llvm-6502/lib/Analysis
Eli Friedman 992205ac71 Add a limit to the number of instructions memdep will scan in a single block. This prevents (at least in some cases) O(N^2) runtime in passes like DSE.
The limit in this patch is probably too high, but it is enough to stop DSE from going completely insane on a testcase I have (which has a single block with around 50,000 non-aliasing stores in it).

rdar://9471075



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133111 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-15 23:59:25 +00:00
..
IPA Teach the CallGraph to ignore calls to intrinsics. 2011-06-09 19:46:27 +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 New BranchProbabilityInfo analysis. Patch by Jakub Staszak! 2011-06-04 01:16:30 +00:00
BasicAliasAnalysis.cpp Initialize BasicAA's AliasCache to set it to use fewer buckets by 2011-06-10 22:30:30 +00:00
BranchProbabilityInfo.cpp Move class into an anonymous namespace. 2011-06-13 18:38:56 +00:00
CaptureTracking.cpp Don't include Operator.h from InstrTypes.h. 2011-04-11 09:35:34 +00:00
CFGPrinter.cpp
CMakeLists.txt New BranchProbabilityInfo analysis. Patch by Jakub Staszak! 2011-06-04 01:16:30 +00:00
ConstantFolding.cpp implement PR9315, constant folding exp2 in terms of pow (since hosts without 2011-05-22 22:22:35 +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 A typedef's context is not the same as type's context. It is the context of typedef decl itself. Use extra parameter to communicate this to DIBuilder. 2011-06-03 17:04:51 +00:00
DominanceFrontier.cpp Move DominanceFrontier from VMCore to Analysis. 2011-01-18 06:06:27 +00:00
DomPrinter.cpp split dom frontier handling stuff out to its own DominanceFrontier header, 2011-01-02 22:09:33 +00:00
InlineCost.cpp Change condition for determining whether a function is small for inlining metrics so that very long functions 2011-05-24 20:22:24 +00:00
InstCount.cpp
InstructionSimplify.cpp The comparision "max(x,y)==x" is equivalent to "x>=y". Since the max is 2011-05-07 16:56:49 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp Update this comment. 2011-05-27 18:42:33 +00:00
LazyValueInfo.cpp llvm.memcpy.* has two distinct associated address spaces; the source address space, and the destination address space. Fix up the interface on MemIntrinsic and MemTransferInst to make this clear, and fix InstructionDereferencesPointer in LazyValueInfo.cpp to use the interface properly. 2011-05-31 20:40:16 +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 Test commit. 2011-06-03 17:15:37 +00:00
LoopDependenceAnalysis.cpp split dom frontier handling stuff out to its own DominanceFrontier header, 2011-01-02 22:09:33 +00:00
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 Add "unknown" results for memdep, which mean "I don't know whether a dependence for the given instruction exists in the given block". This cleans up all the existing hacks in memdep which represent this concept by returning clobber with various unrelated instructions. 2011-06-15 00:47:34 +00:00
MemoryBuiltins.cpp Add comments for the demanglings. Correct mangled form of operator delete! 2011-03-17 05:20:12 +00:00
MemoryDependenceAnalysis.cpp Add a limit to the number of instructions memdep will scan in a single block. This prevents (at least in some cases) O(N^2) runtime in passes like DSE. 2011-06-15 23:59:25 +00:00
ModuleDebugInfoPrinter.cpp
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 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 Minor change: Fix the typo in RegionPass.h and RegionPass.cpp. 2011-05-05 13:59:38 +00:00
RegionPrinter.cpp RegionPrinter: Ignore back edges when layouting the graph 2011-02-27 04:11:07 +00:00
ScalarEvolution.cpp SCEV: missing null check fix for r132360, dragonegg crash. 2011-06-01 19:14:56 +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 Renamed llvm.x86.sse42.crc32 intrinsics; crc64 doesn't exist. 2011-05-26 23:13:19 +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))

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