This reverts commit d8f2bff7.

This was added to inhibit a warning from gcc 7.3 according to
the comment. However, it triggers warning from PVS. In addition
I cannot reproduce it with gcc 7.4 and I also cannot reproduce
it with gcc 7.3 using compiler explorer.

Differential Revision: https://reviews.llvm.org/D69863

When writing an email for a follow up proposal, I realized one of the diffs in the committed change was incorrect.  Digging into it revealed that the fix is complicated enough to require some thought, so reverting in the meantime.

The problem is visible in this diff (from the revert):
 ; X64-SSE-LABEL: store_fp128:
 ; X64-SSE:       # %bb.0:
-; X64-SSE-NEXT:    movaps %xmm0, (%rdi)
+; X64-SSE-NEXT:    subq $24, %rsp
+; X64-SSE-NEXT:    .cfi_def_cfa_offset 32
+; X64-SSE-NEXT:    movaps %xmm0, (%rsp)
+; X64-SSE-NEXT:    movq (%rsp), %rsi
+; X64-SSE-NEXT:    movq {{[0-9]+}}(%rsp), %rdx
+; X64-SSE-NEXT:    callq __sync_lock_test_and_set_16
+; X64-SSE-NEXT:    addq $24, %rsp
+; X64-SSE-NEXT:    .cfi_def_cfa_offset 8
 ; X64-SSE-NEXT:    retq
   store atomic fp128 %v, fp128* %fptr unordered, align 16
   ret void

The problem here is three fold:
1) x86-64 doesn't guarantee atomicity of anything larger than 8 bytes.  Some platforms observably break this guarantee, others don't, but the codegen isn't considering this, so it's wrong on at least some platforms.
2) When I started to track down the problem, I discovered that DAGCombiner had stripped the atomicity off the store entirely.  This comes down to idiomatic usage of DAG.getStore passing all MMO components separately as opposed to just passing the MMO.
3) On x86 (not -64), there are cases where 8 byte atomiciy is supported, but only for floating point operations.  This would seem to imply that operation typing matters for correctness, and DAGCombine happily folds away bitcasts.  I'm not 100% sure there's a problem here, but I'm not entirely sure there isn't either.

I plan on returning to each issue in turn;  sorry for the churn here.

Summary:
- Fix a bug which misses the change for a variable to be set with
  target-specific attributes.

Reviewers: yaxunl

Subscribers: jvesely, nhaehnle, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63020

[llvm-objdump] Fix spurious "The end of the file was unexpectedly encountered" if a SHT_NOBITS sh_offset is larger than the file size

llvm-objdump -D this file:

  int a[100000];
  int main() { return 0; }

Will produce an error: "The end of the file was unexpectedly encountered".

This happens because of a check in Binary.h checkOffset.  (Addr + Size > M.getBufferEnd()).

The sh_offset and sh_size fields can be ignored for SHT_NOBITS sections.
Fix the error by changing ELFObjectFile<ELFT>::getSectionContents to use
the file base for SHT_NOBITS sections.

Reviewed By: grimar, MaskRay

Differential Revision: https://reviews.llvm.org/D69192

Without this patch, when using lit's internal shell, if `not` on a lit
RUN line calls `env`, `diff`, or any of the other in-process shell
builtins that lit implements, lit accidentally searches for the latter
as an external executable.  What's worse is that works fine when a
developer is testing on a platform where those executables are
available and behave as expected, but it then breaks on other
platforms.

`not` seems useful for some builtins, such as `diff`, so this patch
supports such uses.  `not --crash` does not seem useful for builtins,
so this patch diagnoses such uses.  In all cases, this patch ensures
shell builtins are found behind any sequence of `env` and `not`
commands.

`not` calling `env` calling an external command appears useful when
the `env` and external command are part of a lit substitution, as in
D65156.  This patch supports that by looking through any sequence of
`env` and `not` commands, building the environment from the `env`s,
and storing the `not`s.  The `not`s are then added back to the command
line without the `env`s to execute externally.  This avoids the need
to replicate the `not` implementation, in particular the `--crash`
option, in lit.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D66531

Static analyzer complains about always false condition.
See https://bugs.llvm.org/show_bug.cgi?id=43886

Differential Revision: https://reviews.llvm.org/D69860

First, add LLD as a dependency on Windows. The windows batch scripts
pass -fuse-ld=lld, so they need it.

Second, decode builder stdout/stderr even if the command fails.
Otherwise it gets printed as b'line 1\n\rline 2\n\r'.

Last, make the batch script one line less noisy. We might want to try to
do more here, though. It would be nice if we could get as close to
possible as lit, where you can literally copy & paste the failing
command to re-run it.

With the two changes above, now the feature tests that use clang++.bat
pass for me. The clang-cl_vs2015 ones still fail, and I'll fix them
separately.

Reviewers: jmorse

Differential Revision: https://reviews.llvm.org/D69725

This is checking the version of Python used to run lit, which is not
necessarily the same as the version used to run the dexter tests.  If
the tests are run via the build/bin/llvm-lit[.py] helper script, then
that is likely to pick up whatever version of Python is on PATH.
Conventionally, this will find Python 2. CMake already checks that
Python 3 is in use and puts the path to it in the lit site config, so
this check is redundant, and Python 3 will ultimately be used to run
dexter.

Reviewers: jmorse

Differential Revision: https://reviews.llvm.org/D69724

The backend UnsafeFPMath flag is not a superset of all the others, so
limit it to the exact bits needed.

Summary:
G_GEP is rather poorly named. It's a simple pointer+scalar addition and
doesn't support any of the complexities of getelementptr. I therefore
propose that we rename it. There's a G_PTR_MASK so let's follow that
convention and go with G_PTR_ADD

Reviewers: volkan, aditya_nandakumar, bogner, rovka, arsenm

Subscribers: sdardis, jvesely, wdng, nhaehnle, hiraditya, jrtc27, atanasyan, arphaman, Petar.Avramovic, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69734

addOperand() method of AMDGPU disassembler returns SoftFail
on error. All instances which may lead to that place are
an impossible encdoing, not something which is possible to
encode, but semantically incorrect as described for SoftFail.

Then tablegen generates a check of the following form:

if (Decode...(..) == MCDisassembler::Fail) { return MCDisassembler::Fail; }

Since we can only return Success and SoftFail that is dead
code as detected by the static code analyzer.

Solution: return Fail as it should be.

See https://bugs.llvm.org/show_bug.cgi?id=43886

Differential Revision: https://reviews.llvm.org/D69819

Summary:
To keep the logic of finding locations of interesting AST nodes in one
place.

The advantage is better coverage of various AST nodes, both now and in
the future: as new nodes get added to `findExplicitReferences`, semantic
highlighting will automatically pick them up.

The drawback of this change is that we have to traverse declarations
inside our file twice in order to highlight dependent names, 'auto'
and 'decltype'. Hopefully, this should not affect the actual latency
too much, most time should be spent in building the AST and not
traversing it.

Reviewers: hokein

Reviewed By: hokein

Subscribers: nridge, merge_guards_bot, MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69673

This code path is only taken on the sanitized bot, where it caused a
TypeError: "Can't mix strings and bytes in path components".

Reviewers: tra, rjmccall, yaxunl

Subscribers: jvesely, nhaehnle, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69826

Summary: Check for MainOp and AltOp for NULL before dereferencing or issue NULL.

Reviewers: Vasilis, dtemirbulatov, RKSimon, ABataev

Reviewed By: ABataev

Subscribers: mehdi_amini, hiraditya, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69812

Summary:
This is largely based off of the slides from the keynote

Depends on D69545

Reviewers: volkan, rovka, arsenm

Subscribers: wdng, arphaman, Petar.Avramovic, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69644

Summary:
This patch factors out code to merge a basic block with its sole
successor -- partly for readability and partly to facilitate an
upcoming patch of my own.

Reviewers: wmi

Subscribers: hiraditya, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69852

The invalid binary trying to construct triggers an assertion.

Fixes cppcheck warning.

Rewrite one of the invalid macho test input file with YAML file. The
original invalid macho is breaking our internal test infrastusture
because it is too broken to be copy around.

rdar://problem/56879982

--only-keep-debug produces a debug file as the output that only
preserves contents of sections useful for debugging purposes (the
binutils implementation preserves SHT_NOTE and non-SHF_ALLOC sections),
by changing their section types to SHT_NOBITS and rewritting file
offsets.

See https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html

The intended use case is:

```
llvm-objcopy --only-keep-debug a a.dbg
llvm-objcopy --strip-debug a b
llvm-objcopy --add-gnu-debuglink=a.dbg b
```

The current layout algorithm is incapable of deleting contents and
shrinking segments, so it is not suitable for implementing the
functionality.

This patch adds a new algorithm which assigns sh_offset to sections
first, then modifies p_offset/p_filesz of program headers. It bears a
resemblance to lld/ELF/Writer.cpp.

Reviewed By: jhenderson, jakehehrlich

Differential Revision: https://reviews.llvm.org/D67137

`llvm::objcopy::elf::*Section::classof` matches Type and Flags, yet Type
and Flags are mutable (by setSectionFlagsAndTypes and upcoming
--only-keep-debug feature). Add OriginalType & OriginalFlags to be used
in classof, to prevent classof results from changing.

Reviewed By: jakehehrlich, jhenderson, alexshap

Differential Revision: https://reviews.llvm.org/D69739

This is a test from D67169, that can now be added after the vld2
intrinsics were committed upstream.

Restrict building the readline override to Linux only.  It both does not
build on *BSD systems, and is largely irrelevant since they default to
using libedit over readline anyway.  This restores the behavior
of the old readline override that also was built only on Linux.

Differential Revision: https://reviews.llvm.org/D69846

Summary:
To drive the automaton we used a uint64_t as an action type. This
contained the transition's resource requirements as a conjunction:

  (a OR b) AND (b OR c)

We encoded this conjunction as a sequence of four 16-bit bitmasks.
This limited the number of addressable functional units to 16, which
is quite low and has bitten many people in the past.

Instead, the DFAEmitter now generates a lookup table from InstrItinerary
class (index of the ItinData inside the ProcItineraries) to an internal
action index which is essentially a dense embedding of the conjunctive
form. Because we never materialize the conjunctive form, we no longer
have the 16 FU restriction.

In this patch we limit to 64 functional units due to using a uint64_t
bitmask in the DFAEmitter. Now that we've decoupled these representations
we can increase this in future.

Reviewers: ThomasRaoux, kparzysz, majnemer

Reviewed By: ThomasRaoux

Subscribers: hiraditya, llvm-commits

Tags: #llvm

D...

Improved diagnostics for better user experience.

This recommits 2be17087 (reverted in
d3ec06d2 for heap-use-after-free) with a fix
in IAI's reset() which was not clearing the set of interleave groups after
deleting them.

When eliminating a pair of

`llvm.objc.autoreleaseReturnValue`

followed by

`llvm.objc.retainAutoreleasedReturnValue`

we need to make sure that the instructions in between are safe to
ignore.

Other than bitcasts and useless GEPs, it's also safe to ignore lifetime
markers for both static allocas (lifetime.start/lifetime.end) and dynamic
allocas (stacksave/stackrestore).

These get added by the inliner as part of the return sequence and can
prevent the transformation from happening in practice.

Differential Revision: https://reviews.llvm.org/D69833

Add tests for bitcasts + zero GEPs, and pre-commit tests for lifetime
markers.

Summary:
This patch factors out common code to update the SSA form in
JumpThreading.cpp -- partly for readability and partly to facilitate
an coming patch of my own.

Reviewers: wmi

Subscribers: hiraditya, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69811

Fixes PVS Studio warning that the 'ValueTable' class implements a copy constructor, but lacks the '=' operator.