mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2025-01-31 20:51:52 +01:00
f60a29f8fa
We fail to canonicalize IR this way (prefer 'not' ops to arbitrary 'xor'), but that would not matter without this patch because DAGCombiner was reversing that transform. I think we need this transform in the backend regardless of what happens in IR to catch cases where the shift-xor is formed late from GEP or other ops. https://rise4fun.com/Alive/NC1 Name: shl Pre: (-1 << C2) == C1 %shl = shl i8 %x, C2 %r = xor i8 %shl, C1 => %not = xor i8 %x, -1 %r = shl i8 %not, C2 Name: shr Pre: (-1 u>> C2) == C1 %sh = lshr i8 %x, C2 %r = xor i8 %sh, C1 => %not = xor i8 %x, -1 %r = lshr i8 %not, C2 https://bugs.llvm.org/show_bug.cgi?id=39657 llvm-svn: 347478
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.