Runtime 5 changes that are specific to flambda‐backend

GC

(See below for Flambda 2-specific GC changes.)

Support for new language features

• Locals (stack allocation)

• Mixed blocks (including new size macros)

• Unboxed values in closures

Other features

• Long frames

• Put frametables in .text with relative offsets for return addresses (PR1227)

• Allocate pools for the shared heap in batches rather than one at a time (PR2248)

• Mark delay (K=1) (PR2348)

Misc small features

• Add some checks that the minor GC does not recurse (PR1743, PR2075 and PR2098)

• Silence the debug runtime by default (runtime5 only) (PR2195)

Configuration changes

• space_overhead=160 by default

• Increased minor heap size by default

GC bugfixes

• Ensure the minor heap is actually empty before reallocating it (PR2208)

• Reorder call to caml_domain_external_interrupt_hook (PR2204) (think this is probably fixed upstream)

• Fix caml_alloc_shr_check_gc for tags >= No_scan_tag (PR2203)

• Fix assertion in caml_ephe_clean (PR2192) (submitted upstream)

• Reinitialize IO mutexes in systhreads5 (PR2160) (think this is fixed upstream)

• Fix segfault when signal handlers invoked in non-OCaml threads on runtime5 (PR2154) (fixed upstream)

• Fix caml_gc_compaction in the 5 runtime to run finalizers (PR2135) (should now be fixed upstream)

Flambda 2

• Support for registering closures in caml_globals

• Asynchronous exception handling via Sys.with_async_exns

• Flambda 2 invalid trap

Effects

• No-stack-checks

• Integration of effects and locals (not yet merged)

Multi-domain

• New safepoints strategy (not yet merged)

Dynlink

• Check to prevent duplicate root registration

• Fix for naked pointer problem in unsafe_get_global_value (PR2317)

Systhreads

• Ability to swap out the runtime lock

• Implementation of the master lock without using pthread condvars

Numbers, arrays, etc

• float32 runtime support

• SIMD runtime support e.g. for array operations

• Various other array / boxed number primitives

Misc features

• Improved implementation of reachable words algorithm (c.f. Obj.reachable_words) for retainer profiling

• Atomic printing of GC logs (PR2874)

• Timestamp printing in GC logs (PR2216)

• Add caml_hot__code{begin,end} symbols in runtime5 (#2133)

• Compression in Marshal is not supported (to avoid a zlib dependency)

Small bug fixes/improvements

• Hoist Wosize_val from end conditions of loops (PR2301)

• Cause a C warning when CAMLreturn is missing in C stubs (PR2102)

• Compile with -mbranches-within-32B

• Dune build fixes