[CodeGen] Drop dead SlotIndexes before allocation
SlotIndexes keeps the index list entry of an erased instruction and only
clears its instruction pointer. Live range sizes are measured in slot
indexes and greedy ranks ranges by size, so the leftovers inflate some
ranges more than others and reorder allocation, spilling heavily on
register-starved functions.
Add SlotIndexes::compactIndexes() to erase them. Erased entries are
unlinked, so LiveIntervals first reports the indexes it holds via
appendReferencedIndexes().
Off by default behind -greedy-compact-slot-indexes, since it changes
allocation across much of the test suite.
[lldb] Don't fail initialization when Python can't be loaded (#229891)
SystemInitializerFull::Initialize returns early when the Python runtime
loader fails, preventing remaining plugins (like the platform) to be
initialized.
Both with the statically and dynamically linked plugins, not finding
Python at that point is non-fatal. The error can be more appropriately
handled later, when initializing the plugin as all the subsystems (i.e.
logging) have been initialized.
rdar://188858954
[BoundsSafety] Handle the counted_by family as a type attribute
counted_by / sized_by (and their _or_null variants) were handled as a
declaration-position attribute through handleCountedByAttrField.
Build the type during type construction instead and properly handle as a
type-position attribute. Building the node in type position also allows
the new way of late-parsing for type attributes: creates a type node
in place and fills it in once late parsing is done, which will be
enabled in the follow-up commits.
Assisted-by: Opus 4.8
[CIR] Classify reference-to-pointer catch parameters in CIRGen (#229579)
When a handler catches a reference to a pointer, __cxa_begin_catch
returns the caught pointer by value instead of the address of the
exception object, and how the reference is bound depends on whether the
pointer points to a class. The CIR type of the catch parameter cannot
always tell whether it is a reference to a pointer, or whether the
pointee is a class. CIRGen now records both facts from the AST in two
new InitCatchKind values, reference_to_pointer and
reference_to_record_pointer. The Itanium EH lowering switches on the
kind alone, the way classic codegen does.
Assisted-by: Claude Code / Claude Opus 5.5
