From 167a57ca452efbb014ebce7ecfa99501b5039611 Mon Sep 17 00:00:00 2001 From: Eli Bendersky Date: Thu, 1 May 2014 18:38:36 +0000 Subject: Add an optimization that does CSE in a group of similar GEPs. This optimization merges the common part of a group of GEPs, so we can compute each pointer address by adding a simple offset to the common part. The optimization is currently only enabled for the NVPTX backend, where it has a large payoff on some benchmarks. Review: http://reviews.llvm.org/D3462 Patch by Jingyue Wu. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207783 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/NVPTX/NVPTXTargetMachine.cpp | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) (limited to 'lib/Target/NVPTX') diff --git a/lib/Target/NVPTX/NVPTXTargetMachine.cpp b/lib/Target/NVPTX/NVPTXTargetMachine.cpp index 0cc5c51629..26a4f84052 100644 --- a/lib/Target/NVPTX/NVPTXTargetMachine.cpp +++ b/lib/Target/NVPTX/NVPTXTargetMachine.cpp @@ -147,10 +147,23 @@ void NVPTXPassConfig::addIRPasses() { addPass(createNVPTXAssignValidGlobalNamesPass()); addPass(createGenericToNVVMPass()); addPass(createNVPTXFavorNonGenericAddrSpacesPass()); - // The FavorNonGenericAddrSpaces pass may remove instructions and leave some - // values unused. Therefore, we run a DCE pass right afterwards. We could - // remove unused values in an ad-hoc manner, but it requires manual work and - // might be error-prone. + addPass(createSeparateConstOffsetFromGEPPass()); + // The SeparateConstOffsetFromGEP pass creates variadic bases that can be used + // by multiple GEPs. Run GVN or EarlyCSE to really reuse them. GVN generates + // significantly better code than EarlyCSE for some of our benchmarks. + if (getOptLevel() == CodeGenOpt::Aggressive) + addPass(createGVNPass()); + else + addPass(createEarlyCSEPass()); + // Both FavorNonGenericAddrSpaces and SeparateConstOffsetFromGEP may leave + // some dead code. We could remove dead code in an ad-hoc manner, but that + // requires manual work and might be error-prone. + // + // The FavorNonGenericAddrSpaces pass shortcuts unnecessary addrspacecasts, + // and leave them unused. + // + // SeparateConstOffsetFromGEP rebuilds a new index from the old index, and the + // old index and some of its intermediate results may become unused. addPass(createDeadCodeEliminationPass()); } -- cgit v1.2.3