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Commit Graph

7296 Commits

Author SHA1 Message Date
Craig Topper
27aa226f8e [Docs] Use code-block:: text for part of the callbr documentation to attempt to make the bot happy.
llvm-svn: 353567
2019-02-08 21:09:33 +00:00
Craig Topper
ea7e6b3857 Implementation of asm-goto support in LLVM
This patch accompanies the RFC posted here:
http://lists.llvm.org/pipermail/llvm-dev/2018-October/127239.html

This patch adds a new CallBr IR instruction to support asm-goto
inline assembly like gcc as used by the linux kernel. This
instruction is both a call instruction and a terminator
instruction with multiple successors. Only inline assembly
usage is supported today.

This also adds a new INLINEASM_BR opcode to SelectionDAG and
MachineIR to represent an INLINEASM block that is also
considered a terminator instruction.

There will likely be more bug fixes and optimizations to follow
this, but we felt it had reached a point where we would like to
switch to an incremental development model.

Patch by Craig Topper, Alexander Ivchenko, Mikhail Dvoretckii

Differential Revision: https://reviews.llvm.org/D53765

llvm-svn: 353563
2019-02-08 20:48:56 +00:00
Jonathan Metzman
49e5279126 Document libFuzzer on Windows.
Summary:
Document that libFuzzer supports Windows, how to get it,
and its limitations.

Reviewers: kcc, morehouse, rnk, metzman

Reviewed By: kcc, rnk, metzman

Subscribers: hans, rnk

Differential Revision: https://reviews.llvm.org/D57597

llvm-svn: 353551
2019-02-08 19:35:04 +00:00
Rong Xu
10486b5c91 [Cmake] Add an option to build LLVM using the experimental new pass manager
Add LLVM_USE_NEWPM to build LLVM using the experimental new pass manager.

Differential Revision: http://reviews.llvm.org/D57068

llvm-svn: 353550
2019-02-08 19:31:03 +00:00
Dmitry Preobrazhensky
5c2d369b08 [AMDGPU][MC][CODEOBJECT] Added predefined symbols to access GPU minor and stepping numbers
Added the following Code Object v3 symbols:
    .amdgcn.gfx_generation_minor
    .amdgcn.gfx_generation_stepping

Reviewers: artem.tamazov, kzhuravl

Differential Revision: https://reviews.llvm.org/D57826

llvm-svn: 353515
2019-02-08 13:51:31 +00:00
JF Bastien
406b84702a Bump minimum toolchain version
Summary:
The RFC on moving past C++11 got good traction:
  http://lists.llvm.org/pipermail/llvm-dev/2019-January/129452.html

This patch therefore bumps the toolchain versions according to our policy:
  llvm.org/docs/DeveloperPolicy.html#toolchain

Subscribers: mgorny, jkorous, dexonsmith, llvm-commits, mehdi_amini, jyknight, rsmith, chandlerc, smeenai, hans, reames, lattner, lhames, erichkeane

Differential Revision: https://reviews.llvm.org/D57264

llvm-svn: 353374
2019-02-07 05:20:00 +00:00
Lang Hames
f9bddc40cd [ADT] Add a fallible_iterator wrapper.
A fallible iterator is one whose increment or decrement operations may fail.
This would usually be supported by replacing the ++ and -- operators with
methods that return error:

    class MyFallibleIterator {
    public:
      // ...
      Error inc();
      Errro dec();
      // ...
    };

The downside of this style is that it no longer conforms to the C++ iterator
concept, and can not make use of standard algorithms and features such as
range-based for loops.

The fallible_iterator wrapper takes an iterator written in the style above
and adapts it to (mostly) conform with the C++ iterator concept. It does this
by providing standard ++ and -- operator implementations, returning any errors
generated via a side channel (an Error reference passed into the wrapper at
construction time), and immediately jumping the iterator to a known 'end'
value upon error. It also marks the Error as checked any time an iterator is
compared with a known end value and found to be inequal, allowing early exit
from loops without redundant error checking*.

Usage looks like:

    MyFallibleIterator I = ..., E = ...;

    Error Err = Error::success();
    for (auto &Elem : make_fallible_range(I, E, Err)) {
      // Loop body is only entered when safe.

      // Early exits from loop body permitted without checking Err.
      if (SomeCondition)
        return;

    }
    if (Err)
      // Handle error.

* Since failure causes a fallible iterator to jump to end, testing that a
  fallible iterator is not an end value implicitly verifies that the error is a
  success value, and so is equivalent to an error check.

Reviewers: dblaikie, rupprecht

Subscribers: mgorny, dexonsmith, kristina, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57618

llvm-svn: 353237
2019-02-05 23:17:11 +00:00
Leonard Chan
7230ae9ced [Intrinsic] Unsigned Fixed Point Multiplication Intrinsic
Add an intrinsic that takes 2 unsigned integers with the scale of them
provided as the third argument and performs fixed point multiplication on
them.

This is a part of implementing fixed point arithmetic in clang where some of
the more complex operations will be implemented as intrinsics.

Differential Revision: https://reviews.llvm.org/D55625

llvm-svn: 353059
2019-02-04 17:18:11 +00:00
Roman Lebedev
1cc6540ed5 [llvm-exegesis] Don't default to running&dumping all analyses to '-'
Summary:
Up until the point i have looked in the source, i didn't even understood that
i can disable 'cluster' output. I have always silenced it via ` &> /dev/null`.
(And hoped it wasn't contributing much of the run time.)

While i expect that it has it's use-cases i never once needed it so far.
If i forget to silence it, console is completely flooded with that output.

How about not expecting users to opt-out of analyses,
but to explicitly specify the analyses that should be performed?

Reviewers: courbet, gchatelet

Reviewed By: courbet

Subscribers: tschuett, RKSimon, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57648

llvm-svn: 353021
2019-02-04 09:12:08 +00:00
Davide Italiano
acab453d6b [docs] Recommend assertions when testing.
Pointed out by Shoaib Meenai.

llvm-svn: 353008
2019-02-03 20:37:13 +00:00
JF Bastien
495652a992 Revert "Bump minimum toolchain version"
Reverting D57264 again, it looks like we're down to two bots that need fixing:

polly-amd64-linux
polly-arm-linux

They both have old versions of libstdc++ and recent clang.

llvm-svn: 352954
2019-02-02 06:01:12 +00:00
JF Bastien
5b2eb5b50c Bump minimum toolchain version
Summary:
The RFC on moving past C++11 got good traction:
  http://lists.llvm.org/pipermail/llvm-dev/2019-January/129452.html

This patch therefore bumps the toolchain versions according to our policy:
  llvm.org/docs/DeveloperPolicy.html#toolchain

Subscribers: mgorny, jkorous, dexonsmith, llvm-commits, mehdi_amini, jyknight, rsmith, chandlerc, smeenai, hans, reames, lattner, lhames, erichkeane

Differential Revision: https://reviews.llvm.org/D57264

llvm-svn: 352951
2019-02-02 05:15:34 +00:00
James Y Knight
20eda1344e Hopefully fix a couple more sphinx doc errors.
These seem to only appear on the buildbot runner, and it looks like we
tried to suppress them, but it's not working. Not sure why.

llvm-svn: 352903
2019-02-01 19:40:07 +00:00
James Y Knight
9c7ac47512 Fix some sphinx doc errors.
llvm-svn: 352887
2019-02-01 17:06:41 +00:00
James Henderson
2f544e718b [doc]Update String Error documentation in Programmer Manual
A while back, createStringError was added to provide easier construction
of StringError instances, especially with formatting options. Prior to
this patch, that the documentation only mentions the standard method of
using it. Since createStringError is slightly shorter to type, and also
provides the formatting options, this patch updates the Programmer's
Manual to use the new function in its examples, and to mention the
printf formatting options. It also fixes a small typo in one of the
examples and removes the unnecessary make_error_code call.

llvm-svn: 352846
2019-02-01 10:02:42 +00:00
JF Bastien
d34b028451 Revert "Bump minimum toolchain version"
Looks like we still have a few bots that are sad. Let try to get them fixed!

llvm-svn: 352835
2019-02-01 04:44:39 +00:00
JF Bastien
0621177282 Bump minimum toolchain version
Summary:
The RFC on moving past C++11 got good traction:
  http://lists.llvm.org/pipermail/llvm-dev/2019-January/129452.html

This patch therefore bumps the toolchain versions according to our policy:
  llvm.org/docs/DeveloperPolicy.html#toolchain

Subscribers: mgorny, jkorous, dexonsmith, llvm-commits, mehdi_amini, jyknight, rsmith, chandlerc, smeenai, hans, reames, lattner, lhames, erichkeane

Differential Revision: https://reviews.llvm.org/D57264

llvm-svn: 352834
2019-02-01 04:33:21 +00:00
James Y Knight
846be29e5e [opaque pointer types] Add a FunctionCallee wrapper type, and use it.
Recommit r352791 after tweaking DerivedTypes.h slightly, so that gcc
doesn't choke on it, hopefully.

Original Message:
The FunctionCallee type is effectively a {FunctionType*,Value*} pair,
and is a useful convenience to enable code to continue passing the
result of getOrInsertFunction() through to EmitCall, even once pointer
types lose their pointee-type.

Then:
- update the CallInst/InvokeInst instruction creation functions to
  take a Callee,
- modify getOrInsertFunction to return FunctionCallee, and
- update all callers appropriately.

One area of particular note is the change to the sanitizer
code. Previously, they had been casting the result of
`getOrInsertFunction` to a `Function*` via
`checkSanitizerInterfaceFunction`, and storing that. That would report
an error if someone had already inserted a function declaraction with
a mismatching signature.

However, in general, LLVM allows for such mismatches, as
`getOrInsertFunction` will automatically insert a bitcast if
needed. As part of this cleanup, cause the sanitizer code to do the
same. (It will call its functions using the expected signature,
however they may have been declared.)

Finally, in a small number of locations, callers of
`getOrInsertFunction` actually were expecting/requiring that a brand
new function was being created. In such cases, I've switched them to
Function::Create instead.

Differential Revision: https://reviews.llvm.org/D57315

llvm-svn: 352827
2019-02-01 02:28:03 +00:00
JF Bastien
d979e38527 Revert "Bump minimum toolchain version"
A handful of bots are still breaking, either because I missed them in my audit,
they were offline, or something else. I'm contacting their authors, but I'll
revert for now and re-commit later.

llvm-svn: 352814
2019-01-31 23:29:39 +00:00
JF Bastien
39999b579f DeveloperPolicy: update toolchain with sample RFC / patch
As was suggested when the policy originally went in.

llvm-svn: 352812
2019-01-31 23:18:11 +00:00
JF Bastien
023da30e96 Bump minimum toolchain version
Summary:
The RFC on moving past C++11 got good traction:
  http://lists.llvm.org/pipermail/llvm-dev/2019-January/129452.html

This patch therefore bumps the toolchain versions according to our policy:
  llvm.org/docs/DeveloperPolicy.html#toolchain

Subscribers: mgorny, jkorous, dexonsmith, llvm-commits, mehdi_amini, jyknight, rsmith, chandlerc, smeenai, hans, reames, lattner, lhames, erichkeane

Differential Revision: https://reviews.llvm.org/D57264

llvm-svn: 352811
2019-01-31 23:13:10 +00:00
James Y Knight
06da6dcca4 Revert "[opaque pointer types] Add a FunctionCallee wrapper type, and use it."
This reverts commit f47d6b38c7a61d50db4566b02719de05492dcef1 (r352791).

Seems to run into compilation failures with GCC (but not clang, where
I tested it). Reverting while I investigate.

llvm-svn: 352800
2019-01-31 21:51:58 +00:00
James Y Knight
fa51e33345 [opaque pointer types] Add a FunctionCallee wrapper type, and use it.
The FunctionCallee type is effectively a {FunctionType*,Value*} pair,
and is a useful convenience to enable code to continue passing the
result of getOrInsertFunction() through to EmitCall, even once pointer
types lose their pointee-type.

Then:
- update the CallInst/InvokeInst instruction creation functions to
  take a Callee,
- modify getOrInsertFunction to return FunctionCallee, and
- update all callers appropriately.

One area of particular note is the change to the sanitizer
code. Previously, they had been casting the result of
`getOrInsertFunction` to a `Function*` via
`checkSanitizerInterfaceFunction`, and storing that. That would report
an error if someone had already inserted a function declaraction with
a mismatching signature.

However, in general, LLVM allows for such mismatches, as
`getOrInsertFunction` will automatically insert a bitcast if
needed. As part of this cleanup, cause the sanitizer code to do the
same. (It will call its functions using the expected signature,
however they may have been declared.)

Finally, in a small number of locations, callers of
`getOrInsertFunction` actually were expecting/requiring that a brand
new function was being created. In such cases, I've switched them to
Function::Create instead.

Differential Revision: https://reviews.llvm.org/D57315

llvm-svn: 352791
2019-01-31 20:35:56 +00:00
Kostya Serebryany
e52e1e1e30 [libFuzzer] update docs
llvm-svn: 352715
2019-01-31 01:47:29 +00:00
Erik Pilkington
133b958621 Add a 'dynamic' parameter to the objectsize intrinsic
This is meant to be used with clang's __builtin_dynamic_object_size.
When 'true' is passed to this parameter, the intrinsic has the
potential to be folded into instructions that will be evaluated
at run time. When 'false', the objectsize intrinsic behaviour is
unchanged.

rdar://32212419

Differential revision: https://reviews.llvm.org/D56761

llvm-svn: 352664
2019-01-30 20:34:35 +00:00
Clement Courbet
359f23868e [llvm-exegesis] Add throughput mode.
Summary:
This just uses the latency benchmark runner on the parallel uops snippet
generator.

Fixes PR37698.

Reviewers: gchatelet

Subscribers: tschuett, RKSimon, llvm-commits

Differential Revision: https://reviews.llvm.org/D57000

llvm-svn: 352632
2019-01-30 16:02:20 +00:00
Shoaib Meenai
e4bff2064d [docs] Prevent O0 optnone for opt input
If we just compile with -O0, clang will add optnone attributes
everywhere, so opt won't actually be able to perform any passes.
Instruct clang to not emit the optnone so opt can do its thing.

Differential Revision: https://reviews.llvm.org/D56950

llvm-svn: 352550
2019-01-29 22:17:51 +00:00
James Y Knight
f09d803a07 Adjust documentation for git migration.
This fixes most references to the paths:
 llvm.org/svn/
 llvm.org/git/
 llvm.org/viewvc/
 github.com/llvm-mirror/
 github.com/llvm-project/
 reviews.llvm.org/diffusion/

to instead point to https://github.com/llvm/llvm-project.

This is *not* a trivial substitution, because additionally, all the
checkout instructions had to be migrated to instruct users on how to
use the monorepo layout, setting LLVM_ENABLE_PROJECTS instead of
checking out various projects into various subdirectories.

I've attempted to not change any scripts here, only documentation. The
scripts will have to be addressed separately.

Additionally, I've deleted one document which appeared to be outdated
and unneeded:
  lldb/docs/building-with-debug-llvm.txt

Differential Revision: https://reviews.llvm.org/D57330

llvm-svn: 352514
2019-01-29 16:37:27 +00:00
James Henderson
b26151629d [llvm-symbolizer][doc] Tweak wording of --adjust-vma switch description
The address isn't dynamically relocated. The object is.

llvm-svn: 352477
2019-01-29 10:43:48 +00:00
Eli Friedman
2408979b55 [docs] Fix a couple spelling errors.
llvm-svn: 352439
2019-01-28 23:03:41 +00:00
Simon Pilgrim
a921a48e3f [LangRef] Mention vector support for bitreverse/bswap intrinsics (PR38012)
Differential Revision: https://reviews.llvm.org/D57309

llvm-svn: 352386
2019-01-28 16:56:38 +00:00
Javed Absar
84a3b263c4 [TblGen][NFC] Fix documentation formatting
llvm-svn: 352212
2019-01-25 16:17:57 +00:00
James Henderson
011ee92bbc [llvm-symbolizer] Add switch to adjust addresses by fixed offset
If a stack trace or similar has a list of addresses from an executable
or DSO loaded at a variable address (e.g. due to ASLR), the addresses
will not directly correspond to the addresses stored in the object file.
If a user wishes to use llvm-symbolizer, they have to subtract the load
address from every address. This is somewhat inconvenient, especially as
the output of --print-address will result in the adjusted address being
listed, rather than the address coming from the stack trace, making it
harder to map results between the two.

This change adds a new switch to llvm-symbolizer --adjust-vma which
takes an offset, which is then used to automatically do this
calculation. The printed address remains the input address (allowing for
easy mapping), whilst the specified offset is applied to the addresses
when performing the lookup.

The switch is conceptually similar to llvm-objdump's new switch of the
same name (see D57051), which in turn mirrors a GNU switch. There is no
equivalent switch in addr2line.

Reviewed by: grimar

Differential Revision: https://reviews.llvm.org/D57151

llvm-svn: 352195
2019-01-25 11:49:21 +00:00
Javed Absar
173ca6da08 [TblGen] Extend !if semantics through new feature !cond
This patch extends TableGen language with !cond operator.
Instead of embedding !if inside !if which can get cumbersome,
one can now use !cond.
Below is an example to convert an integer 'x' into a string:

    !cond(!lt(x,0) : "Negative",
          !eq(x,0) : "Zero",
          !eq(x,1) : "One,
          1        : "MoreThanOne")

Reviewed By: hfinkel, simon_tatham, greened
Differential Revision: https://reviews.llvm.org/D55758

llvm-svn: 352185
2019-01-25 10:25:25 +00:00
Julian Lettner
86d339523f Revert "[Sanitizers] UBSan unreachable incompatible with ASan in the presence of noreturn calls"
This reverts commit cea84ab93aeb079a358ab1c8aeba6d9140ef8b47.

llvm-svn: 352069
2019-01-24 18:04:21 +00:00
Michael Platings
63bb4d070c [Docs] Add information about unit tests to the testing guide
Differential Revision: https://reviews.llvm.org/D57088

llvm-svn: 352052
2019-01-24 15:11:26 +00:00
Douglas Yung
2ba526902f [docs] Remove extra character from git URL in Getting Started guide.
llvm-svn: 352005
2019-01-24 01:22:32 +00:00
Julian Lettner
c814a6a425 [Sanitizers] UBSan unreachable incompatible with ASan in the presence of noreturn calls
Summary:
UBSan wants to detect when unreachable code is actually reached, so it
adds instrumentation before every `unreachable` instruction. However,
the optimizer will remove code after calls to functions marked with
`noreturn`. To avoid this UBSan removes `noreturn` from both the call
instruction as well as from the function itself. Unfortunately, ASan
relies on this annotation to unpoison the stack by inserting calls to
`_asan_handle_no_return` before `noreturn` functions. This is important
for functions that do not return but access the the stack memory, e.g.,
unwinder functions *like* `longjmp` (`longjmp` itself is actually
"double-proofed" via its interceptor). The result is that when ASan and
UBSan are combined, the `noreturn` attributes are missing and ASan
cannot unpoison the stack, so it has false positives when stack
unwinding is used.

Changes:
  # UBSan now adds the `expect_noreturn` attribute whenever it removes
    the `noreturn` attribute from a function
  # ASan additionally checks for the presence of this attribute

Generated code:
```
call void @__asan_handle_no_return    // Additionally inserted to avoid false positives
call void @longjmp
call void @__asan_handle_no_return
call void @__ubsan_handle_builtin_unreachable
unreachable
```

The second call to `__asan_handle_no_return` is redundant. This will be
cleaned up in a follow-up patch.

rdar://problem/40723397

Reviewers: delcypher, eugenis

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D56624

llvm-svn: 352003
2019-01-24 01:06:19 +00:00
Douglas Yung
52ae0002e5 [llvm-symbolizer] Add support for -i and -inlines as aliases for -inlining
This change adds two options, -i and -inlines as aliases for the -inlining option to llvm-symbolizer to improve compatibility with the GNU addr2line utility which accepts these options.

It also modifies existing tests that use -inlining to exercise these new aliases as well.

This fixes PR40073.

Reviewed by: jhenderson, Quolyk, ruiu

Differential Revision: https://reviews.llvm.org/D57083

llvm-svn: 351999
2019-01-24 00:34:09 +00:00
James Henderson
4949c8df9b [llvm-symbolizer] Improve compatibility of --functions with GNU addr2line
This fixes https://bugs.llvm.org/show_bug.cgi?id=40072.

GNU addr2line's --functions switch is off by default, has a short alias
of -f, and does not take an argument. This patch changes llvm-symbolizer
to allow the second and third point (changing the default behaviour may
have negative impacts on users). If the option is missing a value, it
now treats it as "linkage".

This change does cause one previously valid command-line to behave
differently. Before --functions <value> was accepted, but now only
--functions=<value> is allowed (as well as --functions). The old
behaviour will result in the value being treated as a positional
argument.

The previous testing for --functions=short has been pulled out into a
new test that also tests the other accepted values and option formats.

Reviewed by: ruiu

Differential Revision: https://reviews.llvm.org/D57049

llvm-svn: 351968
2019-01-23 17:27:48 +00:00
Davide Italiano
bc9dd9225e [Docs] Add a note clarifying how to get good test performances.
Differential Revision:  https://reviews.llvm.org/D56337

llvm-svn: 351885
2019-01-22 21:52:50 +00:00
Joel E. Denny
ef0283f95a [FileCheck] Suppress old -v/-vv diags if dumping input
The old diagnostic form of the trace produced by -v and -vv looks
like:

```
check1:1:8: remark: CHECK: expected string found in input
CHECK: abc
       ^
<stdin>:1:3: note: found here
; abc def
  ^~~
```

When dumping annotated input is requested (via -dump-input), I find
that this old trace is not useful and is sometimes harmful:

1. The old trace is mostly redundant because the same basic
   information also appears in the input dump's annotations.

2. The old trace buries any error diagnostic between it and the input
   dump, but I find it useful to see any error diagnostic up front.

3. FILECHECK_OPTS=-dump-input=fail requests annotated input dumps only
   for failed FileCheck calls.  However, I have to also add -v or -vv
   to get a full set of annotations, and that can produce massive
   output from all FileCheck calls in all tests.  That's a real
   problem when I run this in the IDE I use, which grinds to a halt as
   it tries to capture all that output.

When -dump-input=fail|always, this patch suppresses the old trace from
-v or -vv.  Error diagnostics still print as usual.  If you want the
old trace, perhaps to see variable expansions, you can set
-dump-input=none (the default).

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D55825

llvm-svn: 351881
2019-01-22 21:41:42 +00:00
Matt Arsenault
fd94cae16d Reapply "IR: Add fp operations to atomicrmw"
This reapplies commits r351778 and r351782 with
RISCV test fixes.

llvm-svn: 351850
2019-01-22 18:18:02 +00:00
Kostya Kortchinsky
a0f8859483 [docs] Scudo: document error messages & their potential cause
Summary:
A couple of changes in the Scudo documentation:
- tag the shell code blocks as `console`;
- document error messages that are displayed in some termination conditions,
  the reason they triggered, and potential causes.

Reviewers: eugenis, enh

Reviewed By: eugenis

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D56857

llvm-svn: 351838
2019-01-22 16:43:45 +00:00
Adrian Prantl
a066459576 Add DIGlobalVariableExpression to LangRef
llvm-svn: 351837
2019-01-22 16:40:18 +00:00
Chandler Carruth
3764443332 Revert r351778: IR: Add fp operations to atomicrmw
This broke the RISCV build, and even with that fixed, one of the RISCV
tests behaves surprisingly differently with asserts than without,
leaving there no clear test pattern to use. Generally it seems bad for
hte IR to differ substantially due to asserts (as in, an alloca is used
with asserts that isn't needed without!) and nothing I did simply would
fix it so I'm reverting back to green.

This also required reverting the RISCV build fix in r351782.

llvm-svn: 351796
2019-01-22 10:29:58 +00:00
James Henderson
23166c2b13 [llvm-symbolizer] Add support for --basenames/-s
This fixes https://bugs.llvm.org/show_bug.cgi?id=40068.

--basenames is a GNU addr2line switch which strips the directory names
from the file path in the output.

Reviewed by: ruiu

Differential Revision: https://reviews.llvm.org/D56919

llvm-svn: 351795
2019-01-22 10:24:32 +00:00
Matt Arsenault
44582e29c8 IR: Add fp operations to atomicrmw
Add just fadd/fsub for now.

llvm-svn: 351778
2019-01-22 03:32:36 +00:00
Eli Friedman
9361d42b5e [LangRef] Clarify semantics of volatile operations.
Specifically, clarify the following:

1. Volatile load and store may access addresses that are not memory.
2. Volatile load and store do not modify arbitrary memory.
3. Volatile load and store do not trap.

Prompted by recent volatile discussion on llvmdev.

Currently, there's sort of a split in the source code about whether
volatile operations are allowed to trap; this resolves that dispute in
favor of not allowing them to trap.

Differential Revision: https://reviews.llvm.org/D53184

llvm-svn: 351772
2019-01-22 00:42:20 +00:00
JF Bastien
dec3ae0936 Document toolchain update policy
Summary:
Capture the current agreed-upon toolchain update policy based on the following
discussions:

  - LLVM dev meeting 2018 BoF "Migrating to C++14, and beyond!"
    llvm.org/devmtg/2018-10/talk-abstracts.html#bof3
  - A Short Policy Proposal Regarding Host Compilers
    lists.llvm.org/pipermail/llvm-dev/2018-May/123238.html
  - Using C++14 code in LLVM (2018)
    lists.llvm.org/pipermail/llvm-dev/2018-May/123182.html
  - Using C++14 code in LLVM (2017)
    lists.llvm.org/pipermail/llvm-dev/2017-October/118673.html
  - Using C++14 code in LLVM (2016)
    lists.llvm.org/pipermail/llvm-dev/2016-October/105483.html
  - Document and Enforce new Host Compiler Policy
    llvm.org/D47073
  - Require GCC 5.1 and LLVM 3.5 at a minimum
    llvm.org/D46723

Subscribers: jkorous, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D56819

llvm-svn: 351765
2019-01-21 23:53:52 +00:00