llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-13 21:05:16 +00:00

History

Chris Lattner fe8c7c807c teach libanalysis to fold int and fp loads from almost arbitrary non-type-safe constant initializers. This sort of thing happens quite a bit for 4-byte loads out of string constants, unions, bitfields, and an interesting endianness check from sqlite, which is something like this: const int sqlite3one = 1; # define SQLITE_BIGENDIAN ((char )(&sqlite3one)==0) # define SQLITE_LITTLEENDIAN ((char )(&sqlite3one)==1) # define SQLITE_UTF16NATIVE (SQLITE_BIGENDIAN?SQLITE_UTF16BE:SQLITE_UTF16LE) all of these macros now constant fold away. This implements PR3152 and is based on a patch started by Eli, but heavily modified and extended. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84936 91177308-0d34-0410-b5e6-96231b3b80d8		2009-10-23 06:23:49 +00:00
..
IPA	Remove MallocInst from LLVM Instructions.	2009-10-17 01:18:07 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp	inline isGEP away.	2009-10-17 23:48:54 +00:00
CaptureTracking.cpp
CFGPrinter.cpp	make DOTGraphTraits public, patch by Tobias Grosser!	2009-10-18 04:09:11 +00:00
CMakeLists.txt	add function passes for printing various dominator datastructures	2009-10-18 04:10:40 +00:00
ConstantFolding.cpp	teach libanalysis to fold int and fp loads from almost arbitrary	2009-10-23 06:23:49 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp
DomPrinter.cpp	fix the other issue with ID's, hopefully really fixing the linux build.	2009-10-18 04:58:34 +00:00
InlineCost.cpp	Remove MallocInst from LLVM Instructions.	2009-10-17 01:18:07 +00:00
InstCount.cpp	Remove MallocInst from LLVM Instructions.	2009-10-17 01:18:07 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
LiveValues.cpp
LoopDependenceAnalysis.cpp
LoopInfo.cpp	Fix another place that calls Loop::contains a lot to construct a sorted	2009-10-20 20:41:13 +00:00
LoopPass.cpp
Makefile
MallocHelper.cpp
MemoryDependenceAnalysis.cpp
PointerTracking.cpp
PostDominators.cpp
ProfileEstimatorPass.cpp
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
ScalarEvolution.cpp
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
SparsePropagation.cpp
Trace.cpp
ValueTracking.cpp	Remove MallocInst from LLVM Instructions.	2009-10-17 01:18:07 +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.

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