forked from OSchip/llvm-project
746ebb4ee8
This is retrying the fold from rL345717 (reverted at rL347780) ...with a fix for the miscompile demonstrated by PR39510: https://bugs.llvm.org/show_bug.cgi?id=39510 Original commit message: This is a fix for PR39475: https://bugs.llvm.org/show_bug.cgi?id=39475 We managed to get some of these patterns using computeKnownBits in https://reviews.llvm.org/D47041, but that can't be used for nabs(). Instead, put in some range-based logic, so we can fold both abs/nabs with icmp with a constant value. Alive proofs: https://rise4fun.com/Alive/21r Name: abs_nsw_is_positive %cmp = icmp slt i32 %x, 0 %negx = sub nsw i32 0, %x %abs = select i1 %cmp, i32 %negx, i32 %x %r = icmp sgt i32 %abs, -1 => %r = i1 true Name: abs_nsw_is_not_negative %cmp = icmp slt i32 %x, 0 %negx = sub nsw i32 0, %x %abs = select i1 %cmp, i32 %negx, i32 %x %r = icmp slt i32 %abs, 0 => %r = i1 false Name: nabs_is_negative_or_0 %cmp = icmp slt i32 %x, 0 %negx = sub i32 0, %x %nabs = select i1 %cmp, i32 %x, i32 %negx %r = icmp slt i32 %nabs, 1 => %r = i1 true Name: nabs_is_not_over_0 %cmp = icmp slt i32 %x, 0 %negx = sub i32 0, %x %nabs = select i1 %cmp, i32 %x, i32 %negx %r = icmp sgt i32 %nabs, 0 => %r = i1 false Differential Revision: https://reviews.llvm.org/D53844 llvm-svn: 345832 |
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| lib | ||
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| runtimes | ||
| test | ||
| tools | ||
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| .gitattributes | ||
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| CMakeLists.txt | ||
| CODE_OWNERS.TXT | ||
| CREDITS.TXT | ||
| LICENSE.TXT | ||
| LLVMBuild.txt | ||
| README.txt | ||
| RELEASE_TESTERS.TXT | ||
| configure | ||
| llvm.spec.in | ||
README.txt
The LLVM Compiler Infrastructure ================================ This directory and its subdirectories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and runtime environments. LLVM is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt. Please see the documentation provided in docs/ for further assistance with LLVM, and in particular docs/GettingStarted.rst for getting started with LLVM and docs/README.txt for an overview of LLVM's documentation setup. If you are writing a package for LLVM, see docs/Packaging.rst for our suggestions.