Hi,
currently there is a problem when debugging a virtual thunk. That is
a decl with DECL_IGNORED_P. Currently the line information displayed
in gdb is completely bogus, thus the last line of whatever function
is immediately before the PC of the thunk.
This patch improves the debug experience at least a bit by emitting
at the line number information where the thunk has been defined.
I do not dare to touch anything but dwarf2 debug info, therefore
the patch is a bit awkward.
Bootstrapped and reg-tested on x86_64-pc-linux-gnu.
Is it OK for trunk?
Thanks
Bernd.
From 0a44bb870e90623689cae484f8a8899706480876 Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlin...@hotmail.de>
Date: Sun, 3 Jan 2021 11:18:39 +0100
Subject: [PATCH] Add line debug info for virtual thunks
There is no full debug info since the DECL_IGNORED_P
flag is set on virtual thunks.
But instead of no line info at all, emit at least
the location of the function decl.
2021-01-03 Bernd Edlinger <bernd.edlin...@hotmail.de>
PR ipa/97937
* final.c (final_start_function_1): Always emit function start line
information for dwarf2 debug.
(final_end_function): Always call end_function for dwarf2 debug.
* varasm.c (assemble_start_function): Always call begin_function
for dwarf2 debug.
---
gcc/final.c | 9 +++++++--
gcc/varasm.c | 2 +-
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/gcc/final.c b/gcc/final.c
index fc9a05e..5a274c1 100644
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -1735,7 +1735,12 @@ final_start_function_1 (rtx_insn **firstp, FILE *file, int *seen,
last_filename);
if (!dwarf2_debug_info_emitted_p (current_function_decl))
- dwarf2out_begin_prologue (0, 0, NULL);
+ {
+ if (write_symbols == DWARF2_DEBUG)
+ dwarf2out_begin_prologue (last_linenum, last_columnnum, last_filename);
+ else
+ dwarf2out_begin_prologue (0, 0, NULL);
+ }
#ifdef LEAF_REG_REMAP
if (crtl->uses_only_leaf_regs)
@@ -1879,7 +1884,7 @@ final_end_function (void)
{
app_disable ();
- if (!DECL_IGNORED_P (current_function_decl))
+ if (!DECL_IGNORED_P (current_function_decl) || write_symbols == DWARF2_DEBUG)
debug_hooks->end_function (high_function_linenum);
/* Finally, output the function epilogue:
diff --git a/gcc/varasm.c b/gcc/varasm.c
index ce5d449..513922d 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -1930,7 +1930,7 @@ assemble_start_function (tree decl, const char *fnname)
ASM_OUTPUT_FUNCTION_PREFIX (asm_out_file, fnname);
#endif
- if (!DECL_IGNORED_P (decl))
+ if (!DECL_IGNORED_P (decl) || write_symbols == DWARF2_DEBUG)
(*debug_hooks->begin_function) (decl);
/* Make function name accessible from other files, if appropriate. */
--
1.9.1
