Changes

[libcxx] [test] Don't assert that moved-from containers with non-POCMA
allocators are empty.

[LICM] NFC. Remove AST caching infrastructure
Since LICM doesn't use AST caching any more (see D73081), this 
infrastructure is now obsolete and we can remove it.
Reviewers: asbirlea, fhahn, efriedma, reames
Reviewed-By: asbirlea
Differential Revision: https://reviews.llvm.org/D73084

[DWARF] Allow empty address range tables.
Empty address range tables are allowed by the DWARF standard; Moreover,
generating them is recommended as a best practice, see 
http://wiki.dwarfstd.org/index.php?title=Best_Practices#Generating_.debug_aranges_data
Differential Revision: https://reviews.llvm.org/D71931

[DWARF] Return Error from DWARFDebugArangeSet::extract().
This helps to detect and report parsing errors better. The patch follows
the ideas of LLDB's patches D59370 and D59381.
It adds tests for valid and some invalid cases. More checks and tests to
come. Note that the patch fixes validation of the Length field because
the value does not include the field itself.
The existing users are updated to show the error messages.
Differential Revision: https://reviews.llvm.org/D71875

[DWARF] Make dwarf::getUnitLengthFieldByteSize() constexpr. NFC.
This will help make some expressions in upcoming patches constexpr.
Differential Revision: https://reviews.llvm.org/D73036

[DWARF] Make dwarf::getDwarfOffsetByteSize() a free function. NFC.
This will help simplify code in upcoming patches and make some 
expressions constexpr.
Differential Revision: https://reviews.llvm.org/D73039

[DWARF] Support DWARF64 in DWARFDebugArangeSet.
This allows parsing Address Range Tables in the 64-bit DWARF format.
Differential Revision: https://reviews.llvm.org/D71876

[DWARF] Better detect errors in Address Range Tables.
The patch tries to cover most remaining cases of wrong data.
Differential Revision: https://reviews.llvm.org/D71932

[gn build] Port dcff3961c2d

Fix build bot failures.
Unfortunately, not all compilers allow using llvm_unreachable in a
constexpr function.

NFC. Remove obsolete SimpleAnalysis infrastructure
Apparently cache of AliasSetTrackers held by LICM was the only user of 
SimpleAnalysis infrastructure. Now, given that we no longer have that 
cache, this infrastructure is obsolete and, taking into account its 
nature, we don't want any new solutions to be based on it.
Reviewers: asbirlea, fhahn, efriedma, reames
Reviewed-By: asbirlea
Differential Revision: https://reviews.llvm.org/D73085

NFC. Add PR44320 IR test case.

[lldb/Test] Don't add a check-* target as dependency in
add_lit_testsuite
This causes the toplevel "test-depends" target, which should only build 
all the dependencies necessary for running tests, to suddenaly also run 
the check-lldb-repro-capture tests.
Instead add check-lldb-repro-capture as a dependency to check-lldb-repro 
with a separate explicit add_dependencies call.

[Concepts] Profile TypeConstraints in ProfileTemplateParameterList
Profile TypeConstraints in ProfileTemplateParameterList so we can
distinguish between partial specializations which differ in their
TemplateParameterList type constraints

[DWARF] Support 64-bit DWARF in .debug_pubnames and similar tables.
Differential Revision: https://reviews.llvm.org/D73103

Revert "[Concepts] Profile TypeConstraints in
ProfileTemplateParameterList"
This temporarily reverts commit 0e3ae353a47273825cd2f20f4777dcb5731cf8ec
because of a potential bug.

[Concepts] Profile TypeConstraints in ProfileTemplateParameterList
Profile TypeConstraints in ProfileTemplateParameterList so we can
distinguish between partial specializations which differ in their
TemplateParameterList type constraints.
Recommit, now profiling the IDC so that we can deal with situations
where the TemplateArgsAsWritten are nullptr (happens when canonicalizing
type constraints).

[DWARF] Get rid of DWARFDebugNames::HeaderPOD. NFC.
This structure was used to get the size of the fixed-size part of a Name 
Index header for 32-bit DWARF. It is unsuitable for 64-bit DWARF because 
the size of the unit length field is different.
Differential Revision: https://reviews.llvm.org/D73040

[DWARF] Eliminate the DWARFDebugNames::Header::Padding field.
The padding field is reserved for DWARF and does not contain any useful 
information. No need to read, store and report it.
Differential Revision: https://reviews.llvm.org/D73042

[SSAUpdater] Don't call ValueIsRAUWd upon single use replacement
It is incorrect to call ValueHandleBase::ValueIsRAUWd when only one use 
is replaced since it simply violates semantics of the callback and leads 
to bugs like PR44320.
Previously this call was used specifically to keep LICM's cache of 
AliasSetTrackers up to date across passes (as PR36801 showed, even for 
that purpose it didn't work properly), but since LICM doesn't have that 
cache anymore, we can safely remove this incorrect call with no 
repercussions.
This patch fixes https://bugs.llvm.org/show_bug.cgi?id=44320
Reviewers: asbirlea, fhahn, efriedma, reames
Reviewed-By: asbirlea
Differential Revision: https://reviews.llvm.org/D73089

[LLD][COFF] Enable linking of __declspec(selectany) symbols from Clang
and GCC
When annotating a symbol with __declspec(selectany), Clang assigns it 
comdat 2 while GCC assigns it comdat 3. This patch enables two object 
files that contain a __declspec(selectany) symbol, one created by gcc 
and the other by clang, to be linked together instead of issuing a 
duplicate symbol error.
Differential Revision: https://reviews.llvm.org/D73139

[llvm-exegesis] Restrict to allowed back-to-back instructions in
SerialSnippetGenerator.
Summary: Followup to D73161.
Reviewers: gchatelet, mstojanovic
Subscribers: tschuett, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73256

[lldb][NFC] Rename ClangASTContext to TypeSystemClang
Summary: This commit renames ClangASTContext to TypeSystemClang to
better reflect what this class is actually supposed to do
(implement the TypeSystem interface for Clang). It also gets rid of the
very confusing situation that we have both a
`clang::ASTContext` and a `ClangASTContext` in clang (which sometimes
causes Clang people to think I'm fiddling with Clang's ASTContext when
I'm actually just doing LLDB work).
I also have plans to potentially have multiple clang::ASTContext
instances associated with one ClangASTContext so the ASTContext naming
will then become even more confusing to people.
Reviewers: #lldb, aprantl, shafik, clayborg, labath, JDevlieghere,
davide, espindola, jdoerfert, xiaobai
Reviewed By: clayborg, labath, xiaobai
Subscribers: wuzish, emaste, nemanjai, mgorny, kbarton, MaskRay,
arphaman, jfb, usaxena95, jingham, xiaobai, abidh, JDevlieghere,
lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D72684

[Object][test] - Remove readobj-elf-versioning.test and support files.
`readobj-elf-versioning.test` was added in rL152436 and checks how
llvm-readobj --dyn-syms prints versioned symbols. We test the same in
`llvm-readobj\ELF\dyn-symbols.test` currently.
This patch removes the test and 4 more support files from Inputs.
Differential revision: https://reviews.llvm.org/D73163

[llvm-readobj][test] - Add a check for --dyn-syms.
We have a `-dyn-symbols` option. It has a `--dyn-syms` alias that is not
tested in llvm-readobj tests currently.
There was a Object/readobj-elf-versioning.test where it is used, but
I've removed it in D73163. And also it is not the right place to test it
anyways.
Differential revision: https://reviews.llvm.org/D73164

[test] Avoid loop-unroll.c test getting confused by fadd in git revision
Differential Revision: https://reviews.llvm.org/D73162

[lldb][NFC] Delete empty file source/Host/linux/ProcessLauncherLinux.cpp
This was renamed in 816ae4b0dfac9a2bd964e8c4dae6dd7183ceb92a but it
seems the commit only emptied the file instead of deleting it.

Revert "[Concepts] Placeholder constraints and abbreviated templates"
This reverts commit e57a9abc4b01fa69fe81ace8df70517983b6cbac.
Parser/cxx2a-placeholder-type-constraint.cpp has MSan failures.
Present at 7b81c3f8793d30a4285095a9b67dcfca2117916c: 
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap-msan/builds/17133/steps/check-clang%20msan/logs/stdio 
not present at eaa594f4ec54eba52b03fd9f1c789b214c66a753: 
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap-msan/builds/17132/steps/check-clang%20msan/logs/stdio
Stack trace:
```
==57032==WARNING: MemorySanitizer: use-of-uninitialized-value
   #0 0xccfe016 in clang::AutoTypeLoc::getLocalSourceRange() const
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/include/clang/AST/TypeLoc.h:2036:19
   #1 0xcc56758 in CheckDeducedPlaceholderConstraints(clang::Sema&,
clang::AutoType const&, clang::AutoTypeLoc, clang::QualType)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Sema/SemaTemplateDeduction.cpp:4505:56
   #2 0xcc550ce in clang::Sema::DeduceAutoType(clang::TypeLoc,
clang::Expr*&, clang::QualType&, llvm::Optional<unsigned int>, bool)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Sema/SemaTemplateDeduction.cpp:4707:11
   #3 0xcc52407 in clang::Sema::DeduceAutoType(clang::TypeSourceInfo*,
clang::Expr*&, clang::QualType&, llvm::Optional<unsigned int>, bool)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Sema/SemaTemplateDeduction.cpp:4457:10
   #4 0xba38332 in
clang::Sema::deduceVarTypeFromInitializer(clang::VarDecl*,
clang::DeclarationName, clang::QualType, clang::TypeSourceInfo*,
clang::SourceRange, bool, clang::Expr*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Sema/SemaDecl.cpp:11351:7
   #5 0xba3a8a9 in
clang::Sema::DeduceVariableDeclarationType(clang::VarDecl*, bool,
clang::Expr*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Sema/SemaDecl.cpp:11385:26
   #6 0xba3c520 in clang::Sema::AddInitializerToDecl(clang::Decl*,
clang::Expr*, bool)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Sema/SemaDecl.cpp:11725:9
   #7 0xb39c498 in
clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&,
clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/ParseDecl.cpp:2399:17
   #8 0xb394d80 in
clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&,
clang::DeclaratorContext, clang::SourceLocation*,
clang::Parser::ForRangeInit*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/ParseDecl.cpp:2128:21
   #9 0xb383bbf in
clang::Parser::ParseSimpleDeclaration(clang::DeclaratorContext,
clang::SourceLocation&, clang::Parser::ParsedAttributesWithRange&, bool,
clang::Parser::ForRangeInit*, clang::SourceLocation*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/ParseDecl.cpp:1848:10
   #10 0xb383129 in
clang::Parser::ParseDeclaration(clang::DeclaratorContext,
clang::SourceLocation&, clang::Parser::ParsedAttributesWithRange&,
clang::SourceLocation*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/llvm/include/llvm/ADT/PointerUnion.h
   #11 0xb53a388 in
clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*,
32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*,
clang::Parser::ParsedAttributesWithRange&)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/ParseStmt.cpp:221:13
   #12 0xb539309 in
clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*,
32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/ParseStmt.cpp:106:20
   #13 0xb55610e in clang::Parser::ParseCompoundStatementBody(bool)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/ParseStmt.cpp:1079:11
   #14 0xb559529 in
clang::Parser::ParseFunctionStatementBody(clang::Decl*,
clang::Parser::ParseScope&)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/ParseStmt.cpp:2204:21
   #15 0xb33c13e in
clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&,
clang::Parser::ParsedTemplateInfo const&,
clang::Parser::LateParsedAttrList*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/Parser.cpp:1339:10
   #16 0xb394703 in
clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&,
clang::DeclaratorContext, clang::SourceLocation*,
clang::Parser::ForRangeInit*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/ParseDecl.cpp:2068:11
   #17 0xb338e52 in
clang::Parser::ParseDeclOrFunctionDefInternal(clang::Parser::ParsedAttributesWithRange&,
clang::ParsingDeclSpec&, clang::AccessSpecifier)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/Parser.cpp:1099:10
   #18 0xb337674 in
clang::Parser::ParseDeclarationOrFunctionDefinition(clang::Parser::ParsedAttributesWithRange&,
clang::ParsingDeclSpec*, clang::AccessSpecifier)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/Parser.cpp:1115:12
   #19 0xb334a96 in
clang::Parser::ParseExternalDeclaration(clang::Parser::ParsedAttributesWithRange&,
clang::ParsingDeclSpec*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/Parser.cpp:935:12
   #20 0xb32f12a in
clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&,
bool)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/Parser.cpp:686:12
   #21 0xb31e193 in clang::ParseAST(clang::Sema&, bool, bool)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Parse/ParseAST.cpp:158:20
   #22 0x80263f0 in clang::FrontendAction::Execute()
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Frontend/FrontendAction.cpp:936:8
   #23 0x7f2a257 in
clang::CompilerInstance::ExecuteAction(clang::FrontendAction&)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:965:33
   #24 0x8288bef in
clang::ExecuteCompilerInvocation(clang::CompilerInstance*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:290:25
   #25 0xad44c2 in cc1_main(llvm::ArrayRef<char const*>, char const*,
void*)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/tools/driver/cc1_main.cpp:239:15
   #26 0xacd76a in ExecuteCC1Tool(llvm::ArrayRef<char const*>)
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/tools/driver/driver.cpp:325:12
   #27 0xacc9fd in main
/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm-project/clang/tools/driver/driver.cpp:398:12
   #28 0x7f7d82cdb2e0 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x202e0)
   #29 0xa4dde9 in _start
(/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build_msan/bin/clang-11+0xa4dde9)
```

[llvm-exegesis] Allow the randomizer to fail nicely...
Summary:
... instead of crashing. On typical exmaple is when there are no
available registers.
Reviewers: gchatelet
Subscribers: tschuett, mstojanovic, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73196

[mlir] Shrink-wrap anonymous namespaces around the classes it's supposed
to enclose. NFC.
The coding standards prefer smaller anonymous namespaces with free 
functions just being static and in the global namespace.

[NFC][DwarfDebug] Use proper analog GNU attribute for the pc address
The low_pc is analog to the DW_AT_call_return_pc, since it describes the
return address after the call. The DW_AT_call_pc is the address of the
call instruction, and we don't use it at the moment.
Differential Revision: https://reviews.llvm.org/D73173