https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83010
Bug ID: 83010
Summary: DW_AT_location is not emitted for thread local
variable
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: qiyao at gcc dot gnu.org
Target Milestone: ---
$ cat 1.c
__thread int a_thread_local;
$ gcc -g -c 1.c -o 1.o
$ readelf -wi ./1.o
....
<0><b>: Abbrev Number: 1 (DW_TAG_compile_unit)
<c> DW_AT_producer : (indirect string, offset: 0x38): GNU C17
8.0.0 20171102 (experimental) -mlittle-endian -mabi=lp64 -g
<10> DW_AT_language : 12 (ANSI C99)
<11> DW_AT_name : 1.c
<15> DW_AT_comp_dir : (indirect string, offset: 0x0): gdb
<19> DW_AT_stmt_list : 0x0
<1><1d>: Abbrev Number: 2 (DW_TAG_variable)
<1e> DW_AT_name : (indirect string, offset: 0x29): a_thread_local
<22> DW_AT_decl_file : 1
<23> DW_AT_decl_line : 1
<24> DW_AT_decl_column : 14
<25> DW_AT_type : <0x29>
<29> DW_AT_external : 1
DW_AT_location is missing, so GDB can't locate this variable. However, on arm
and x86_64, DW_AT_location is emitted.
x86_64:
<1><1d>: Abbrev Number: 2 (DW_TAG_variable)
<1e> DW_AT_name : (indirect string, offset: 0x3e): a_thread_local
<22> DW_AT_decl_file : 1
<23> DW_AT_decl_line : 1
<24> DW_AT_type : <0x33>
<28> DW_AT_external : 1
<28> DW_AT_location : 10 byte block: e 0 0 0 0 0 0 0 0 e0
(DW_OP_const8u: 0 0; DW_OP_GNU_push_tls_address or DW_OP_HP_unknown)
arm:
<1><1d>: Abbrev Number: 2 (DW_TAG_variable)
<1e> DW_AT_name : (indirect string, offset: 0xa2): a_thread_local
<22> DW_AT_decl_file : 1
<23> DW_AT_decl_line : 1
<24> DW_AT_type : <0x2f>
<28> DW_AT_external : 1
<28> DW_AT_location : 6 byte block: c 0 0 0 0 e0
(DW_OP_const4u: 0; DW_OP_GNU_push_tls_address or DW_OP_HP_unknown)
