Files
sx/examples/1206-ffi-medium-struct.sx
agra 731fb8de64 refactor(ffi-linkage): Phase 7.1 — migrate incidental 12xx ffi examples #foreign→extern
12 plain-C examples that use #foreign incidentally (as FFI plumbing, output
unchanged): 1200/1206/1209-1215/1220/1221/1222. Blanket keyword swap; all fn/global
markers (no class forms in 12xx). Empty snapshot diff; corpus validates directly
(all marker'd). Suite green (647 corpus / 444 unit, 0 failed).

KEPT on #foreign (deferred to Phase 8 cutover): identity-#foreign feature tests
(filename ffi-foreign-*: 1205/1207/1216/1218/1219), the equivalence test 1228, and
the diagnostics that assert on #foreign source/message (1172/1174/1620). Comment-only
provenance prose (1223/1229/1230/1231) left intact per Decision-6-recommended.
2026-06-15 06:49:36 +03:00

34 lines
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// 16-byte integer-only struct passed by value through `extern`.
//
// emit_llvm.zig's `abiCoerceParamType` routes 9..16-byte non-HFA
// structs through `[2 x i64]` for register-pair passing on AAPCS64 /
// SysV AMD64. The call-site side loads the sx struct as `{ i64, i64 }`,
// so the verifier needs a memory-bitcast bridge in both directions
// (`abi.struct2arr` on the way in, `abi.arr2struct` on the way back).
//
// Different ABI path from 8-byte register-pair structs (coerce to
// i64), HFAs at the same total size (Vec4f stays a struct), and
// >16-byte aggregates (passed via pointer + byval).
//
// This file was originally filed as issue-0036 (LLVM verifier
// failure repro). Promoted to a focused feature example once the
// emit_llvm.zig coerceArg branches landed.
#import "modules/std.sx";
#import c {
#source "1206-ffi-medium-struct.c";
};
Pair64 :: struct { a: i64; b: i64; }
ffi_pair64_swap :: (p: Pair64) -> Pair64 extern;
main :: () -> i32 {
p : Pair64 = .{ a = 1, b = 2 };
q := ffi_pair64_swap(p);
print("swap = ({}, {})\n", q.a, q.b);
print("ok = {}\n", q.a == 2 and q.b == 1);
0
}