[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 Andrew Pinski changed: What|Removed |Added Target Milestone|10.2|11.0
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 --- Comment #1 from acsawdey at gcc dot gnu.org --- Created attachment 49123 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49123&action=edit hashtab.c with target power9 attribute on htab_delete()
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 --- Comment #2 from acsawdey at gcc dot gnu.org --- I'm seeing some load-past-store code motion that happens when compiling for power10 vs power9 that makes me suspicious.
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 --- Comment #3 from acsawdey at gcc dot gnu.org --- Never mind that, all I'm seeing is the lack of save/restore of r2 in the power10 version.
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 David Edelsohn changed: What|Removed |Added Last reconfirmed||2020-08-26 Target Milestone|--- |10.2 CC||bergner at gcc dot gnu.org Ever confirmed|0 |1 Status|UNCONFIRMED |NEW --- Comment #4 from David Edelsohn --- Confirmed.
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 --- Comment #5 from Bill Schmidt --- The divergence occurs after .L75 in the two versions. In the P10 version, we see that the second bctrl has been converted into a bctr. It looks like a tail call optimization happening, but we aren't at the end of the function. This happens again later for the second bctrl after .L78. Why would we think a tail call optimization can happen in the middle of a block...
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 Bill Schmidt changed: What|Removed |Added CC||amodra at gcc dot gnu.org --- Comment #6 from Bill Schmidt --- Ah, I can't read. These really are at the end(s) of the function, so it does appear to be a tail call optimization that we've decided is legitimate. It looks like the problem is that we don't set up r12 prior to the tail call. Unlike the usual case, here we have "mtctr 9" to set up the CTR and r12 still points to the previously called function. That can't be good. This is exposed by my recent patch to allow more tail calls in rs6000_decl_ok_for_sibcall, but it's not clear to me where we need to fix things up so that r12 gets set.
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 --- Comment #7 from Bill Schmidt --- I believe the problem may be that rs6000_sibcall_aix doesn't contain any handling for indirect calls, whereas similar code for other ABIs, like rs6000_sibcall_sysv, does. Alan, does this make sense?
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 --- Comment #8 from Bill Schmidt --- I'm working on a patch.
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 --- Comment #9 from CVS Commits --- The master branch has been updated by William Schmidt : https://gcc.gnu.org/g:abca87c57847cd04f5e05935ff9ae5121c1ecb1d commit r11-2908-gabca87c57847cd04f5e05935ff9ae5121c1ecb1d Author: Bill Schmidt Date: Thu Aug 27 11:17:06 2020 -0500 rs6000: Support ELFv2 sibcall for indirect calls [PR96787] Prior to P10, ELFv2 hasn't implemented nonlocal sibcalls. Now that we do, we need to be sure that r12 is set up prior to such a call. 2020-08-27 Bill Schmidt gcc/ PR target/96787 * config/rs6000/rs6000.c (rs6000_sibcall_aix): Support indirect call for ELFv2. gcc/testsuite/ PR target/96787 * gcc.target/powerpc/pr96787-1.c: New. * gcc.target/powerpc/pr96787-2.c: New.
[Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787 Bill Schmidt changed: What|Removed |Added Status|NEW |RESOLVED Resolution|--- |FIXED --- Comment #10 from Bill Schmidt --- Work is complete.
