mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-02-21 06:30:16 +00:00
44926033f6
Now that SimplifyCFG uses TTI for the cost heuristic, we can teach BasicTTIImpl how to query TLI in order to get a more accurate cost for truncates and zero-extends. Before this patch, the basic cost heuristic in TargetTransformInfoImplCRTPBase would have conservatively returned a 'default' TCC_Basic for all zero-extends, and TCC_Free for truncates on native types. This patch improves the heuristic so that we query TLI (if available) to get more accurate answers. If TLI is available, then methods 'isZExtFree' and 'isTruncateFree' can be used to check if a zext/trunc is free for the target. Added more test cases to SimplifyCFG/X86/speculate-cttz-ctlz.ll. With this change, SimplifyCFG is now able to speculate a 'cheap' cttz/ctlz immediately followed by a free zext/trunc. Differential Revision: http://reviews.llvm.org/D7585 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228923 91177308-0d34-0410-b5e6-96231b3b80d8
Low Level Virtual Machine (LLVM) ================================ 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're writing a package for LLVM, see docs/Packaging.rst for our suggestions.