https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91794
Bug ID: 91794
Summary: exception and unwind state is not carried to LTO but
controls EH vs debug frame
Product: gcc
Version: 9.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: driver
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
On targets where -funwind-tables is not enabled by default doing
gcc -c -flto -funwind-tables t.c -g
gcc t.o -g
ends up without unwind tables even if the flags state is recorded in
per-function settings. dwarf2out.c suggests the state is accumulated
from all functions in the TU
/* Unlike the debug version, the EH version of frame unwind info is a per-
function setting so we need to record whether we need it for the unit. */
do_eh_frame |= dwarf2out_do_eh_frame ();
but that doesn't work since dwarf2out_do_eh_frame looks at the global
flag_unwind_tables (and global flag_exceptions and passes global opts to
the target hook).
We probably can switch between EH-frame and debug-frame per function but
a way out would be to handle flag_{,asynchronous_}unwind_tables in
lto-wrapper.
Eric was here fixing the similar PR81351.
One target where this shows is riscv.
