llvm-project/llvm/lib/Analysis
Chandler Carruth 443e57e01d [PM] Teach the CGSCC's CG update utility to more carefully invalidate
analyses when we're about to break apart an SCC.

We can't wait until after breaking apart the SCC to invalidate things:
1) Which SCC do we then invalidate? All of them?
2) Even if we invalidate all of them, a newly created SCC may not have
   a proxy that will convey the invalidation to functions!

Previously we only invalidated one of the SCCs and too late. This led to
stale analyses remaining in the cache. And because the caching strategy
actually works, they would get used and chaos would ensue.

Doing invalidation early is somewhat pessimizing though if we *know*
that the SCC structure won't change. So it turns out that the design to
make the mutation API force the caller to know the *kind* of mutation in
advance was indeed 100% correct and we didn't do enough of it. So this
change also splits two cases of switching a call edge to a ref edge into
two separate APIs so that callers can clearly test for this and take the
easy path without invalidating when appropriate. This is particularly
important in this case as we expect most inlines to be between functions
in separate SCCs and so the common case is that we don't have to so
aggressively invalidate analyses.

The LCG API change in turn needed some basic cleanups and better testing
in its unittest. No interesting functionality changed there other than
more coverage of the returned sequence of SCCs.

While this seems like an obvious improvement over the current state, I'd
like to revisit the core concept of invalidating within the CG-update
layer at all. I'm wondering if we would be better served forcing the
callers to handle the invalidation beforehand in the cases that they
can handle it. An interesting example is when we want to teach the
inliner to *update and preserve* analyses. But we can cross that bridge
when we get there.

With this patch, the new pass manager an build all of the LLVM test
suite at -O3 and everything passes. =D I haven't bootstrapped yet and
I'm sure there are still plenty of bugs, but this gives a nice baseline
so I'm going to increasingly focus on fleshing out the missing
functionality, especially the bits that are just turned off right now in
order to let us establish this baseline.

llvm-svn: 290664
2016-12-28 10:34:50 +00:00
..
AliasAnalysis.cpp [PM] Remove a pointless optimization. 2016-12-27 18:04:11 +00:00
AliasAnalysisEvaluator.cpp Consistently use FunctionAnalysisManager 2016-08-09 00:28:15 +00:00
AliasAnalysisSummary.cpp Update a comment. 2016-08-25 01:29:55 +00:00
AliasAnalysisSummary.h Make some LLVM_CONSTEXPR variables const. NFC. 2016-08-25 01:05:08 +00:00
AliasSetTracker.cpp [AliasSetTracker] Make AST smarter about assume intrinsics that don't actually affect memory. 2016-11-07 14:11:45 +00:00
Analysis.cpp [LCSSA] Perform LCSSA verification only for the current loop nest. 2016-10-28 12:57:20 +00:00
AssumptionCache.cpp Add files I seem to have dropped in my revert (r290086). 2016-12-19 08:32:13 +00:00
BasicAliasAnalysis.cpp [PM] Remove a pointless optimization. 2016-12-27 18:04:11 +00:00
BlockFrequencyInfo.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
BlockFrequencyInfoImpl.cpp [GraphTraits] Replace all NodeType usage with NodeRef 2016-08-22 21:09:30 +00:00
BranchProbabilityInfo.cpp Retry: [BPI] Use a safer constructor to calculate branch probabilities 2016-12-17 01:02:08 +00:00
CFG.cpp Avoid overly large SmallPtrSet/SmallSet 2016-01-30 01:24:31 +00:00
CFGPrinter.cpp [PM] Port CFGViewer and CFGPrinter to the new Pass Manager 2016-09-15 18:35:27 +00:00
CFLAndersAliasAnalysis.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
CFLGraph.h [CFLAA] Check for pointer types in more places. 2016-07-29 01:23:45 +00:00
CFLSteensAliasAnalysis.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
CGSCCPassManager.cpp [PM] Teach the CGSCC's CG update utility to more carefully invalidate 2016-12-28 10:34:50 +00:00
CMakeLists.txt Revert @llvm.assume with operator bundles (r289755-r289757) 2016-12-19 08:22:17 +00:00
CallGraph.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
CallGraphSCCPass.cpp Use StringRef in Pass/PassManager APIs (NFC) 2016-10-01 02:56:57 +00:00
CallPrinter.cpp [CG] Rename the DOT printing pass to actually reference "DOT". 2016-03-10 11:04:40 +00:00
CaptureTracking.cpp [CaptureTracking] Volatile operations capture their memory location 2016-05-26 17:36:22 +00:00
CodeMetrics.cpp Revert @llvm.assume with operator bundles (r289755-r289757) 2016-12-19 08:22:17 +00:00
ConstantFolding.cpp [InstCombiner] Simplify lib calls to `round{,f}` 2016-12-26 14:29:29 +00:00
CostModel.cpp [CostModel] Pass shuffle mask args with ArrayRef. NFCI. 2016-12-21 15:49:01 +00:00
Delinearization.cpp [NFC] Header cleanup 2016-04-18 09:17:29 +00:00
DemandedBits.cpp Revert @llvm.assume with operator bundles (r289755-r289757) 2016-12-19 08:22:17 +00:00
DependenceAnalysis.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
DivergenceAnalysis.cpp DivergenceAnalysis: Fix crash with no return blocks 2016-05-09 16:57:08 +00:00
DomPrinter.cpp Introduce analysis pass to compute PostDominators in the new pass manager. NFC 2016-02-25 17:54:07 +00:00
DominanceFrontier.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
EHPersonalities.cpp [tsan] Add support for C++ exceptions into TSan (call __tsan_func_exit during unwinding), LLVM part 2016-11-14 21:41:13 +00:00
GlobalsModRef.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
IVUsers.cpp Revert @llvm.assume with operator bundles (r289755-r289757) 2016-12-19 08:22:17 +00:00
IndirectCallPromotionAnalysis.cpp Remove another unused variable from r275216 2016-07-12 23:49:17 +00:00
InlineCost.cpp [PM] Provide an initial, minimal port of the inliner to the new pass manager. 2016-12-20 03:15:32 +00:00
InstCount.cpp
InstructionSimplify.cpp Revert @llvm.assume with operator bundles (r289755-r289757) 2016-12-19 08:22:17 +00:00
Interval.cpp Apply clang-tidy's modernize-loop-convert to lib/Analysis. 2016-06-26 17:27:42 +00:00
IntervalPartition.cpp Apply clang-tidy's modernize-loop-convert to lib/Analysis. 2016-06-26 17:27:42 +00:00
IteratedDominanceFrontier.cpp Normalize file docs. NFC. 2016-07-21 20:52:35 +00:00
LLVMBuild.txt Restore "[ThinLTO] Prevent exporting of locals used/defined in module level asm" 2016-11-14 17:12:32 +00:00
LazyBlockFrequencyInfo.cpp [BPI] Add new LazyBPI analysis 2016-07-28 23:31:12 +00:00
LazyBranchProbabilityInfo.cpp [BPI] Add new LazyBPI analysis 2016-07-28 23:31:12 +00:00
LazyCallGraph.cpp [PM] Teach the CGSCC's CG update utility to more carefully invalidate 2016-12-28 10:34:50 +00:00
LazyValueInfo.cpp Revert @llvm.assume with operator bundles (r289755-r289757) 2016-12-19 08:22:17 +00:00
Lint.cpp Revert @llvm.assume with operator bundles (r289755-r289757) 2016-12-19 08:22:17 +00:00
Loads.cpp [Loads] Fix crash in is isDereferenceableAndAlignedPointer() 2016-10-28 15:32:28 +00:00
LoopAccessAnalysis.cpp [LAA] Prevent invalid IR for loop-invariant bound in loop body 2016-12-05 21:25:03 +00:00
LoopInfo.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
LoopPass.cpp [LCSSA] Perform LCSSA verification only for the current loop nest. 2016-10-28 12:57:20 +00:00
LoopPassManager.cpp [PM] Introduce the facilities for registering cross-IR-unit dependencies 2016-12-27 08:40:39 +00:00
LoopUnrollAnalyzer.cpp [LoopUnrollAnalyzer] Handle out of bounds accesses in visitLoad 2016-07-23 02:56:49 +00:00
MemDepPrinter.cpp Apply clang-tidy's modernize-loop-convert to lib/Analysis. 2016-06-26 17:27:42 +00:00
MemDerefPrinter.cpp NFC. Move isDereferenceable to Loads.h/cpp 2016-02-24 12:49:04 +00:00
MemoryBuiltins.cpp [Analysis] Ignore `nobuiltin` on `allocsize` function calls. 2016-12-27 06:32:14 +00:00
MemoryDependenceAnalysis.cpp [PM] Teach MemDep to invalidate its result object when its cached 2016-12-27 19:33:04 +00:00
MemoryLocation.cpp [TLI] Unify LibFunc signature checking. NFCI. 2016-04-27 19:04:35 +00:00
ModuleDebugInfoPrinter.cpp [IR] Remove the DIExpression field from DIGlobalVariable. 2016-12-20 02:09:43 +00:00
ModuleSummaryAnalysis.cpp [ThinLTO] Fix "||" vs "|" mixup. 2016-12-27 17:45:09 +00:00
ObjCARCAliasAnalysis.cpp Consistently use FunctionAnalysisManager 2016-08-09 00:28:15 +00:00
ObjCARCAnalysisUtils.cpp
ObjCARCInstKind.cpp Create llvm.addressofreturnaddress intrinsic 2016-10-12 22:13:19 +00:00
OptimizationDiagnosticInfo.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
OrderedBasicBlock.cpp
PHITransAddr.cpp Revert @llvm.assume with operator bundles (r289755-r289757) 2016-12-19 08:22:17 +00:00
PostDominators.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
ProfileSummaryInfo.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
RegionPass.cpp [RegionPass] Some minor cleanups 2016-07-19 17:50:27 +00:00
RegionPrinter.cpp Apply clang-tidy's modernize-loop-convert to lib/Analysis. 2016-06-26 17:27:42 +00:00
ScalarEvolution.cpp [SCEV] Be less conservative when extending bitwidths for computing ranges. 2016-12-20 23:03:42 +00:00
ScalarEvolutionAliasAnalysis.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
ScalarEvolutionExpander.cpp Revert @llvm.assume with operator bundles (r289755-r289757) 2016-12-19 08:22:17 +00:00
ScalarEvolutionNormalization.cpp Remove emacs mode markers from .cpp files. NFC 2016-04-24 17:55:41 +00:00
ScopedNoAliasAA.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
SparsePropagation.cpp Apply clang-tidy's modernize-loop-convert to lib/Analysis. 2016-06-26 17:27:42 +00:00
StratifiedSets.h Do a sweep over move ctors and remove those that are identical to the default. 2016-10-20 12:20:28 +00:00
TargetLibraryInfo.cpp [SimplifyLibCalls] Lower fls() to llvm.ctlz(). 2016-12-15 23:45:11 +00:00
TargetTransformInfo.cpp [PM] Change the static object whose address is used to uniquely identify 2016-11-23 17:53:26 +00:00
Trace.cpp Annotate dump() methods with LLVM_DUMP_METHOD, addressing Richard Smith r259192 post commit comment. 2016-01-29 20:50:44 +00:00
TypeBasedAliasAnalysis.cpp [TBAA] Don't generate invalid TBAA when merging nodes 2016-12-11 20:07:25 +00:00
TypeMetadataUtils.cpp TypeMetadataUtils: Simplify; spotted by Mehdi. 2016-12-21 19:00:47 +00:00
ValueTracking.cpp Use MaxDepth instead of repeating its value 2016-12-20 19:06:15 +00:00
VectorUtils.cpp IR: Change the gep_type_iterator API to avoid always exposing the "current" type. 2016-12-02 02:24:42 +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))

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