forked from OSchip/llvm-project
3bd4b5a925
Summary: In r355512 CGP was changed to build the DominatorTree only once per function traversal, to avoid repeatedly building it each time it was accessed. This solved one compile time issue but introduced another. In the second case, we now were building the DT unnecessarily many times when we performed many function traversals (i.e. more than once per function when running CGP because of changes made each time). Change to saving the DT in the CodeGenPrepare object, and building it lazily when needed. It is reset whenever we need to rebuild it. The case that exposed the issue there are 617 functions, and we walk them (i.e. execute the "while (MadeChange)" loop in runOnFunction) a total of 12083 times (so previously we were building the DT 12083 times). With this patch we only build the DT 844 times (average of 1.37 times per function). We dropped the total time to compile this file from 538.11s without this patch to 339.63s with it. There is still an issue as CGP is taking much longer than all other passes even with this patch, and before a recent compiler release cut at r355392 the total time to this compile was only 97 sec with a huge reduction in CGP time. I suspect that one of the other recent changes to CGP led to iterating each function many more times on average, but I need to do some more investigation. Reviewers: spatel Subscribers: jdoerfert, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D59696 llvm-svn: 356937 |
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| runtimes | ||
| test | ||
| tools | ||
| unittests | ||
| utils | ||
| .arcconfig | ||
| .clang-format | ||
| .clang-tidy | ||
| .gitattributes | ||
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| CMakeLists.txt | ||
| CODE_OWNERS.TXT | ||
| CREDITS.TXT | ||
| LICENSE.TXT | ||
| LLVMBuild.txt | ||
| README.txt | ||
| RELEASE_TESTERS.TXT | ||
| configure | ||
| llvm.spec.in | ||
README.txt
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