llvm/Analysis at 1973b3e2541f95c87e4acb7e134362ff306ec9ed - llvm

RPCSX/llvm

mirror of https://github.com/RPCSX/llvm.git synced 2024-12-11 13:46:13 +00:00

History

Nick Lewycky c14bc77315 Add more analysis of the sign bit of an srem instruction. If the LHS is negative then the result could go either way. If it's provably positive then so is the srem. Fixes PR9343 #7! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127146 91177308-0d34-0410-b5e6-96231b3b80d8		2011-03-07 01:50:10 +00:00
..
IPA
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp	Delete the LiveValues pass. I won't get get back to the project it	2011-02-28 19:37:59 +00:00
BasicAliasAnalysis.cpp
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt	Unbreak CMake build.	2011-03-01 00:02:51 +00:00
ConstantFolding.cpp
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	Today, the language front ends produces llvm.dbg.* intrinsics, used to encode arguments' debug info, in order any way, most of the times. However, if a front end mix-n-matches llvm.dbg.declare and llvm.dbg.value intrinsics to encode debug info for arguments then code generator needs a way to find argument order.	2011-03-01 22:58:13 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
InlineCost.cpp
InstCount.cpp
InstructionSimplify.cpp	Thread comparisons over udiv/sdiv/ashr/lshr exact and lshr nuw/nsw whenever	2011-03-05 05:19:11 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp
Loads.cpp
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PathNumbering.cpp
PathProfileInfo.cpp
PathProfileVerifier.cpp
PHITransAddr.cpp
PostDominators.cpp
ProfileEstimatorPass.cpp
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp	RegionPrinter: Ignore back edges when layouting the graph	2011-02-27 04:11:07 +00:00
ScalarEvolution.cpp
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	When decling to reuse existing expressions that involve casts, ignore	2011-03-04 20:46:46 +00:00
ScalarEvolutionNormalization.cpp
SparsePropagation.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Add more analysis of the sign bit of an srem instruction. If the LHS is negative	2011-03-07 01:50:10 +00:00

README.txt

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))

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