https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108600
Bug ID: 108600
Summary: Use DW_LNS_set_prologue_end
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: vries at gcc dot gnu.org
Target Milestone: ---
The prologue_end marker (introduced in dwarf v3) is currently not emitted by
gcc.
This is the case for -gno-as-loc-support (gcc emitting .debug_line
contribution).
And for -gas-loc-support (gcc emitting .loc directives).
Note that there is an existing convention that marks the end of the prologue:
the second entry in the line table marks the first insn after the prologue.
However, that convention is not known by everyone, which makes it easier to
break it without noticing.
Note that for for instance gdb test-case gdb.ada/ref_param.exp, this convention
was broken for gcc 7.5.0 (and I don't know how much earlier), and my current
guess is that it got fixed in gcc 11.1.0, by commit c029fcb5680 ("Reset
force_source_line in final.c").
The only way to make the end of the prologue visible in assembly as well as
disassembly is to make it explicit by using DW_LNS_set_prologue_end.
