llvm/test/Transforms
Wei Mi eafb39b656 [SCEV] Try to reuse existing value during SCEV expansion
Current SCEV expansion will expand SCEV as a sequence of operations
and doesn't utilize the value already existed. This will introduce
redundent computation which may not be cleaned up throughly by
following optimizations.

This patch introduces an ExprValueMap which is a map from SCEV to the
set of equal values with the same SCEV. When a SCEV is expanded, the
set of values is checked and reused whenever possible before generating
a sequence of operations.

The original commit triggered regressions in Polly tests. The regressions
exposed two problems which have been fixed in current version.

1. Polly will generate a new function based on the old one. To generate an
instruction for the new function, it builds SCEV for the old instruction,
applies some tranformation on the SCEV generated, then expands the transformed
SCEV and insert the expanded value into new function. Because SCEV expansion
may reuse value cached in ExprValueMap, the value in old function may be
inserted into new function, which is wrong.
   In SCEVExpander::expand, there is a logic to check the cached value to
be used should dominate the insertion point. However, for the above
case, the check always passes. That is because the insertion point is
in a new function, which is unreachable from the old function. However
for unreachable node, DominatorTreeBase::dominates thinks it will be
dominated by any other node.
   The fix is to simply add a check that the cached value to be used in
expansion should be in the same function as the insertion point instruction.

2. When the SCEV is of scConstant type, expanding it directly is cheaper than
reusing a normal value cached. Although in the cached value set in ExprValueMap,
there is a Constant type value, but it is not easy to find it out -- the cached
Value set is not sorted according to the potential cost. Existing reuse logic
in SCEVExpander::expand simply chooses the first legal element from the cached
value set.
   The fix is that when the SCEV is of scConstant type, don't try the reuse
logic. simply expand it.

Differential Revision: http://reviews.llvm.org/D12090



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259736 91177308-0d34-0410-b5e6-96231b3b80d8
2016-02-04 01:27:38 +00:00
..
ADCE [PM] Port ADCE to the new pass manager 2015-10-30 23:13:18 +00:00
AddDiscriminators Reimplement discriminator assignment algorithm. 2015-11-19 19:53:05 +00:00
AlignmentFromAssumptions Revert "Change memcpy/memset/memmove to have dest and source alignments." 2015-11-19 05:56:52 +00:00
ArgumentPromotion DI: Reverse direction of subprogram -> function edge. 2015-11-05 22:03:56 +00:00
AtomicExpand [IR] Add support for floating pointer atomic loads and stores 2015-12-16 00:49:36 +00:00
BBVectorize Have a single way for creating unique value names. 2015-11-22 00:16:24 +00:00
BDCE Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
BranchFolding Move branch folding test to a better location. 2015-12-03 19:41:25 +00:00
CodeExtractor Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
CodeGenPrepare [InstCombine] Rewrite bswap/bitreverse handling completely. 2016-01-15 09:20:19 +00:00
ConstantHoisting [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
ConstantMerge [opaque pointer type] Add textual IR support for explicit type parameter for global aliases 2015-09-11 03:22:04 +00:00
ConstProp IR: Make ConstantDataArray::getFP actually return a ConstantDataArray 2015-12-09 21:21:07 +00:00
CorrelatedValuePropagation [LVI] Introduce an intersect operation on lattice values 2016-02-02 03:15:40 +00:00
CrossDSOCFI [cfi] Cross-DSO CFI diagnostic mode (LLVM part). 2016-01-25 23:35:03 +00:00
DeadArgElim [OperandBundles] Have DeadArgElim play nice with operand bundles 2015-12-23 09:58:36 +00:00
DeadStoreElimination [BasicAliasAnalysis] Take into account operand bundles in the getModRefInfo function 2016-01-16 12:15:53 +00:00
EarlyCSE Fix several accidental DOS line endings in source files 2016-01-03 17:22:03 +00:00
EliminateAvailableExternally Don't change the visibility when converting a definition to a declaration. 2015-07-13 14:18:22 +00:00
Float2Int [Float2Int] Don't operate on vector instructions 2015-12-09 21:08:18 +00:00
ForcedFunctionAttrs [attrs] Split off the forced attributes utility into its own pass that 2015-12-27 08:13:45 +00:00
FunctionAttrs [attrs] Split the late-revisit pattern for deducing norecurse in 2016-01-08 10:55:52 +00:00
FunctionImport Fix bot failure from r257493: remove extraneous temp file read 2016-01-12 17:53:59 +00:00
GCOVProfiling [GCOV] Avoid emitting profile arcs for module and skeleton CUs 2016-01-21 17:04:42 +00:00
GlobalDCE [opaque pointer type] Add textual IR support for explicit type parameter for global aliases 2015-09-11 03:22:04 +00:00
GlobalOpt Make sure that any new and optimized objects created during GlobalOPT copy all the attributes from the base object. 2016-01-22 21:18:20 +00:00
GVN Fix for two constant propagation problems in GVN with the assume intrinsic 2016-01-21 21:32:35 +00:00
IndVarSimplify [SCEV] Try to reuse existing value during SCEV expansion 2016-02-04 01:27:38 +00:00
InferFunctionAttrs [BasicAA] Remove special casing of memset_pattern16 in favor of generic attribute inference 2016-01-06 04:53:16 +00:00
Inline Avoid inlining call sites in unreachable-terminated block 2016-02-01 20:55:11 +00:00
InstCombine [InstCombine] Revert r238452: Fold IntToPtr and PtrToInt into preceding loads. 2016-02-03 18:04:13 +00:00
InstMerge [opaque pointer type] Add textual IR support for explicit type parameter to gep operator 2015-03-13 18:20:45 +00:00
InstSimplify [InstCombine] Simplify (x >> y) <= x 2016-01-21 18:55:54 +00:00
Internalize [opaque pointer type] Add textual IR support for explicit type parameter for global aliases 2015-09-11 03:22:04 +00:00
IPConstantProp [SCCP] Don't violate the lattice invariants 2016-01-07 21:36:16 +00:00
IRCE [SCEV] Try to reuse existing value during SCEV expansion 2016-02-04 01:27:38 +00:00
JumpThreading [LVI] Introduce an intersect operation on lattice values 2016-02-02 03:15:40 +00:00
LCSSA [WinEH] Update LCSSA to handle catchswitch with handlers inside and outside a loop 2015-12-18 18:12:35 +00:00
LICM [LICM] Keep metadata on control equivalent hoists 2016-01-28 15:51:58 +00:00
LoadCombine [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
LoopDeletion [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
LoopDistribute Allow LLE/LD and the loop versioning infrastructure to use SCEV predicates 2015-11-09 13:26:09 +00:00
LoopIdiom [LIR] Add support for structs and hand unrolled loops 2016-01-26 02:27:47 +00:00
LoopInterchange Add support to interchange loops with reductions. 2015-04-23 04:51:44 +00:00
LoopLoadElim Allow LLE/LD and the loop versioning infrastructure to use SCEV predicates 2015-11-09 13:26:09 +00:00
LoopReroll Enable loopreroll to rerool loop with pointer induction variable. 2016-01-25 19:43:45 +00:00
LoopRotate DI: Reverse direction of subprogram -> function edge. 2015-11-05 22:03:56 +00:00
LoopSimplify DI: Reverse direction of subprogram -> function edge. 2015-11-05 22:03:56 +00:00
LoopSimplifyCFG Add LoopSimplifyCFG pass 2016-01-29 22:35:36 +00:00
LoopStrengthReduce [SCEV] Try to reuse existing value during SCEV expansion 2016-02-04 01:27:38 +00:00
LoopUnroll LoopUnroll: Use the optsize threshold for minsize as well 2016-01-11 22:39:43 +00:00
LoopUnswitch [IR] Reformulate LLVM's EH funclet IR 2015-12-12 05:38:55 +00:00
LoopVectorize [DemandedBits] Revert r249687 due to PR26071 2016-02-03 15:05:06 +00:00
LoopVersioning [LoopVersioning] Expose loop versioning as a pass too 2016-02-03 00:06:10 +00:00
LowerAtomic [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
LowerBitSets [cfi] Fix LowerBitSets on 32-bit targets. 2015-12-21 22:14:04 +00:00
LowerExpectIntrinsic [PM] Port StripDeadPrototypes to the new pass manager 2015-10-30 23:28:12 +00:00
LowerInvoke Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
LowerSwitch Have a single way for creating unique value names. 2015-11-22 00:16:24 +00:00
Mem2Reg [Mem2Reg] Respect optnone 2015-12-11 13:36:59 +00:00
MemCpyOpt Fix PR26051: Memcpy optimization should introduce a call to memcpy before the store destination position 2016-01-06 23:50:22 +00:00
MergeFunc [IR] Remove terminatepad 2015-12-14 18:34:23 +00:00
MetaRenamer Revert "Change memcpy/memset/memmove to have dest and source alignments." 2015-11-19 05:56:52 +00:00
NaryReassociate [NaryReassociate] allow candidate to have a different type 2015-12-18 21:36:30 +00:00
ObjCARC Add support for objc_unsafeClaimAutoreleasedReturnValue to the 2016-01-27 19:05:08 +00:00
PartiallyInlineLibCalls PartiallyInlineLibCalls: Check sqrt result type before transforming it. 2014-08-01 23:21:21 +00:00
PGOProfile [PGO] IR level instrumentation of indirect call value profiling 2016-01-21 18:11:44 +00:00
PhaseOrdering Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
PlaceSafepoints [PlaceSafepoints] Clamp NoStatepoints to true 2016-01-28 21:51:14 +00:00
PruneEH [PruneEH] Don't try to insert a terminator after another terminator 2016-01-23 06:00:44 +00:00
Reassociate Reassociate: Reprocess RedoInsts after each inst 2016-01-26 18:42:36 +00:00
Reg2Mem Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
RewriteStatepointsForGC [RS4GC] Remove unnecessary redirections from tests; NFC 2016-01-29 16:32:30 +00:00
SafeStack [safestack] Make sure the unsafe stack pointer is popped in all cases 2016-02-02 01:03:11 +00:00
SampleProfile SamplePGO - Add initial support for inliner annotations. 2015-11-27 23:14:51 +00:00
Scalarizer DI: Reverse direction of subprogram -> function edge. 2015-11-05 22:03:56 +00:00
ScalarRepl Revert "Change memcpy/memset/memmove to have dest and source alignments." 2015-11-19 05:56:52 +00:00
SCCP [opaque pointer type] Add textual IR support for explicit type parameter for global aliases 2015-09-11 03:22:04 +00:00
SeparateConstOffsetFromGEP [SeparateConstOffsetFromGEP] sext(a)+sext(b) => sext(a+b) when a+b can't sign-overflow. 2015-08-14 02:02:05 +00:00
SimplifyCFG [SimplifyCFG] Fix for "endless" loop after dead code removal (Alternative to 2016-02-03 23:54:25 +00:00
Sink [IR] Reformulate LLVM's EH funclet IR 2015-12-12 05:38:55 +00:00
SLPVectorizer Add test case missing from r259357 (NFC) 2016-02-01 19:09:24 +00:00
SpeculativeExecution Add a speculative execution pass 2015-05-15 17:54:48 +00:00
SROA [SROA] Also insert a bit piece expression if only one piece is needed 2016-01-14 20:06:34 +00:00
StraightLineStrengthReduce [SeparateConstOffsetFromGEP] strengthen the inbounds attribute 2015-08-13 18:48:49 +00:00
StripDeadPrototypes [PM] Port StripDeadPrototypes to the new pass manager 2015-10-30 23:28:12 +00:00
StripSymbols DI: Reverse direction of subprogram -> function edge. 2015-11-05 22:03:56 +00:00
StructurizeCFG AMDGPU: Replace some deprecated intrinsic uses in tests 2016-01-23 05:42:49 +00:00
TailCallElim Push isDereferenceableAndAlignedPointer down into isSafeToLoadUnconditionally 2016-01-17 12:35:29 +00:00
TailDup [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
Util This patch adds MemorySSA to LLVM. 2016-02-02 22:46:49 +00:00