mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-01-28 21:34:23 +00:00
3d47855394
So there are a couple of issues with indirect calls on thumbv4t. First, the most 'obvious' instruction, 'blx' isn't available until v5t. And secondly, the next-most-obvious sequence: 'mov lr, pc; bx rN' doesn't DTRT in thumb code because the saved off pc has its thumb bit cleared, so when the callee returns we end up in ARM mode.... yuck. The solution is to 'bl' to a nearby landing pad with a 'bx rN' in it. We could cut down on code size by sharing the landing pads between call sites that are close enough, but for the moment let's do correctness first and look at performance later. Patch by: Iain Sandoe http://reviews.llvm.org/D6519 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223380 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.