[PATCH][gdb/symtab] Don't create duplicate psymtab for forward-imported CU
Tom de Vries
tdevries@suse.de
Wed Apr 8 10:19:13 GMT 2020
Hi,
Consider the executable generated for test-case gdb.dwarf2/imported-unit.exp.
When loading the executable using various tracing:
...
$ gdb \
outputs/gdb.dwarf2/imported-unit/imported-unit \
-batch \
-iex "set verbose on" \
-iex "set debug symtab-create 1"
...
Created psymtab 0x213f380 for module <artificial>@0xc7.
Created psymtab 0x20e7b00 for module imported_unit.c.
Created psymtab 0x215da20 for module imported_unit.c.
Created psymtab 0x2133630 for module elf-init.c.
Created psymtab 0x215b910 for module ../sysdeps/x86_64/crtn.S.
...
we notice that there are two psymtabs generated for imported_unit.c.
This is due to the following: in dwarf2_build_psymtabs_hard we loop over CUs
and generate partial symtabs for those, and if we encounter an import of
another CU, we also generate a partial symtab for that one, unless already
created.
This works well with backward import references:
- the imported CU is read
- then the importing CU is read
- the import is encountered, but the imported CU is already read, so
we're done.
But with forward import references, we have instead:
- the importing CU is read
- the import is encountered, and the imported CU is read
- the imported CU is read once more
Fix this by skipping already created psymtabs in the loop in
dwarf2_build_psymtabs_hard.
Build in combination with the tentative fix for PR25718 - "[ada] symbol in
imported unit not found"
( https://sourceware.org/pipermail/gdb-patches/2020-March/167152.html ) to
prevent this regression:
...
FAIL: gdb.ada/char_enum.exp: ptype pck.Global_Enum_Type
...
Tested on x86_64-linux, with native and target board
unix/-flto/-O0/-flto-partition=none/-ffat-lto-objects.
This causes this regression with the target board:
...
FAIL: gdb.ada/dgopt.exp: list x.adb:16, 16
...
which I consider a seperate PR, filed as PR25801 - "Filename of shared psymtab
is ignored".
OK for trunk?
Thanks,
- Tom
[gdb/symtab] Don't create duplicate psymtab for forward-imported CU
gdb/ChangeLog:
2020-04-08 Tom de Vries <tdevries@suse.de>
PR symtab/25700
* dwarf2/read.c (dwarf2_build_psymtabs_hard): Don't create psymtab for
CU if already created.
gdb/testsuite/ChangeLog:
2020-04-08 Tom de Vries <tdevries@suse.de>
PR symtab/25700
* gdb.dwarf2/imported-unit.exp: Verify that there's only one partial
symtab for imported_unit.c.
---
gdb/dwarf2/read.c | 7 ++++++-
gdb/testsuite/gdb.dwarf2/imported-unit.exp | 18 ++++++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index c0b5e58b17..8b761e891e 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -7781,7 +7781,12 @@ dwarf2_build_psymtabs_hard (struct dwarf2_per_objfile *dwarf2_per_objfile)
addrmap_create_mutable (&temp_obstack));
for (dwarf2_per_cu_data *per_cu : dwarf2_per_objfile->all_comp_units)
- process_psymtab_comp_unit (per_cu, false, language_minimal);
+ {
+ if (per_cu->v.psymtab != NULL)
+ /* In case a forward DW_TAG_imported_unit has read the CU already. */
+ continue;
+ process_psymtab_comp_unit (per_cu, false, language_minimal);
+ }
/* This has to wait until we read the CUs, we need the list of DWOs. */
process_skeletonless_type_units (dwarf2_per_objfile);
diff --git a/gdb/testsuite/gdb.dwarf2/imported-unit.exp b/gdb/testsuite/gdb.dwarf2/imported-unit.exp
index 41a7505459..d7b3d4c539 100644
--- a/gdb/testsuite/gdb.dwarf2/imported-unit.exp
+++ b/gdb/testsuite/gdb.dwarf2/imported-unit.exp
@@ -168,6 +168,24 @@ if { $psymtabs_p } {
} else {
unsupported $test
}
+
+# Verify that there's only one partial symtab for imported_unit.c. Test-case
+# for PR25700.
+set test "no duplicate psymtab for imported_unit.c"
+if { $psymtabs_p } {
+ set line "Partial symtab for source file imported_unit.c"
+ gdb_test_multiple "maint print psymbols" $test {
+ -re -wrap "$line.*$line.*" {
+ fail $gdb_test_name
+ }
+ -re -wrap "$line.*" {
+ pass $gdb_test_name
+ }
+ }
+} else {
+ unsupported $test
+}
+
# Sanity check
gdb_test "ptype main" "= int \\(void\\)"
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