forked from OSchip/llvm-project
42af3601c2
While we can already transform A | (A ^ B) into A | B, things get bad once we have (A ^ B) | (A ^ B ^ Cst) because reassociation will morph this into (A ^ B) | ((A ^ Cst) ^ B). Our existing patterns fail once this happens. To fix this, we add a new pattern which looks through the tree of xor binary operators to see that, in fact, there exists a redundant xor operation. What follows bellow is a correctness proof of the transform using CVC3. $ cat t.cvc A, B, C : BITVECTOR(64); QUERY BVXOR(A, B) | BVXOR(BVXOR(B, C), A) = BVXOR(A, B) | C; QUERY BVXOR(BVXOR(A, C), B) | BVXOR(A, B) = BVXOR(A, B) | C; QUERY BVXOR(A, B) & BVXOR(BVXOR(B, C), A) = BVXOR(A, B) & ~C; QUERY BVXOR(BVXOR(A, C), B) & BVXOR(A, B) = BVXOR(A, B) & ~C; $ cvc3 < t.cvc Valid. Valid. Valid. Valid. llvm-svn: 214342 |
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| include | ||
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| tools | ||
| unittests | ||
| utils | ||
| .arcconfig | ||
| .clang-format | ||
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| CODE_OWNERS.TXT | ||
| CREDITS.TXT | ||
| LICENSE.TXT | ||
| LLVMBuild.txt | ||
| Makefile | ||
| Makefile.common | ||
| Makefile.config.in | ||
| Makefile.rules | ||
| README.txt | ||
| configure | ||
| llvm.spec.in | ||
README.txt
Low Level Virtual Machine (LLVM) ================================ This directory and its subdirectories contain source code for the Low Level Virtual Machine, 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're writing a package for LLVM, see docs/Packaging.rst for our suggestions.