Chris Lattner 9e59c64c14 Implement initial support for PHI translation in memdep. This means that ... memdep keeps track of how PHIs affect the pointer in dep queries, which allows it to eliminate the load in cases like rle-phi-translate.ll, which basically end up being: BB1: X = load P br BB3 BB2: Y = load Q br BB3 BB3: R = phi [P] [Q] load R turning "load R" into a phi of X/Y. In addition to additional exposed opportunities, this makes memdep safe in many cases that it wasn't before (which is required for load PRE) and also makes it substantially more efficient. For example, consider: bb1: // has many predecessors. P = some_operator() load P In this example, previously memdep would scan all the predecessors of BB1 to see if they had something that would mustalias P. In some cases (e.g. test/Transforms/GVN/rle-must-alias.ll) it would actually find them and end up eliminating something. In many other cases though, it would scan and not find anything useful. MemDep now stops at a block if the pointer is defined in that block and cannot be phi translated to predecessors. This causes it to miss the (rare) cases like rle-must-alias.ll, but makes it faster by not scanning tons of stuff that is unlikely to be useful. For example, this speeds up GVN as a whole from 3.928s to 2.448s (60%)!. IMO, scalar GVN should be enhanced to simplify the rle-must-alias pointer base anyway, which would allow the loads to be eliminated. In the future, this should be enhanced to phi translate through geps and bitcasts as well (as indicated by FIXMEs) making memdep even more powerful. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61022 91177308-0d34-0410-b5e6-96231b3b80d8		2008-12-15 03:35:32 +00:00
..
IPA	reapply Sanjiv's patch to genericize memcpy/memset/memmove to take an	2008-11-21 16:42:48 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp	Allow basicaa to walk through geps with identical indices in	2008-12-10 01:04:47 +00:00
CFGPrinter.cpp	Rationalize the names of passes that print information:	2008-09-23 12:47:39 +00:00
CMakeLists.txt	add new file	2008-11-10 02:58:28 +00:00
ConstantFolding.cpp	Fix whitespace in comment.	2008-12-15 01:35:36 +00:00
DebugInfo.cpp	Fix getFieldAs() to use the parameter instead of 6.	2008-12-13 08:25:29 +00:00
EscapeAnalysis.cpp	Trim #includes.	2008-10-16 20:18:31 +00:00
InstCount.cpp
Interval.cpp
IntervalPartition.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
LoopInfo.cpp
LoopPass.cpp
LoopVR.cpp	Avoid crashing if instruction is not part of a loop.	2008-10-27 10:18:45 +00:00
Makefile
MemoryDependenceAnalysis.cpp	Implement initial support for PHI translation in memdep. This means that	2008-12-15 03:35:32 +00:00
PostDominators.cpp
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ScalarEvolution.cpp	Revert my re-instated reverted commit, fixes the bootstrap build on x86-64 linux.	2008-12-12 17:09:07 +00:00
ScalarEvolutionExpander.cpp	Add a new SCEV representing signed division.	2008-12-02 08:05:48 +00:00
SparsePropagation.cpp
Trace.cpp
ValueTracking.cpp	Re-apply 55137 with fixes.	2008-10-27 23:24:03 +00:00