitshufflevector

Hello While building LLVM, the compiler (static analysis) is giving me a warning about "if (RangeUse[0] == 0 && RangeUse[0] == 0) {". Can somebody familar with the codebase look over it, maybe this should be "if (RangeUse[0] == 0 && RangeUse[1] == 0) {", otherwise sorry for the noise. Index: F:/dev/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp

I ran into some odd code being generated today and I came across something that doesn't look quite right. In SelectionDAGBuilder::visitShuffleVector there's some code to see if we can convert the shuffle to an EXTRACT_SUBVECTOR. After computing min/max values of the mask for each operand, there's a look that looks at the ranges and determines whether an EXTRACT_SUBVECTOR can be used: for (int Input=0; Input < 2; ++Input) {...

Hi, I've been taking a look at http://llvm.org/bugs/show_bug.cgi?id=8411, which is essentially improving how shufflevector instructions are handled for ARM. It looks like the main complexity comes from the fact that the DAG which emerges from SelectionDAGBuilder::visitShuffleVector is often rather low-level. A case could probably be made for keeping more information around in the DAG, but that would require cooperation among all the backends. For now, both EXTRACT_SUBVECTORs and BUILD_VECTORs seem to be handled on ARM mainly by resorting to the stack, which often leads to ra...