mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-03-12 01:41:37 +00:00
c7b902e7fe
The current Intel Atom microarchitecture has a feature whereby when a function returns early then it is slightly faster to execute a sequence of NOP instructions to wait until the return address is ready, as opposed to simply stalling on the ret instruction until the return address is ready. When compiling for X86 Atom only, this patch will run a pass, called "X86PadShortFunction" which will add NOP instructions where less than four cycles elapse between function entry and return. It includes tests. This patch has been updated to address Nadav's review comments - Optimize only at >= O1 and don't do optimization if -Os is set - Stores MachineBasicBlock* instead of BBNum - Uses DenseMap instead of std::map - Fixes placement of braces Patch by Andy Zhang. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171879 91177308-0d34-0410-b5e6-96231b3b80d8
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.