LLVM IR currently assumes some form of forward progress. This form is
not explicitly defined anywhere, and is the cause of miscompilations
in most languages that are not C++11 or later. This implicit forward progress
guarantee can not be opted out of on a function level nor on a loop
level. Languages such as C (C11 and later), C++ (pre-C++11), and Rust
have different forward progress requirements and this needs to be
evident in the IR.
Specifically, C11 and onwards (6.8.5, Paragraph 6) states that "An
iteration statement whose controlling expression is not a constant
expression, that performs no input/output operations, does not access
volatile objects, and performs no synchronization or atomic operations
in its body, controlling expression, or (in the case of for statement)
its expression-3, may be assumed by the implementation to terminate."
C++11 and onwards does not have this assumption, and instead assumes
that every thread must make progress as defined in [intro.progress] when
it comes to scheduling.
This was initially brought up in [0] as a bug, a solution was presented
in [1] which is the current workaround, and the predecessor to this
change was [2].
After defining a notion of forward progress for IR, there are two
options to address this:
1) Set the default to assuming Forward Progress and provide an opt-out for functions and an opt-in for loops.
2) Set the default to not assuming Forward Progress and provide an opt-in for functions, and an opt-in for loops.
Option 2) has been selected because only C++11 and onwards have a
forward progress requirement and it makes sense for them to opt-into it
via the defined `mustprogress` function attribute. The `mustprogress`
function attribute indicates that the function is required to make
forward progress as defined. This is sharply in contrast to the status
quo where this is implicitly assumed. In addition, `willreturn` implies `mustprogress`.
The background for why this definition was chosen is in [3] and for why
the option was chosen is in [4] and the corresponding thread(s). The implementation is in D85393, the
clang patch is in D86841, the LoopDeletion patch is in D86844, the
Inliner patches are in D87180 and D87262, and there will be more
incoming.
[0] https://bugs.llvm.org/show_bug.cgi?id=965#c25
[1] https://lists.llvm.org/pipermail/llvm-dev/2017-October/118558.html
[2] https://reviews.llvm.org/D65718
[3] https://lists.llvm.org/pipermail/llvm-dev/2020-September/144919.html
[4] https://lists.llvm.org/pipermail/llvm-dev/2020-September/145023.html
Reviewed By: jdoerfert, efriedma, nikic
Differential Revision: https://reviews.llvm.org/D86233
I did some profiling of lit while trying to optimize the libc++ test
startup for remote hosts and it turns out that there is a realpath() call
for every message printed and this shows up in the profile.
The inspect.getframeinfo() function calls realpath() internally and
moreover we don't need most of the other information returned from it.
This patch uses inspect.getsourcefile() and os.path.abspath() to remove
../ from the path instead. Not resolving symlinks reduces the startup time
for running a single test with lit by about 50ms for me.
Reviewed By: ldionne, yln
Differential Revision: https://reviews.llvm.org/D89186
In CodeGenDAGPatterns.cpp we were relying upon TypeSize comparison
operators for ordering types, when we can actually just use the known
minimum size since the scalable property is already being taken into
account. Also, in TypeInfer::EnforceSameSize I fixed some implicit
TypeSize->uint64_t casts by changing the code to test the equality
of TypeSize objects instead.
In other places I have replaced calls to getSizeInBits() with
getFixedSizeInBits() because we are only ever expecting integer values.
Differential Revision: https://reviews.llvm.org/D88947
This makes diffing with the manual tables easier. And if we ever
directly use the autogenerated tables instead of the manual tables
we'll need them to be in sorted order for the binary search.
Apparenlty I added these in https://reviews.llvm.org/rL350628 but
I'm not sure why. They never existed in the CMake build, and now
they're causing trouble.
This patch adds support for assemble disassemble intrinsics
for MMA.
Reviewed By: bsaleil, #powerpc
Differential Revision: https://reviews.llvm.org/D88739
I recently had to run the test suite with a debug Python which got started
warning about some invalid escape sequences in LLDB's Python code. They all
attempt to add a backslash by doing a single backslash instead of a double
backslash in a normal string. This seems to work fine for now, but Python says
this behaviour is deprecated, so this patch turns all those strings into raw
strings (where a single backslash is actually a single backslash)
Reviewed By: JDevlieghere
Differential Revision: https://reviews.llvm.org/D88289
Commit 6e56046f65 may trigger SEGV in llvm-tablegen if the latter
is built with -DLLVM_OPTIMIZED_TABLEGEN=OFF. The reason of SEGV was
accessing stale memory after expansion of std::vector.
It's built with just-built clang, like all other compiler-rt parts
in the GN build.
This requires adding some cross build support to the mac toolchain.
Also add explicit mmacosx-version-min and miphoneos-version-min
flags to the build.
ios.a is only built with the arm64 slice, iossim.a only with the
x86_64 slice for now. (The latter should maybe become host_cpu
when Arm Macs become a common iOS development platform.)
With this, it's possible to build chromium/iOS with a GN-built LLVM.
Differential Revision: https://reviews.llvm.org/D89260
Summary: Since willreturn will soon be added as default attribute, we can end up with both noreturn and willreturn on the same intrinsic. This was exposed by llvm.wasm.throw which has IntrNoReturn.
Reviewers: jdoerfert, arsenm
Differential Revision: https://reviews.llvm.org/D88644
The tests previously relied on the `short.py` and `FirstTest.subTestA`
script being executed on a machine within a short time window (1 or 2
seconds). While this "seems to work" it can fail on resource constrained
machines. We could bump the timeout a little bit (bumping it too
much would mean the test would take a long time to execute) but it wouldn't
really solve the problem of the test being prone to failures.
This patch tries to remove this flakeyness by separating testing into
two separate parts:
1. Testing if a test can hit a timeout.
2. Testing if a test can run to completion in the presence of a
timeout.
This way we can give (1.) a really short timeout (to make the test run
as fast as possible) and (2.) a really long timeout. This means for (2.)
we are no longer trying to rely on the "short" test executing within
some short time window. Instead the window is now 3600 seconds which
should be long enough even for a heavily resource constrained machine to
execute the "short" test.
Thanks to Julian Lettner for suggesting this approach. This superseeds
my original approach in https://reviews.llvm.org/D88807.
This patch also changes the command line override test to run the quick
test rather than the slow one to make the test run faster.
Differential Revision: https://reviews.llvm.org/D89020
This is a cherrypick of the upstream fix commit ffe1342 onto
`llvm/utils/benchmark` and `libcxx/utils/google-benchmark`.
This adds CycleTimer implementation for M680x0, which simply
uses `gettimeofday` same as MIPS.
Differential Review: https://reviews.llvm.org/D88868
This reverts b3418cb4eb and d12ae042e1
This breaks some external bots, see discussion in https://reviews.llvm.org/D84380
In the meanwhile, please use `cmake -DLLVM_LIT_TOOLS_DIR="C:/Program Files/Git/usr/bin"` or add it to %PATH%.
Summary:
This patch adds an error to Clang that detects if OpenMP offloading is
used between two architectures with incompatible pointer sizes. This
ensures that the data mapping can be done correctly and solves an issue
in code generation generating the wrong size pointer. This patch adds a
new lit substitution, %omp_powerpc_triple that, if the system is 32-bit or
64-bit, sets the powerpc triple accordingly. This was required to fix
some OpenMP tests that automatically populated the target architecture.
Reviewers: jdoerfert
Subscribers: cfe-commits guansong sstefan1 yaxunl delcypher
Tags: OpenMP clang LLVM
Differential Revision: https://reviews.llvm.org/D88594
This change implements generation of a function which may be used by a backend to check if a given instruction is supported for a specific subtarget.
Reviewers: sdesmalen
Differential Revision: https://reviews.llvm.org/D88214
When nesting INSERT_SUBREG and EXTRACT_SUBREG, GlobalISelEmitter would
fail to find the register class of the nested node. This patch fixes
that for registers with subregs.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D88487
Atmn Patel