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llvm-project/llvm/lib/Transforms/Utils
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Sanjay Patel 7756edfa93 [LibCallSimplifier] try harder to fold memcmp with constant arguments 
Try to fold:
memcmp(X, C, ConstantLength) == 0 --> load X == *C

Without this change, we're unnecessarily checking the alignment of the constant data, 
so we miss the transform in the first 2 tests in the patch.

I noted this shortcoming of LibCallSimpifier in one of the recent CGP memcmp expansion 
patches. This doesn't help the example in:
https://bugs.llvm.org/show_bug.cgi?id=34032#c13
...directly, but it's worth short-circuiting more of these simple cases since we're 
already trying to do that.

The benefit of transforming to load+cmp is that existing IR analysis/transforms may
further simplify that code. For example, if the load of the variable is common to 
multiple memcmp calls, CSE can remove the duplicate instructions.

Differential Revision: https://reviews.llvm.org/D36922

llvm-svn: 311333
 		2017-08-21 13:55:49 +00:00
..
ASanStackFrameLayout.cpp [asan] Replace std::to_string with llvm::to_string 2016-10-19 00:16:56 +00:00
AddDiscriminators.cpp [AddDiscriminators] Assign discriminators to MemIntrinsic calls. 2017-04-11 19:07:30 +00:00
BasicBlockUtils.cpp Rename WeakVH to WeakTrackingVH; NFC 2017-05-01 17:07:49 +00:00
BreakCriticalEdges.cpp [Dominators] Teach LoopUnswitch to use the incremental API 2017-08-17 16:45:35 +00:00
BuildLibCalls.cpp Add argmononly attribute to strlen and wcslen, i.e. they only read memory (string) passed to them. 2017-06-18 03:10:26 +00:00
BypassSlowDivision.cpp [KnownBits] Add bit counting methods to KnownBits struct and use them where possible 2017-05-12 17:20:30 +00:00
CMakeLists.txt Recommit r310869, "[InstSimplify][InstCombine] Modify the interface of decomposeBitTestICmp and use it in the InstSimplify" 2017-08-14 21:39:51 +00:00
CloneFunction.cpp [Inliner] Fix a nasty bug when inlining a non-recursive trace of 2017-08-19 06:56:11 +00:00
CloneModule.cpp [Cloning] Move distinct GlobalVariable debug info metadata in CloneModule 2017-08-03 09:23:03 +00:00
CodeExtractor.cpp [CodeExtractor] Remove unneded and commented out debugging stmts. 2017-07-02 00:07:18 +00:00
CtorUtils.cpp [CtorUtils] Modernize. No functional changes intended. 2016-10-22 01:21:24 +00:00
DemoteRegToStack.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
EscapeEnumerator.cpp Suppress all uses of LLVM_END_WITH_NULL. NFC. 2017-05-09 19:31:13 +00:00
Evaluator.cpp [Constants] If we already have a ConstantInt*, prefer to use isZero/isOne/isMinusOne instead of isNullValue/isOneValue/isAllOnesValue inherited from Constant. NFCI 2017-07-06 18:39:47 +00:00
FlattenCFG.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
FunctionComparator.cpp Enhance synchscope representation 2017-07-11 22:23:00 +00:00
FunctionImportUtils.cpp Fix assert from r309278 2017-07-27 15:28:10 +00:00
GlobalStatus.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
ImportedFunctionsInliningStatistics.cpp [ThinLTO] Correct counting of functions in inliner stats 2017-03-24 17:59:06 +00:00
InlineFunction.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
InstructionNamer.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
IntegerDivision.cpp
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LCSSA.cpp [LCSSA] Don't insert tokens into the worklist at all. 2017-04-17 14:32:05 +00:00
LLVMBuild.txt
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LibCallsShrinkWrap.cpp [LibCallsShrinkWrap] Remove an unnecessary class member variable. 2017-04-26 21:28:40 +00:00
Local.cpp Remove the obsolete offset parameter from @llvm.dbg.value 2017-07-28 20:21:02 +00:00
LoopSimplify.cpp [LoopSimplify] Re-instate r306081 with a bug fix w.r.t. indirectbr. 2017-06-25 22:45:31 +00:00
LoopUnroll.cpp [LoopUnroll] Enable option to peel remainder loop 2017-08-14 09:25:26 +00:00
LoopUnrollPeel.cpp [LoopPeeling] Get rid of Phis that become invariant after N steps 2017-04-17 09:52:02 +00:00
LoopUnrollRuntime.cpp [LoopUnroll] Enable option to peel remainder loop 2017-08-14 09:25:26 +00:00
LoopUtils.cpp [LV] Minor savings to Sink casts to unravel first order recurrence 2017-08-15 08:32:59 +00:00
LoopVersioning.cpp [LoopVersioning] Require loop-simplify form for loop versioning. 2016-12-19 17:13:37 +00:00
LowerInvoke.cpp [PM] Port LowerInvoke to the new pass manager 2016-08-12 17:28:27 +00:00
LowerMemIntrinsics.cpp Extend memcpy expansion in Transform/Utils to handle wider operand types. 2017-07-07 02:00:06 +00:00
LowerSwitch.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
Mem2Reg.cpp [Mem2Reg] Remove AliasSetTracker updating logic from the pass. 2017-04-09 20:47:14 +00:00
MetaRenamer.cpp [MetaRenamer] Leave `@main` alone. 2017-08-01 05:14:45 +00:00
ModuleUtils.cpp Suppress all uses of LLVM_END_WITH_NULL. NFC. 2017-05-09 19:31:13 +00:00
NameAnonGlobals.cpp Use StringRef in Pass/PassManager APIs (NFC) 2016-10-01 02:56:57 +00:00
OrderedInstructions.cpp Remove unneeded else from OrderedInstructions::dominates. 2017-06-29 17:01:03 +00:00
PredicateInfo.cpp [DebugCounter] Move the semicolon out of the DEBUG_COUNTER macro and require it to be placed at the end of each use. 2017-08-10 17:48:11 +00:00
PromoteMemoryToRegister.cpp [Mem2Reg] Modernize code a bit. 2017-08-20 14:34:44 +00:00
SSAUpdater.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
SanitizerStats.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
SimplifyCFG.cpp Merge debug info when hoist then-else code to if. 2017-08-16 01:55:26 +00:00
SimplifyIndVar.cpp Re-enable "[IndVars] Canonicalize comparisons between non-negative values and indvars" 2017-07-08 17:17:30 +00:00
SimplifyInstructions.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
SimplifyLibCalls.cpp [LibCallSimplifier] try harder to fold memcmp with constant arguments 2017-08-21 13:55:49 +00:00
SplitModule.cpp
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StripGCRelocates.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
StripNonLineTableDebugInfo.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
SymbolRewriter.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
UnifyFunctionExitNodes.cpp
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Utils.cpp Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
VNCoercion.cpp [IR] Make use of Type::isPtrOrPtrVectorTy/isIntOrIntVectorTy/isFPOrFPVectorTy to shorten code. NFC 2017-07-09 07:04:00 +00:00
ValueMapper.cpp Suppress all uses of LLVM_END_WITH_NULL. NFC. 2017-05-09 19:31:13 +00:00