This implements a traditional freelist to be used by the freelist
allocator. It operates on spans of bytes which can be anything. The
freelist allocator will store Blocks inside them.
This is a part of #94270 to land in smaller patches.
A block represents a chunk of memory used by the freelist allocator. It
contains header information denoting the usable space and pointers as
offsets to the next and previous block.
On it's own, this doesn't do much. This is a part of
https://github.com/llvm/llvm-project/pull/94270 to land in smaller
patches.
This is a subset of pigweed's freelist allocator implementation.
For baremetal targets that don't support FILE, this version of printf
just writes directly to a function provided by a vendor. To do this both
printf and vprintf were moved to /generic (vprintf since they need the
same flags and cmake gets funky about setting variables in one file and
reading them in another).
This adds:
- A ctor accepting a start and end iterator
- A ctor accepting a count and const T&
- size()
- subscript operators
- begin() and end() iterators
- added at_quick_exit function
- used helper file exit_handler which reuses code from atexit
- atexit now calls helper functions from exit_handler
- test cases and dependencies are added
---------
Co-authored-by: Aaryan Shukla <aaryanshukla@google.com>
This is a mostly-target-independent variadic function optimisation and
lowering pass. It is only enabled for AMDGPU in this initial commit.
The purpose is to make C style variadic functions a zero cost
abstraction. They are lowered to equivalent IR which is then amenable to
other optimisations. This is inherently slightly target specific but
much less so than one might expect - the C varargs interface heavily
constrains the ABI design divergence.
The pass is primarily tested from webassembly. This is because wasm has
a straightforward variadic lowering strategy which coincides exactly
with what this pass transforms code into and a struct passing convention
with few cases to check. Adding further targets conventions is
straightforward and elided from this patch primarily to simplify the
review. Implemented in other branches are Linux X86, AMD64, AArch64 and
NVPTX.
Testing for targets that have existing lowering for va_arg from clang is
most efficiently done by checking that clang | opt completely elides the
variadic syntax from test cases. The lowering produces a struct for each
call site which can be inspected to check the various alignment and
indirections are correct.
AMDGPU presently has no variadic support other than some ad hoc printf
handling. Combined with the pass being inactive on all other targets
landing this represents strict increase in capability with zero risk.
Testing and refining will continue post commit.
In addition to the compiler tests included here, a self contained x64
clang/musl toolchain was constructed using the "lowering" instead of the
systemv ABI and used to build various C programs like lua and libxml2.
Summary:
The GPU needs both the loader utility and the architecture to be present
to run tests. This simply makes it easier to detect which is missing in
case of problems.
Summary:
These new tests fails on the GPU due to the exception testing. Disable
it for now because these aren't supported and can't be supported on
NVPTX.
This manifests as `AddressSanitizer: stack-use-after-return` w/o this
change. The `~CheckFEnv()` method of checking fenv seems to only work
for test fixtures.
Summary:
These tools need to be built before we can do the library creation
stage. If they are generated in the same build then this is not
guaranteed so we should add explicit dependencies.
