https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102441
Bug ID: 102441
Summary: Incorrect location list in debug info
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: liyd2021 at gmail dot com
Target Milestone: ---
Affected versions: gcc 11.1.0 with gdb (Ubuntu 20.04.2)
(terminal) $ cat simple.c && gcc -g -O2 simple.c
void __attribute__((noipa)) not_opt_this(int *r) {}
int __attribute__((noinline)) foo(int x) {
int r = 0;
not_opt_this(&r);
return r;
}
int main (void) {
return foo (10);
}
--------------------
(terminal) $ cat run.gdb
b foo
b 5
r
c
(terminal) $ gdb -x run.gdb a.out
Breakpoint 1 at 0x401190: file simple.c, line 4.
Breakpoint 2 at 0x4011a1: file simple.c, line 5.
Breakpoint 1, foo (x=10) at simple.c:4
4 int r = 0;
Breakpoint 2, foo (x=-9492) at simple.c:5 <-- **BUG**: x should be 10
5 not_opt_this(&r);
--------------------
debug info and assembly:
<2><88>: Abbrev Number: 7 (DW_TAG_formal_parameter)
<89> DW_AT_name : x
<8b> DW_AT_decl_file : 1
<8c> DW_AT_decl_line : 3
<8d> DW_AT_decl_column : 39
<8e> DW_AT_type : <0x5f>
<92> DW_AT_location : 0x4 (location list)
<96> DW_AT_GNU_locviews: 0x0
Contents of the .debug_loc section:
Offset Begin End Expression
00000000 v000000000000000 v000000000000000 location view pair
00000002 v000000000000000 v000000000000000 location view pair
00000004 v000000000000000 v000000000000000 views at 00000000 for:
0000000000401190 00000000004011a5 (DW_OP_reg5 (rdi))
00000017 v000000000000000 v000000000000000 views at 00000002 for:
00000000004011a5 00000000004011af (DW_OP_GNU_entry_value:
(DW_OP_reg5 (rdi)); DW_OP_stack_value)
0000002d <End of list>
0x401190 <foo> sub $0x18,%rsp
0x401194 <foo+4> lea 0xc(%rsp),%rdi
0x401199 <foo+9> movl $0x0,0xc(%rsp)
0x4011a1 <foo+17> callq 0x401180 <not_opt_this>
0x4011a6 <foo+22> mov 0xc(%rsp),%eax
0x4011aa <foo+26> add $0x18,%rsp
0x4011ae <foo+30> retq
Debug info shows x in register %rdi, but %rdi was clobbered after 0x401194.
