TheRock/rocm-systems/emulation/rocjitsu/lib/util/README.md

Shared Utilities

The util library provides low-level building blocks shared across rocjitsu and simdojo. It is a header-heavy library with minimal compiled sources.

Headers

Bit Manipulation

File	Description
bit.h	Bit masks, insertion, extraction, counting, alignment. Provides mask(), insert_bits(), bits(), is_power_of_2(), align_up().
bitfield.h	Typed bitfield access over integral or array storage. Bitfield<N> with templated get<>() / set() for arbitrary bit ranges.

Data Types and Conversions

File	Description
data_types.h	Floating-point format conversions: FP16, BF16, FP8 (E4M3), BF8 (E5M2), FP4, FP6. Scalar and vectorized block converters with IEEE-754 rounding modes (truncation, round-to-nearest-even, stochastic).
convert.h	Type-erasing conversion between opaque C API handles and internal object pointers.

SIMD

File	Description
simd.h	Vectorized operations via <experimental/simd> with scalar fallback. Float conversions, integer arithmetic (mul_hi, popcount, clz), rounding, and transcendental approximations (rcp, rsq, log, exp).
simd_test_hooks.h	Test-only seam for forcing scalar execution to compare against SIMD paths.

Memory and Concurrency

File	Description
arena_alloc.h	Fixed-size block pool allocator with free-list. ArenaAlloc<BlockSize, NumBlocks, BlockAlign> provides O(1) alloc/dealloc with global-allocator fallback.
spinlock.h	TTAS spinlock optimized for sub-microsecond critical sections. Uses C++20 atomic::wait() with ThreadSanitizer annotations.
intrusive_list.h	Bidirectional intrusive linked list with optional parent-pointer tracking. IntrusiveList<T> and IListNode<T> with O(1) insert/erase.
unique_handle.h	Move-only RAII ownership for POSIX file descriptors, Win32 handles, and custom handle traits.

Diagnostics

File	Description
log.h	Compile-time and runtime configurable logging with named groups (VM, CP). Thread-safe, supports lazy evaluation via lambda forms. Use Logger::print<GroupId>() for group-filtered output.
except.h	Exception hierarchy: Exception (base), InvalidInst, UnimplementedInst, ConfigError. All derive from std::exception.

Miscellaneous

File	Description
dynamic_loader.h	Runtime symbol resolution via dlsym (Linux) / GetProcAddress (Windows). lookup_symbol<T>() returns a typed function pointer.
meta_programming.h	Type traits and concepts: IsIntegral, IsUnsigned, IsArithmetic, IsVoid. Also provides GetOption for template option extraction and always_false_v<T> for deferred static assertions.

Usage

All headers are under lib/util/include/util/ and can be included as:

#include "util/log.h"
#include "util/bit.h"

Header-only consumers link util_headers in CMake. The util target links util_headers publicly and adds the small compiled SIMD implementation used by rocjitsu and simdojo.