This makes sure to emit full declaration DIEs including
formal parameters for used external functions. This helps
debugging when debug information of the external entity is
not available and also helps external tools cross-checking
ABI compatibility which was the bug reporters use case.
For cc1 this affects debug information size as follows:
VM SIZE FILE SIZE
++++++++++++++ GROWING ++++++++++++++
[ = ] 0 .debug_info +1.63Mi +1.3%
[ = ] 0 .debug_str +263Ki +3.4%
[ = ] 0 .debug_abbrev +101Ki +4.9%
[ = ] 0 .debug_line +5.71Ki +0.0%
+44% +16 [Unmapped] +48 +1.2%
-------------- SHRINKING --------------
[ = ] 0 .debug_loc -213 -0.0%
-0.0% -48 .text -48 -0.0%
[ = ] 0 .debug_ranges -16 -0.0%
-0.0% -32 TOTAL +1.99Mi +0.6%
and DWARF compression via DWZ can only shave off minor bits
here.
Previously we emitted no DIEs for external functions at all
unless they were referenced via DW_TAG_GNU_call_site which
for some GCC revs caused a regular DIE to appear and since
GCC 4.9 only a stub without formal parameters. This means
at -O0 we did not emit any DIE for external functions
but with optimization we emitted stubs.
Bootstrap and regtest running on x86_64-unknown-linux-gnu.
OK for trunk and backports?
Thanks,
Richard.
2020-07-30 Richard Biener <rguent...@suse.de>
PR debug/96383
* cgraphunit.c (symbol_table::finalize_compilation_unit):
Emit debug information for all used functions, not for
definitions.
* gcc.dg/debug/dwarf2/pr96383-1.c: New testcase.
* gcc.dg/debug/dwarf2/pr96383-2.c: Likewise.
---
gcc/cgraphunit.c | 2 +-
gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-1.c | 17 +++++++++++++++++
gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-2.c | 17 +++++++++++++++++
3 files changed, 35 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-1.c
create mode 100644 gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-2.c
diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
index ea9a34bda6f..3873cf1195d 100644
--- a/gcc/cgraphunit.c
+++ b/gcc/cgraphunit.c
@@ -2989,7 +2989,7 @@ symbol_table::finalize_compilation_unit (void)
/* Emit early debug for reachable functions, and by consequence,
locally scoped symbols. */
struct cgraph_node *cnode;
- FOR_EACH_FUNCTION_WITH_GIMPLE_BODY (cnode)
+ FOR_EACH_FUNCTION (cnode)
(*debug_hooks->early_global_decl) (cnode->decl);
/* Clean up anything that needs cleaning up after initial debug
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-1.c
b/gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-1.c
new file mode 100644
index 00000000000..ede30f9a95e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-1.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-g -gdwarf -dA" } */
+
+extern void foo (int);
+extern void bar (int);
+
+int main()
+{
+ foo (1);
+}
+
+/* We want subprogram DIEs for both foo and main and a DIE for
+ the formal parameter of foo. We do not want a DIE for
+ unusedbar. */
+/* { dg-final { scan-assembler-times "DW_TAG_subprogram" 4 } } */
+/* { dg-final { scan-assembler-times "DW_TAG_formal_parameter" 2 } } */
+/* { dg-final { scan-assembler-not "unusedbar" } } */
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-2.c
b/gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-2.c
new file mode 100644
index 00000000000..c3a710e2f89
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/pr96383-2.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-g -O2 -gdwarf -dA" } */
+
+extern void foo (int);
+extern void unusedbar (int);
+
+int main()
+{
+ foo (1);
+}
+
+/* We want subprogram DIEs for both foo and main and a DIE for
+ the formal parameter of foo. We do not want a DIE for
+ unusedbar. */
+/* { dg-final { scan-assembler-times "DW_TAG_subprogram" 4 } } */
+/* { dg-final { scan-assembler-times "DW_TAG_formal_parameter" 2 } } */
+/* { dg-final { scan-assembler-not "unusedbar" } } */
--
2.26.2
