From b8b40e05649e6ba731b7387df534d513af469ddc Mon Sep 17 00:00:00 2001 From: Andrew Trick Date: Sat, 25 Oct 2014 19:42:07 +0000 Subject: [PATCH] Fix LSR compile time. This is a simple fix that brings the compilation time from 5min to 5s on a specific real-world example. It's a large chain of computation in a crypto routine (always a problem for SCEV). A unit test is not feasible and there would be no way to check it. The fix is just basic good practice for dealing with SCEVs, there's no risk of regression. Patch by Daniel Reynaud! llvm-svn: 220622 --- lib/Transforms/Scalar/LoopStrengthReduce.cpp | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index fbc8e0e1e7b..e1d18e8f99b 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -3117,10 +3117,15 @@ void LSRInstance::CollectLoopInvariantFixupsAndFormulae() { SmallVector Worklist(RegUses.begin(), RegUses.end()); SmallPtrSet Inserted; + SmallPtrSet Done; while (!Worklist.empty()) { const SCEV *S = Worklist.pop_back_val(); + // Don't process the same SCEV twice + if (!Done.insert(S)) + continue; + if (const SCEVNAryExpr *N = dyn_cast(S)) Worklist.append(N->op_begin(), N->op_end()); else if (const SCEVCastExpr *C = dyn_cast(S))