Changes

Revert "Allow system header to provide their own implementation of some
builtin"
This reverts commit 921f871ac438175ca8fcfcafdfcfac4d7ddf3905 because it 
causes libc++ code to trigger __warn_memset_zero_len.
See https://reviews.llvm.org/D71082.

[COFF] Warn that LLD does not support /PDBSTRIPPED:
Doesn't really fix PR44491, but it avoids treating it as an input.

[libcxx] Use mtx_plain | mtx_recursive following C11 API
The C11 API specifies that to initialize a recursive mutex, mtx_plain |
mtx_recursive should be used with mtx_init.
Differential Revision: https://reviews.llvm.org/D72809

[lldb/Utils] Patch all variables used by lldb-dotest
Instead of passing all the arguments for dotest.py as a single CMake 
variable, lldb-dotest now uses separate variables for the different test 
binaries. Before this change they'd all get patched as part of the 
LLDB_DOTEST_ARGS. We need to patch the new variables as well.

[IR] Module's NamedMD table needn't be 'void *'
Summary: In July 21 2010 `llvm::NamedMDNode` was refactored such that it
would no longer subclass `llvm::Value`: 
https://github.com/llvm/llvm-project/commit/2637cc1a38d7336ea30caf
As part of this change, a map type from metadata names to their named 
metadata, `llvm::MDSymbolTable`, was deleted. In its place, the type of
member `llvm::Module::NamedMDSymTab` was changed, from
`llvm::MDSymbolTable` to `void *`. The underlying memory allocations for
this pointer were changed to `new StringMap<NamedMDNode *>()`.
However, as far as I can tell, there's no need for obscuring the 
underlying type being pointed to by the `void *`, and no need for static
casts from `void *` to `StringMap`. In fact, I don't think there's a
need for explicit calls to `new` and `delete` at all.
This commit changes `NamedMDSymTab` from a pointer to a reference, which 
automatically couples its lifetime with the lifetime of its owning
`llvm::Module` instance, thus removing the explicit calls to `new` and
`delete` in the `llvm::Module` constructor and destructor. It also 
changes the type from `void *` to a newly defined `NamedMDSymTabType`, 
and removes the static casts.
Test Plan: An ASAN-enabled build and run of `check-all` succeeds with
this change
(aside from some tests that always fail for me in ASAN for some reason, 
such as `check-clang` `SemaTemplate/stack-exhaustion.cpp`).
Reviewers: aprantl, dblaikie, chandlerc, pcc, echristo
Reviewed By: dblaikie
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D72812

GlobalISel: Handle more cases of G_SEXT narrowing
This now develops the same problem G_ZEXT/G_ANYEXT have where the 
requested type is assumed to be the source type. This will be fixed 
separately by creating intermediate merges.

AMDGPU: Remove custom node for exports
I'm mildly worried about potentially reordering exp/exp_done with 
IntrWriteMem on the intrinsic.
Requires hacking out the illegal type on SI, so manually select that 
case during lowering.

AMDGPU/GlobalISel: Select exp with patterns
This does produce slightly different code. Now a unique IMPLICIT_DEF is
emitted for each of the implicit_def operands, rather than reusing the
same one.

[CodeExtractor] Transfer debug info to extracted function
After extracting, fix up debug info in both the old and new functions by
1) Pointing line locations and debug intrinsics to the new subprogram
  scope, and
2) Deleting intrinsics which point to values outside of the new
  function.
Depends on https://reviews.llvm.org/D72795.
Testing: check-llvm, check-clang, a build of LNT in the `-Os -g` config 
with "-mllvm -hot-cold-split=1" set, and end-to-end debugging of a toy 
program which undergoes splitting to verify that lldb can find 
variables, single step, etc. in extracted code.
rdar://45507940
Differential Revision: https://reviews.llvm.org/D72801

[OPENMP]Use regular processing of vtable used when TU is a prefix.
If current kind of the translation unit is TU_Prefix and it is not 
complete, cannot decide what to do with virtual members/table at that 
time, need to delay it to later stages.

Revert "Further implement CWG 2292"
This reverts commit ee0f1f1edc3ec0d4e698d50cc3180217448802b7 because it 
causes an error on valid code. See
https://reviews.llvm.org/rGee0f1f1edc3ec0d4e698d50cc3180217448802b7.

Process BUNDLE in tail duplication
When tail duplication estimates a size of tail it uses instruction 
count. Account for a number of instrictions in a bundle too.
Differential Revision: https://reviews.llvm.org/D72783

[lldb/Utils] Patch all variables used by lldb-dotest (2/2)
Instead of passing all the arguments for dotest.py as a single CMake 
variable, lldb-dotest now uses separate variables for the different test 
binaries. Before this change they'd all get patched as part of the 
LLDB_DOTEST_ARGS. We need to patch the new variables as well.

[lldb/Utils] Patch all variables used by lit (3/3)
Instead of passing all the arguments for dotest.py as a single CMake 
variable, lit now uses separate variables for the different test 
binaries. Before this change they'd all get patched as part of the 
LLDB_DOTEST_ARGS. We need to patch the new variables as well.

Fix pack deduction to only deduce the arity of packs that are actually
expanded by the deduced pack.
We recently started also deducing the arity of separately-expanded packs 
that are merely mentioned within the pack in question, which is 
incorrect.

[LLDB] Add ObjectFileWasm plugin for WebAssembly debugging
Summary: This is the first in a series of patches to enable LLDB
debugging of WebAssembly targets.
Current versions of Clang emit (partial) DWARF debug information in
WebAssembly modules and we can leverage this debug information to give
LLDB the ability to do source-level debugging of Wasm code that runs in
a WebAssembly engine.
A way to do this could be to use the remote debugging functionalities
provided by LLDB via the GDB-remote protocol. Remote debugging can
indeed be useful not only to connect a debugger to a process running on
a remote machine, but also to connect the debugger to a managed VM or
script engine that runs locally, provided that the engine implements a
GDB-remote stub that offers the ability to access the engine runtime
internal state.
To make this work, the GDB-remote protocol would need to be extended
with a few Wasm-specific custom query commands, used to access aspects
of the Wasm engine state (like the Wasm memory, Wasm local and global
variables, and so on). Furthermore, the DWARF format would need to be
enriched with a few Wasm-specific extensions, here detailed:
https://yurydelendik.github.io/webassembly-dwarf.
This CL introduce classes **ObjectFileWasm**, a file plugin to represent
a Wasm module loaded in a debuggee process. It knows how to parse Wasm
modules and store the Code section and the DWARF-specific sections.
Reviewers: jasonmolenda, clayborg, labath
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D71575

llc: Change behavior of -mattr with existing attribute
Append this to the existing target-features attribute on the function.
Some flags ignore existing attributes, and some overwrite them. Move 
towards consistently respecting existing attributes if present. Since 
target features act as a state machine on their own, append to the 
function attribute. The backend default added feature list, function 
attributes, and -mattr will all be appended together, and the later 
features can individually toggle the earlier settings.

[lldb/Tools] Remove lldb-mi.exports
lldb-mi was removed from the repo a while ago.

[Support] make report_fatal_error `abort` instead of `exit`
Summary: This patch could be treated as a rebase of D33960. It also
fixes PR35547. A fix for `llvm/test/Other/close-stderr.ll` is proposed
in D68164. Seems the consensus is that the test is passing by chance and
I'm not sure how important it is for us. So it is removed like in D33960
for now. The rest of the test fixes are just adding `--crash` flag to
`not` tool.
** The reason it fixes PR35547 is
`exit` does cleanup including calling class destructor whereas `abort` 
does not do any cleanup. In multithreading environment such as ThinLTO
or JIT, threads may share states which mostly are ManagedStatic<>. If
faulting thread tearing down a class when another thread is using it,
there are chances of memory corruption. This is bad 1. It will stop
error reporting like pretty stack printer; 2. The memory corruption is
distracting and nondeterministic in terms of error message, and
corruption type (depending one the timing, it could be double free, heap
free after use, etc.).
Reviewers: rnk, chandlerc, zturner, sepavloff, MaskRay, espindola
Reviewed By: rnk, MaskRay
Subscribers: wuzish, jholewinski, qcolombet, dschuff, jyknight, emaste,
sdardis, nemanjai, jvesely, nhaehnle, sbc100, arichardson,
jgravelle-google, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso,
simoncook, apazos, sabuasal, niosHD, jrtc27, zzheng, edward-jones,
atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei,
jsji, lenary, s.egerton, pzheng, cfe-commits, MaskRay, filcab, davide,
MatzeB, mehdi_amini, hiraditya, steven_wu, dexonsmith, rupprecht, seiya,
llvm-commits
Tags: #llvm, #clang
Differential Revision: https://reviews.llvm.org/D67847

debugserver: Cut dependency on intrinsics_gen
debugserver does not depend on intrinsics_gen or on llvm.

Revert "[Support] make report_fatal_error `abort` instead of `exit`"
This reverts commit 647c3f4e47de8a850ffcaa897db68702d8d2459a.
Got bots failure from sanitizer-windows and maybe others.

llc: Don't overwrite frame-pointer attribute
Continue making command line flags with matching attribute behavior 
consistent.

Fix the macos build after D71575.
size_t and uint64_t are spelled slightly differently on macOS, which was 
causing the compiler to error out calling std::min - since the two types
have to be the same.
I fixed this by casting the uint64_t computation to a size_t.  That's
probably not the cleanest solution, but it gets us back to building.

[X86] Add 32-bit mode sse1 command line to scalar-int-to-fp.ll. NFC

[X86] When handling i64->f32 sint_to_fp on 32-bit targets only bitcast
to f64 if sse2 is enabled.
The code is trying to copy the i64 value to an xmm register to use a
64-bit store so that the 64-bit fild can benefit from store forwarding.
But this trick only works if f64 is going to be stored in an XMM
register. If we only have SSE1 then only float is in xmm register. So
this trick just causes 2 stores i32 stores, an f64 load into the x87, an
f64 from x87, and a 64-bit fild. So we end up with an extra stack
temporary and still didn't get store forwarding.
We might be able to use v2f32 here instead, but I didn't check. I just
wanted the code to make sense.
Found by inspection as I continue to stare too hard at our int_to_fp
conversions.

[SampleFDO] Fix invalid branch profile generated by indirect call
promotion.
Suppose an inline instance has hot total sample count but 0 entry count,
and it is an indirect call target. If the indirect call has no other
call target and inline instance associated with it and it is promoted,
currently the conditional branch generated by indirect call promotion
will have invalid branch profile which is !{!"branch_weights", i32 0,
i32 0} -- because the entry count of the promoted target is 0 and the
total entry count of all targets is also 0. This caused a SEGV in
Control Height Reduction and may cause problem in other passes.
Function entry count of an inline instance is computed by a heuristic -- 
using either the sample of the starting line or starting inner inline 
instance. The patch changes the heuristic a little bit so that when
total sample count is larger than 0, the computed entry count will be at
least 1. Then the new branch profile will be !{!"branch_weights", i32 1,
i32 0}.
Differential Revision: https://reviews.llvm.org/D72790

PR42694 Support explicit(bool) in older language modes as an extension.
This needs somewhat careful disambiguation, as C++2a explicit(bool) is a 
breaking change. We only enable it in cases where the source construct 
could not possibly be anything else.

[lldb/Reproducers] Extract function for reading environment override
(NFC)
Create a helper function for reading reproducer overrides from 
environment variables.

Set some fast math attributes in setFunctionAttributes
This will provide a more consistent view to codegen for these 
attributes. The current system is somewhat awkward, and the fields in 
TargetOptions are reset based on the command line flag if the attribute
isn't set. By forcing these attributes with the flag, there can never be
an inconsistency in the behavior if code directly inspects the attribute
on the function without considering the command line flags.

[lldb/Reproducers] Add a flag to always generating a reproducer
Add a flag which always generates a reproducer when normally it would be 
discarded. This is meant for testing purposes to capture a debugger 
session without modification the session itself.

Insert wait instruction after X87 instructions which could raise
float-point exception.
This patch also modify some mayRaiseFPException flag which set in
D68854.
Differential Revision: https://reviews.llvm.org/D72750

[gn build] Port 8fdafb7dced

[lldb/Reproducers] Print more info for reproducer status
Reproducer status now prints the capture/replay path. It will also print 
the status of auto generation when enabled.

[mlir] fix broken links to Glossary
Differential Revision: https://reviews.llvm.org/D72697

[LegalizeDAG][TargetLowering] Move vXi64/i64->vXf32/f32 uint_to_fp
legalizing code from TargetLowering::expandUINT_TO_FP back to
LegalizeDAG.
This was moved in October 2018, but we don't appear to be using this for
vectors on any in tree target.
Moving it back simplifies D72794 so we can share the code for i32->f32.

[DebugInfo] Simplify the constructor of DWARFDebugAranges::Range. NFC.
This removes the default values of the arguments. The only caller, 
DWARFDebugAranges::construct(), provides all three parameters.
Differential Revision: https://reviews.llvm.org/D72757