[v2,gdb/testsuite] Fix gdb.base/enum_cond.exp on arm-linux
Checks
| Context |
Check |
Description |
| linaro-tcwg-bot/tcwg_gdb_build--master-aarch64 |
success
|
Build passed
|
| linaro-tcwg-bot/tcwg_gdb_build--master-arm |
success
|
Build passed
|
| linaro-tcwg-bot/tcwg_gdb_check--master-arm |
success
|
Test passed
|
| linaro-tcwg-bot/tcwg_gdb_check--master-aarch64 |
fail
|
Patch failed to apply
|
Commit Message
On arm-linux, I run into:
...
gdb compile failed, ld: warning: enum_cond.o uses variable-size enums yet \
the output is to use 32-bit enums; use of enum values across objects may fail
UNTESTED: gdb.base/enum_cond.exp: failed to compile
...
Fix this by using -nostdlib.
Tested on arm-linux and x86_64-linux.
---
gdb/testsuite/gdb.base/enum_cond.c | 16 ++++++++++++++++
gdb/testsuite/gdb.base/enum_cond.exp | 15 ++++++++++++++-
gdb/testsuite/lib/gdb.exp | 12 ++++++++++++
3 files changed, 42 insertions(+), 1 deletion(-)
base-commit: 7b2a5f7183b946a0a2644a505892b7e0aefbbfd1
Comments
On 2025-03-18 03:28, Tom de Vries wrote:
> On arm-linux, I run into:
> ...
> gdb compile failed, ld: warning: enum_cond.o uses variable-size enums yet \
> the output is to use 32-bit enums; use of enum values across objects may fail
> UNTESTED: gdb.base/enum_cond.exp: failed to compile
> ...
>
> Fix this by using -nostdlib.
>
> Tested on arm-linux and x86_64-linux.
> ---
> gdb/testsuite/gdb.base/enum_cond.c | 16 ++++++++++++++++
> gdb/testsuite/gdb.base/enum_cond.exp | 15 ++++++++++++++-
> gdb/testsuite/lib/gdb.exp | 12 ++++++++++++
> 3 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/testsuite/gdb.base/enum_cond.c b/gdb/testsuite/gdb.base/enum_cond.c
> index 35e126aed45..df8830f0c9e 100644
> --- a/gdb/testsuite/gdb.base/enum_cond.c
> +++ b/gdb/testsuite/gdb.base/enum_cond.c
> @@ -46,3 +46,19 @@ main (void)
> return 0;
> }
>
> +void
> +exit (int status)
> +{
> +#if HAVE_BUILTIN_TRAP
> + __builtin_trap ();
> +#endif
> + while (1)
> + ;
Huh, it would be nice to find something that works everywhere. We do
have "my_exit" in lib/my-syscalls.h, which we could call, but we would
need to provide a syscall implementation for all arches we want to test
(not too hard, but still).
What about having a global:
volatile int *dummy = nullptr;
and then do:
*dummy = 1;
Would that successfully stop the program on all known platforms?
Simon
On 3/18/25 14:46, Simon Marchi wrote:
>
>
> On 2025-03-18 03:28, Tom de Vries wrote:
>> On arm-linux, I run into:
>> ...
>> gdb compile failed, ld: warning: enum_cond.o uses variable-size enums yet \
>> the output is to use 32-bit enums; use of enum values across objects may fail
>> UNTESTED: gdb.base/enum_cond.exp: failed to compile
>> ...
>>
>> Fix this by using -nostdlib.
>>
>> Tested on arm-linux and x86_64-linux.
>> ---
>> gdb/testsuite/gdb.base/enum_cond.c | 16 ++++++++++++++++
>> gdb/testsuite/gdb.base/enum_cond.exp | 15 ++++++++++++++-
>> gdb/testsuite/lib/gdb.exp | 12 ++++++++++++
>> 3 files changed, 42 insertions(+), 1 deletion(-)
>>
>> diff --git a/gdb/testsuite/gdb.base/enum_cond.c b/gdb/testsuite/gdb.base/enum_cond.c
>> index 35e126aed45..df8830f0c9e 100644
>> --- a/gdb/testsuite/gdb.base/enum_cond.c
>> +++ b/gdb/testsuite/gdb.base/enum_cond.c
>> @@ -46,3 +46,19 @@ main (void)
>> return 0;
>> }
>>
>> +void
>> +exit (int status)
>> +{
>> +#if HAVE_BUILTIN_TRAP
>> + __builtin_trap ();
>> +#endif
>> + while (1)
>> + ;
>
> Huh, it would be nice to find something that works everywhere.
> We do
> have "my_exit" in lib/my-syscalls.h, which we could call, but we would
> need to provide a syscall implementation for all arches we want to test
> (not too hard, but still).
>
> What about having a global:
>
> volatile int *dummy = nullptr;
>
> and then do:
>
> *dummy = 1;
>
> Would that successfully stop the program on all known platforms?
AFAIU that's undefined behaviour, so a valid implementation might just
skip the store.
I can submit a v3 using this (note NULL instead of nullptr since this is
C, not C++):
...
void
exit (int status)
{
#if HAVE_BUILTIN_TRAP
__builtin_trap ();
#endif
{
volatile int *dummy = NULL;
*dummy = 1;
}
while (1)
;
...
but AFAIC I'm fine with this v2.
Thanks,
- Tom
On 3/18/25 10:08 AM, Tom de Vries wrote:
> On 3/18/25 14:46, Simon Marchi wrote:
>>
>>
>> On 2025-03-18 03:28, Tom de Vries wrote:
>>> On arm-linux, I run into:
>>> ...
>>> gdb compile failed, ld: warning: enum_cond.o uses variable-size enums yet \
>>> the output is to use 32-bit enums; use of enum values across objects may fail
>>> UNTESTED: gdb.base/enum_cond.exp: failed to compile
>>> ...
>>>
>>> Fix this by using -nostdlib.
>>>
>>> Tested on arm-linux and x86_64-linux.
>>> ---
>>> gdb/testsuite/gdb.base/enum_cond.c | 16 ++++++++++++++++
>>> gdb/testsuite/gdb.base/enum_cond.exp | 15 ++++++++++++++-
>>> gdb/testsuite/lib/gdb.exp | 12 ++++++++++++
>>> 3 files changed, 42 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/gdb/testsuite/gdb.base/enum_cond.c b/gdb/testsuite/gdb.base/enum_cond.c
>>> index 35e126aed45..df8830f0c9e 100644
>>> --- a/gdb/testsuite/gdb.base/enum_cond.c
>>> +++ b/gdb/testsuite/gdb.base/enum_cond.c
>>> @@ -46,3 +46,19 @@ main (void)
>>> return 0;
>>> }
>>> +void
>>> +exit (int status)
>>> +{
>>> +#if HAVE_BUILTIN_TRAP
>>> + __builtin_trap ();
>>> +#endif
>>> + while (1)
>>> + ;
>>
>> Huh, it would be nice to find something that works everywhere.
>> We do
>> have "my_exit" in lib/my-syscalls.h, which we could call, but we would
>> need to provide a syscall implementation for all arches we want to test
>> (not too hard, but still).
>>
>> What about having a global:
>>
>> volatile int *dummy = nullptr;
>>
>> and then do:
>>
>> *dummy = 1;
>>
>> Would that successfully stop the program on all known platforms?
>
> AFAIU that's undefined behaviour, so a valid implementation might just skip the store.
>
> I can submit a v3 using this (note NULL instead of nullptr since this is C, not C++):
> ...
> void
> exit (int status)
> {
> #if HAVE_BUILTIN_TRAP
> __builtin_trap ();
> #endif
>
> {
> volatile int *dummy = NULL;
> *dummy = 1;
> }
>
> while (1)
> ;
> ...
> but AFAIC I'm fine with this v2.
>
> Thanks,
> - Tom
Ok, fair enough, that's a very edgy case anyway.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Simon
@@ -46,3 +46,19 @@ main (void)
return 0;
}
+void
+exit (int status)
+{
+#if HAVE_BUILTIN_TRAP
+ __builtin_trap ();
+#endif
+ while (1)
+ ;
+}
+
+void
+_start (void)
+{
+ main ();
+ exit (0);
+}
@@ -19,7 +19,20 @@
standard_testfile .c
-set opts [list debug additional_flags=-fshort-enums]
+set opts {}
+lappend opts debug
+lappend opts additional_flags=-fshort-enums
+# Without -nostdlib, on arm we run into:
+#
+# ld: warning: enum_cond.o uses variable-size enums yet the output is to use
+# 32-bit enums; use of enum values across objects may fail
+#
+# due to conflicting values for Tag_ABI_enum_size between enum_cond.o and
+# linked-in objects. Work around this by using -nostdlib, making sure there's
+# just one object, and no such conflict can happen.
+lappend opts additional_flags=-nostdlib
+lappend opts additional_flags=-DHAVE_BUILTIN_TRAP=[have_builtin_trap]
+
if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable $opts] != "" } {
untested "failed to compile"
return -1
@@ -11072,5 +11072,17 @@ proc section_get {exec section} {
return $retval
}
+# Return 1 if the compiler supports __builtin_trap, else return 0.
+
+gdb_caching_proc have_builtin_trap {} {
+
+ return [gdb_can_simple_compile builtin_trap {
+ int main() {
+ __builtin_trap ();
+ return 0;
+ }
+ } executable]
+}
+
# Always load compatibility stuff.
load_lib future.exp