llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-02 22:04:55 +00:00

History

Dan Gohman 8566963713 Make LoopSimplify change conditional branches in loop exiting blocks which branch on undef to branch on a boolean constant for the edge exiting the loop. This helps ScalarEvolution compute trip counts for loops. Teach ScalarEvolution to recognize single-value PHIs, when safe, and ForgetSymbolicName to forget such single-value PHI nodes as apprpriate in ForgetSymbolicName. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97126 91177308-0d34-0410-b5e6-96231b3b80d8		2010-02-25 06:57:05 +00:00
..
IPA	There are two ways of checking for a given type, for example isa<PointerType>(T)	2010-02-16 11:11:14 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp	drop the pass name from the output.	2010-01-22 05:52:51 +00:00
AliasAnalysisEvaluator.cpp	There are two ways of checking for a given type, for example isa<PointerType>(T)	2010-02-16 11:11:14 +00:00
AliasDebugger.cpp	adopt getAdjustedAnalysisPointer in a few more passes.	2010-01-20 20:09:02 +00:00
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp	There are two ways of checking for a given type, for example isa<PointerType>(T)	2010-02-16 11:11:14 +00:00
CaptureTracking.cpp	There are two ways of checking for a given type, for example isa<PointerType>(T)	2010-02-16 11:11:14 +00:00
CFGPrinter.cpp
CMakeLists.txt
ConstantFolding.cpp	Remove the code which constant-folded ptrtoint(inttoptr(x)+c) to	2010-02-23 16:35:41 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp	Use line and column number to distinguish two lexical blocks at the same level.	2010-02-16 21:39:34 +00:00
DomPrinter.cpp
InlineCost.cpp	There are two ways of checking for a given type, for example isa<PointerType>(T)	2010-02-16 11:11:14 +00:00
InstCount.cpp
InstructionSimplify.cpp	Constant-fold certain comparisons with infinity and negative infinity.	2010-02-22 04:06:03 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp	Remove unused variables and parameters.	2010-02-22 04:11:59 +00:00
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
LiveValues.cpp	Fix "the the" and similar typos.	2010-02-10 16:03:48 +00:00
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp	eliminate a bunch more unneeded dynamic_cast's.	2010-01-22 05:37:10 +00:00
Makefile	make -fno-rtti the default unless a directory builds with REQUIRES_RTTI.	2010-01-24 20:43:08 +00:00
MemoryBuiltins.cpp	Fix "the the" and similar typos.	2010-02-10 16:03:48 +00:00
MemoryDependenceAnalysis.cpp	Reapply r97010, the speculative revert failed.	2010-02-24 08:48:04 +00:00
PHITransAddr.cpp	Reapply r97010, the speculative revert failed.	2010-02-24 08:48:04 +00:00
PointerTracking.cpp	There are two ways of checking for a given type, for example isa<PointerType>(T)	2010-02-16 11:11:14 +00:00
PostDominators.cpp
ProfileEstimatorPass.cpp	adopt getAdjustedAnalysisPointer in a few more passes.	2010-01-20 20:09:02 +00:00
ProfileInfo.cpp	adopt getAdjustedAnalysisPointer in a few more passes.	2010-01-20 20:09:02 +00:00
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp	adopt getAdjustedAnalysisPointer in a few more passes.	2010-01-20 20:09:02 +00:00
ProfileVerifierPass.cpp
README.txt
ScalarEvolution.cpp	Make LoopSimplify change conditional branches in loop exiting blocks	2010-02-25 06:57:05 +00:00
ScalarEvolutionAliasAnalysis.cpp	There are two ways of checking for a given type, for example isa<PointerType>(T)	2010-02-16 11:11:14 +00:00
ScalarEvolutionExpander.cpp	Fix SCEVExpander's existing PHI reuse checking to recognize the	2010-02-17 02:39:31 +00:00
SparsePropagation.cpp
Trace.cpp
ValueTracking.cpp	There are two ways of checking for a given type, for example isa<PointerType>(T)	2010-02-16 11:11:14 +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.

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