This affects only the RISC-V targets, where the compiler options
-gvariable-location-views and consequently also -ginline-points
are disabled by default, which is unexpected and disables some
useful features of the generated debug info.
Due to a bug in the gas assembler the .loc statement
is not usable to generate location view debug info.
That is detected by configure:
configure:31500: checking assembler for dwarf2 debug_view support
configure:31509: .../riscv-unknown-elf/bin/as -o conftest.o conftest.s >&5
conftest.s: Assembler messages:
conftest.s:5: Error: .uleb128 only supports constant or subtract expressions
conftest.s:6: Error: .uleb128 only supports constant or subtract expressions
configure:31512: $? = 1
configure: failed program was
.file 1 "conftest.s"
.loc 1 3 0 view .LVU1
nop
.data
.uleb128 .LVU1
.uleb128 .LVU1
configure:31523: result: no
This results in dwarf2out_as_locview_support being set to false,
and that creates a sequence of events, with the end result that
most inlined functions either have no DW_AT_entry_pc, or one
with a wrong entry pc value.
But the location views can also be generated without using any
.loc statements, therefore we should enable the option
-gvariable-location-views by default, regardless of the status
of -gas-locview-support.
Note however, that the combination of the following compiler options
-g -O2 -gvariable-location-views -gno-as-loc-support
turned out to create invalid assembler intermediate files,
with lots of assembler errors like:
Error: leb128 operand is an undefined symbol: .LVU3
This affects all targets, except RISC-V of course ;-)
and is fixed by the changes in dwarf2out.cc
Finally the .debug_loclists created without assembler locview support
did contain location view pairs like v0000000ffffffff v000000000000000
which is the value from FORCE_RESET_NEXT_VIEW, but that is most likely
not as expected either, so change that as well.
gcc/ChangeLog:
* dwarf2out.cc (dwarf2out_maybe_output_loclist_view_pair,
output_loc_list): Correct handling of -gno-as-loc-support,
use ZERO_VIEW_P to output view number as zero value.
* toplev.cc (process_options): Do not automatically disable
-gvariable-location-views when -gno-as-loc-support or
-gno-as-locview-support is used.
gcc/testsuite/ChangeLog:
* gcc.dg/debug/dwarf2/inline2.c: Add checks for inline entry_pc.
* gcc.dg/debug/dwarf2/inline6.c: Add -gno-as-loc-support and check
the resulting location views.
---
gcc/dwarf2out.cc | 16 ++++++++++------
gcc/testsuite/gcc.dg/debug/dwarf2/inline2.c | 3 +++
gcc/testsuite/gcc.dg/debug/dwarf2/inline6.c | 7 ++++++-
gcc/toplev.cc | 4 +---
4 files changed, 20 insertions(+), 10 deletions(-)
v2: fixed the boot-strap error triggered by v1 on any target, except RISC-V,
the issue was triggered by libstdc++-v3/src/c++11/cxx11-ios_failure-lt.s
which is generated using -gno-as-loc-support, which triggered a latent issue.
v3: added some tests for the fixed bugs.
Regression-tested on x86_64-pc-linux-gnu, riscv-unknown-elf
and riscv64-unknown-elf, OK for trunk?
diff --git a/gcc/dwarf2out.cc b/gcc/dwarf2out.cc
index 346feeb53c8..79f97b5a55e 100644
--- a/gcc/dwarf2out.cc
+++ b/gcc/dwarf2out.cc
@@ -10374,7 +10374,7 @@ dwarf2out_maybe_output_loclist_view_pair
(dw_loc_list_ref curr)
#ifdef DW_LLE_view_pair
dw2_asm_output_data (1, DW_LLE_view_pair, "DW_LLE_view_pair");
- if (dwarf2out_as_locview_support)
+ if (dwarf2out_as_locview_support && dwarf2out_as_loc_support)
{
if (ZERO_VIEW_P (curr->vbegin))
dw2_asm_output_data_uleb128 (0, "Location view begin");
@@ -10396,8 +10396,10 @@ dwarf2out_maybe_output_loclist_view_pair
(dw_loc_list_ref curr)
}
else
{
- dw2_asm_output_data_uleb128 (curr->vbegin, "Location view begin");
- dw2_asm_output_data_uleb128 (curr->vend, "Location view end");
+ dw2_asm_output_data_uleb128 (ZERO_VIEW_P (curr->vbegin)
+ ? 0 : curr->vbegin, "Location view begin");
+ dw2_asm_output_data_uleb128 (ZERO_VIEW_P (curr->vend)
+ ? 0 : curr->vend, "Location view end");
}
#endif /* DW_LLE_view_pair */
@@ -10430,7 +10432,7 @@ output_loc_list (dw_loc_list_ref list_head)
vcount++;
/* ?? dwarf_split_debug_info? */
- if (dwarf2out_as_locview_support)
+ if (dwarf2out_as_locview_support && dwarf2out_as_loc_support)
{
char label[MAX_ARTIFICIAL_LABEL_BYTES];
@@ -10460,10 +10462,12 @@ output_loc_list (dw_loc_list_ref list_head)
}
else
{
- dw2_asm_output_data_uleb128 (curr->vbegin,
+ dw2_asm_output_data_uleb128 (ZERO_VIEW_P (curr->vbegin)
+ ? 0 : curr->vbegin,
"View list begin (%s)",
list_head->vl_symbol);
- dw2_asm_output_data_uleb128 (curr->vend,
+ dw2_asm_output_data_uleb128 (ZERO_VIEW_P (curr->vend)
+ ? 0 : curr->vend,
"View list end (%s)",
list_head->vl_symbol);
}
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/inline2.c
b/gcc/testsuite/gcc.dg/debug/dwarf2/inline2.c
index 9c36450ae2d..03d1a73c0c4 100644
--- a/gcc/testsuite/gcc.dg/debug/dwarf2/inline2.c
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/inline2.c
@@ -30,6 +30,9 @@
layout. */
/* { dg-final { scan-assembler-times "\\(DIE \\(\[^\n\]*\\)
DW_TAG_lexical_block" 0 } } */
+/* Each inline instance should have DW_AT_entry_pc and DW_AT_GNU_entry_view.
*/
+/* { dg-final { scan-assembler-times "# DW_AT_entry_pc" 6 } } */
+/* { dg-final { scan-assembler-times "# DW_AT_GNU_entry_view" 6 } } */
/* There are 3 DW_AT_inline attributes: one per abstract inline instance.
The value of the attribute must be 0x3, meaning the function was
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/inline6.c
b/gcc/testsuite/gcc.dg/debug/dwarf2/inline6.c
index fde8c27820d..a3b0e6dac18 100644
--- a/gcc/testsuite/gcc.dg/debug/dwarf2/inline6.c
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/inline6.c
@@ -16,7 +16,7 @@
/* Explicitly use dwarf-5 which uses DW_FORM_implicit_const. */
/* { dg-do compile } */
-/* { dg-options "-O -g3 -gdwarf-5 -dA -fgnu89-inline" } */
+/* { dg-options "-O -g3 -gdwarf-5 -dA -fgnu89-inline -gno-as-loc-support" } */
/* There are 6 inlined subroutines:
- One for each subroutine inlined into main, that's 3.
@@ -29,6 +29,11 @@
layout. */
/* { dg-final { scan-assembler-times "\\(DIE \\(\[^\n\]*\\)
DW_TAG_lexical_block" 0 } } */
+/* Each inline instance should have DW_AT_entry_pc and DW_AT_GNU_entry_view. */
+/* { dg-final { scan-assembler-times "# DW_AT_entry_pc" 6 } } */
+/* { dg-final { scan-assembler-times "# DW_AT_GNU_entry_view" 6 } } */
+/* { dg-final { scan-assembler-times "uleb128\[^\n\]*LVU\[^\n\]*# View list
(begin|end)" 0 } } */
+/* { dg-final { scan-assembler-times "uleb128\[^\n\]*0xffffffff\[^\n\]*# View
list (begin|end)" 0 } } */
/* There are 3 DW_AT_inline attributes: one per abstract inline instance.
The value of the attribute must be 0x3, meaning the function was
diff --git a/gcc/toplev.cc b/gcc/toplev.cc
index eee4805b504..292948122de 100644
--- a/gcc/toplev.cc
+++ b/gcc/toplev.cc
@@ -1475,9 +1475,7 @@ process_options ()
= (flag_var_tracking
&& debug_info_level >= DINFO_LEVEL_NORMAL
&& dwarf_debuginfo_p ()
- && !dwarf_strict
- && dwarf2out_as_loc_support
- && dwarf2out_as_locview_support);
+ && !dwarf_strict);
}
else if (debug_variable_location_views == -1 && dwarf_version != 5)
{
--
2.39.2
