forked from OSchip/llvm-project
4c6658feb0
On PPC64, we end up with lots of i32 -> i64 zero extensions, not only from all of the usual places, but also from the ABI, which specifies that values passed are zero extended. Almost all 32-bit PPC instructions in PPC64 mode are defined to do *something* to the higher-order bits, and for some instructions, that action clears those bits (thus providing a zero-extended result). This is especially common after rotate-and-mask instructions. Adding an additional instruction to zero-extend the results of these instructions is unnecessary. This PPCISelDAGToDAG peephole optimization examines these zero-extensions, and looks back through their operands to see if all instructions will implicitly zero extend their results. If so, we convert these instructions to their 64-bit variants (which is an internal change only, the actual encoding of these instructions is the same as the original 32-bit ones) and remove the unnecessary zero-extension (changing where the INSERT_SUBREG instructions are to make everything internally consistent). llvm-svn: 224169 |
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| 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.