llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-09-15 11:57:30 +00:00

History

Duncan Sands 6dc9e2bf74 Reapply commit 143214 with a fix: m_ICmp doesn't match conditions with the given predicate, it matches any condition and returns the predicate - d'oh! Original commit message: The expression icmp eq (select (icmp eq x, 0), 1, x), 0 folds to false. Spotted by my super-optimizer in 186.crafty and 450.soplex. We really need a proper infrastructure for handling generalizations of this kind of thing (which occur a lot), however this case is so simple that I decided to go ahead and implement it directly. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143318 91177308-0d34-0410-b5e6-96231b3b80d8		2011-10-30 19:56:36 +00:00
..
IPA	Simplify; no intended functional change.	2011-10-20 03:23:14 +00:00
AliasAnalysis.cpp	Enhance alias analysis for atomic instructions a bit. Upgrade a couple alias-analysis tests to the new atomic instructions.	2011-09-26 20:15:28 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp	Remove the old atomic instrinsics. autoupgrade functionality is included with this patch.	2011-10-06 23:20:49 +00:00
BlockFrequencyInfo.cpp	Add pass printing support to BlockFrequencyInfo pass. The implementation	2011-10-19 10:12:41 +00:00
BranchProbabilityInfo.cpp	Fix the API usage in loop probability heuristics. It was incorrectly	2011-10-25 09:47:41 +00:00
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt
ConstantFolding.cpp
DbgInfoPrinter.cpp	Fix for DbgInfoPrinter.cpp:174:12: warning: ‘LineNo’ may be used uninitialized in this function.	2011-09-21 23:34:23 +00:00
DebugInfo.cpp	Update DebugInfoFinder to match recent debug info encoding changes.	2011-10-17 22:30:34 +00:00
DIBuilder.cpp	Add a new wrapper node for a DILexicalBlock that encapsulates it and a	2011-10-11 22:59:11 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
InlineCost.cpp	A FIXME about block addresses and indirectbr.	2011-10-20 04:05:33 +00:00
InstCount.cpp
InstructionSimplify.cpp	Reapply commit 143214 with a fix: m_ICmp doesn't match conditions	2011-10-30 19:56:36 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp	Slightly more useful tracing.	2011-10-13 17:06:38 +00:00
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp
Loads.cpp
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp
Makefile
MemDepPrinter.cpp	Enhance the memdep interface so that users can tell the difference between a dependency which cannot be calculated and a path reaching the entry point of the function. This patch introduces isNonFuncLocal, which replaces isUnknown in some cases.	2011-10-13 22:14:57 +00:00
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp	Enhance the memdep interface so that users can tell the difference between a dependency which cannot be calculated and a path reaching the entry point of the function. This patch introduces isNonFuncLocal, which replaces isUnknown in some cases.	2011-10-13 22:14:57 +00:00
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
ScalarEvolution.cpp	Restore commits 142790 and 142843 - they weren't breaking the build	2011-10-25 12:28:52 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	Fix SCEVExpander assert during LSR: "argument of incompatible type".	2011-10-15 06:19:55 +00:00
ScalarEvolutionNormalization.cpp	Fix memory corruption I introduced a few checkins ago.	2011-10-13 18:49:23 +00:00
SparsePropagation.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	A shift of a power of two is a power of two or zero.	2011-10-28 18:30:05 +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))

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