Summary:
This document is an attempt at showing how XRay could be used to debug
latency issues with LLVM tools, and how to use the llvm-xray tool to
analyse XRay traces.
Reviewers: echristo, mehdi_amini, davide
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D31493
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Summary:
This is the initial version of the documentation for how to use XRay as
it stands in LLVM, Clang, and compiler-rt. We leave some room for later
expansion mentioining what is work in progress and what could be
expected moving forward.
We also give a high level overview of future work that's both ongoing
and planned.
Reviewers: echristo, dblaikie, chandlerc
Subscribers: mehdi_amini, llvm-commits
Differential Revision: https://reviews.llvm.org/D26386
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This reflects the current state of Global ISel. As progress is
made, we'll document our design decisions in it.
Comments very welcome!
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This document describes the proposal to move to GitHub, and
compare the two proposals through various workflow examples,
presenting the current set of commands following by the ones
involved in each of the two proposals.
It is intended to supersede the previous "submodule proposal"
document entirely, and drive the discussion at the BoF during
the next Dev Meeting.
Differential Revision: https://reviews.llvm.org/D24167
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Given that other proposals are making their way through, it's better if we
specify what GitHub proposal this is, in case there are others that also
involve GitHub, but not sub-modules.
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The bitset metadata currently used in LLVM has a few problems:
1. It has the wrong name. The name "bitset" refers to an implementation
detail of one use of the metadata (i.e. its original use case, CFI).
This makes it harder to understand, as the name makes no sense in the
context of virtual call optimization.
2. It is represented using a global named metadata node, rather than
being directly associated with a global. This makes it harder to
manipulate the metadata when rebuilding global variables, summarise it
as part of ThinLTO and drop unused metadata when associated globals are
dropped. For this reason, CFI does not currently work correctly when
both CFI and vcall opt are enabled, as vcall opt needs to rebuild vtable
globals, and fails to associate metadata with the rebuilt globals. As I
understand it, the same problem could also affect ASan, which rebuilds
globals with a red zone.
This patch solves both of those problems in the following way:
1. Rename the metadata to "type metadata". This new name reflects how
the metadata is currently being used (i.e. to represent type information
for CFI and vtable opt). The new name is reflected in the name for the
associated intrinsic (llvm.type.test) and pass (LowerTypeTests).
2. Attach metadata directly to the globals that it pertains to, rather
than using the "llvm.bitsets" global metadata node as we are doing now.
This is done using the newly introduced capability to attach
metadata to global variables (r271348 and r271358).
See also: http://lists.llvm.org/pipermail/llvm-dev/2016-June/100462.html
Differential Revision: http://reviews.llvm.org/D21053
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* Renamed to be camel case, consistent with other docs.
* Fixed non-ascii characters (this is what I get for writing docs on an iPad).
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This document covers how to use some of the new complex build configurations CMake supports.
Feedback and improvements welcomed!
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I broke the documentation builds when I deleted the MakefileGuide as part of the autoconf removal. At some point I'll need to do a more in-depth pass updating the documentation to remove references to the old build system.
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Summary:
This patch adds documentation on compiling CUDA with LLVM as requested by many
engineers and researchers. It includes not only user guides but also some
internals (mostly optimizations) so that early adopters can start hacking and
contributing.
Quite a few researchers who contacted us haven't used LLVM before, which is
unsurprising as it hasn't been long since LLVM picked up CUDA. So I added a
short summary to help these folks get started with LLVM.
I expect this document to evolve substantially down the road. The user guides
will be much simplified after the Clang integration is done. However, the
internals should continue growing to include for example performance debugging
and key areas to improve.
Reviewers: chandlerc, meheff, broune, tra
Subscribers: silvas, jingyue, llvm-commits, eliben
Differential Revision: http://reviews.llvm.org/D14370
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Summary:
Move lib/Fuzzer docs from a README.txt to a proper .rst file.
This change does not add any content, just formatting.
Test Plan: n/a
Reviewers: samsonov
Reviewed By: samsonov
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D8710
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As mentioned on llvm-dev, this is a new documentation page intended to collect tips for frontend authors on how to generate IR that LLVM is able to optimize well. These types of things come up repeated in review threads and it would be good to have a place to save them.
I added a small handful to start us off, but I mostly want to get the framework in place. Once the docs are here, we can add to them incrementally. If you know of something appropriate for this page, please add it!
Differential Revision: http://reviews.llvm.org/D7890
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This patch introduces a new mechanism that allows IR modules to co-operatively
build pointer sets corresponding to addresses within a given set of
globals. One particular use case for this is to allow a C++ program to
efficiently verify (at each call site) that a vtable pointer is in the set
of valid vtable pointers for the class or its derived classes. One way of
doing this is for a toolchain component to build, for each class, a bit set
that maps to the memory region allocated for the vtables, such that each 1
bit in the bit set maps to a valid vtable for that class, and lay out the
vtables next to each other, to minimize the total size of the bit sets.
The patch introduces a metadata format for representing pointer sets, an
'@llvm.bitset.test' intrinsic and an LTO lowering pass that lays out the globals
and builds the bitsets, and documents the new feature.
Differential Revision: http://reviews.llvm.org/D7288
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This was done using the Sparc and PowerPC AsmParsers as guides. So far it
is very simple and only supports sopp instructions.
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There are some interesting decisions based on non-obvious rationale in
the ARM64-BE NEON implementation - decent documentation is definitely required.
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docs/TableGen/ is not really just "fundamentals" anymore, but rather
more of a portal for all things TableGen.
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Making the new TableGen documentation official and marking the old file as
"Moved". Also, reverting the original LangRef as the normative formal
description of the language, while keeping the "new" LangRef as LangIntro
for the less inlcined to reading language grammars.
We should remove TableGenFundamentals.rst one day, but for now, just a
warning that it moved will have to do, while we make sure there are no more
links to it from elsewhere.
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This is mainly a movement of content around to give place to new content
allowing different people to add bits to it in the right place. There is some
new content, but mostly to fill the gaps left by text movement.
I'm dropping the old syntax documentation as it has the problem of being
quickly outdated by changes and largely unnecessary to people not involved
in creating the language, but using it, which is the whole point of the
documentation.
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The docs now build cleanly. Yay!
The following warnings were fixed:
/home/sean/pg/llvm/llvm/docs/HowToReleaseLLVM.rst:364: WARNING: Enumerated list ends without a blank line; unexpected unindent.
/home/sean/pg/llvm/llvm/docs/InAlloca.rst:: WARNING: document isn't included in any toctree
/home/sean/pg/llvm/llvm/docs/CodingStandards.rst:85: WARNING: Title underline too short.
Supported C++11 Language and Library Features
-------------------------------------------
/home/sean/pg/llvm/llvm/docs/CodingStandards.rst:85: WARNING: Title underline too short.
Supported C++11 Language and Library Features
-------------------------------------------
/home/sean/pg/llvm/llvm/docs/GettingStarted.rst:185: WARNING: Explicit markup ends without a blank line; unexpected unindent.
/home/sean/pg/llvm/llvm/docs/GettingStarted.rst:565: WARNING: Explicit markup ends without a blank line; unexpected unindent.
/home/sean/pg/llvm/llvm/docs/GettingStarted.rst:567: WARNING: Block quote ends without a blank line; unexpected unindent.
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These still have "experimental" status, meaning we don't guarantee
backward compatibility. However, they are already actively used by the
open source WebKit project, and have started to be adopted by other
projects.
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Add support for the COFF relocation types IMAGE_REL_I386_DIR32NB and
IMAGE_REL_AMD64_ADDR32NB for 32- and 64-bit respectively. These are
similar to normal 4-byte relocations except that they do not include
the base address of the image.
Image-relative relocations are used for debug information (32-bit) and
SEH unwind tables (64-bit).
A new MCSymbolRef variant called 'VK_COFF_IMGREL32' is introduced to
specify such relocations. For AT&T assembly, this variant can be accessed
using the symbol suffix '@imgrel'.
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