Sorry for the build break, apparently forgot to build ARM target.

`-flto -gsplit-dwarf -g -O[123]` may create .debug_gnu_pubnames with 0 DIE
offset entries. llvm-dwarfdump -debug-gnu-pubnames/ld.lld --gdb-index errors for that.

```
        .section        .debug_gnu_pubnames,"",@progbits
        .long   .LpubNames_end2-.LpubNames_begin2 # Length of Public Names Info
.LpubNames_begin2:
        .short  2                               # DWARF Version
        .long   .Lcu_begin2                     # Offset of Compilation Unit Info
        .long   57                              # Compilation Unit Length
        .long   0                               # DIE offset
        .byte   16                              # Attributes: TYPE, EXTERNAL
        .asciz  "absl"                          # External Name
        .long   0                               # DIE offset
        .byte   16                              # Attributes: TYPE, EXTERNAL
        .asciz  "absl::base_internal"           # External Name
        .long   0                               # End Mark
```

If we know that the scalar epilogue is required to run, modify the CFG to end the middle block with an unconditional branch to scalar preheader. This is instead of a conditional branch to either the preheader or the exit block.

The motivation to do this is to support multiple exit blocks. Specifically, the current structure forces us to identify immediate dominators and *which* exit block to branch from in the middle terminator. For the multiple exit case - where we know require scalar will hold - these questions are ill formed.

This is the last change needed to support multiple exit loops, but since the diffs are already large enough, I'm going to land this, and then enable separately. You can think of this as being NFCI-ish prep work, but the changes are a bit too involved for me to feel comfortable tagging the change that way.

Differential Revision: https://reviews.llvm.org/D94892

[OpenMP][libomptarget] Fixed an issue that device sync is skipped if the kernel doesn't have any argument

Currently if there is not kernel argument, device synchronization will
be skipped. This can lead to two issues:
1. If there is any device error, it will not be captured;
2. The target region might end before the kernel is done, which is not spec
   conformant.

The test added in this patch only runs on NVPTX platform, although it will not
be executed by Phab at all. It also requires `not` which is not available on most
systems.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D96067

Differential Revision: https://reviews.llvm.org/D96092

This improves our coverage of these operations and shows that we
use really large constants for division by constant on i8/i16
especially on RV64. The issue is that BuildSDIV/BuildUDIV are
limited to legal types so we have to promote to i64 before it
kicks in. At that point we've lost the range information for the
original type.

The added test case failed on ppc, android, and other buildbots,
so require x86 targets.

when we skip the call stack starting with an external address, we should also skip the bottom LBR entry, otherwise it will cause a truncated context issue.

Reviewed By: hoy, wenlei

Differential Revision: https://reviews.llvm.org/D95480

D94563 implemented `ReadBinaryName` on Windows, which causes a test case
to now pass, so remove the `XFAIL: windows-msvc` line.

[asan] Add %d variable to external_symbolizer_path option, so that user can specify paths relative to the location of the binary.

We want way to set a path to llvm-symbolizer that isn't relative
to the current working directory; this change adds a variable that
expands to the path relative to the current binary.
This approach came from comments in https://reviews.llvm.org/D93070

Differential Revision: https://reviews.llvm.org/D94563

This makes ignoring a result explicit by the user, and helps to prevent accidental errors with dropped results. Marking LogicalResult as no discard was always the intention from the beginning, but got lost along the way.

Differential Revision: https://reviews.llvm.org/D95841

Defer constant checking of dependent initializer to template instantiation
since it cannot be done for dependent values.

Reviewed by: Artem Belevich

Differential Revision: https://reviews.llvm.org/D95840

These are no longer part of FIR.
https://github.com/flang-compiler/f18-llvm-project/pull/267

Differential Revision: https://reviews.llvm.org/D96077

Reapply {D88052}

Reviewed By: Meinersbur

Differential Revision: https://reviews.llvm.org/D96066

This reverts commit 207d4be4 due to returning incorrect results. Regression test case posted in D96074.

These attributes were all incorrect or inappropriate for LLVM to infer:
- inaccessiblememonly is generally wrong; user replacement operator new
  can access memory that's visible to the caller, as can a new_handler
  function.
- willreturn is generally wrong; a custom new_handler is not guaranteed
  to terminate.
- noalias is inappropriate: Clang has a flag to determine whether this
  attribute should be present and adds it itself when appropriate.
- noundef and nonnull on the return value should be specified by the
  frontend on all 'operator new' functions if we want them, not here.

In any case, inferring attributes on functions declared 'nobuiltin' (as
these are when Clang emits them) seems questionable.

Several of the new attributes here were incorrect, and even the ones
that are generally correct were being added even to nobuiltin calls.

This reverts commit bb3f169b.

For those using a GUI, it can be very helpful to have a
particular suffix appended to the report file name, so
it can be opened with a double-click.

(see also: https://github.com/google/sanitizers/issues/951)

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D46546

- attribute-dict production is redundant with dictionary-attribute
- definitions of attribute aliases were part of the same production as
  uses of attribute aliases
- `std.dim` now accepts the dimension number as an operand, so the
  example is out of date. Use the predicate of std.cmpi as a better
  example.

Differential Revision: https://reviews.llvm.org/D96076

This enables:
 - completion in { .x.^ }
 - completion in { .x = { .^ } }
 - type-based ranking of candidates for { .x = ^ }

Differential Revision: https://reviews.llvm.org/D96058

explicitly qualified as members of the current instantiation.

Despite the nested name specifier being fully-dependent in this case,
the elaborated type might only be instantiation-dependent, because the
type is a member of the current instantiation.

The ldrexd/strexd instructions are not supported on M-class chips, see
for example
https://developer.arm.com/documentation/dui0489/e/arm-and-thumb-instructions/memory-access-instructions/ldrex-and-strex
which says:

> All these 32-bit Thumb instructions are available in ARMv6T2 and
> above, except that LDREXD and STREXD are not available in the ARMv7-M
> architecture.

Looking at the ARMv8-M architecture, it appears that these instructions
aren't supported either. The Architecture Reference Manual lists
ldrex/strex but not ldrexd/strexd:
https://developer.arm.com/documentation/ddi0553/bn/

Godbolt example on LLVM 11.0.0, which incorrectly emits ldrexd/strexd
instructions: https://llvm.godbolt.org/z/5qqPnE

Differential Revision: https://reviews.llvm.org/D95891

Attributes accept arguments, not parameters, so we should report that
the duplicate attribute arguments don't match.

https://github.com/flang-compiler/f18-llvm-project/pull/413

Differential Revision: https://reviews.llvm.org/D96072

Follow-up on D95925: adds better detection for function arguments and also
checks for conflicts in muli-variable init statements in ForStmt.

Reviewed By: hokein

Differential Revision: https://reviews.llvm.org/D96009

Note: contrary to what I said previously, I didn't change .clang-format nor utils/generate_feature_test_macro_components.py script.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D92229

MemorySSA currently treats lifetime.end intrinsics as not aliasing
anything. This breaks MemorySSA-based MemCpyOpt, because we'll happily
move a read of a pointer below a lifetime.end intrinsic, as no clobber
is reported.

I think the MemorySSA modelling here isn't correct: lifetime.end(p)
has approximately the same effect as doing a memcpy(p, undef), and
should be treated as a clobber.

This patch removes the special handling of lifetime.end, leaving
alias analysis to handle it appropriately.

Differential Revision: https://reviews.llvm.org/D95763

... and not when the typesystem failed to initialize.

rdar://72562341

Differential Revision: https://reviews.llvm.org/D95992

This change allows merging and trimming cold context profile in llvm-profgen to solve profile size bloat problem. Currently when the profile's total sample is below threshold(supported by a switch), it will be considered cold and merged into a base context-less profile, which will at least keep the profile quality as good as the baseline(non-cs).

For example, two input profiles:
 [main @ foo @ bar]:60
 [main @ bar]:50
Under threshold = 100, the two profiles will be merge into one with the base context, get result:
 [bar]:110

Added two switches:
`--csprof-cold-thres=<value>`: Specified the total samples threshold for a context profile to be considered cold, with 100 being the default. Any cold context profiles will be merged into context-less base profile by default.
`--csprof-keep-cold`: Force profile generation to keep cold context profiles instead of dropping them. By default, any cold context will not be written to output profile.

Results:
Though not yet evaluating it with the latest CSSPGO, our internal branch shows neutral on performance but significantly reduce the profile size. Detailed evaluation on llvm-profgen with CSSPGO will come later.

Differential Revision: https://reviews.llvm.org/D94111

@mstorsjo found a mistake that I made when trying to fix some Windows
compilation errors encountered by @stella.stamenova.

I was incorrectly using the LLVM_ON_UNIX macro. In any case, proper use
of

  #if defined(_WIN32)

should be the actual fix.

Differential Revision: https://reviews.llvm.org/D96060

This reverts commit 953086dd because
it breaks GCC 5 build:

  error: could not convert '(const char*)""' from 'const char*' to 'llvm::StringLiteral'
     static ::llvm::StringLiteral getDialectNamespace() { return ""; }

Based on the comments in the code, the idea is that AsmPrinter is
unable to produce entry value blocks of arbitrary length, such as
DW_OP_entry_value [DW_OP_reg5 DW_OP_lit1 DW_OP_plus]. But the way the
Verifier check is written it also disallows DW_OP_entry_value
[DW_OP_reg5] DW_OP_lit1 DW_OP_plus which seems to overshoot the
target.

Note that this patch does not change any of the safety guards in
LiveDebugValues — there is zero behavior change for clang. It just
allows us to legalize more complex expressions in future patches.

rdar://73907559

Differential Revision: https://reviews.llvm.org/D95990

Reviewed By: mehdi_amini, rriddle

Differential Revision: https://reviews.llvm.org/D95906

The upstream callers (the vectorizers) were fixed with:
bbed5f2f ( D95690 )
77adbe6a

We should remove this pass entirely now that reduction
legalization/lowering is expected to work just as well,
but we need to confirm that the shuffle ops do not
regress (for x86 in particular).

This should be the last step needed to close:
https://llvm.org/PR23116

The operator< in the previous attempt was incorrect. It is unfortunate
that this was only caught by the expensive checks.

This reverts commit ff1147c3.

Fix clang compiler warning from `-Wrange-loop-analysis`.

Reviewed By: andreadb

Differential Revision: https://reviews.llvm.org/D95997