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gdb/gdb-symtab-work-around-pr-gas-29517.patch

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From 92a5f5ae1b71d152d943ee896bf6cd073d50daa7 Mon Sep 17 00:00:00 2001
From: Tom de Vries <tdevries@suse.de>
Date: Thu, 28 Sep 2023 13:55:07 +0200
Subject: [PATCH 02/12] [gdb/symtab] Work around PR gas/29517
When using glibc debuginfo generated with gas 2.39, we run into PR gas/29517:
...
$ gdb -q -batch a.out -ex start -ex "p (char *)strstr (\"haha\", \"ah\")"
Temporary breakpoint 1 at 0x40051b: file hello.c, line 6.
Temporary breakpoint 1, main () at hello.c:6
6 printf ("hello\n");
Invalid cast.
...
while without glibc debuginfo installed we get the expected result:
...
$n = 0x7ffff7daa1b1 "aha"
...
and likewise with glibc debuginfo generated with gas 2.40.
The strstr ifunc resolves to __strstr_sse2_unaligned. The problem is that gas
generates dwarf that states that the return type is void:
...
<1><3e1e58>: Abbrev Number: 2 (DW_TAG_subprogram)
<3e1e59> DW_AT_name : __strstr_sse2_unaligned
<3e1e5d> DW_AT_external : 1
<3e1e5e> DW_AT_low_pc : 0xbbd2e
<3e1e66> DW_AT_high_pc : 0xbc1c3
...
while the return type should be a DW_TAG_unspecified_type, as is the case
with gas 2.40.
We can still use the workaround of casting to another function type for both
__strstr_sse2_unaligned:
...
(gdb) p ((char * (*) (const char *, const char *))__strstr_sse2_unaligned) \
("haha", "ah")
$n = 0x7ffff7daa211 "aha"
...
and strstr (which requires using *strstr to dereference the ifunc before we
cast):
...
gdb) p ((char * (*) (const char *, const char *))*strstr) ("haha", "ah")
$n = 0x7ffff7daa251 "aha"
...
but that's a bit cumbersome to use.
Work around this in the dwarf reader, such that we have instead:
...
(gdb) p (char *)strstr ("haha", "ah")
$n = 0x7ffff7daa1b1 "aha"
...
This also requires fixing producer_is_gcc to stop returning true for
producer "GNU AS 2.39.0".
Tested on x86_64-linux.
PR symtab/30911
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30911
---
gdb/dwarf2/cu.c | 1 +
gdb/dwarf2/cu.h | 1 +
gdb/dwarf2/read.c | 22 ++++++++++++
gdb/producer.c | 8 ++++-
.../gdb.dwarf2/dw2-unspecified-type.c | 9 ++++-
.../gdb.dwarf2/dw2-unspecified-type.exp | 36 +++++++++++++++----
6 files changed, 68 insertions(+), 9 deletions(-)
diff --git a/gdb/dwarf2/cu.c b/gdb/dwarf2/cu.c
index 9c1691c90e9..42fd4f4441b 100644
--- a/gdb/dwarf2/cu.c
+++ b/gdb/dwarf2/cu.c
@@ -40,6 +40,7 @@ dwarf2_cu::dwarf2_cu (dwarf2_per_cu_data *per_cu,
producer_is_icc_lt_14 (false),
producer_is_codewarrior (false),
producer_is_clang (false),
+ producer_is_gas_2_39 (false),
processing_has_namespace_info (false),
load_all_dies (false)
{
diff --git a/gdb/dwarf2/cu.h b/gdb/dwarf2/cu.h
index e8dbde9c019..710aeb5b237 100644
--- a/gdb/dwarf2/cu.h
+++ b/gdb/dwarf2/cu.h
@@ -265,6 +265,7 @@ struct dwarf2_cu
bool producer_is_icc_lt_14 : 1;
bool producer_is_codewarrior : 1;
bool producer_is_clang : 1;
+ bool producer_is_gas_2_39 : 1;
/* When true, the file that we're processing is known to have
debugging info for C++ namespaces. GCC 3.3.x did not produce
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index b9e7e18f2a6..f39eba7a008 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -13370,6 +13370,8 @@ check_producer (struct dwarf2_cu *cu)
cu->producer_is_codewarrior = true;
else if (producer_is_clang (cu->producer, &major, &minor))
cu->producer_is_clang = true;
+ else if (startswith (cu->producer, "GNU AS 2.39.0"))
+ cu->producer_is_gas_2_39 = true;
else
{
/* For other non-GCC compilers, expect their behavior is DWARF version
@@ -13405,6 +13407,15 @@ producer_is_codewarrior (struct dwarf2_cu *cu)
return cu->producer_is_codewarrior;
}
+static bool
+producer_is_gas_2_39 (struct dwarf2_cu *cu)
+{
+ if (!cu->checked_producer)
+ check_producer (cu);
+
+ return cu->producer_is_gas_2_39;
+}
+
/* Return the accessibility of DIE, as given by DW_AT_accessibility.
If that attribute is not available, return the appropriate
default. */
@@ -16581,6 +16592,17 @@ read_subroutine_type (struct die_info *die, struct dwarf2_cu *cu)
type = die_type (die, cu);
+ if (type->code () == TYPE_CODE_VOID
+ && !type->is_stub ()
+ && die->child == nullptr
+ && producer_is_gas_2_39 (cu))
+ {
+ /* Work around PR gas/29517, pretend we have an DW_TAG_unspecified_type
+ return type. */
+ type = init_type (cu->per_objfile->objfile, TYPE_CODE_VOID, 0, NULL);
+ type->set_is_stub (true);
+ }
+
/* The die_type call above may have already set the type for this DIE. */
ftype = get_die_type (die, cu);
if (ftype)
diff --git a/gdb/producer.c b/gdb/producer.c
index 655eb971283..9fcf749e3d4 100644
--- a/gdb/producer.c
+++ b/gdb/producer.c
@@ -54,13 +54,19 @@ producer_is_gcc (const char *producer, int *major, int *minor)
if (minor == NULL)
minor = &min;
+ /* Skip GNU. */
+ cs = &producer[strlen ("GNU ")];
+
+ /* Bail out for GNU AS. */
+ if (startswith (cs, "AS "))
+ return 0;
+
/* Skip any identifier after "GNU " - such as "C11" "C++" or "Java".
A full producer string might look like:
"GNU C 4.7.2"
"GNU Fortran 4.8.2 20140120 (Red Hat 4.8.2-16) -mtune=generic ..."
"GNU C++14 5.0.0 20150123 (experimental)"
*/
- cs = &producer[strlen ("GNU ")];
while (*cs && !isspace (*cs))
cs++;
if (*cs && isspace (*cs))
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.c b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.c
index 1df09214d4a..e07d9517ff2 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.c
+++ b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.c
@@ -17,9 +17,16 @@
extern int foo (void);
+int
+bar (void)
+{
+ asm ("bar_label: .globl bar_label");
+ return 0;
+}
+
int
main (void)
{
- int res = foo ();
+ int res = foo () + bar ();
return res;
}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.exp b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.exp
index a353395592e..bd707204fba 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.exp
+++ b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.exp
@@ -29,10 +29,18 @@ lassign $foo_res \
foo_start foo_len
set foo_end "$foo_start + $foo_len"
+set bar_res \
+ [function_range bar \
+ [list ${srcdir}/${subdir}/$srcfile ${srcdir}/${subdir}/$srcfile2]]
+lassign $bar_res \
+ bar_start bar_len
+set bar_end "$bar_start + $bar_len"
+
# Create the DWARF.
set asm_file [standard_output_file $srcfile3]
Dwarf::assemble $asm_file {
global foo_start foo_end
+ global bar_start bar_end
declare_labels unspecified_type_label
cu {} {
@@ -47,7 +55,19 @@ Dwarf::assemble $asm_file {
{high_pc $foo_end addr}
{type :$unspecified_type_label}
}
+ }
+ }
+ cu {} {
+ compile_unit {
+ {language @DW_LANG_Mips_Assembler}
+ {producer "GNU AS 2.39.0"}
+ } {
+ DW_TAG_subprogram {
+ {name bar}
+ {low_pc $bar_start addr}
+ {high_pc $bar_end addr}
+ }
}
}
}
@@ -61,12 +81,14 @@ if ![runto_main] {
return -1
}
-# Print the function type. Return type should be stub type, which is printed
-# as void.
-gdb_test "ptype foo" "type = void \\(void\\)"
+foreach f {foo bar} {
+ # Print the function type. Return type should be stub type, which is printed
+ # as void.
+ gdb_test "ptype $f" "type = void \\(void\\)"
-# Call the function, casting the function to the correct function type.
-gdb_test "p ((int (*) ()) foo) ()" " = 0"
+ # Call the function, casting the function to the correct function type.
+ gdb_test "p ((int (*) ()) $f) ()" " = 0"
-# Call the function, casting the function result to the correct type.
-gdb_test "p (int) foo ()" " = 0"
+ # Call the function, casting the function result to the correct type.
+ gdb_test "p (int) $f ()" " = 0"
+}
--
2.35.3
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