forked from OSchip/llvm-project
9895c7012d
This patch adds an alternative cost metric for the inliner to take into account both the cost (i.e. size) and cycle count savings into account. Without this patch, we decide to inline a given call site if the size of inlining the call site is below the threshold that is computed according to the hotness of the call site. This patch adds a new cost metric, turned off by default, to take over the handling of hot call sites. Specifically, with the new cost metric, we decide to inline a given call site if the ratio of cycle savings to size exceeds a threshold. The cycle savings are computed from call site costs, parameter propagation, folded conditional branches, etc, all weighted by their respective profile counts. The size is primarily the callee size, but we subtract call site costs and the size of basic blocks that are never executed. The new cost metric implicitly takes advantage of the machine function splitter recently introduced by Snehasish Kumar, which dramatically reduces the cost of duplicating (e.g. inlining) cold basic blocks by placing cold basic blocks of hot functions in the .text.split section. We evaluated the new cost metric on clang bootstrap and SPECInt 2017. For clang bootstrap, we observe 0.69% runtime improvement. For SPECInt we report the change in IntRate the C/C++ benchmarks. All benchmarks apart from perlbench and omnetpp improve, on average by 0.21% with the max for mcf at 1.96%. Benchmark % Change 500.perlbench_r -0.45 502.gcc_r 0.13 505.mcf_r 1.96 520.omnetpp_r -0.28 523.xalancbmk_r 0.49 525.x264_r 0.00 531.deepsjeng_r 0.00 541.leela_r 0.35 557.xz_r 0.21 Differential Revision: https://reviews.llvm.org/D92780 |
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| tools | ||
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| .clang-format | ||
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| CODE_OWNERS.TXT | ||
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| LICENSE.TXT | ||
| README.txt | ||
| RELEASE_TESTERS.TXT | ||
| configure | ||
| llvm.spec.in | ||
README.txt
The LLVM Compiler Infrastructure ================================ 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 are writing a package for LLVM, see docs/Packaging.rst for our suggestions.