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Test build perf v2#835

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mjp41 wants to merge 24 commits intomicrosoft:mainfrom
mjp41:test-build-perf-v2
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Test build perf v2#835
mjp41 wants to merge 24 commits intomicrosoft:mainfrom
mjp41:test-build-perf-v2

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@mjp41 mjp41 commented Mar 28, 2026

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@SchrodingerZhu
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We can also try modules if speed is a concern.

@mjp41
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mjp41 commented Mar 28, 2026

We can also try modules if speed is a concern.

Mostly there is a lot of redundant work in the build, and I wanted to experiment with improving that.

@mjp41 mjp41 force-pushed the test-build-perf-v2 branch 4 times, most recently from e0efc18 to 8eb5e51 Compare March 30, 2026 13:21
mjp41 added 23 commits March 30, 2026 16:09
Pure file move. allocconfig.h contains only compile-time constants with
dependencies only on bits.h and mitigations.h (both in ds_core/).
Moving it enables sizeclassstatic.h (next step) to live in ds_core/
without pulling in ds/.

Changes:
- git mv ds/allocconfig.h -> ds_core/allocconfig.h
- Add #include bits.h and mitigations.h to moved file
- Update include paths in ds/ds.h, ds/mpmcstack.h
- Add allocconfig.h to ds_core/ds_core.h umbrella
Create ds_core/sizeclassstatic.h with compile-time sizeclass functions
extracted from mem/sizeclasstable.h:
- smallsizeclass_t (size_t typedef)
- size_to_sizeclass_const()
- NUM_SMALL_SIZECLASSES
- sizeclass_to_size_const()
- is_small_sizeclass()

Move sizeclasstable.h from mem/ to ds/ (depends on PAL, not allocator).
Remove redundant sizeclasstable.h includes from mem/ files.
Convert smallsizeclass_t from a size_t typedef to a struct with:
- Explicit construction from size_t (no implicit conversion FROM)
- Implicit conversion to size_t (for array indexing, comparisons)
- Pre/post increment operators

Provides type safety: alloc(size_t) (byte size) cannot be confused
with alloc(smallsizeclass_t) (sizeclass index).

Update all iteration sites to use explicit construction.
Add alloc(smallsizeclass_t) overload to corealloc and globalalloc that
skips the dynamic sizeclass lookup. Refactor small_alloc to accept
(smallsizeclass_t, size_t) and keep the single-arg (size_t) version
as a forwarding overload.

Update alloc<size>() to use compile-time sizeclass when the size is
a known small sizeclass.

Add libc::malloc_small(smallsizeclass_t) and
libc::malloc_small_zero(smallsizeclass_t) as non-template entry points.
These are general-purpose data structures, not allocator-specific.
Moving them reduces the dependency surface of mem/.
Add __malloc_start_pointer() and __malloc_last_byte_pointer() to libc.h,
alongside the existing __malloc_end_pointer(). These provide the
external_pointer functionality through the libc API surface.
Add snmalloc_testlib.h (thin header with API declarations) and
snmalloc_testlib.cc (single TU compiling full allocator + wrappers).

CMake: build_test_library() creates a static library per flavour.
All test executables link against it (ODR-safe). No tests converted
yet — this just adds the infrastructure.
Convert simple alloc/dealloc tests to use snmalloc_testlib.h instead
of snmalloc.h:
- func/first_operation
- func/teardown
- func/multi_atexit
- func/multi_threadatexit

Replace MAX_SMALL_SIZECLASS_BITS with max_small_sizeclass_bits().
Replace alloc<Zero> with alloc<ZeroMem::YesZero>.
Add pal/pal.h include to testlib header for report_fatal_error.
Convert perf tests that use only the public API:
- perf/startup
- perf/contention
- perf/large_alloc
- perf/low_memory

Replace DefaultPal::tick() with pal_tick(), Aal::pause() with pal_pause().
Convert tests that use only the public API to snmalloc_testlib.h:
- func/bits, func/memory, func/memory_usage, func/pool
- func/protect_fork, func/redblack, func/statistics
- perf/external_pointer, perf/lotsofthreads, perf/post_teardown
- perf/singlethread

Replace DefaultPal/Aal calls with pal_*() wrappers.
Replace external_pointer<> with libc __malloc_*_pointer().
Replace alloc<Zero/Uninit> with alloc<ZeroMem::YesZero/NoZero>.
Fix include order in ds/ds.h for pool.h/pooled.h dependencies.
Convert tests that need allocator internals (sizeclasses, pagemap, etc.)
to use snmalloc_core.h alongside snmalloc_testlib.h:
- func/malloc (replace our_* with testlib_* prefix)
- func/pagemap
- func/release-rounding
- func/sizeclass
Move report_fatal_error() and message() template definitions from
pal/pal.h into ds_core/helpers.h. They now call error() and
message_impl() which are forward-declared non-template functions
in ds_core/defines.h, with implementations in pal/pal.h that
delegate to DefaultPal.

This breaks the dependency of ds_core/ code on pal/: any code
that includes ds_core/helpers.h can call report_fatal_error()
without needing PAL headers. The linker resolves error() and
message_impl() from the translation unit that includes pal.h.

Update testlib.h to include pal/pal_consts.h instead of pal/pal.h.
Fix memory.cc to use ds_aal/ds_aal.h for address_cast.
Fix protect_fork.cc to include ds_aal/prevent_fork.h explicitly.
Revert low-memory.cc to snmalloc.h (needs PalNotificationObject).
The header doesn't use errno itself. Tests that need it can
include it directly.
Replace snmalloc_testlib.h with ds_core/helpers.h + ds_aal/prevent_fork.h.
This test only uses PreventFork and message(), no allocator API.
Create ds_core/sizeclassconfig.h with the mitigation-independent
sizeclass constants (INTERMEDIATE_BITS, MIN_ALLOC_STEP_SIZE, etc.).
This file depends only on bits.h — no mitigations.h.

Update sizeclassstatic.h to include sizeclassconfig.h instead of
allocconfig.h. allocconfig.h now includes sizeclassconfig.h and
keeps only the mitigation-dependent constants (MIN_OBJECT_COUNT,
DEALLOC_BATCH_*, MAX_SLAB_SPAN_*, etc.).

This makes the testlib header chain fully mitigation-independent:
testlib.h -> sizeclassstatic.h -> sizeclassconfig.h -> bits.h
Move mitigations.h, allocconfig.h, and cheri.h from ds_core/ to a new
mitigations/ directory. These files depend on SNMALLOC_CHECK_CLIENT
compile-time flags and don't belong in ds_core/ (which should be
mitigation-independent).

New include hierarchy:
  ds_core/ → aal/ → ds_aal/ → mitigations/ → pal/ → ds/ → mem/

ds_core/ is now fully mitigation-independent. The testlib header
(which includes only ds_core/ headers) produces identical output
regardless of SNMALLOC_CHECK_CLIENT, enabling tests to be compiled
once and linked against both fast and check testlib variants.
Tests that only include snmalloc_testlib.h are mitigation-independent:
their compiled output is identical regardless of SNMALLOC_CHECK_CLIENT.
Compile these into a shared OBJECT library and link against both the
fast and check testlib variants, saving 15 redundant compilations.

Build targets: 171 (down from 186). Test count unchanged: 56 func.
Introduce SNMALLOC_API macro for public API functions (dealloc,
debug_teardown, libc::malloc, etc.) that need standalone definitions
when compiled into a static library.

Defaults to SNMALLOC_FAST_PATH_INLINE (normal header-only usage).
testlib.cc defines SNMALLOC_API as NOINLINE on MSVC before including
snmalloc.h, producing strong definitions that ARM64EC exit-thunks
can reference. On GCC/Clang, __attribute__((used)) via the existing
SNMALLOC_USED_FUNCTION annotation suffices.
Add a const void* overload of remaining_bytes alongside the existing
address_t version. The testlib API uses const void* so callers don't
need address_cast or ds_aal headers. Remove address_t from testlib.h.

This makes memory.cc a testlib-only test (no ds_aal.h needed),
adding it to the compile-once list.
Expose snmalloc's checked memcpy through the libc API surface:
  libc::memcpy<Checked, ReadsChecked>(dst, src, len)

Checked controls destination bounds checking, ReadsChecked controls
source bounds checking (defaults to same as Checked).

Explicit instantiations provided in testlib for the common variants:
<true,true>, <true,false>, <false,false>.
Replace DefaultPal::message() calls in START_TEST and INFO macros
with snmalloc::message() which is now defined in ds_core/helpers.h.
This removes the PAL dependency from test infrastructure, allowing
tests that only need ds_core/ or ds_aal/ headers to avoid including
pal/pal.h.
The seqset test is a unit test for ds_aal/seqset.h and only needs
ds_aal and ds_core headers. With test/helpers.h no longer depending
on DefaultPal, the pal.h include is unnecessary.
@mjp41 mjp41 force-pushed the test-build-perf-v2 branch from 8eb5e51 to 9abd831 Compare March 30, 2026 18:35
@mjp41 mjp41 force-pushed the test-build-perf-v2 branch from ff3b9f1 to b87a6a0 Compare March 30, 2026 19:53
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