Re: [libatomic PATCH] Fix testsuite regressions on ARM [raspberry pi].
On 1/11/24 15:55, Roger Sayle wrote: Hi Richard, As you've recommended, this issue has now been filed in bugzilla as PR other/113336. As explained in the new PR, libatomic's testsuite used to pass on armv6 (raspberry pi) in previous GCC releases, but the code was incorrect/non-synchronous; this was reported as PR target/107567 and PR target/109166. Now that those issues have been fixed, we now see that there's a missing dependency in libatomic that's required to implement this functionality correctly. I'm more convinced that my fix is correct, but it's perhaps a little disappointing that libatomic doesn't have a (multi-threaded) run-time test to search for race conditions, and confirm its implementations are correctly serializing. Please let me know what you think. Best regards, Roger -- I do think that if the regression is caused by HAVE_ATOMIC_TAS now being detected as false due to a bugfix elsewhere as you kindly pointed out, then the fix perhaps ought to change the compile-time behavior for TAS alone. As I point out in Bugzilla, we can get away with replacing the proposed libatomic_la_LIBADD += $(addsuffix _1_2_.lo,$(SIZEOBJS)) with libatomic_la_LIBADD += tas_1_2_.lo so that we generate the missing `libat_test_and_set_1_i2' specifically. I've not manage to detect the need for any other *_1_i2 thus far and this alone appears sufficient to fix all observed regressions. Happy to investigate further, but my initial findings seem to be that this may be a better fix. Let me know if you disagree ;). Regards, Victor -Original Message- From: Richard Earnshaw Sent: 10 January 2024 15:34 To: Roger Sayle ; gcc-patches@gcc.gnu.org Subject: Re: [libatomic PATCH] Fix testsuite regressions on ARM [raspberry pi]. On 08/01/2024 16:07, Roger Sayle wrote: Bootstrapping GCC on arm-linux-gnueabihf with --with-arch=armv6 currently has a large number of FAILs in libatomic (regressions since last time I attempted this). The failure mode is related to IFUNC handling with the file tas_8_2_.o containing an unresolved reference to the function libat_test_and_set_1_i2. Bearing in mind I've no idea what's going on, the following one line change, to build tas_1_2_.o when building tas_8_2_.o, resolves the problem for me and restores the libatomic testsuite to 44 expected passes and 5 unsupported tests [from 22 unexpected failures and 22 unresolved testcases]. If this looks like the correct fix, I'm not confident with rebuilding Makefile.in with correct version of automake, so I'd very much appreciate it if someone/the reviewer/mainainer could please check this in for me. Thanks in advance. 2024-01-08 Roger Sayle libatomic/ChangeLog * Makefile.am: Build tas_1_2_.o on ARCH_ARM_LINUX * Makefile.in: Regenerate. Roger -- Hi Roger, I don't really understand all this make foo :( so I'm not sure if this is the right fix either. If this is, as you say, a regression, have you been able to track down when it first started to occur? That might also help me to understand what changed to cause this. Perhaps we should have a PR for this, to make tracking the fixes easier. R.
RE: [libatomic PATCH] Fix testsuite regressions on ARM [raspberry pi].
Hi Richard, As you've recommended, this issue has now been filed in bugzilla as PR other/113336. As explained in the new PR, libatomic's testsuite used to pass on armv6 (raspberry pi) in previous GCC releases, but the code was incorrect/non-synchronous; this was reported as PR target/107567 and PR target/109166. Now that those issues have been fixed, we now see that there's a missing dependency in libatomic that's required to implement this functionality correctly. I'm more convinced that my fix is correct, but it's perhaps a little disappointing that libatomic doesn't have a (multi-threaded) run-time test to search for race conditions, and confirm its implementations are correctly serializing. Please let me know what you think. Best regards, Roger -- > -Original Message- > From: Richard Earnshaw > Sent: 10 January 2024 15:34 > To: Roger Sayle ; gcc-patches@gcc.gnu.org > Subject: Re: [libatomic PATCH] Fix testsuite regressions on ARM [raspberry > pi]. > > > > On 08/01/2024 16:07, Roger Sayle wrote: > > > > Bootstrapping GCC on arm-linux-gnueabihf with --with-arch=armv6 > > currently has a large number of FAILs in libatomic (regressions since > > last time I attempted this). The failure mode is related to IFUNC > > handling with the file tas_8_2_.o containing an unresolved reference > > to the function libat_test_and_set_1_i2. > > > > Bearing in mind I've no idea what's going on, the following one line > > change, to build tas_1_2_.o when building tas_8_2_.o, resolves the > > problem for me and restores the libatomic testsuite to 44 expected > > passes and 5 unsupported tests [from 22 unexpected failures and 22 > > unresolved > testcases]. > > > > If this looks like the correct fix, I'm not confident with rebuilding > > Makefile.in with correct version of automake, so I'd very much > > appreciate it if someone/the reviewer/mainainer could please check this in > > for > me. > > Thanks in advance. > > > > > > 2024-01-08 Roger Sayle > > > > libatomic/ChangeLog > > * Makefile.am: Build tas_1_2_.o on ARCH_ARM_LINUX > > * Makefile.in: Regenerate. > > > > > > Roger > > -- > > > > Hi Roger, > > I don't really understand all this make foo :( so I'm not sure if this is the > right fix > either. If this is, as you say, a regression, have you been able to track > down when > it first started to occur? That might also help me to understand what > changed to > cause this. > > Perhaps we should have a PR for this, to make tracking the fixes easier. > > R.
Re: [libatomic PATCH] Fix testsuite regressions on ARM [raspberry pi].
On 08/01/2024 16:07, Roger Sayle wrote: Bootstrapping GCC on arm-linux-gnueabihf with --with-arch=armv6 currently has a large number of FAILs in libatomic (regressions since last time I attempted this). The failure mode is related to IFUNC handling with the file tas_8_2_.o containing an unresolved reference to the function libat_test_and_set_1_i2. Bearing in mind I've no idea what's going on, the following one line change, to build tas_1_2_.o when building tas_8_2_.o, resolves the problem for me and restores the libatomic testsuite to 44 expected passes and 5 unsupported tests [from 22 unexpected failures and 22 unresolved testcases]. If this looks like the correct fix, I'm not confident with rebuilding Makefile.in with correct version of automake, so I'd very much appreciate it if someone/the reviewer/mainainer could please check this in for me. Thanks in advance. 2024-01-08 Roger Sayle libatomic/ChangeLog * Makefile.am: Build tas_1_2_.o on ARCH_ARM_LINUX * Makefile.in: Regenerate. Roger -- Hi Roger, I don't really understand all this make foo :( so I'm not sure if this is the right fix either. If this is, as you say, a regression, have you been able to track down when it first started to occur? That might also help me to understand what changed to cause this. Perhaps we should have a PR for this, to make tracking the fixes easier. R.
