Fangrui Song adddf2a5ad Revert D71539 "Recommit "[SCEV] Look through single value PHIs."" ... This reverts commit 11dccf8d3aa5d55210f8b886fb21926c7a8353ca. A bootstrapped clang crashes (due to ArrayRef::front called on an empty ArrayRef) when compiling some files. Very strangely, this only reproduces with modules. ``` 13 0x0000564d3349e968 llvm::ArrayRef<llvm::BasicBlock*>::front() const /proc/self/cwd/llvm/include/llvm/ADT/ArrayRef.h:160:7 14 0x0000564d3349e896 llvm::LoopBase<llvm::BasicBlock, llvm::Loop>::getHeader() const /proc/self/cwd/llvm/include/llvm/Analysis/LoopInfo.h:104:50 15 0x0000564d3349fd9d llvm::LoopBase<llvm::BasicBlock, llvm::Loop>::getLoopLatch() const /proc/self/cwd/llvm/include/llvm/Analysis/LoopInfoImpl.h:210:11 16 0x0000564d33593c8a llvm::ScalarEvolution::computeBackedgeTakenCount(llvm::Loop const*, bool) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:6933:15 17 0x0000564d33592ebc llvm::ScalarEvolution::getBackedgeTakenInfo(llvm::Loop const*) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:0:30 18 0x0000564d33593a54 llvm::ScalarEvolution::getBackedgeTakenCount(llvm::Loop const*, llvm::ScalarEvolution::ExitCountKind) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:6487:36 19 0x0000564d32be2402 llvm::ScalarEvolution::getConstantMaxBackedgeTakenCount(llvm::Loop const*) /proc/self/cwd/llvm/include/llvm/Analysis/ScalarEvolution.h:768:5 20 0x0000564d33590807 llvm::ScalarEvolution::getRangeRef(llvm::SCEV const*, llvm::ScalarEvolution::RangeSignHint) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:5495:19 21 0x0000564d320abab7 llvm::ScalarEvolution::getSignedRange(llvm::SCEV const*) /proc/self/cwd/llvm/include/llvm/Analysis/ScalarEvolution.h:840:12 22 0x0000564d335a03aa llvm::ScalarEvolution::isKnownPredicateViaConstantRanges(llvm::CmpInst::Predicate, llvm::SCEV const*, llvm::SCEV const*) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:9239:60 23 0x0000564d33586a80 llvm::ScalarEvolution::isKnownViaNonRecursiveReasoning(llvm::CmpInst::Predicate, llvm::SCEV const*, llvm::SCEV const*) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:10284:60 ```		2020-09-21 17:21:43 -07:00
..
Analysis	Revert D71539 "Recommit "[SCEV] Look through single value PHIs.""	2020-09-21 17:21:43 -07:00
Assembler
Bindings
Bitcode
BugPoint
CodeGen	[AArch64][GlobalISel] Merge selection of vector-vector G_ASHR/G_LSHR and support more cases.	2020-09-21 16:04:52 -07:00
DebugInfo	[CodeGen] [WinException] Only produce handler data at the end of the function if needed	2020-09-21 23:42:59 +03:00
Demangle
Examples
ExecutionEngine
Feature	[DIE] Remove DeadInstEliminationPass	2020-09-21 12:12:25 -07:00
FileCheck
Instrumentation	[ASAN] Properly deal with musttail calls in ASAN	2020-09-18 23:10:34 -07:00
Integer
JitListener
Linker
LTO
MachineVerifier
MC	[PowerPC] Add vector pair load/store instructions and vector pair register class	2020-09-21 10:27:47 -05:00
Object
ObjectYAML
Other
Reduce
SafepointIRVerifier
Support
SymbolRewriter
TableGen
ThinLTO/X86
tools	[llvm-readelf/obj] - Stop printing invalid names for unnamed section symbols.	2020-09-21 13:05:46 +03:00
Transforms	Revert D71539 "Recommit "[SCEV] Look through single value PHIs.""	2020-09-21 17:21:43 -07:00
Unit
Verifier
YAMLParser
.clang-format
CMakeLists.txt	[llvm-objcopy][MachO] Add llvm-bitcode-strip driver	2020-09-18 18:13:05 -07:00
lit.cfg.py	[llvm-objcopy][MachO] Add llvm-bitcode-strip driver	2020-09-18 18:13:05 -07:00
lit.site.cfg.py.in
TestRunner.sh