6512 Commits

Author SHA1 Message Date
Daniel Berlin
a9c06e75f1 Fix some indenting and line-wrapping issues identified in ProgrammersManual. Make description of debugCounters a little clearer
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297656 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-13 19:09:23 +00:00
Daniel Berlin
b9513eac4a Add documentation on debug counters to Programmers Manual.
Reviewers: mehdi_amini

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D30842

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297575 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-12 04:46:41 +00:00
Daniel Berlin
57bd1ea8eb Remove opt-bisect support for "cases" in favor of debug counters
Summary:
Ths "cases" support was not quite finished, is unused, and is really just debug counters.
(well, almost, debug counters are slightly more powerful, in that they can skip things at the start, too).
Note, opt-bisect itself could also be implemented as a wrapper around
debug counters, but not sure it's worth it ATM.

I'll shove it on a todo list if we think it is.

Reviewers: MatzeB, chandlerc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D30856

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297542 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-11 01:41:03 +00:00
Artem Belevich
bb9779aa2e [FileCheck] Added --enable-var-scope option to enable scope for regex variables.
If `--enable-var-scope` is in effect, variables with names that
start with `$` are considered to be global. All other variables are
local. All local variables get undefined at the beginning of each
CHECK-LABEL block. Global variables are not affected by CHECK-LABEL.
This makes it easier to ensure that individual tests are not affected
by variables set in preceding tests.

Differential Revision: https://reviews.llvm.org/D30749

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297396 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-09 17:59:04 +00:00
Sanjay Patel
dccf5a1320 [InstSimplify] vector div/rem with any zero element in divisor is undef
This was suggested as a DAG simplification in the review for rL297026 :
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170306/435253.html
...but let's start with IR since we have actual docs for IR (LangRef).

Differential Revision:
https://reviews.llvm.org/D30665


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297390 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-09 16:20:52 +00:00
Konstantin Zhuravlyov
2cee5cc825 [DebugInfo] Emit address space with DW_AT_address_class attribute for pointer and reference types
Differential Revision: https://reviews.llvm.org/D29670


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297320 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-08 23:55:44 +00:00
Konstantin Zhuravlyov
df032da7f1 [DebugInfo] Make legal and emit DW_OP_swap and DW_OP_xderef
Differential Revision: https://reviews.llvm.org/D29672


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297247 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-08 00:28:57 +00:00
Gor Nishanov
2d33745172 [coroutines] Add handling for unwind coro.ends
Summary:
The purpose of coro.end intrinsic is to allow frontends to mark the cleanup and
other code that is only relevant during the initial invocation of the coroutine
and should not be present in resume and destroy parts.

In landing pads coro.end is replaced with an appropriate instruction to unwind to
caller. The handling of coro.end differs depending on whether the target is
using landingpad or WinEH exception model.

For landingpad based exception model, it is expected that frontend uses the
`coro.end`_ intrinsic as follows:

```
    ehcleanup:
      %InResumePart = call i1 @llvm.coro.end(i8* null, i1 true)
      br i1 %InResumePart, label %eh.resume, label %cleanup.cont

    cleanup.cont:
      ; rest of the cleanup

    eh.resume:
      %exn = load i8*, i8** %exn.slot, align 8
      %sel = load i32, i32* %ehselector.slot, align 4
      %lpad.val = insertvalue { i8*, i32 } undef, i8* %exn, 0
      %lpad.val29 = insertvalue { i8*, i32 } %lpad.val, i32 %sel, 1
      resume { i8*, i32 } %lpad.val29

```
The `CoroSpit` pass replaces `coro.end` with ``True`` in the resume functions,
thus leading to immediate unwind to the caller, whereas in start function it
is replaced with ``False``, thus allowing to proceed to the rest of the cleanup
code that is only needed during initial invocation of the coroutine.

For Windows Exception handling model, a frontend should attach a funclet bundle
referring to an enclosing cleanuppad as follows:

```
    ehcleanup:
      %tok = cleanuppad within none []
      %unused = call i1 @llvm.coro.end(i8* null, i1 true) [ "funclet"(token %tok) ]
      cleanupret from %tok unwind label %RestOfTheCleanup
```

The `CoroSplit` pass, if the funclet bundle is present, will insert
``cleanupret from %tok unwind to caller`` before
the `coro.end`_ intrinsic and will remove the rest of the block.

Reviewers: majnemer

Reviewed By: majnemer

Subscribers: llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D25543

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297223 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-07 21:00:54 +00:00
Ayman Musa
b59d8041db [X86][AVX512] Adding new LLVM TableGen backend which generates the EVEX2VEX compressing tables.
X86EvexToVex machine instruction pass compresses EVEX encoded instructions by replacing them with their identical VEX encoded instructions when possible.
It uses manually supported 2 large tables that map the EVEX instructions to their VEX ideticals.
This TableGen backend replaces the tables by automatically generating them.

Differential Revision: https://reviews.llvm.org/D30451



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297127 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-07 08:11:19 +00:00
Sylvestre Ledru
d2a4d59de7 Revert commit r296967, no typo
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296984 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-05 07:46:24 +00:00
Sylvestre Ledru
f15590a7fb Fix a typo. Patch by fcrick on github https://github.com/llvm-mirror/llvm/pull/23
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296969 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-04 14:01:38 +00:00
Sylvestre Ledru
99aada9bea Remove redundant code block and update comment.
By patch zoren here: https://github.com/llvm-mirror/llvm/pull/20



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296968 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-04 14:00:44 +00:00
Sylvestre Ledru
d64d538640 Fix a typo. Thanks to huangml. Reported here: https://github.com/llvm-mirror/llvm/pull/6
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296967 91177308-0d34-0410-b5e6-96231b3b80d8
2017-03-04 13:56:11 +00:00
Dean Michael Berris
7577713c9b [XRay][Docs] Update the XRay documentation
Summary:
Update the XRay docs to mention new subcomands to the llvm-xray tool,
and details on FDR mode logging. Also list down available libraries for
use part of the LLVM distribution.

Reviewers: rSerge, pelikan, echristo, timshen, sdardis, rengolin

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D30395

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296528 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-28 22:01:26 +00:00
Dehao Chen
e26c421c66 Add function importing info from samplepgo profile to the module summary.
Summary: For SamplePGO, the profile may contain cross-module inline stacks. As we need to make sure the profile annotation happens when all the hot inline stacks are expanded, we need to pass this info to the module importer so that it can import proper functions if necessary. This patch implemented this feature by emitting cross-module targets as part of function entry metadata. In the module-summary phase, the metadata is used to build call edges that points to functions need to be imported.

Reviewers: mehdi_amini, tejohnson

Reviewed By: tejohnson

Subscribers: davidxl, llvm-commits

Differential Revision: https://reviews.llvm.org/D30053

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296498 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-28 18:09:44 +00:00
Lang Hames
97a1c1b90e [docs] Fix a think-o in the Programmer's Manual.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296421 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-28 01:35:31 +00:00
Lang Hames
530cc1a7c8 [Support][Error] Add a 'cantFail' utility function for known-safe calls to
fallible functions.

Some fallible functions (those returning Error or Expected<T>) may only fail
for a subset of their inputs. For example, a "safe" square root function will
succeed for all finite positive inputs:

  Expected<double> safeSqrt(double d) {
    if (d < 0 && !isnan(d) && !isinf(d))
      return make_error<...>("Cannot sqrt -ve values, nans or infs");
    return sqrt(d);
  }

At a safe callsite for such a function, checking the error return value is
redundant:

  if (auto ValOrErr = safeSqrt(42.0)) {
    // use *ValOrErr.
  } else
    llvm_unreachable("safeSqrt should always succeed for +ve values");

The cantFail function wraps this check and extracts the contained value,
simplifying control flow:

  double Result = cantFail(safeSqrt(42.0));

This function should be used with care: it is a programmatic error to wrap a
call with cantFail if it can in fact fail. For debug builds this will
result in llvm_unreachable being called. For release builds the behavior is
undefined.

Use of this function is likely to be rare in library code, but more common
for tool and unit-test code where inputs and mock functions may be known to be
safe.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296384 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-27 21:09:47 +00:00
Piotr Padlewski
79b977862e [Doc] Modernize programmers manual
Summary:
Fixed bunch of for loops to range based for loop
and bunch of rendundat types with auto.

Reviewers: echristo, silvas, chandlerc

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D30338

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296251 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-25 10:33:37 +00:00
Tobias Grosser
34c1d56ba3 [docs] Add information about how to checkout polly to getting started page
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295974 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-23 14:27:07 +00:00
Eli Friedman
e597c2c861 Explicitly state the behavior of inbounds with a null pointer.
See https://llvm.org/bugs/show_bug.cgi?id=31439; this reflects LLVM's
behavior in practice, and should be compatible with C/C++ rules.

Differential Revision: https://reviews.llvm.org/D28026



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295916 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-23 00:48:18 +00:00
Wei Ding
8d22e6f3bb AMDGPU : AMDGPU : Update AMDGPU Trap Handler ABI.
Differential Revision: http://reviews.llvm.org/D29913

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295745 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-21 18:48:01 +00:00
Ismail Donmez
f93e288abc Update Bugzilla URLs in docs
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295432 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-17 08:26:11 +00:00
Sanjoy Das
6980b109cd [LangRef] Explicitly allow readnone and reaodnly functions to unwind
Summary:
This change edits the language reference to explicitly allow the
existence of readnone and readonly functions that can throw.  Full
discussion at
http://lists.llvm.org/pipermail/llvm-dev/2017-January/108637.html

Reviewers: dberlin, chandlerc, hfinkel, majnemer

Reviewed By: majnemer

Subscribers: majnemer, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D28740

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295000 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-13 23:19:07 +00:00
Sanjoy Das
c812cd6542 [LangRef] Update the TBAA section
Summary:
Update the TBAA section to mention the struct path TBAA that LLVM
implements today.  This is not a proposal or change in semantics -- it
is intended only to **document** what LLVM already does today.

This is related to https://reviews.llvm.org/D26438 where I've tried to
implement some of the constraints as verifier checks.

Reviewers: anna, reames, rsmith, chandlerc, hfinkel, rjmccall, mehdi_amini, dexonsmith, manmanren

Reviewed By: manmanren

Subscribers: dberlin, dberris, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D26831

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294999 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-13 23:14:03 +00:00
Mehdi Amini
e0ae1eda9c Update Kaleidoscope tutorial and improve Windows support
Many quoted code blocks were not in sync with the actual toy.cpp
files. Improve tutorial text slightly in several places.
Added some step descriptions crucial to avoid crashes (like
InitializeNativeTarget* calls).
Solve/workaround problems with Windows (JIT'ed method not found, using
custom and standard library functions from host process).

Patch by: Moritz Kroll <moritz.kroll@gmx.de>

Differential Revision: https://reviews.llvm.org/D29864

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294870 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-11 21:26:52 +00:00
Aaron Ballman
342bf77f71 Correcting several sphinx errors; should fix the LLVM documentation build.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294865 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-11 18:45:24 +00:00
Dehao Chen
d0b28d942d Encode duplication factor from loop vectorization and loop unrolling to discriminator.
Summary:
This patch starts the implementation as discuss in the following RFC: http://lists.llvm.org/pipermail/llvm-dev/2016-October/106532.html

When optimization duplicates code that will scale down the execution count of a basic block, we will record the duplication factor as part of discriminator so that the offline process tool can find the duplication factor and collect the accurate execution frequency of the corresponding source code. Two important optimization that fall into this category is loop vectorization and loop unroll. This patch records the duplication factor for these 2 optimizations.

The recording will be guarded by a flag encode-duplication-in-discriminators, which is off by default.

Reviewers: probinson, aprantl, davidxl, hfinkel, echristo

Reviewed By: hfinkel

Subscribers: mehdi_amini, anemet, mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D26420

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294782 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-10 21:09:07 +00:00
Mehdi Amini
00b42cc2f1 Fix doc for -opt-bisect-limit: the LTO option prefix for lld is -mllvm
Thanks Davide to catch it in my previous patch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294759 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-10 17:16:00 +00:00
Mehdi Amini
2fabd44db6 Fix doc for -opt-bisect-limit: the LTO option is linker specific
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294725 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-10 07:21:06 +00:00
Wei Ding
c75c94d0eb AMDGPU : Add trap handler support.
Differential Revision: http://reviews.llvm.org/D26010

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294692 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-10 02:15:29 +00:00
Matthias Braun
05638abb6d docs/conf.py: Suppress sphinx highlighting failure warnings
The pygments syntax highlighting package used by sphinx fails to parse
newer LLVM constructs or valid (at least to me) gas constructs like
`.secrel32 _function_name + 0`.

Disable this particular warning so the build doesn't abort as fixing
pygments doesn't seem a workable option here.

Differential Revision: https://reviews.llvm.org/D29794

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294672 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-10 00:00:22 +00:00
Hans Wennborg
07a58ad1e0 Don't try to link to the 4.0 release notes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294647 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-09 23:03:34 +00:00
Matthias Braun
9e6fc42f4f lit.rst: Fix sphinx complaint about multiple option definitions
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294646 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-09 23:03:22 +00:00
Jonathan Roelofs
65b9667f0a [docs] Fix typo
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294645 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-09 23:02:37 +00:00
Kostya Kortchinsky
4795c086b6 [docs] Documentation update for Scudo
Summary:
Documentation update to reflect the changes that occured in the allocator:
- additional architectures support;
- modification of the header;
- options default values for 32 & 64-bit.

Reviewers: kcc, alekseyshl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29592

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294595 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-09 16:07:52 +00:00
Rafael Espindola
5a2d92c7cf Make it possible to set SHF_LINK_ORDER explicitly.
This will make it possible to add support for gcing user metadata
(asan for example).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294589 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-09 14:59:20 +00:00
David Bozier
56b920f6fe [docs] cleanup documentation on lit substitutions
1. Added missing substitutions to the documentation in docs/TestingGuide.rst
2. Modified docs/CommandGuide/lit.rst to only document the "base" set of substitutions and to refer the reader to docs/TestingGuide.rst for more detailed info on substitutions.

Patch by bd1976llvm

Differential Revision: https://reviews.llvm.org/D29281



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294586 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-09 14:12:30 +00:00
Sanjoy Das
9ac774d7cf Fix the docs build
(and add a bit of formatting.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294347 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-07 20:36:03 +00:00
Daniel Berlin
f2da6f93fe This patch adds a ssa_copy intrinsic, as part of splitting up D29316.
Summary:
The intrinsic, marked as returning it's first argument, has no code
generation effect (though currently not every optimization pass knows
that intrinsics with the returned attribute can be looked through).

It is about to be used to by the PredicateInfo pass to attach
predicate information to existing operands, and be able to tell what
the predicate information affects.

We deliberately do not attach any info through a second operand so
that the intrinsics do not need to dominate the comparisons/etc (since
in the case of assume, we may want to push them up the post-dominator
tree).

Reviewers: davide, sanjoy

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29517

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294341 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-07 19:29:25 +00:00
Sanjoy Das
a0be0b1390 [ImplicitNullCheck] Extend Implicit Null Check scope by using stores
Summary:
This change allows usage of store instruction for implicit null check.

Memory Aliasing Analisys is not used and change conservatively supposes
that any store and load may access the same memory. As a result
re-ordering of store-store, store-load and load-store is prohibited.

Patch by Serguei Katkov!

Reviewers: reames, sanjoy

Reviewed By: sanjoy

Subscribers: atrick, llvm-commits

Differential Revision: https://reviews.llvm.org/D29400

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294338 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-07 19:19:49 +00:00
Reid Kleckner
2a4edb648f [LangRef] Document some LLVM inline asm special escapes
As discussed on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2017-February/109862.html

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294204 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-06 18:08:45 +00:00
Dylan McKay
c24ff540a8 [docs] Document the staging buildbot
Summary:
This also adds docs to suggest that maintainers of buildbots for
experimental backends should use this buildmaster.

Reviewers: dsanders, grosser, asb, mehdi_amini

Reviewed By: grosser

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29560

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294144 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-05 21:21:23 +00:00
Vedant Kumar
2006b414f1 [llvm-cov] Don't show function summaries when filtering by filename (fixes PR31395)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294137 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-05 20:11:08 +00:00
Peter Collingbourne
043d1a96c9 MC: Introduce the ABS8 symbol modifier.
@ABS8 can be applied to symbols which appear as immediate operands to
instructions that have a 8-bit immediate form for that operand. It causes
the assembler to use the 8-bit form and an 8-bit relocation (e.g. R_386_8
or R_X86_64_8) for the symbol.

Differential Revision: https://reviews.llvm.org/D28688

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293667 91177308-0d34-0410-b5e6-96231b3b80d8
2017-01-31 18:28:44 +00:00
Alexey Bader
7726f8808d [LanRef] Fix typo in getelementptr example.
Summary: Change B type from double to pointer to double.

Reviewers: delena, sanjoy

Reviewed By: sanjoy

Subscribers: sanjoy, llvm-commits

Differential Revision: https://reviews.llvm.org/D29009

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293467 91177308-0d34-0410-b5e6-96231b3b80d8
2017-01-30 07:38:58 +00:00
Matthias Braun
d6da5dbf7b Use print() instead of dump() in code
The dump() functions are meant to be used in a debugger, code should
typically use something like print(errs());

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293365 91177308-0d34-0410-b5e6-96231b3b80d8
2017-01-28 02:47:46 +00:00
Justin Lebar
16270ea540 Update NVVMReflect usage doc to new idiom for adding target-specific early passes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293327 91177308-0d34-0410-b5e6-96231b3b80d8
2017-01-27 19:44:24 +00:00
Justin Lebar
0c6a4bdbb7 [LangRef] Make @llvm.sqrt(x) return undef, rather than have UB, for negative x.
Summary:
Some frontends emit a speculate-and-select idiom for sqrt, wherein they compute
sqrt(x), check if x is negative, and select NaN if it is:

  %cmp = fcmp olt double %a, -0.000000e+00
  %sqrt = call double @llvm.sqrt.f64(double %a)
  %ret = select i1 %cmp, double 0x7FF8000000000000, double %sqrt

This is technically UB as the LangRef is written today if %a is ever less than
-0.  But emitting code that's compliant with the current definition of sqrt
would require a branch, which would then prevent us from matching this idiom in
SelectionDAG (which we do today -- ISD::FSQRT has defined behavior on negative
inputs), because SelectionDAG looks at one BB at a time.

Nothing in LLVM takes advantage of this undefined behavior, as far as we can
tell, and the fact that llvm.sqrt has UB dates from its initial addition to the
LangRef.

Reviewers: arsenm, mehdi_amini, hfinkel

Subscribers: wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D28797

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293242 91177308-0d34-0410-b5e6-96231b3b80d8
2017-01-27 00:58:03 +00:00
Andrew Kaylor
e6f10d3481 Add intrinsics for constrained floating point operations
This commit introduces a set of experimental intrinsics intended to prevent
optimizations that make assumptions about the rounding mode and floating point
exception behavior.  These intrinsics will later be extended to specify
flush-to-zero behavior.  More work is also required to model instruction
dependencies in machine code and to generate these instructions from clang
(when required by pragmas and/or command line options that are not currently
supported).

Differential Revision: https://reviews.llvm.org/D27028



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293226 91177308-0d34-0410-b5e6-96231b3b80d8
2017-01-26 23:27:59 +00:00
Zvi Rackover
8f4444960f [Doc][LangRef] Fix typo-ish error in description of Masked Gather
Summary: Fix the example of equivalent expansion for when mask is all ones.

Reviewers: delena

Reviewed By: delena

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29179

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293206 91177308-0d34-0410-b5e6-96231b3b80d8
2017-01-26 20:29:15 +00:00