https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120308
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Thomas Schwinge <tschwi...@gcc.gnu.org>: https://gcc.gnu.org/g:9063810c86beee6274d745b91d8fb43a81c9683e commit r16-738-g9063810c86beee6274d745b91d8fb43a81c9683e Author: Thomas Schwinge <tschwi...@baylibre.com> Date: Thu May 15 18:11:16 2025 +0200 'TYPE_EMPTY_P' vs. code offloading [PR120308] We've got 'gcc/stor-layout.cc:finalize_type_size': /* Handle empty records as per the x86-64 psABI. */ TYPE_EMPTY_P (type) = targetm.calls.empty_record_p (type); (Indeed x86_64 is still the only target to define 'TARGET_EMPTY_RECORD_P', calling 'gcc/tree.cc-default_is_empty_record'.) And so it happens that for an empty struct used in code offloaded from x86_64 host (but not powerpc64le host, for example), we get to see 'TYPE_EMPTY_P' in offloading compilation (where the offload targets (currently?) don't use it themselves, and therefore aren't prepared to handle it). For nvptx offloading compilation, this causes wrong code generation: 'ptxas [...] error : Call has wrong number of parameters', as nvptx code generation for function definition doesn't pay attention to this flag (say, in 'gcc/config/nvptx/nvptx.cc:pass_in_memory', or whereever else would be appropriate to handle that), but the generic code 'gcc/calls.cc:expand_call' via 'gcc/function.cc:aggregate_value_p' does pay attention to it, and we thus get mismatching function definition vs. function call. This issue apparently isn't a problem for GCN offloading, but I don't know if that's by design or by accident. Richard Biener: > It looks like TYPE_EMPTY_P is only used during RTL expansion for ABI > purposes, so computing it during layout_type is premature as shown here. > > I would suggest to simply re-compute it at offload stream-in time. (For avoidance of doubt, the additions to 'gcc.target/nvptx/abi-struct-arg.c', 'gcc.target/nvptx/abi-struct-ret.c' are not dependent on the offload streaming code changes, but are just to mirror the changes to 'libgomp.oacc-c-c++-common/abi-struct-1.c'.) PR lto/120308 gcc/ * lto-streamer-out.cc (hash_tree): Don't handle 'TYPE_EMPTY_P' for 'lto_stream_offload_p'. * tree-streamer-in.cc (unpack_ts_type_common_value_fields): Likewise. * tree-streamer-out.cc (pack_ts_type_common_value_fields): Likewise. libgomp/ * testsuite/libgomp.oacc-c-c++-common/abi-struct-1.c: Add empty structure testing. gcc/testsuite/ * gcc.target/nvptx/abi-struct-arg.c: Add empty structure testing. * gcc.target/nvptx/abi-struct-ret.c: Likewise.
