* [lttng-dev] with -Og option, lttng-ust compile failed on 32bit arm
@ 2021-09-30 3:47 Changqing Li via lttng-dev
2021-09-30 13:14 ` Mathieu Desnoyers via lttng-dev
0 siblings, 1 reply; 3+ messages in thread
From: Changqing Li via lttng-dev @ 2021-09-30 3:47 UTC (permalink / raw)
To: lttng-dev; +Cc: Changqing Li
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Hi,
The problem happened after upgrade to lttng-ust 2.13.0. 2.12.0 don't
have this issue.
liburcu version: 0.13.0
gcc: 11.2.0
This is my reproduce steps, it is cross compile enviroment based on
yocto project.
1. git clone git://git.yoctoproject.org/poky
2. . oe-init-build-env
3. echo "MACHINE='qemuarm'" >> conf/local.conf
4. echo "DEBUG_BUILD='1'" >> conf/local.conf
5. bitbake lttng-ust
compile failed with error:
|
/work/cortexa15t2hf-neon-poky-linux-gnueabi/lttng-ust/2_2.13.0-r0/recipe-sysroot-native/usr/bin/arm-poky-linux-gnueabi/../../libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/11.2.0/ld:
../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to
`_uatomic_link_error'
| collect2: error: ld returned 1 exit status
| Makefile:399: recipe for target 'test_ust_error' failed
checked with "nm ../../../src/lib/lttng-ust/.libs/liblttng-ust.so" |
grep atomic, we can see 'U _uatomic_link_error', but since -Og
is used, liburcu don't define this function.
[snip]
#if !defined __OPTIMIZE__ || defined UATOMIC_NO_LINK_ERROR
static inline __attribute__((always_inline, noreturn))
void _uatomic_link_error(void)
{
#ifdef ILLEGAL_INSTR
/*
* generate an illegal instruction. Cannot catch this with
* linker tricks when optimizations are disabled.
*/
__asm__ __volatile__(ILLEGAL_INSTR);
#else
__builtin_trap();
#endif
}
#else /* #if !defined __OPTIMIZE__ || defined UATOMIC_NO_LINK_ERROR */
extern void _uatomic_link_error(void);
#endif /* #else #if !defined __OPTIMIZE__ || defined
UATOMIC_NO_LINK_ERROR */
[snip]
we cannot see 'U _uatomic_link_error' in following conditions, so
compile successed:
1. without -Og(using -O2), + 32bit arm
2. -Og + 64bit arm
3. -Og + x86/x86-64
Do you have any idea about how to fix this? I don't understand why only
"-Og + 32bit arm" will call function _uatomic_link_error.
Thanks
//Changqing
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [lttng-dev] with -Og option, lttng-ust compile failed on 32bit arm
2021-09-30 3:47 [lttng-dev] with -Og option, lttng-ust compile failed on 32bit arm Changqing Li via lttng-dev
@ 2021-09-30 13:14 ` Mathieu Desnoyers via lttng-dev
2021-10-08 8:12 ` Changqing Li via lttng-dev
0 siblings, 1 reply; 3+ messages in thread
From: Mathieu Desnoyers via lttng-dev @ 2021-09-30 13:14 UTC (permalink / raw)
To: Changqing Li; +Cc: lttng-dev
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----- On Sep 29, 2021, at 11:47 PM, lttng-dev <lttng-dev@lists.lttng.org> wrote:
> Hi,
> The problem happened after upgrade to lttng-ust 2.13.0. 2.12.0 don't have this
> issue.
> liburcu version: 0.13.0
> gcc: 11.2.0
> This is my reproduce steps, it is cross compile enviroment based on yocto
> project.
> 1. git clone git://git.yoctoproject.org/poky
> 2. . oe-init-build-env
> 3. echo "MACHINE='qemuarm'" >> conf/local.conf
> 4. echo "DEBUG_BUILD='1'" >> conf/local.conf
> 5. bitbake lttng-ust
> compile failed with error:
>| /work/cortexa15t2hf-neon-poky-linux-gnueabi/lttng-ust/2_2.13.0-r0/recipe-sysroot-native/usr/bin/arm-poky-linux-gnueabi/../../libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/11.2.0/ld:
>| ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to
> | `_uatomic_link_error'
> | collect2: error: ld returned 1 exit status
> | Makefile:399: recipe for target 'test_ust_error' failed
> checked with "nm ../../../src/lib/lttng-ust/.libs/liblttng-ust.so" | grep
> atomic, we can see 'U _uatomic_link_error', but since -Og
> is used, liburcu don't define this function.
> [snip]
> #if !defined __OPTIMIZE__ || defined UATOMIC_NO_LINK_ERROR
> static inline __attribute__((always_inline, noreturn))
> void _uatomic_link_error(void)
> {
> #ifdef ILLEGAL_INSTR
> /*
> * generate an illegal instruction. Cannot catch this with
> * linker tricks when optimizations are disabled.
> */
> __asm__ __volatile__(ILLEGAL_INSTR);
> #else
> __builtin_trap();
> #endif
> }
> #else /* #if !defined __OPTIMIZE__ || defined UATOMIC_NO_LINK_ERROR */
> extern void _uatomic_link_error(void);
> #endif /* #else #if !defined __OPTIMIZE__ || defined UATOMIC_NO_LINK_ERROR */
> [snip]
> we cannot see 'U _uatomic_link_error' in following conditions, so compile
> successed:
> 1. without -Og(using -O2), + 32bit arm
> 2. -Og + 64bit arm
> 3. -Og + x86/x86-64
> Do you have any idea about how to fix this? I don't understand why only "-Og +
> 32bit arm" will call function _uatomic_link_error.
I suspect it depends on which optimizations are being enabled at -Og on each architecture.
The "_uatomic_link_error()" trick indeed depends on the compiler optimizing away
unreachable calls.
If you really intend on using "-Og" on arm32, trying building with "-DUATOMIC_NO_LINK_ERROR".
It should take care of making sure to generate an illegal instruction rather than rely on the linker
error.
Thanks,
Mathieu
> Thanks
> //Changqing
> _______________________________________________
> lttng-dev mailing list
> lttng-dev@lists.lttng.org
> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [lttng-dev] with -Og option, lttng-ust compile failed on 32bit arm
2021-09-30 13:14 ` Mathieu Desnoyers via lttng-dev
@ 2021-10-08 8:12 ` Changqing Li via lttng-dev
0 siblings, 0 replies; 3+ messages in thread
From: Changqing Li via lttng-dev @ 2021-10-08 8:12 UTC (permalink / raw)
To: Mathieu Desnoyers; +Cc: lttng-dev
[-- Attachment #1.1: Type: text/plain, Size: 3966 bytes --]
On 9/30/21 9:14 PM, Mathieu Desnoyers wrote:
>
> **[Please note: This e-mail is from an EXTERNAL e-mail address]
>
> ----- On Sep 29, 2021, at 11:47 PM, lttng-dev
> <lttng-dev@lists.lttng.org> wrote:
>
> Hi,
>
> The problem happened after upgrade to lttng-ust 2.13.0. 2.12.0
> don't have this issue.
>
> liburcu version: 0.13.0
>
> gcc: 11.2.0
>
> This is my reproduce steps, it is cross compile enviroment based
> on yocto project.
>
> 1. git clone git://git.yoctoproject.org/poky
> 2. . oe-init-build-env
> 3. echo "MACHINE='qemuarm'" >> conf/local.conf
> 4. echo "DEBUG_BUILD='1'" >> conf/local.conf
> 5. bitbake lttng-ust
>
> compile failed with error:
>
> |
> /work/cortexa15t2hf-neon-poky-linux-gnueabi/lttng-ust/2_2.13.0-r0/recipe-sysroot-native/usr/bin/arm-poky-linux-gnueabi/../../libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/11.2.0/ld:
> ../../../src/lib/lttng-ust/.libs/liblttng-ust.so
> <https://urldefense.com/v3/__http://liblttng-ust.so__;!!AjveYdw8EvQ!LLTouw-mBEBAY8hObF75ydNA3D3KMc0Hla12A4D4cQ-hm-F5lidnggb4zDVbAwolB77-gw$>:
> undefined reference to `_uatomic_link_error'
> | collect2: error: ld returned 1 exit status
> | Makefile:399: recipe for target 'test_ust_error' failed
>
> checked with "nm ../../../src/lib/lttng-ust/.libs/liblttng-ust.so
> <https://urldefense.com/v3/__http://liblttng-ust.so__;!!AjveYdw8EvQ!LLTouw-mBEBAY8hObF75ydNA3D3KMc0Hla12A4D4cQ-hm-F5lidnggb4zDVbAwolB77-gw$>"
> | grep atomic, we can see 'U _uatomic_link_error', but since -Og
>
> is used, liburcu don't define this function.
>
> [snip]
> #if !defined __OPTIMIZE__ || defined UATOMIC_NO_LINK_ERROR
> static inline __attribute__((always_inline, noreturn))
> void _uatomic_link_error(void)
> {
> #ifdef ILLEGAL_INSTR
> /*
> * generate an illegal instruction. Cannot catch this with
> * linker tricks when optimizations are disabled.
> */
> __asm__ __volatile__(ILLEGAL_INSTR);
> #else
> __builtin_trap();
> #endif
> }
> #else /* #if !defined __OPTIMIZE__ || defined
> UATOMIC_NO_LINK_ERROR */
> extern void _uatomic_link_error(void);
> #endif /* #else #if !defined __OPTIMIZE__ || defined
> UATOMIC_NO_LINK_ERROR */
>
> [snip]
>
> we cannot see 'U _uatomic_link_error' in following conditions, so
> compile successed:
>
> 1. without -Og(using -O2), + 32bit arm
>
> 2. -Og + 64bit arm
>
> 3. -Og + x86/x86-64
>
>
> Do you have any idea about how to fix this? I don't understand why
> only "-Og + 32bit arm" will call function _uatomic_link_error.
>
>
> I suspect it depends on which optimizations are being enabled at -Og
> on each architecture.
> The "_uatomic_link_error()" trick indeed depends on the compiler
> optimizing away
> unreachable calls.
>
> If you really intend on using "-Og" on arm32, trying building with
> "-DUATOMIC_NO_LINK_ERROR".
> It should take care of making sure to generate an illegal instruction
> rather than rely on the linker
> error.
>
> Thanks,
>
> Mathieu
Thanks. I have tried with "-DUATOMIC_NO_LINK_ERROR". With this, it
can compile successfully.
Changqing
>
> Thanks
>
> //Changqing
>
>
> _______________________________________________
> lttng-dev mailing list
> lttng-dev@lists.lttng.org
> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> <https://urldefense.com/v3/__https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev__;!!AjveYdw8EvQ!LLTouw-mBEBAY8hObF75ydNA3D3KMc0Hla12A4D4cQ-hm-F5lidnggb4zDVbAwqteQD9FQ$>
>
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
> <https://urldefense.com/v3/__http://www.efficios.com__;!!AjveYdw8EvQ!LLTouw-mBEBAY8hObF75ydNA3D3KMc0Hla12A4D4cQ-hm-F5lidnggb4zDVbAwo9O85jiQ$>
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2021-09-30 3:47 [lttng-dev] with -Og option, lttng-ust compile failed on 32bit arm Changqing Li via lttng-dev
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2021-10-08 8:12 ` Changqing Li via lttng-dev
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