llvm-6502/lib/Analysis
Chris Lattner 4034e14985 teach GVN to widen integer loads when they are overaligned, when doing an
wider load would allow elimination of subsequent loads, and when the wider
load is still a native integer type.  This eliminates a ton of loads on 
various benchmarks involving struct fields, though it is somewhat hobbled
by clang not being very aggressive about field alignment.

This is yet another step along the way towards resolving PR6627.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130390 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-28 07:29:08 +00:00
..
IPA Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
AliasAnalysis.cpp When analyzing functions known to only access argument pointees, 2011-04-27 18:39:03 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp PR9604; try to deal with RAUW updates correctly in the AST. I'm not convinced 2011-04-09 06:55:46 +00:00
Analysis.cpp remove postdom frontiers, because it is dead. Forward dom frontiers are 2011-04-05 21:57:17 +00:00
BasicAliasAnalysis.cpp Teach BasicAA about arm.neon.vld1 and vst1. 2011-04-27 20:44:28 +00:00
CaptureTracking.cpp Don't include Operator.h from InstrTypes.h. 2011-04-11 09:35:34 +00:00
CFGPrinter.cpp
CMakeLists.txt Unbreak CMake build. 2011-03-01 00:02:51 +00:00
ConstantFolding.cpp Don't include Operator.h from InstrTypes.h. 2011-04-11 09:35:34 +00:00
DbgInfoPrinter.cpp Move DbgInfoPrinter specific utlities inside DbgInfoPrinter.cpp 2011-02-15 17:36:11 +00:00
DebugInfo.cpp Remove DIFactory. Patch by Devang. 2011-03-02 20:30:37 +00:00
DIBuilder.cpp Fix an off by one error while accessing complex address element of a DIVariable. 2011-04-26 18:24:39 +00:00
DominanceFrontier.cpp Move DominanceFrontier from VMCore to Analysis. 2011-01-18 06:06:27 +00:00
DomPrinter.cpp
InlineCost.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
InstCount.cpp
InstructionSimplify.cpp Don't include Operator.h from InstrTypes.h. 2011-04-11 09:35:34 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp Avoid creating canonical induction variables for non-native types. 2011-03-18 16:50:32 +00:00
LazyValueInfo.cpp Remove unused STL header includes. 2011-04-23 19:53:52 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp PR9214: Convert ConstantExpr::getIndices() to return an ArrayRef, plus 2011-04-13 15:22:40 +00:00
Loads.cpp Don't include Operator.h from InstrTypes.h. 2011-04-11 09:35:34 +00:00
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp Introduce DebugInfoProbe. This is used to monitor how llvm optimizer is treating debugging information. 2011-03-10 00:21:25 +00:00
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp Add comments for the demanglings. Correct mangled form of operator delete! 2011-03-17 05:20:12 +00:00
MemoryDependenceAnalysis.cpp teach GVN to widen integer loads when they are overaligned, when doing an 2011-04-28 07:29:08 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PathNumbering.cpp Remove unused STL header includes. 2011-04-23 19:53:52 +00:00
PathProfileInfo.cpp Implementation of path profiling. 2011-01-29 01:09:53 +00:00
PathProfileVerifier.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
PHITransAddr.cpp Don't include Operator.h from InstrTypes.h. 2011-04-11 09:35:34 +00:00
PostDominators.cpp remove postdom frontiers, because it is dead. Forward dom frontiers are 2011-04-05 21:57:17 +00:00
ProfileEstimatorPass.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ProfileInfo.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ProfileInfoLoader.cpp Remove unused STL header includes. 2011-04-23 19:53:52 +00:00
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
RegionInfo.cpp Region: Allow user control the printing style of the print function. 2011-04-04 07:19:18 +00:00
RegionPass.cpp
RegionPrinter.cpp RegionPrinter: Ignore back edges when layouting the graph 2011-02-27 04:11:07 +00:00
ScalarEvolution.cpp Corrects an old, old typo in a case that doesn't seem to be reached in practice. 2011-04-27 18:17:36 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp Remove PHINode::reserveOperandSpace(). Instead, add a parameter to 2011-03-30 11:28:46 +00:00
ScalarEvolutionNormalization.cpp Added SCEV::NoWrapFlags to manage unsigned, signed, and self wrap 2011-03-14 16:50:06 +00:00
SparsePropagation.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ValueTracking.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00

Analysis Opportunities:

//===---------------------------------------------------------------------===//

In test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll, the
ScalarEvolution expression for %r is this:

  {1,+,3,+,2}<loop>

Outside the loop, this could be evaluated simply as (%n * %n), however
ScalarEvolution currently evaluates it as

  (-2 + (2 * (trunc i65 (((zext i64 (-2 + %n) to i65) * (zext i64 (-1 + %n) to i65)) /u 2) to i64)) + (3 * %n))

In addition to being much more complicated, it involves i65 arithmetic,
which is very inefficient when expanded into code.

//===---------------------------------------------------------------------===//

In formatValue in test/CodeGen/X86/lsr-delayed-fold.ll,

ScalarEvolution is forming this expression:

((trunc i64 (-1 * %arg5) to i32) + (trunc i64 %arg5 to i32) + (-1 * (trunc i64 undef to i32)))

This could be folded to

(-1 * (trunc i64 undef to i32))

//===---------------------------------------------------------------------===//