From 998ef4a92d74be9ca6dd06a986aad282a5263951 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Fri, 14 Jan 2011 08:21:08 +0000 Subject: [PATCH] switch the second scalarrepl pass to use SSAUpdater. We run two scalarrepl passes: one early in the cleanup code and one late interlaced with the inliner. The second one is important because inlining and other scalar optzns can unpin allocas, allowing them to be split up and promoted. While important for performance, this is also relatively rare, and we would previously force a (non-lazy) computation of DomFrontiers, which happened even if nothing became unpinned. With this patch, the first pass of scalarrepl still promotes the vast bulk of allocas in programs, but hte second pass has changed to use SSAUpdater, which is more "sparse" and lazy. This speeds up opt -O3 time on kimwitu++ (a c++ app) by about 1%. The numbers are interesting: the first pass promotes ~17500 allocas. The second pass promotes about 1600. For non-C++ codes, the compile time win should be greater, because the second pass of scalarrepl does less. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123437 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Support/StandardPasses.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/llvm/Support/StandardPasses.h b/include/llvm/Support/StandardPasses.h index 9cd210e2b01..8be2699e3cf 100644 --- a/include/llvm/Support/StandardPasses.h +++ b/include/llvm/Support/StandardPasses.h @@ -125,7 +125,8 @@ namespace llvm { PM->add(createArgumentPromotionPass()); // Scalarize uninlined fn args // Start of function pass. - PM->add(createScalarReplAggregatesPass()); // Break up aggregate allocas + // Break up aggregate allocas, using SSAUpdater. + PM->add(createScalarReplAggregatesPass(-1, false)); PM->add(createEarlyCSEPass()); // Catch trivial redundancies if (OptimizeBuiltins) PM->add(createSimplifyLibCallsPass()); // Library Call Optimizations