From 2bce22e88e1c8486a0f2d42311506a8d3da20fb7 Mon Sep 17 00:00:00 2001 From: David Faust Date: Wed, 7 Dec 2022 11:44:28 -0800 Subject: btf: add 'extern' linkage for variables [PR106773] Add support for the 'extern' linkage value for BTF_KIND_VAR records, which is used for variables declared as extern in the source file. This also fixes a bug with BTF generation for extern variables which have both a non-defining declaration and a defining declaration in the same CU. PR target/106773 gcc/ * btfout.cc (btf_collect_datasec): Mark extern variables as such. (btf_dvd_emit_preprocess_cb): Skip non-defining extern variable decl if there is a defining decl for the same variable. (btf_asm_varent): Accomodate 'extern' linkage. gcc/testsuite/ * gcc.dg/debug/btf/btf-variables-4.c: New test. * gcc.dg/debug/btf/btf-variables-5.c: New test. include/ * btf.h (enum btf_var_linkage): New. (struct btf_var): Update comment to note 'extern' linkage. --- gcc/btfout.cc | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'gcc/btfout.cc') diff --git a/gcc/btfout.cc b/gcc/btfout.cc index aef9fd7..677e832 100644 --- a/gcc/btfout.cc +++ b/gcc/btfout.cc @@ -314,6 +314,9 @@ btf_collect_datasec (ctf_container_ref ctfc) continue; const char *section_name = node->get_section (); + /* Mark extern variables. */ + if (DECL_EXTERNAL (node->decl)) + dvd->dvd_visibility = BTF_VAR_GLOBAL_EXTERN; if (section_name == NULL) { @@ -431,6 +434,12 @@ btf_dvd_emit_preprocess_cb (ctf_dvdef_ref *slot, ctf_container_ref arg_ctfc) { ctf_dvdef_ref var = (ctf_dvdef_ref) * slot; + /* If this is an extern variable declaration with a defining declaration + later, skip it so that only the defining declaration is emitted. + This is the same case, fix and reasoning as in CTF; see PR105089. */ + if (ctf_dvd_ignore_lookup (arg_ctfc, var->dvd_key)) + return 1; + /* Do not add variables which refer to unsupported types. */ if (btf_removed_type_p (var->dvd_type)) return 1; @@ -676,7 +685,7 @@ btf_asm_varent (ctf_dvdef_ref var) dw2_asm_output_data (4, var->dvd_name_offset, "btv_name"); dw2_asm_output_data (4, BTF_TYPE_INFO (BTF_KIND_VAR, 0, 0), "btv_info"); dw2_asm_output_data (4, get_btf_id (var->dvd_type), "btv_type"); - dw2_asm_output_data (4, (var->dvd_visibility ? 1 : 0), "btv_linkage"); + dw2_asm_output_data (4, var->dvd_visibility, "btv_linkage"); } /* Asm'out a member description following a BTF_KIND_STRUCT or -- cgit v1.1