From 2312a06c87207d28c83707db019b4053ceea9bae Mon Sep 17 00:00:00 2001 From: Alina Sbirlea Date: Fri, 12 Apr 2019 19:16:07 +0000 Subject: [SCEV] Add option to forget everything in SCEV. Summary: Create a method to forget everything in SCEV. Add a cl::opt and PassManagerBuilder option to use this in LoopUnroll. Motivation: Certain Halide applications spend a very long time compiling in forgetLoop, and prefer to forget everything and rebuild SCEV from scratch. Sample difference in compile time reduction: 21.04 to 14.78 using current ToT release build. Testcase showcasing this cannot be opensourced and is fairly large. The option disabled by default, but it may be desirable to enable by default. Evidence in favor (two difference runs on different days/ToT state): File Before (s) After (s) clang-9.bc 7267.91 6639.14 llvm-as.bc 194.12 194.12 llvm-dis.bc 62.50 62.50 opt.bc 1855.85 1857.53 File Before (s) After (s) clang-9.bc 8588.70 7812.83 llvm-as.bc 196.20 194.78 llvm-dis.bc 61.55 61.97 opt.bc 1739.78 1886.26 Reviewers: sanjoy Subscribers: mehdi_amini, jlebar, zzheng, javed.absar, dmgreen, jdoerfert, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D60144 llvm-svn: 358304 --- llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp') diff --git a/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp b/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp index d5ccadde3f9..a53ee9d2687 100644 --- a/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp +++ b/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp @@ -197,8 +197,8 @@ LoopUnrollResult llvm::UnrollAndJamLoop( if (TripMultiple == 1 || TripMultiple % Count != 0) { if (!UnrollRuntimeLoopRemainder(L, Count, /*AllowExpensiveTripCount*/ false, /*UseEpilogRemainder*/ true, - UnrollRemainder, LI, SE, DT, AC, true, - EpilogueLoop)) { + UnrollRemainder, /*ForgetAllSCEV*/ false, + LI, SE, DT, AC, true, EpilogueLoop)) { LLVM_DEBUG(dbgs() << "Won't unroll-and-jam; remainder loop could not be " "generated when assuming runtime trip count\n"); return LoopUnrollResult::Unmodified; -- cgit v1.2.3