b1daf0aef6
Summary: In r354298 a DominatorTree construction was added via new function combineToUSubWithOverflow, which was subsequently restructured into replaceMathCmpWithIntrinsic in r354689. We are hitting a very long compile time due to this repeated construction, once per math cmp in the function. We shouldn't need to build the DominatorTree more than once per function, except when a transformation invalidates it. There is already a boolean flag that is returned from these methods indicating whether the DT has been modified. We can simply build the DT once per Function walk in CodeGenPrepare::runOnFunction, since any time a change is made we break out of the Function walk and restart it. I modified the code so that both replaceMathCmpWithIntrinsic as well as mergeSExts (which was also building a DT) use the DT constructed by the run method. From -mllvm -time-passes: Before this patch: CodeGen Prepare user time is 328s With this patch: CodeGen Prepare user time is 21s Reviewers: spatel Subscribers: jdoerfert, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D58995 llvm-svn: 355512
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.