feat(cc): call through function-pointer parameters and locals#493
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A call site whose callee name resolves to a function-pointer parameter (e.g. ``int (*cmp)(const void *, const void *)``) used to raise ``unknown function: cmp`` because ``compute_safe_pin_registers`` only treated VarDecl-introduced function pointers (and file-scope function-pointer globals) as indirect callees. Function parameters carry the same ``"function_pointer"`` spelling on the Param node but were never seeded into that set, so the pin-cost pre-pass classified the call as "unknown" before ``generate_call`` ever ran. ``_collect_function_pointer_vars`` now also folds in any parameter whose ``Param.type`` is ``"function_pointer"``; both callers (``compute_safe_pin_registers`` and ``_select_auto_pin_candidates``) thread the function's parameter list through to it. The indirect-call emission in ``generate_call`` previously assumed every fn-pointer call routed arguments through registers — it required ``len(arguments) == len(function_pointer_in_regs)`` and emitted no stack pushes. Function-pointer parameters from qsort/bsearch-style prototypes carry no inner ``in_register`` annotations (the parser discards the inner parameter list), so the indirect-call path now falls back to standard cdecl when ``function_pointer_in_regs`` is empty: push args right-to-left, ``call <acc>``, ``add <sp>, N*int_size`` cleanup. stdlib.c now parses past line 224 (the qsort fn-pointer call site); the next failure is the array-of-function-pointers shape ``static void (*_atexit_fns[N])(void);`` which is out of scope here. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
int (*cmp)(...)declared as a function parameter could not be called:compute_safe_pin_registersonly fed VarDecl- and global-typed function-pointers into its indirect-callee set, so the pin-cost pre-pass raisedunknown function: cmpbeforegenerate_callever ran._collect_function_pointer_varsnow folds the function's parameter list in too, and both callers thread it through.generate_callpreviously requiredlen(arguments) == len(function_pointer_in_regs)and emitted no stack pushes, so every fn-pointer call had to be routed through registers. Function-pointer parameters from qsort/bsearch-style prototypes carry no innerin_registerannotations (the parser discards the inner parameter list), so the indirect-call path now falls back to standard cdecl whenfunction_pointer_in_regsis empty: push args right-to-left,call <acc>,add <sp>, N*int_sizecleanup.test_function_pointer_parameter_emits_indirect_call_with_stack_args) exercises the new path.Test plan
--bits 32 --objectand emitscall eax+add esp, 8cleanup.user/libbboeos/stdlib.cnow parses past the qsort indirect call at line 224; next failure is the array-of-function-pointers shapestatic void (*_atexit_fns[N])(void);(out of scope, parser-level).python3 -m pytest tests/unit/ tests/test_ccobj.py tests/test_ccld.py tests/test_ccar.py -x -q— 559 passedpython3 tests/test_cc_local_structs.py— 9 / 9python3 tests/test_cc_bits.py— 112 / 112timeout 240 python3 tests/test_asm.py— 42 / 42./make_os.sh— builds cleanRemaining gaps in the function-pointer story
static void (*_atexit_fns[N])(void);) — parser-level, separate work.int (*cmp)(int x __attribute__((in_register("bx"))), int y)parameter would still call via the stack, not via BX. Routing in_register parameters through fn-pointer params would need the inner Param list preserved on the outer Param node.🤖 Generated with Claude Code