forked from OSchip/llvm-project
b79b4f539b
Summary: [[ https://bugs.llvm.org/show_bug.cgi?id=38149 | PR38149 ]] As discussed in https://reviews.llvm.org/D49179#1158957 and later, the IR for 'check for [no] signed truncation' pattern can be improved: https://rise4fun.com/Alive/gBf ^ that pattern will be produced by Implicit Integer Truncation sanitizer, https://reviews.llvm.org/D48958 https://bugs.llvm.org/show_bug.cgi?id=21530 in signed case, therefore it is probably a good idea to improve it. Proofs for this transform: https://rise4fun.com/Alive/mgu This transform is surprisingly frustrating. This does not deal with non-splat shift amounts, or with undef shift amounts. I've outlined what i think the solution should be: ``` // Potential handling of non-splats: for each element: // * if both are undef, replace with constant 0. // Because (1<<0) is OK and is 1, and ((1<<0)>>1) is also OK and is 0. // * if both are not undef, and are different, bailout. // * else, only one is undef, then pick the non-undef one. ``` The DAGCombine will reverse this transform, see https://reviews.llvm.org/D49266 Reviewers: spatel, craig.topper Reviewed By: spatel Subscribers: JDevlieghere, rkruppe, llvm-commits Differential Revision: https://reviews.llvm.org/D49320 llvm-svn: 337190 |
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| AggressiveInstCombine | ||
| Coroutines | ||
| Hello | ||
| IPO | ||
| InstCombine | ||
| Instrumentation | ||
| ObjCARC | ||
| Scalar | ||
| Utils | ||
| Vectorize | ||
| CMakeLists.txt | ||
| LLVMBuild.txt | ||