llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-05 13:09:10 +00:00

History

David Peixotto ea468dddfe Ignore annotation function calls in cost computation The annotation instructions are dropped during codegen and have no impact on size. In some cases, the annotations were preventing the unroller from unrolling a loop because the annotation calls were pushing the cost over the unrolling threshold. Differential Revision: http://reviews.llvm.org/D5335 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218525 91177308-0d34-0410-b5e6-96231b3b80d8		2014-09-26 17:48:40 +00:00
..
IPA	Add functions for finding ephemeral values	2014-09-07 13:49:57 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp	Add a CFL Alias Analysis implementation	2014-09-02 21:43:13 +00:00
AssumptionTracker.cpp	Add an Assumption-Tracking Pass	2014-09-07 12:44:26 +00:00
BasicAliasAnalysis.cpp	Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)	2014-09-07 18:57:58 +00:00
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp
BranchProbabilityInfo.cpp
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp
CFLAliasAnalysis.cpp	[CFLAA] Remove one final initializer list	2014-09-03 00:06:47 +00:00
CGSCCPassManager.cpp
CMakeLists.txt	Add file to CMake build as well.	2014-09-18 00:39:20 +00:00
CodeMetrics.cpp	Add functions for finding ephemeral values	2014-09-07 13:49:57 +00:00
ConstantFolding.cpp
CostModel.cpp
Delinearization.cpp
DependenceAnalysis.cpp
DominanceFrontier.cpp
DomPrinter.cpp
FunctionTargetTransformInfo.cpp	Add a new pass FunctionTargetTransformInfo. This pass serves as a	2014-09-18 00:34:14 +00:00
InstCount.cpp
InstructionSimplify.cpp	InstSimplify: Don't allow (x srem y) urem y -> x srem y	2014-09-17 04:16:35 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
JumpInstrTableInfo.cpp
LazyCallGraph.cpp
LazyValueInfo.cpp	Add two thresholds lvi-overdefined-BB-threshold and lvi-overdefined-threshold	2014-09-22 02:23:05 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp	Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)	2014-09-07 18:57:58 +00:00
LLVMBuild.txt
Loads.cpp
LoopInfo.cpp
LoopPass.cpp	Fix assertion in LICM doFinalization()	2014-09-24 16:48:31 +00:00
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp	Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)	2014-09-07 18:57:58 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp	Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)	2014-09-07 18:57:58 +00:00
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Make use @llvm.assume for loop guards in ScalarEvolution	2014-09-07 21:37:59 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)	2014-09-07 18:57:58 +00:00
ScalarEvolutionNormalization.cpp	Fix typos in comments, NFC	2014-08-29 21:53:01 +00:00
ScopedNoAliasAA.cpp	Add override to overriden virtual methods, remove virtual keywords.	2014-09-03 11:41:21 +00:00
SparsePropagation.cpp
StratifiedSets.h	[CFLAA] And even more MSVC fixes	2014-09-02 23:50:01 +00:00
TargetTransformInfo.cpp	Ignore annotation function calls in cost computation	2014-09-26 17:48:40 +00:00
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Fix an ODR violation consisting of two 'struct Query' in the global namespace.	2014-09-12 08:56:53 +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))

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