llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-19 17:33:29 +00:00

History

Andrew Trick b12a754cce Added isValidRewrite() to check the result of ScalarEvolutionExpander. SCEV may generate expressions composed of multiple pointers, which can lead to invalid GEP expansion. Until we can teach SCEV to follow strict pointer rules, make sure no bad GEPs creep into IR. Fixes rdar://problem/9038671. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127839 91177308-0d34-0410-b5e6-96231b3b80d8		2011-03-17 23:51:11 +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	convert ConstantVector::get to use ArrayRef.	2011-02-15 00:14:00 +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	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	Fix two cases I forgot to update when doing a mental "getSwappedPredicate".	2011-03-09 08:20:06 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp
Loads.cpp
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
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	Added isValidRewrite() to check the result of ScalarEvolutionExpander.	2011-03-17 23:51:11 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	Added SCEV::NoWrapFlags to manage unsigned, signed, and self wrap	2011-03-14 16:50:06 +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
ValueTracking.cpp	Teach ComputeMaskedBits about sub nsw.	2011-03-12 17:18:11 +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))

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