Summary:
Add a method to set the release to OS value as the system runs,
and allow this to be set differently in the primary and the secondary.
Also, add a default value to use for primary and secondary. This
allows Android to have a default that is different for
primary/secondary.

Update mallopt to support setting the release to OS value.

Reviewers: pcc, cryptoad

Reviewed By: cryptoad

Subscribers: cryptoad, jfb, #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D74448

In https://reviews.llvm.org/rG8b737688c21a9755cae14cb9343930e0882164ab I
switched the condition gating the creation of the descriptor symbol from
checking the MCAsmInfo if we need to support descriptors, to if the OS
was AIX. Technically the 2 should be interchangeable: if we are
targeting AIX then we need to emit XCOFF object files, and the MCAsmInfo
must return true for needing function descriptors.

This doesn't account for lit test with runsteps that only set the arch.
Eg: test/CodeGen/XCore/section-name.ll
which when run natively on AIX we end up with a target xcore-ibm-aix and
needFunctionDescriptors is false.

This patch reverts to using the MCAsmInfo and adds an assert that the
target OS must be AIX since that is the only target using the descriptor
hook.

Differential Revision: https://reviews.llvm.org/D74622

This is like -fdata-sections, and it's not part of /O2 by default for some reason.

In the cmake build, reduces the size of clang.exe from 70,358,016 bytes to 69,982,720 bytes.

clang-format.exe goes from 3,703,296 bytes to 3,331,072 bytes.

Differential Revision: https://reviews.llvm.org/D74573

Differential Revision: https://reviews.llvm.org/D74630

Repeat the build instructions from the top level README in the Getting
Started guide.

The division expansions in AMDGPUCodeGenPrepare can't be relied on for
correctness, since they punt to later optimization and possibly
legalization in some cases. We still need a way to be able to write
tests for the legalizer versions of the expansion. This is mostly for
GlobalISel, since the expected optimzations is expecting aren't
implemented.

The interaction with the flag to expand 64-bit division in the IR is
pretty confusing, but these flags have different purposes.

I updated the prefix and forgot to manually remove the old names
as part of rG6071fc57a45.f

The existing checks were trying to test both CPU-specific
codegen and generic codegen with explicit attributes for
the various sqrt estimate possibilities, but that was hard
to decipher and update (D69989).

Instead generate the complete results for various CPUs,
and that makes it clear which models have slow/fast sqrt
attributes along with all of the other potential diffs
(FMA, AVX2, scheduling).

Also, explicitly add the function attributes corresponding
to whether DAZ/FTZ denorm settings are expected.

I didn't realize we were already expanding 24/32-bit division here
already. Use the available IntegerDivision utilities. This uses loops,
so produces significantly smaller code than the inline DAG expansion.

This now requires width reductions of 64-bit divisions before
introducing the expanded loops.

This helps work around missing legalization in GlobalISel for
division, which are the only remaining core instructions that didn't
work at all.

I think this is plausibly a better implementation than exists in the
DAG, although turning it on by default misses out on the constant
value optimizations and also needs benchmarking.

Summary:
Potential fix for: https://bugs.llvm.org/show_bug.cgi?id=44889 and https://bugs.llvm.org/show_bug.cgi?id=44408

In the legacy pass manager, loop rotate need not compute MemorySSA when not being in the same loop pass manager with other loop passes.
There isn't currently a way to differentiate between the two cases, so this attempts to limit the usage in LoopRotate to only update MemorySSA when the analysis is already available.
The side-effect of this is that it will split the Loop pipeline.

This issue does not apply to the new pass manager, where we have a flag specifying if all loop passes in that loop pass manager preserve MemorySSA.

Reviewers: dmgreen, fedor.sergeev, nikic

Subscribers: Prazek, hiraditya, george.burgess.iv, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74574

This is more or less directly ported from the AMDGPU custom lowering
for FP_TO_FP16. I made a few minor fixups (using G_UNMERGE_VALUES
instead of creating shift/trunc to extract the two halves, and zexting
an inverted compare instead of select_cc).

This also does not include the fast math expansion the DAG which
converts to f32 and then to f16. I think that belongs in a
pre-legalize combine instead.

Like COPY instructions explained in D70616, we don't check the constraints
when combining G_UNMERGE_VALUES. Use the same logic used in D70616 to check
if registers can be replaced, or a COPY instruction needs to be built.

https://reviews.llvm.org/D70564

Assembler now permits pairs like 'v0:1', which are encoded
differently from the odd-first pairs like 'v1:0'.

The compiler will require more work to leverage these new register
pairs.

We don't want to test for this warning, so we just fix it.

Summary:
Zero-parameter K&R definitions specify that the function has no
parameters, but they are still not prototypes, so calling the function
with the wrong number of parameters is just a warning, not an error.

The C11 standard doesn't seem to directly define what a prototype is,
but it can be inferred from 6.9.1p7: "If the declarator includes a
parameter type list, the list also specifies the types of all the
parameters; such a declarator also serves as a function prototype
for later calls to the same function in the same translation unit."
This refers to 6.7.6.3p5: "If, in the declaration “T D1”, D1 has
the form
    D(parameter-type-list)
or
    D(identifier-list_opt)
[...]". Later in 6.11.7 it also refers only to the parameter-type-list
variant as prototype: "The use of function definitions with separate
parameter identifier and declaration lists (not prototype-format
parameter type and identifier declarators) is an obsolescent feature."

We already correctly treat an empty parameter list as non-prototype
declaration, so we can just take that information.

GCC also warns about this with -Wstrict-prototypes.

This shouldn't affect C++, because there all FunctionType's are
FunctionProtoTypes. I added a simple test for that.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D66919

As noted on D74621 we currently have no test coverage

Rename LLDB_PLUGIN to LLDB_PLUGIN_DEFINE as Pavel suggested in D73067 to
avoid name conflict.

This was caused by byte depending on traits. This patch moves
the minimal amount of meta-programming into <cstddef> to break the cycle.

Also fix BitVector unittest failure when DLLVM_ENABLE_ASSERTIONS are OFF, introduced by d110c3a9.

AddGoldPlugin does more than adding `-plugin path/to/LLVMgold.so`.
It works with lld and GNU ld, and adds other LTO options.
So AddGoldPlugin is no longer a suitable name.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D74591

Reverting D73027 [DependenceAnalysis] Dependecies for loads marked with "ivnariant.load" should not be shared with general accesses(PR42151).

This reverts commit 0a1123eb.
Want to revert this because it's causing trouble for PowerPC
I also fixed test fp-model.c which was looking for an incorrect error message

The goal of this patch is to maximize CPU utilization on multi-socket or high core count systems, so that parallel computations such as LLD/ThinLTO can use all hardware threads in the system. Before this patch, on Windows, a maximum of 64 hardware threads could be used at most, in some cases dispatched only on one CPU socket.

== Background ==
Windows doesn't have a flat cpu_set_t like Linux. Instead, it projects hardware CPUs (or NUMA nodes) to applications through a concept of "processor groups". A "processor" is the smallest unit of execution on a CPU, that is, an hyper-thread if SMT is active; a core otherwise. There's a limit of 32-bit processors on older 32-bit versions of Windows, which later was raised to 64-processors with 64-bit versions of Windows. This limit comes from the affinity mask, which historically is represented by the sizeof(void*). Consequently, the concept of "processor groups" was introduced for dealing with systems with more than 64 hyper-threads.

By default, the Windows OS assigns only one "processor group" to each starting application, in a round-robin manner. If the application wants to use more processors, it needs to programmatically enable it, by assigning threads to other "processor groups". This also means that affinity cannot cross "processor group" boundaries; one can only specify a "preferred" group on start-up, but the application is free to allocate more groups if it wants to.

This creates a peculiar situation, where newer CPUs like the AMD EPYC 7702P (64-cores, 128-hyperthreads) are projected by the OS as two (2) "processor groups". This means that by default, an application can only use half of the cores. This situation could only get worse in the years to come, as dies with more cores will appear on the market.

== The problem ==
The heavyweight_hardware_concurrency() API was introduced so that only *one hardware thread per core* was used. Once that API returns, that original intention is lost, only the number of threads is retained. Consider a situation, on Windows, where the system has 2 CPU sockets, 18 cores each, each core having 2 hyper-threads, for a total of 72 hyper-threads. Both heavyweight_hardware_concurrency() and hardware_concurrency() currently return 36, because on Windows they are simply wrappers over std::thread::hardware_concurrency() -- which can only return processors from the current "processor group".

== The changes in this patch ==
To solve this situation, we capture (and retain) the initial intention until the point of usage, through a new ThreadPoolStrategy class. The number of threads to use is deferred as late as possible, until the moment where the std::threads are created (ThreadPool in the case of ThinLTO).

When using hardware_concurrency(), setting ThreadCount to 0 now means to use all the possible hardware CPU (SMT) threads. Providing a ThreadCount above to the maximum number of threads will have no effect, the maximum will be used instead.
The heavyweight_hardware_concurrency() is similar to hardware_concurrency(), except that only one thread per hardware *core* will be used.

When LLVM_ENABLE_THREADS is OFF, the threading APIs will always return 1, to ensure any caller loops will be exercised at least once.

Differential Revision: https://reviews.llvm.org/D71775

Use a ThreadPool instead of plain std::threads in clang-scan-deps.
This is needed to further support https://reviews.llvm.org/D71775.

Differential Revision: https://reviews.llvm.org/D74569

This patch adds DenseMapInfo<> support for BitVector and SmallBitVector.

This is part of https://reviews.llvm.org/D71775, where a BitVector is used as a thread affinity mask.

Use the same appraoch as update_llc_test_checks.py to always write \n
line endings. This should fix the Windows buildbots.

There are some unnecessary typenames in std/numerics/c.math/abs.pass.cpp;
e.g. they're not in a dependent context.

Patch by Bryce Adelstein Lelbach

Differential Revision: https://reviews.llvm.org/D72106

This reverts commit 1d40c415.
This seemed to have caused build failures on ARM/AArch64.