This patch corrects a problem in which GDB ignores the debug info for
offload kernel entry functions because they're represented as nested
functions inside a function that does not exist on the accelerator
device (only on the host).
The fix is to add a notional code range to the non-existent parent
function. Setting it the same as the inner function is good enough
because GDB selects the innermost.
I'll submit this the mainline when stage 1 opens. Committed to
devel/omp/gcc-10 for now.
Andrew
Fix offload dwarf info
Add a notional code range to the notional parent function of offload kernel
functions. This is enough to prevent GDB discarding them.
gcc/ChangeLog:
* dwarf2out.c (gen_subprogram_die): Add high/low_pc attributes for
parents of offload kernels.
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 4d84a9e9607..a4a1b934dc7 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -23079,6 +23079,20 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)
/* We have already generated the labels. */
add_AT_low_high_pc (subr_die, fde->dw_fde_begin,
fde->dw_fde_end, false);
+
+ /* Offload kernel functions are nested within a parent function
+ that doesn't actually exist within the offload object. GDB
+ will ignore the function and everything nested within unless
+ we give it a notional code range (the values aren't
+ important, as long as they are valid). */
+ if (flag_generate_offload
+ && lookup_attribute ("omp target entrypoint",
+ DECL_ATTRIBUTES (decl))
+ && subr_die->die_parent
+ && subr_die->die_parent->die_tag == DW_TAG_subprogram
+ && !get_AT_low_pc (subr_die->die_parent))
+ add_AT_low_high_pc (subr_die->die_parent, fde->dw_fde_begin,
+ fde->dw_fde_end, false);
}
else
{
