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Fangrui Song a0c0389ffb [SimplifyLibcalls] Don't replace locked IO (fgetc/fgets/fputc/fputs/fread/fwrite) with unlocked IO (*_unlocked) 
This essentially reverts some of the SimplifyLibcalls part changes of D45736 [SimplifyLibcalls] Replace locked IO with unlocked IO.

C11 7.21.5.2 The fflush function

> If stream is a null pointer, the fflush function performs this flushing action on all streams for which the behavior is defined above.

i.e. fopen'ed FILE* is inherently captured.

POSIX.1-2017 getc_unlocked, getchar_unlocked, putc_unlocked, putchar_unlocked - stdio with explicit client locking

> These functions can safely be used in a multi-threaded program if and only if they are called while the invoking thread owns the ( FILE *) object, as is the case after a successful call to the flockfile() or ftrylockfile() functions.

After a thread fopen'ed a FILE*, when it is calling foobar() which is now replaced by foobar_unlocked(),
if another thread is concurrently calling fflush(0), the behavior is undefined.

C11 7.22.4.4 The exit function

> Next, all open streams with unwritten buffered data are flushed, all open streams are closed, and all files created by the tmpfile function are removed.

The replacement is only feasible if the program is single threaded, or exit or fflush(0) is never called.
See also http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20180528/556615.html
for how the replacement makes libc interceptors difficult to implement.

dalias: in a worst case, it's unbounded data corruption because of concurrent access to pointers
without synchronization.  f->wpos or rpos could get outside of the buffer, thread A could do
f->wpos += j after knowing j is in bounds, while thread B also changes it concurrently.

This can produce exploitable conditions depending on libc internals.

Revert the SimplifyLibcalls part change because the cons obviously
overweigh the pros.  Even when the replacement is feasible, the benefit
is indemonstrable, more so in an application instead of an artificial
glibc benchmark.  Theoretically the replacement could be beneficial when
calling getc_unlocked/putc_unlocked in a loop, but then it is better
using a blocked IO operation and the user is likely aware of that.

The function attribute inference is still useful and thus kept.

Reviewed By: xbolva00

Differential Revision: https://reviews.llvm.org/D75933
 		2020-03-10 11:11:58 -07:00
..
ADCE Migrate function attribute "no-frame-pointer-elim" to "frame-pointer"="all" as cleanups after D56351 2019-12-24 15:57:33 -08:00
AddDiscriminators Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
AggressiveInstCombine [AggressiveInstCombine] Add test with baseline CHECKs for aggressive inst combine for ICmp instruction. 2020-02-12 15:09:38 +02:00
AlignmentFromAssumptions
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ArgumentPromotion [ArgPromo][Tests] Run update_test_checks on all ArgumentPromotion tests 2019-12-14 00:29:38 -06:00
AtomicExpand AMDGPU: Fix copy-pasted test name error 2019-12-11 19:44:47 +05:30
Attributor [Attributor] Deduction based on path exploration 2020-03-09 14:29:26 +09:00
BDCE Clang-trunk Generates Wrong Debug values with -O1 2019-11-21 13:53:10 -08:00
BlockExtractor Revert "Revert "Reland "[Support] make report_fatal_error `abort` instead of `exit`""" 2020-02-13 10:16:06 -08:00
BranchFolding
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CallSiteSplitting
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CalledValuePropagation
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CanonicalizeAliases
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CodeExtractor [LoopExtractor] Convert LoopExtractor from LoopPass to ModulePass 2020-02-09 12:25:21 +02:00
CodeGenPrepare Recommit "[PatternMatch] Match XOR variant of unsigned-add overflow check." 2020-02-23 18:33:18 +00:00
ConstProp [ConstProp] Add test for bitcast to gep fold; NFC 2020-03-04 18:27:20 +01:00
ConstantHoisting Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
ConstantMerge
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Coroutines [Coroutines] Optimized coroutine elision based on reachability 2020-03-05 14:43:50 +08:00
CorrelatedValuePropagation [CVP] Simplify cmp of local phi node 2020-02-26 20:36:41 +01:00
CrossDSOCFI
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DCE [BasicBlockUtils] Add utility to remove redundant dbg.value instrs 2019-12-16 11:41:21 +01:00
DeadArgElim [NFC] Fix trivial typos in comments 2020-01-06 10:50:26 +00:00
DeadStoreElimination Fix DSE miscompile when store is clobbered across loop iterations 2020-02-27 14:43:01 -08:00
DivRemPairs
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EarlyCSE Let EarlyCSE fold equivalent freeze instructions 2020-02-28 20:35:20 +09:00
EliminateAvailableExternally
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EntryExitInstrumenter
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ExpandMemCmp [ExpandMemCmp] Properly constant-fold all compares. 2020-03-09 10:40:52 +01:00
Float2Int
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ForcedFunctionAttrs
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FunctionAttrs [Attributor] Copy or port test cases related to Attributor to` Attributor` test folder 2019-12-02 15:36:29 +00:00
FunctionImport Revert "Revert "Reland "[Support] make report_fatal_error `abort` instead of `exit`""" 2020-02-13 10:16:06 -08:00
GCOVProfiling Revert "Revert "Reland "[Support] make report_fatal_error `abort` instead of `exit`""" 2020-02-13 10:16:06 -08:00
GVN [GVN] Fold equivalent freeze instructions 2020-03-01 07:32:05 +09:00
GVNHoist Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
GVNSink
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GlobalDCE [WPD/VFE] Always emit vcall_visibility metadata for -fwhole-program-vtables 2020-01-23 11:36:01 -08:00
GlobalMerge
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GlobalOpt [Transforms][GlobalSRA] huge array causes long compilation time and huge memory usage. 2020-01-04 16:42:38 +03:00
GlobalSplit [WPD/VFE] Always emit vcall_visibility metadata for -fwhole-program-vtables 2020-01-23 11:36:01 -08:00
GuardWidening Broaden the definition of a "widenable branch" 2019-11-21 10:46:16 -08:00
HardwareLoops Recommit "[HardwareLoops] Optimisation remarks" 2019-11-05 09:06:22 +00:00
HotColdSplit [HotColdSplit] Mark entire function cold when entry block is cold 2020-02-17 15:57:50 -08:00
IPConstantProp [SCCP] Do not mark unknown loads as overdefined. 2020-02-20 22:48:58 +01:00
IRCE [IRCE] Use SCEVExpander to modify loop bound 2020-02-06 12:44:43 +03:00
IndVarSimplify [IndVarSimplify] Extend previous special case for load use instruction to any narrow type loop variant to avoid extra trunc instruction 2020-03-05 16:27:59 -05:00
IndirectBrExpand
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InferAddressSpaces
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InferFunctionAttrs [Attributor] Copy or port test cases related to Attributor to` Attributor` test folder 2019-12-02 15:36:29 +00:00
Inline Devirtualize a call on alloca without waiting for post inline cleanup and next DevirtSCCRepeatedPass iteration. 2020-02-28 09:43:32 -08:00
InstCombine [SimplifyLibcalls] Don't replace locked IO (fgetc/fgets/fputc/fputs/fread/fwrite) with unlocked IO (*_unlocked) 2020-03-10 11:11:58 -07:00
InstMerge
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InstNamer
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InstSimplify [InstSimplify] Simplify calls with "returned" attribute 2020-03-09 18:53:47 +01:00
InterleavedAccess [ARM] Disable VLD4 under MVE 2019-12-08 10:37:29 +00:00
Internalize Reland: Dead Virtual Function Elimination 2019-10-17 09:58:57 +00:00
JumpThreading [JumpThreading] Skip unconditional PredBB when threading jumps through two basic blocks 2020-02-18 11:01:46 -08:00
LCSSA [SSAUpdater] Don't call ValueIsRAUWd upon single use replacement 2020-01-23 15:53:53 +07:00
LICM [LICM] Allow freeze to hoist/sink out of a loop 2020-03-03 12:29:39 +09:00
LoadStoreVectorizer AMDGPU: Don't report 2-byte alignment as fast 2020-02-11 18:35:00 -05:00
LoopDataPrefetch
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LoopDeletion
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LoopDistribute
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LoopFusion [LoopFusion] Move instructions from FC1.GuardBlock to FC0.GuardBlock and 2020-01-30 18:02:22 +00:00
LoopIdiom Revert BCmp Loop Idiom recognition transform (PR43870) 2019-11-02 12:48:03 +03:00
LoopInstSimplify
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LoopInterchange [DA] Delinearization of fixed-size multi-dimensional arrays 2020-02-27 10:29:01 -05:00
LoopLoadElim
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LoopPredication [BasicBlock] fix looping in getPostdominatingDeoptimizeCall 2020-01-17 15:40:02 +03:00
LoopReroll Migrate function attribute "no-frame-pointer-elim" to "frame-pointer"="all" as cleanups after D56351 2019-12-24 15:57:33 -08:00
LoopRotate [Test] Add a regression test for failure introduced by 952ad4701c 2020-03-05 16:32:37 +07:00
LoopSimplify [LoopSimplify] Regenerate test checks; NFC 2020-01-11 11:02:24 +01:00
LoopSimplifyCFG
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LoopStrengthReduce Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
LoopTransformWarning
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LoopUnroll [InstComine] Forego of one-use check in `(X - (X & Y)) --> (X & ~Y)` if Y is a constant 2020-03-06 21:39:07 +03:00
LoopUnrollAndJam [llvm] Make new pass manager's OptimizationLevel a class 2020-01-16 09:00:56 -08:00
LoopUnswitch
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LoopVectorize [InstComine] Forego of one-use check in `(X - (X & Y)) --> (X & ~Y)` if Y is a constant 2020-03-06 21:39:07 +03:00
LoopVersioning
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LoopVersioningLICM
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LowerAtomic
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LowerConstantIntrinsics
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LowerExpectIntrinsic
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LowerGuardIntrinsic
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LowerInvoke
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LowerMatrixIntrinsics [Matrix] Mark matrix memory intrinsics as argmemonly/write|read mem. 2020-02-04 12:32:45 +00:00
LowerSwitch
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LowerTypeTests
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LowerWidenableCondition
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MakeGuardsExplicit
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Mem2Reg
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MemCpyOpt [Transform][MemCpyOpt] Add missing DebugLoc to %tmpbitcast 2020-02-28 15:20:51 +00:00
MergeFunc [NewPM] Port MergeFunctions pass 2020-01-14 20:55:41 +01:00
MergeICmps Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
MetaRenamer
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NameAnonGlobals
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NaryReassociate
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NewGVN Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
ObjCARC [ObjC][ARC] Don't remove autoreleaseRV/retainRV pairs if the call isn't 2020-03-09 13:21:38 -07:00
OpenMP [OpenMP][Opt] Combine `struct ident_t*` during deduplication 2020-02-25 14:07:14 -08:00
PGOProfile [PGO] Attach appropriate funclet operand bundles to value profiling instrumentation calls 2020-01-24 11:20:53 -08:00
PartiallyInlineLibCalls
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PhaseOrdering [InstComine] Forego of one-use check in `(X - (X & Y)) --> (X & ~Y)` if Y is a constant 2020-03-06 21:39:07 +03:00
PlaceSafepoints
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PreISelIntrinsicLowering [ObjC] Override TailCallKind when lowering objc intrinsics 2019-11-11 08:30:06 -08:00
PruneEH
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Reassociate Remove BinaryOperator::CreateFNeg 2020-02-27 09:06:03 -08:00
Reg2Mem
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RewriteStatepointsForGC [RS4GC] Handle uses of extractelement for conversion from vector to scalar base 2020-03-06 16:28:49 -05:00
SCCP [SCCP] Do not mark unknown loads as overdefined. 2020-02-20 22:48:58 +01:00
SLPVectorizer [SLP] Support vectorizing functions provided by vector libs. 2020-03-10 13:10:50 +00:00
SROA SROA: Don't drop atomic load/store alignments (PR45010) 2020-02-28 10:38:40 +01:00
SafeStack Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
SampleProfile Fix test for profile remapper 2020-02-18 17:58:32 -08:00
ScalarizeMaskedMemIntrin/X86
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Scalarizer Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
SeparateConstOffsetFromGEP [SeparateConstOffsetFromGEP] Fix: sext(a) + sext(b) -> sext(a + b) matches add and sub instructions with one another 2020-01-17 12:22:52 -05:00
SimpleLoopUnswitch Revert "[SimpleLoopUnswitch] Fix introduction of UB when hoisted condition may be undef or poison" 2020-02-28 11:10:46 +09:00
SimplifyCFG [SimplifyCFG] Skip merging return blocks if it would break a CallBr. 2020-03-10 14:59:13 +01:00
Sink
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SpeculateAroundPHIs
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SpeculativeExecution
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StraightLineStrengthReduce Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
StripDeadPrototypes
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StripSymbols
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StructurizeCFG StructurizeCFG: simplify phi nodes when possible 2020-03-05 10:33:15 +05:30
SyntheticCountsPropagation
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TailCallElim
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ThinLTOBitcodeWriter ThinLTOBitcodeWriter: drop dso_local when a GlobalVariable is converted to a declaration 2020-03-05 18:09:33 -08:00
TypePromotion/ARM Revert "[ARM][TypePromotion] Enable by default" 2019-12-22 11:27:11 -08:00
Util Fixed [AssumeBundles] Move to IR so it can be used by Analysis 2020-03-10 18:02:39 +01:00
VectorCombine/X86 [VectorCombine] fold extract-extract-op with different extraction indexes 2020-03-08 09:57:55 -04:00
WholeProgramDevirt [WPD] Provide a way to prevent functions from being devirtualized 2020-03-09 14:05:15 +03:00