This patch upstreams support for the Arm-v8 Cortex-A77
processor for AArch64 and ARM.
In detail:
- Adding cortex-a77 as a cpu option for aarch64 and arm targets in clang
- Cortex-A77 CPU name and ProcessorModel in llvm
details of the CPU can be found here:
https://www.arm.com/products/silicon-ip-cpu/cortex-a/cortex-a77
and a similar submission to GCC can be found here:
e0664b7a63
The following people contributed to this patch:
- Luke Geeson
- Mikhail Maltsev
Reviewers: t.p.northover, dmgreen, ostannard, SjoerdMeijer
Reviewed By: dmgreen
Subscribers: dmgreen, kristof.beyls, hiraditya, danielkiss, cfe-commits,
llvm-commits, miyuki
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D82887
This fixes a unit test. Otherwise here is the original commit:
1) Shared writable directories like /tmp are a security problem.
2) Systems provide dedicated cache directories these days anyway.
3) This also refines LLVM's cache_directory() on Darwin platforms to use
the Darwin per-user cache directory.
Reviewers: compnerd, aprantl, jakehehrlich, espindola, respindola, ilya-biryukov, pcc, sammccall
Reviewed By: compnerd, sammccall
Subscribers: hiraditya, llvm-commits, cfe-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D82362
Summary:
Factor out repetetitive code into helper function and split massive
ExpressionFormat method test into separate test for each method,
removing dead code in passing. Also add a MinInt64 and MaxInt64 checks
when testing getMatchingString.
Reviewers: jhenderson, jdenny, probinson, grimar, arichardson
Reviewed By: jhenderson, grimar
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D82132
Skip 'really hidden' options when performing lookup of the nearest
option when invalid option was passed. Since these options aren't even
documented in --help-hidden, it seems inconsistent to suggest them
to users.
This fixes clang-tools-extra test failures due to unexpected suggestions
when linking the tools to LLVM dylib (that provides more options than
the subset of LLVM libraries linked directly).
Differential Revision: https://reviews.llvm.org/D82001
The functions sys::ExcecuteAndWait and sys::Wait now have additional
argument of type pointer to structure, which is filled with process
execution statistics upon process termination. These are total and user
execution times and peak memory consumption. By default this argument is
nullptr so existing users of these function must not change behavior.
Differential Revision: https://reviews.llvm.org/D78901
This patch is part of a patch series to add support for FileCheck
numeric expressions. This specific patch adds support for specifying the
matching constraint for a numeric expression, ie. how the value being
matched should relate to the numeric expression.
This commit only adds the equality constraint where the numeric value
matched must be equal to the numeric expression. It is the default
matching constraint used when not specified. It is added to provision
other matching constraint (e.g. inequality relations).
Copyright:
- Linaro (changes up to diff 183612 of revision D55940)
- GraphCore (changes in later versions of revision D55940 and
in new revision created off D55940)
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D60391
This patch extends numerical expressions to allow calls to
predefined functions. These calls can be combined with the
existing numerical operators, which includes nesting calls.
The call syntax is:
<func>(<args>)
Where <func> is a predefined string literal, currently limited to
one of add, max, min and sub. <arg> is a comma seperated list of
numerical expressions.
Subscribers: arichardson, hiraditya, thopre, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D79936
errs() is now tied to outs() so that if something prints to errs(),
outs() will be flushed before the printing occurs. This avoids
interleaving output between the two and is consistent with standard cout
and cerr behaviour.
Reviewed by: labath, JDevlieghere, MaskRay
Differential Revision: https://reviews.llvm.org/D81156
This moves the SuffixTree test used in the Machine Outliner and moves it into Support for use in other outliners elsewhere in the compilation pipeline.
Differential Revision: https://reviews.llvm.org/D80586
Replace the DisableColors with a ColorMode which can be set to Auto,
Enabled and Disabled. The purpose of this change is to make it possible
to ignore the command line option not only for disabling colors, but
also for enabling them.
Differential revision: https://reviews.llvm.org/D81056
Move the color handling code from raw_fd_ostream to raw_ostream. This
makes it possible to use colors with any ostream when enabled. The
existing behavior where only raw_fd_ostream supports colors by default
remains unchanged.
Differential revision: https://reviews.llvm.org/D81110
Summary:
If the output filename was specified as "-", the ToolOutputFile class
would create a brand new raw_ostream object referring to the stdout.
This patch changes it to reuse the llvm::outs() singleton.
At the moment, this change should be "NFC", but it does enable other
enhancements, like the automatic stdout/stderr synchronization as
discussed on D80803.
I've checked the history, and I did not find any indication that this
class *has* to use a brand new stream object instead of outs() --
indeed, it is special-casing "-" in a number of places already, so this
change fits the pattern pretty well. I suspect the main reason for the
current state of affairs is that the class was originally introduced
(r111595, in 2010) as a raw_fd_ostream subclass, which made any other
solution impossible.
Another potential benefit of this patch is that it makes it possible to
move the raw_ostream class out of the business of special-casing "-" for
stdout handling. That state of affairs does not seem appropriate because
"-" is a valid filename (albeit hard to access with a lot of command
line tools) on most systems. Handling "-" in ToolOutputFile seems more
appropriate.
To make this possible, this patch changes the return type of
llvm::outs() and errs() to raw_fd_ostream&. Previously the functions
were constructing objects of that type, but returning a generic
raw_ostream reference. This makes it possible for new ToolOutputFile and
other code to use raw_fd_ostream methods like error() on the outs()
object. This does not seem like a bad thing (since stdout is a file
descriptor which can be redirected to anywhere, it makes sense to ask it
whether the writing was successful or if it supports seeking), and
indeed a lot of code was already depending on this fact via the
ToolOutputFile "back door".
Reviewers: dblaikie, JDevlieghere, MaskRay, jhenderson
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D81078
New functions `lockFile`, `tryLockFile` and `unlockFile` implement
simple file locking. They lock or unlock entire file. This must be
enough to support simulataneous writes to log files in parallel builds.
Differential Revision: https://reviews.llvm.org/D78896
Summary:
This is a result of the discussion at D78113. Previously we would be
only giving the current offset at which the error was detected. However,
this was phrased somewhat ambiguously (as it could also mean that end of
data was at that offset). The new error message includes the current
offset as well as the extent of the data being read.
I've changed a couple of file-level static functions into private member
functions in order to avoid passing a bunch of new arguments everywhere.
Reviewers: dblaikie, jhenderson
Subscribers: hiraditya, MaskRay, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D78558
Summary:
This patch is part of a patch series to add support for FileCheck
numeric expressions. This specific patch adds support signed numeric
values, thus allowing negative numeric values.
As such, the patch adds a new class to represent a signed or unsigned
value and add the logic for type promotion and type conversion in
numeric expression mixing signed and unsigned values. It also adds
the %d format specifier to represent signed value.
Finally, it also adds underflow and overflow detection when performing a
binary operation.
Copyright:
- Linaro (changes up to diff 183612 of revision D55940)
- GraphCore (changes in later versions of revision D55940 and
in new revision created off D55940)
Reviewers: jhenderson, chandlerc, jdenny, probinson, grimar, arichardson
Reviewed By: jhenderson, arichardson
Subscribers: MaskRay, hiraditya, llvm-commits, probinson, dblaikie, grimar, arichardson, kristina, hfinkel, rogfer01, JonChesterfield
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60390
Patch by Neil Dhar <dhar@alumni.duke.edu>
Current state machine for parsing tokens from response files in Windows
does not correctly handle the case where the last token is "". The current
implementation handles the last token by only adding it if it is not empty,
however this does not cover the case where the last token is meant to be
the empty string. We can cover this case by checking whether the state
machine was last in the UNQUOTED state, which indicates that the last
character of the input was a non-whitespace character.
Differential Revision: https://reviews.llvm.org/D78346
With this change it is be possible to write FileCheck expressions such
as [[#(VAR+1)-2]]. Currently, the only supported arithmetic operators are
plus and minus, so this is not particularly useful yet. However, it our
CHERI fork we have tests that benefit from having multiplication in
FileCheck expressions. Allowing parenthesized expressions is the simplest
way for us to work around the current lack of operator precedence in
FileCheck expressions.
Reviewed By: thopre, jhenderson
Differential Revision: https://reviews.llvm.org/D77383
If the caller needs to reponsible for making sure the MaybeAlign
has a value, then we should just make the caller convert it to an Align
with operator*.
I explicitly deleted the relational comparison operators that
were being inherited from Optional. It's unclear what the meaning
of two MaybeAligns were one is defined and the other isn't
should be. So make the caller reponsible for defining the behavior.
I left the ==/!= operators from Optional. But now that exposed a
weird quirk that ==/!= between Align and MaybeAlign required the
MaybeAlign to be defined. But now we use the operator== from
Optional that takes an Optional and the Value.
Differential Revision: https://reviews.llvm.org/D80455
This is the first checkin to support Marvell ThunderX3T110.
Initial definition of the micro-ops of the instructions in ThunderX3T110
is included.
Differential Revision: https://reviews.llvm.org/D78129
In D49466, sys::path::replace_path_prefix was used instead startswith for -f[macro/debug/file]-prefix-map options.
However those were reverted later (commit rG3bb24bf25767ef5bbcef958b484e7a06d8689204) due to broken Windows tests.
This patch restores those replace_path_prefix calls.
It also modifies the prefix matching to be case-insensitive under Windows.
Differential Revision : https://reviews.llvm.org/D76869
For empty directories (except the first one) we've been adding a file
with the same name as the directory to the result VFS mapping.
Differential Revision: https://reviews.llvm.org/D79551
Essentially takes the lld/Common/Threads.h wrappers and moves them to
the llvm/Support/Paralle.h algorithm header.
The changes are:
- Remove policy parameter, since all clients use `par`.
- Rename the methods to `parallelSort` etc to match LLVM style, since
they are no longer C++17 pstl compatible.
- Move algorithms from llvm::parallel:: to llvm::, since they have
"parallel" in the name and are no longer overloads of the regular
algorithms.
- Add range overloads
- Use the sequential algorithm directly when 1 thread is requested
(skips task grouping)
- Fix the index type of parallelForEachN to size_t. Nobody in LLVM was
using any other parameter, and it made overload resolution hard for
for_each_n(par, 0, foo.size(), ...) because 0 is int, not size_t.
Remove Threads.h and update LLD for that.
This is a prerequisite for parallel public symbol processing in the PDB
library, which is in LLVM.
Reviewed By: MaskRay, aganea
Differential Revision: https://reviews.llvm.org/D79390
Currently, normalize() for posix replaces backslashes to slashes, except
that two backslashes in sequence are kept as-is.
clang calls normalize() to convert \ to / is microsoft compat mode. This
generally works well, but a path like "c:\\foo\\bar.h" with two
backslashes doesn't work due to the exception in normalize().
These paths happen naturally on Windows hosts with e.g.
`#include __FILE__`, and them not working on other hosts makes it
more difficult to write tests for this case.
The special case has been around without justification since this code
was added in r203611 (since then moved around in r215241 r215243). No
integration tests fail if I remove it.
Try removing the special case.
Differential Revision: https://reviews.llvm.org/D79265
Size==0 triggers `assert(Size != 0)` in mapped_file_region::init.
I plan to use an empty file in D79339 (llvm-objcopy --dump-section).
According to POSIX, "If len is zero, mmap() shall fail and no mapping
shall be established." Just specialize case Size=0 to use
createInMemoryBuffer.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D79338
This reverts commit fb5fd74685.
Re-instates commit 53913a65b4
The fix is to trim off trailing separators, as in `/foo/bar/` and
produce `/foo/bar`. VFS tests rely on this. I added unit tests for
remove_dots.
LLD calls this on every source file string in every object file when
writing PDBs, so it is somewhat hot.
Avoid rewriting paths that do not contain path traversal components
(./..). Use find_first_not_of(separators) directly instead of using the
path iterators. The path component iterators appear to be slow, and
directly searching for slashes makes it easier to find double separators
that need to be canonicalized.
I discovered that the VFS relies on remote_dots to not canonicalize
early slashes (/foo or C:/foo) on Windows, so I had to leave that
behavior behind with unit tests for it. This is undesirable, but I claim
that my change is NFC.
This lets it use sized deallocation and make more efficient alignment
decisions. Also adjust BumpPtrAllocator to always allocate at
alignof(std::max_align_t).
The approach in D30000 assumes that the '/' returned by path::begin()
is the first element for absolute paths, but that's not true on
Windows.
Also, on Windows backslashes in include lines often end up escaped
so that there are two of them. Having backslashes in include lines
is undefined behavior in most cases and implementation-defined
behavior in C++20, but since clang treats it as normal repeated
path separators, the diagnostic should too.
Unbreaks -Wnonportable-include-path for absolute paths on Windows,
and unbreaks it on non-Windows in the case of absolute paths with
repeated directory separators.
This affects e.g. the `#include __FILE__` technique if the file
passed to clang has the wrong case for the drive letter. Before:
C:\src\llvm-project>bin\clang-cl.exe c:\src\llvm-project\test.cc
c:\\src\\llvm-project\\test.cc(4,10): warning: non-portable path to file
'"c\\srccllvm-projectctest.cc.'; specified path differs in case from
file name on disk [-Wnonportable-include-path]
^
Now:
C:\src\llvm-project> out\gn\bin\clang-cl c:\src\llvm-project\test.cc
c:\\src\\llvm-project\\test.cc(4,10): warning: non-portable path to file
'"C:\\src\\llvm-project\\test.cc"'; specified path differs in case from
file name on disk [-Wnonportable-include-path]
^
Differential Revision: https://reviews.llvm.org/D79223
This reverts commit ad38f4b371.
As it broke building the unittests:
.../sources/llvm-project/llvm/unittests/Support/Path.cpp:334:5: error: use of undeclared identifier 'set'
set(Value);
^
1 error generated.
Summary:
This patch adds a function that is similar to `llvm::sys::path::home_directory`, but provides access to the system cache directory.
For Windows, that is %LOCALAPPDATA%, and applications should put their files under %LOCALAPPDATA%\Organization\Product\.
For *nixes, it adheres to the XDG Base Directory Specification, so it first looks at the XDG_CACHE_HOME environment variable and falls back to ~/.cache/.
Subsequently, the Clangd Index storage leverages this new API to put index files somewhere else than the users home directory.
Fixes https://github.com/clangd/clangd/issues/341
Reviewers: sammccall, chandlerc, Bigcheese
Reviewed By: sammccall
Subscribers: hiraditya, ilya-biryukov, MaskRay, jkorous, dexonsmith, arphaman, kadircet, ormris, usaxena95, cfe-commits, llvm-commits
Tags: #clang-tools-extra, #clang, #llvm
Differential Revision: https://reviews.llvm.org/D78501
With a fix to unittests/Support/TarWriterTest.cpp
This makes lld's --reproduce output more compatible with tar 1.13 and
before. This is a very old version of tar, but it's the version in
both gnuwin and unxutils, and the cost for supporting them are very
low, so we might as well just do that.
https://bugs.chromium.org/p/chromium/issues/detail?id=1073524#c21
and onward has more details.
Differential Revision: https://reviews.llvm.org/D78945
raw_string_ostream can just use the std::string as a buffer. The buffer
requirement came from the days when the minimum buffer size was 128
(fixed in 2015) and std::string was non-SSO. Now we can just use the
inline capacity for small things and on a good growth strategy later.
This assumes that the standard library isn't doing something bad like
only growing to the exact size. I checked some common implementations
and they grow by 2x (libc++) or 1.5x (msvc) which is reasonable. We
should still check if this incurs any performance regressions though.
This patch upstreams support for the Armv8.6-a Matrix Multiplication
Extension. A summary of the features can be found here:
https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/arm-architecture-developments-armv8-6-a
This patch includes:
- Command line options to enable these features with +i8mm, +f32mm, or f64mm
Note: +f32mm and +f64mm are optional and so are not enabled by default
This is part of a patch series, starting with BFloat16 support and
the other components in the armv8.6a extension (in previous patches
linked in phabricator)
Based on work by:
- Luke Geeson
- Oliver Stannard
- Luke Cheeseman
Reviewers: t.p.northover, DavidSpickett
Reviewed By: DavidSpickett
Subscribers: DavidSpickett, ostannard, kristof.beyls, danielkiss,
cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D77875
There are few `std::vector<std::string>` members in
`FileCheckRequest`. This patch changes these arrays to `std::vector<StringRef>`
and refactors the code related to cleanup/improve/simplify it.
Differential revision: https://reviews.llvm.org/D78202
Summary:
Currently, cl::ConsumeAfter only works for the case that has exactly one
positional argument. Without the fix, it skip fulfilling first positional
argument and put that additional positional argument in interpreter arguments.
Reviewers: bkramer, Mordante, rnk, lattner, beanz, craig.topper
Reviewed By: rnk
Subscribers: JosephTremoulet, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77242
This is needed to fix the reason
0a2be46cfd (Modules: Invalidate out-of-date PCMs as they're
discovered) and 5b44a4b07fc1d ([modules] Do not cache invalid state for
modules that we attempted to load.) were reverted.
These patches changed Clang to use `isVolatile` when loading modules.
This had the side effect of not using mmap when loading modules, and
thus greatly increased memory usage.
The reason it wasn't using mmap is because `MemoryBuffer` plays some
games with file size when you request null termination, and it has to
disable these when `isVolatile` is set as the size may change by the
time it's mmapped. Clang by default passes
`RequiresNullTerminator = true`, and `shouldUseMmap` ignored if
`RequiresNullTerminator` was even requested.
This patch adds `RequiresNullTerminator` to the `FileManager` interface
so Clang can use it when loading modules, and changes `shouldUseMmap` to
only take volatility into account if `RequiresNullTerminator` is true.
This is fine as both `mmap` and a `read` loop are vulnerable to
modifying the file while reading, but are immune to the rename Clang
does when replacing a module file.
Differential Revision: https://reviews.llvm.org/D77772
Summary:
Improve error message in case of conflict between several implicit
format to mention the operand that conflict.
Reviewers: jhenderson, jdenny, probinson, grimar, arichardson, rnk
Reviewed By: jdenny
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77741
This revision moves the various range utilities present in MLIR to LLVM to enable greater reuse. This revision moves the following utilities:
* indexed_accessor_*
This is set of utility iterator/range base classes that allow for building a range class where the iterators are represented by an object+index pair.
* make_second_range
Given a range of pairs, returns a range iterating over the `second` elements.
* hasSingleElement
Returns if the given range has 1 element. size() == 1 checks end up being very common, but size() is not always O(1) (e.g., ilist). This method provides O(1) checks for those cases.
Differential Revision: https://reviews.llvm.org/D78064
It can be used to avoid passing the begin and end of a range.
This makes the code shorter and it is consistent with another
wrappers we already have.
Differential revision: https://reviews.llvm.org/D78016
This patch extracts the RTTI part of llvm::ErrorInfo into its own class
(RTTIExtends) so that it can be used in other non-error hierarchies, and makes
it compatible with the existing LLVM RTTI function templates (isa, cast,
dyn_cast, dyn_cast_or_null) by adding the classof method.
Differential Revision: https://reviews.llvm.org/D39111
Summary:
There are at least three clients for KnownBits calculations:
ValueTracking, SelectionDAG and GlobalISel. To reduce duplication the
common logic should be moved out of these clients and into KnownBits
itself.
This patch does this for AND, OR and XOR calculations by implementing
and using appropriate operator overloads KnownBits::operator& etc.
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D74060
Summary:
If the decoding functions are called with both start and end pointers
being nullptr, the function will crash due to a nullptr dereference.
This happens because the function does not recognise nullptr as a valid
end pointer.
Obviously, nobody is going to pass null pointers here deliberately, but
it can happen indirectly (as it did for me), when calling these
functions on an ArrayRef, as a default-initialized empty ArrayRef will
have both begin() and end() pointers equal to nullptr.
The fix is to simply remove the nullptr check. Passing nullptr for "end"
with a valid "begin" pointer will still work, as one cannot reach
nullptr by incrementing a valid pointer without triggerring UB.
Reviewers: dblaikie
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77304
Summary:
This patch adds the optional Error argument, and the Cursor variants to
more DataExtractor methods. The functions now behave the same way as
other error-aware functions (they set the error when they fail, and
don't do anything if the error is already set).
I have merged the LEB128 implementations via a template (similarly to
how fixed-size functions are handled) to reduce code duplication.
Depends on D77304.
Reviewers: dblaikie, aprantl
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77306
Summary:
This patch adds an optional Error argument to DataExtractor functions
for string extraction, and makes them behave like other DataExtractor
functions (set the error if extraction fails, don't do anything if the
error is already set).
I have merged the StringRef and C string versions of the functions to
reduce code duplication.
Reviewers: dblaikie, MaskRay
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77307
Added unit tests for 2 scenarios that were failing.
Made replace_path_prefix back to 3 parameters instead of 5, simplifying the implementation. The other 2 were always used with the default value.
This commit is intended to be the first of 3:
1) simplify/fix replace_path_prefix.
2) use it in the context of -fdebug-prefix-map and -fmacro-prefix-map (see D76869).
3) Make Windows version of replace_path_prefix insensitive to both case and separators (slash vs backslash).
Differential Revision: https://reviews.llvm.org/D77223
Leverage ARM ELF build attribute section to create ELF attribute section
for RISC-V. Extract the common part of parsing logic for this section
into ELFAttributeParser.[cpp|h] and ELFAttributes.[cpp|h].
Differential Revision: https://reviews.llvm.org/D74023
Extend the FileCollector's API with addDirectory which adds a directory
and its contents to the VFS mapping.
Differential revision: https://reviews.llvm.org/D76671
Extend the FileCollector's API with addDirectory which adds a directory
and its contents to the VFS mapping.
Differential revision: https://reviews.llvm.org/D76671
The current implementation of the JSONWriter does not support writing
out directory entries. Earlier today I added a unit test to illustrate
the problem. When an entry is added to the YAMLVFSWriter and the path is
a directory, it will incorrectly emit the directory as a file, and any
files inside that directory will not be found by the VFS.
It's possible to partially work around the issue by only adding "leaf
nodes" (files) to the YAMLVFSWriter. However, this doesn't work for
representing empty directories. This is a problem for clients of the VFS
that want to iterate over a directory. The directory not being there is
not the same as the directory being empty.
This is not just a hypothetical problem. The FileCollector for example
does not differentiate between file and directory paths. I temporarily
worked around the issue for LLDB by ignoring directories, but I suspect
this will prove problematic sooner rather than later.
This patch fixes the issue by extending the JSONWriter to support
writing out directory entries. We store whether an entry should be
emitted as a file or directory.
Differential revision: https://reviews.llvm.org/D76670
Summary:
This patch introduces command-line support for the Armv8.6-a architecture and assembly support for BFloat16. Details can be found
https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/arm-architecture-developments-armv8-6-a
in addition to the GCC patch for the 8..6-a CLI:
https://gcc.gnu.org/legacy-ml/gcc-patches/2019-11/msg02647.html
In detail this patch
- march options for armv8.6-a
- BFloat16 assembly
This is part of a patch series, starting with command-line and Bfloat16
assembly support. The subsequent patches will upstream intrinsics
support for BFloat16, followed by Matrix Multiplication and the
remaining Virtualization features of the armv8.6-a architecture.
Based on work by:
- labrinea
- MarkMurrayARM
- Luke Cheeseman
- Javed Asbar
- Mikhail Maltsev
- Luke Geeson
Reviewers: SjoerdMeijer, craig.topper, rjmccall, jfb, LukeGeeson
Reviewed By: SjoerdMeijer
Subscribers: stuij, kristof.beyls, hiraditya, dexonsmith, danielkiss, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D76062
The algorithm supports both assigning a fixed offset to a field prior to
layout and allowing fields to have sizes that aren't multiples of their
required alignments. This means that the well-known algorithm of sorting
by decreasing alignment isn't always good enough. Still, we start with
that, and only if that leaves padding around do we fall back on a greedy
padding-minimizing algorithm.
There is no known efficient algorithm for producing a guaranteed-minimal
layout in all cases. In fact, allowing arbitrary fixed-offset fields means
there's a straightforward reduction from bin-packing, making this NP-hard.
But as usual with such problems, we can still efficiently produce adequate
solutions to the cases that matter most to us.
I intend to use this in coroutine frame layout, where the retcon lowerings
very badly want to minimize total space usage, and where the switch lowering
can indeed produce a header with interior padding if the promise field is
highly-aligned. But it may be useful in a much wider variety of situations.
Add a unit test for vfs::YAMLVFSWriter.
This patch exposes an issue in the writer: when we call addFileMapping
with a directory, the VFS writer will emit it as a regular file, causing
any of the nested files or directories to not be found.
Luke Geeson