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| author | Chris Lattner <sabre@nondot.org> | 2004-03-16 19:49:59 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2004-03-16 19:49:59 +0000 |
| commit | a2f652d420ef3023fe105602481f750cbbbf88c5 (patch) | |
| tree | 2d69b2f771c350b5477e09d4601bbea3163c22e7 | |
| parent | 4bebf08d152d84970d250feec72fb734cb8a5316 (diff) | |
| download | external_llvm-a2f652d420ef3023fe105602481f750cbbbf88c5.zip external_llvm-a2f652d420ef3023fe105602481f750cbbbf88c5.tar.gz external_llvm-a2f652d420ef3023fe105602481f750cbbbf88c5.tar.bz2 | |
Do not try to optimize PHI nodes with incredibly high degree. This reduces SCCP
time from 615s to 1.49s on a large testcase that has a gigantic switch statement
that all of the blocks in the function go to (an intepreter).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12442 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/Scalar/SCCP.cpp | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp index 26c246d..75be397 100644 --- a/lib/Transforms/Scalar/SCCP.cpp +++ b/lib/Transforms/Scalar/SCCP.cpp @@ -500,6 +500,13 @@ void SCCP::visitPHINode(PHINode &PN) { return; // Quick exit } + // Super-extra-high-degree PHI nodes are unlikely to ever be marked constant, + // and slow us down a lot. Just mark them overdefined. + if (PN.getNumIncomingValues() > 64) { + markOverdefined(PNIV, &PN); + return; + } + // Look at all of the executable operands of the PHI node. If any of them // are overdefined, the PHI becomes overdefined as well. If they are all // constant, and they agree with each other, the PHI becomes the identical |