llvm-6502/lib/Analysis
Bob Wilson 2d5c28da0d Be conservative about allocations that may alias the accessed pointer.
If an allocation has a must-alias relation to the access pointer, we treat it
as a Def.  Otherwise, without this check, the code here was just skipping over
the allocation call and ignoring it.  I noticed this by inspection and don't
have a specific testcase that it breaks, but it seems like we need to treat
a may-alias allocation as a Clobber.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163127 91177308-0d34-0410-b5e6-96231b3b80d8
2012-09-04 03:30:13 +00:00
..
IPA Make MemoryBuiltins aware of TargetLibraryInfo. 2012-08-29 15:32:21 +00:00
AliasAnalysis.cpp Make MemoryBuiltins aware of TargetLibraryInfo. 2012-08-29 15:32:21 +00:00
AliasAnalysisCounter.cpp Persuade GCC that there is nothing worth warning about here (there isn't). 2012-02-05 14:20:11 +00:00
AliasAnalysisEvaluator.cpp Remove unnecessary default cases in switches that cover all enum values. 2012-01-10 16:47:17 +00:00
AliasDebugger.cpp Extend the AliasAnalysis::pointsToConstantMemory interface to allow it 2010-11-08 16:45:26 +00:00
AliasSetTracker.cpp Reduce use list thrashing by using DenseMap's find_as for maps with ValueHandle keys. 2012-06-30 22:37:15 +00:00
Analysis.cpp Profile: set branch weight metadata with data generated from profiling. 2012-08-28 22:21:25 +00:00
BasicAliasAnalysis.cpp Make MemoryBuiltins aware of TargetLibraryInfo. 2012-08-29 15:32:21 +00:00
BlockFrequencyInfo.cpp Add some constantness to BranchProbabilityInfo and BlockFrequnencyInfo. 2011-12-20 20:03:10 +00:00
BranchProbabilityInfo.cpp BranchProb: modify the definition of an edge in BranchProbabilityInfo to handle 2012-08-24 18:14:27 +00:00
CaptureTracking.cpp Fix intendation. 2012-05-10 23:38:07 +00:00
CFGPrinter.cpp Remove all remaining uses of Value::getNameStr(). 2011-11-15 16:27:03 +00:00
CMakeLists.txt Profile: set branch weight metadata with data generated from profiling. 2012-08-28 22:21:25 +00:00
CodeMetrics.cpp A pile of long over-due refactorings here. There are some very, *very* 2012-05-04 00:58:03 +00:00
ConstantFolding.cpp When constant folding GEP expressions, keep the address space information of pointers. 2012-07-30 07:25:20 +00:00
DbgInfoPrinter.cpp Move lib/Analysis/DebugInfo.cpp to lib/VMCore/DebugInfo.cpp and 2012-06-28 00:05:13 +00:00
DominanceFrontier.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
DomPrinter.cpp remove the blank line from previous ci. 2012-02-04 03:18:47 +00:00
InlineCost.cpp PR13095: Give an inline cost bonus to functions using byval arguments. 2012-08-07 11:13:19 +00:00
InstCount.cpp Get rid of static constructors for pass registration. Instead, every pass exposes an initializeMyPassFunction(), which 2010-10-19 17:21:58 +00:00
InstructionSimplify.cpp Fix PR13412, a nasty miscompile due to the interleaved 2012-08-07 10:59:59 +00:00
Interval.cpp
IntervalPartition.cpp Now with fewer extraneous semicolons! 2010-10-07 22:25:06 +00:00
IVUsers.cpp IVUsers should only generate SCEV's for values that are safe to speculate. 2012-07-13 23:33:05 +00:00
LazyValueInfo.cpp Reduce duplicated hash map lookups. 2012-08-22 15:37:57 +00:00
LibCallAliasAnalysis.cpp Now with fewer extraneous semicolons! 2010-10-07 22:25:06 +00:00
LibCallSemantics.cpp Thread const correctness through a bunch of AliasAnalysis interfaces and 2010-08-03 21:48:53 +00:00
Lint.cpp Always compute all the bits in ComputeMaskedBits. 2012-04-04 12:51:34 +00:00
LLVMBuild.txt LLVMBuild: Introduce a common section which currently has a list of the 2011-12-12 22:45:54 +00:00
Loads.cpp enhance jump threading to preserve TBAA information when PRE'ing loads, 2012-03-13 18:07:41 +00:00
LoopDependenceAnalysis.cpp More dead code removal (using -Wunreachable-code) 2012-01-20 21:51:11 +00:00
LoopInfo.cpp Reduce duplicated hash map lookups. 2012-08-22 15:37:57 +00:00
LoopPass.cpp Enable the new LoopInfo algorithm by default. 2012-06-26 04:11:38 +00:00
Makefile
MemDepPrinter.cpp Mark some static arrays as const. 2012-05-24 06:35:32 +00:00
MemoryBuiltins.cpp Make MemoryBuiltins aware of TargetLibraryInfo. 2012-08-29 15:32:21 +00:00
MemoryDependenceAnalysis.cpp Be conservative about allocations that may alias the accessed pointer. 2012-09-04 03:30:13 +00:00
ModuleDebugInfoPrinter.cpp Move lib/Analysis/DebugInfo.cpp to lib/VMCore/DebugInfo.cpp and 2012-06-28 00:05:13 +00:00
NoAliasAnalysis.cpp Use the new addEscapingValue callback to update GlobalsModRef when GVN adds PHIs of GEPs. For the moment, 2011-01-03 23:51:43 +00:00
PathNumbering.cpp Move llvm/Support/TypeBuilder.h -> llvm/TypeBuilder.h. This completes 2012-07-15 23:45:24 +00:00
PathProfileInfo.cpp Implementation of path profiling. 2011-01-29 01:09:53 +00:00
PathProfileVerifier.cpp Remove all remaining uses of Value::getNameStr(). 2011-11-15 16:27:03 +00:00
PHITransAddr.cpp Uniformize the InstructionSimplify interface by ensuring that all routines 2012-03-13 11:42:19 +00:00
PostDominators.cpp remove postdom frontiers, because it is dead. Forward dom frontiers are 2011-04-05 21:57:17 +00:00
ProfileDataLoader.cpp Clean up ProfileDataLoader a bit. 2012-08-31 12:43:07 +00:00
ProfileDataLoaderPass.cpp Cleanups due to feedback. No functionality change. Patch by Alistair. 2012-08-31 05:18:31 +00:00
ProfileEstimatorPass.cpp Fix floating-point divide by zero, in a case where the value was not going to be used anyway. 2012-08-24 00:31:45 +00:00
ProfileInfo.cpp Profile: set branch weight metadata with data generated from profiling. 2012-08-28 22:21:25 +00:00
ProfileInfoLoader.cpp Remove unused private member variables uncovered by the recent changes to clang's -Wunused-private-field. 2012-07-20 22:05:57 +00:00
ProfileInfoLoaderPass.cpp Round 2 of dead private variable removal. 2012-06-06 19:47:08 +00:00
ProfileVerifierPass.cpp Move code into anonymous namespaces. 2011-11-26 23:01:57 +00:00
README.txt When checking whether the special handling for an addrec increment which 2010-04-26 21:46:36 +00:00
RegionInfo.cpp Remove the the block_node_iterator of Region, replace it by the block_iterator. 2012-08-27 13:49:24 +00:00
RegionPass.cpp Remove the the block_node_iterator of Region, replace it by the block_iterator. 2012-08-27 13:49:24 +00:00
RegionPrinter.cpp Rename the Region::block_iterator to Region::block_node_iterator, and 2012-05-04 20:55:23 +00:00
ScalarEvolution.cpp Stay rational; don't assert trying to take the square root of a negative value. 2012-08-01 09:14:36 +00:00
ScalarEvolutionAliasAnalysis.cpp Get rid of static constructors for pass registration. Instead, every pass exposes an initializeMyPassFunction(), which 2010-10-19 17:21:58 +00:00
ScalarEvolutionExpander.cpp Fix a typo (the the => the) 2012-07-23 08:51:15 +00:00
ScalarEvolutionNormalization.cpp More dead code removal (using -Wunreachable-code) 2012-01-20 21:51:11 +00:00
SparsePropagation.cpp Taken into account Duncan's comments for r149481 dated by 2nd Feb 2012: 2012-03-08 07:06:20 +00:00
Trace.cpp Remove all remaining uses of Value::getNameStr(). 2011-11-15 16:27:03 +00:00
TypeBasedAliasAnalysis.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ValueTracking.cpp Fix integer undefined behavior due to signed left shift overflow in LLVM. 2012-08-24 23:29:28 +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))

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