llvm-6502/lib/Analysis
Arnold Schwaighofer 6bf4f67641 CostModel: Add parameter to instruction cost to further classify operand values
On certain architectures we can support efficient vectorized version of
instructions if the operand value is uniform (splat) or a constant scalar.
An example of this is a vector shift on x86.

We can efficiently support

for (i = 0 ; i < ; i += 4)
  w[0:3] = v[0:3] << <2, 2, 2, 2>

but not

for (i = 0; i < ; i += 4)
  w[0:3] = v[0:3] << x[0:3]

This patch adds a parameter to getArithmeticInstrCost to further qualify operand
values as uniform or uniform constant.

Targets can then choose to return a different cost for instructions with such
operand values.

A follow-up commit will test this feature on x86.

radar://13576547

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178807 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-04 23:26:21 +00:00
..
IPA ArrayRef ca accept one element. Simplify code a little bit, also it matches now 2013-03-07 20:01:19 +00:00
AliasAnalysis.cpp Move isKnownNonNull out of AliasAnalysis.h and into ValueTracking.cpp since 2013-01-31 02:40:59 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp Support in AAEvaluator to print alias queries of loads/stores with TBAA tags. 2013-03-22 22:34:41 +00:00
AliasDebugger.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
AliasSetTracker.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
Analysis.cpp Remove -print-dbginfo as it is unused & bitrotten. 2013-03-08 18:17:46 +00:00
BasicAliasAnalysis.cpp BasicAA: Only query twice if the result of the more general query was MayAlias 2013-03-26 18:07:53 +00:00
BlockFrequencyInfo.cpp
BranchProbabilityInfo.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
CaptureTracking.cpp Remove unneeded #includes. Use forward declarations instead. 2013-03-10 00:34:01 +00:00
CFGPrinter.cpp
CMakeLists.txt Remove -print-dbginfo as it is unused & bitrotten. 2013-03-08 18:17:46 +00:00
CodeMetrics.cpp Begin fleshing out an interface in TTI for modelling the costs of 2013-01-22 11:26:02 +00:00
ConstantFolding.cpp Constant fold vector bitcasts of halves similarly to how floats and doubles are folded. Test case included. 2013-02-26 22:51:07 +00:00
CostModel.cpp CostModel: Add parameter to instruction cost to further classify operand values 2013-04-04 23:26:21 +00:00
DependenceAnalysis.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
InstructionSimplify.cpp Identify and simplify idempotent intrinsics. Test case included. 2013-02-07 19:26:05 +00:00
Interval.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
IntervalPartition.cpp
IVUsers.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
LazyValueInfo.cpp Move isKnownNonNull out of AliasAnalysis.h and into ValueTracking.cpp since 2013-01-31 02:40:59 +00:00
LibCallAliasAnalysis.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
LibCallSemantics.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
Lint.cpp Change GetPointerBaseWithConstantOffset's DataLayout argument from a 2013-01-31 02:00:45 +00:00
LLVMBuild.txt
Loads.cpp Change GetPointerBaseWithConstantOffset's DataLayout argument from a 2013-01-31 02:00:45 +00:00
LoopInfo.cpp Metadata for annotating loops as parallel. The first consumer for this 2013-02-13 18:08:57 +00:00
LoopPass.cpp
Makefile
MemDepPrinter.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
MemoryBuiltins.cpp Early exit from getAllocationData() and isFreeCall() for intrinsics. 2013-03-08 21:15:00 +00:00
MemoryDependenceAnalysis.cpp Fix loop style 2013-03-29 18:48:42 +00:00
ModuleDebugInfoPrinter.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
NoAliasAnalysis.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PathNumbering.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PathProfileInfo.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PathProfileVerifier.cpp Build fixes for STLPort + GCC 2013-03-29 18:48:45 +00:00
PHITransAddr.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PostDominators.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
ProfileDataLoader.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
ProfileDataLoaderPass.cpp Revert "Add LLVMContext::emitWarning methods and use them. <rdar://problem/12867368>" 2013-02-08 21:48:29 +00:00
ProfileEstimatorPass.cpp
ProfileInfo.cpp Build fixes for STLPort + GCC 2013-03-29 18:48:45 +00:00
ProfileInfoLoader.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
ProfileInfoLoaderPass.cpp Revert "Add LLVMContext::emitWarning methods and use them. <rdar://problem/12867368>" 2013-02-08 21:48:29 +00:00
ProfileVerifierPass.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp Fix SCEV forgetMemoizedResults should search and destroy backedge exprs. 2013-03-26 03:14:53 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp SCEVExpander fix. RAUW needs to update the InsertedExpressions cache. 2013-01-14 21:00:37 +00:00
ScalarEvolutionNormalization.cpp
SparsePropagation.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
TargetTransformInfo.cpp CostModel: Add parameter to instruction cost to further classify operand values 2013-04-04 23:26:21 +00:00
Trace.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
TypeBasedAliasAnalysis.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
ValueTracking.cpp Check whether a pointer is non-null (isKnownNonNull) in isKnownNonZero. 2013-03-18 21:23:25 +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))

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