[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 Aldy Hernandez changed: What|Removed |Added Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #10 from Aldy Hernandez --- (In reply to Jeffrey A. Law from comment #8) > I still don't understand why propagating one SSA_NAME for another is causing > headaches later though. TBH, I don't either. When I compile the .c test in this PR with the following options: -O2 -fno-tree-scev-cprop -fdisable-tree-ccp1 -fdisable-tree-ccp2 -fdisable-tree-copyprop1 -fdisable-tree-evrp -fdisable-tree-vrp1 -fdisable-tree-ccp1 -fdisable-tree-ccp2 -fdisable-tree-ccp3 ...I still get an ICE, but there is no change in the IL between trunk without the offending patch, and with the patch that broke the test. This would indicate that there is some on-the-side structure that is being altered by the phi argument propagation. I did notice that the IL *does* change in the middle of one of the copyprop (or ccp?) passes, but it gets cleaned up to whatever was there before. Later in SCEV, we ICE while trying to look at the SSA_NAME_DEF_STMT of an SSA which no longer exists in the IL. This happens in chrec_contains_symbols_defined_in_loop(). A wild guess is that the loop info is getting mucked up somehow. I can investigate more deeply if desired, but since this was a silly typo, I'm gonna leave it alone for now. Closing as fixed in mainline.
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 --- Comment #9 from CVS Commits --- The master branch has been updated by Aldy Hernandez : https://gcc.gnu.org/g:8fb4d1d58362b77da78c09740c6b5562124a369e commit r11-1395-g8fb4d1d58362b77da78c09740c6b5562124a369e Author: Aldy Hernandez Date: Tue Jun 16 13:43:57 2020 +0200 Fix pasto in the substitute_and_fold_engine merge with evrp. The original code only propagated into PHI arguments if the value was a constant. This behavior was lost in the conversion, allowing any value (SSAs for instance) to be propagated into PHIs. gcc/ChangeLog: PR tree-optimization/95649 * tree-ssa-propagate.c (propagate_into_phi_args): Do not propagate unless value is a constant. gcc/testsuite/ChangeLog: * g++.dg/tree-ssa/pr95649.C: New test. * gcc.dg/tree-ssa/pr95649.c: New test.
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 --- Comment #8 from Jeffrey A. Law --- I still don't understand why propagating one SSA_NAME for another is causing headaches later though. I don't see anything fundamentally wrong with your patch and it restores previous behavior since singleton_p would only be true for a constant, so consider it pre-approved.
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 --- Comment #7 from Aldy Hernandez --- Hmmm, previous code propagating into PHI args had: - if (vr->singleton_p () && may_propagate_copy (arg, val)) - propagate_value (use_p, val); We seem to have lost the check for constants, and we're now propagating any old value from get_value_range-- which may be another SSA name: + if (val && may_propagate_copy (arg, val)) + propagate_value (use_p, val); Testing the following: diff --git a/gcc/tree-ssa-propagate.c b/gcc/tree-ssa-propagate.c index 4fda296ef9e..01ee7fd33eb 100644 --- a/gcc/tree-ssa-propagate.c +++ b/gcc/tree-ssa-propagate.c @@ -1035,7 +1035,8 @@ substitute_and_fold_engine::propagate_into_phi_args (basic_block bb) || virtual_operand_p (arg)) continue; tree val = get_value (arg, phi); - if (val && may_propagate_copy (arg, val)) + if (val && is_gimple_min_invariant (val) + && may_propagate_copy (arg, val)) propagate_value (use_p, val); } }
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 Jeffrey A. Law changed: What|Removed |Added CC||law at redhat dot com --- Comment #6 from Jeffrey A. Law --- What precisely is causing the problem? Are we doing something like mucking up the loop closed ssa form? Or do these passes have internal data that's invalidated by the PHI changes? Or something else? Hard to know what to recommend here without more info.
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 Aldy Hernandez changed: What|Removed |Added CC||law at gcc dot gnu.org --- Comment #5 from Aldy Hernandez --- The problem here is that the code in propagate_into_phi_args() was previously in evrp but is now in the engine itself and affecting all clients. CCP and copyprop are two of these clients. The subst & fold engine is changing the CFG (phis in this case) and neither pass is expecting it. A hack showing that it's the PHI propagation is attached below. We could make these passes clean-up the CFG for example, but that may be heavy handed if they're supposed to be lightweight ??. Instead we could either move propagate_into_phi_args back into evrp, or only run it if a CHANGE_CFG_FLAG or somesuch is passed to the engine constructor. I'll work on a patch. - NOT A FIX: diff --git a/gcc/tree-ssa-propagate.c b/gcc/tree-ssa-propagate.c index 4fda296ef9e..249867d8633 100644 --- a/gcc/tree-ssa-propagate.c +++ b/gcc/tree-ssa-propagate.c @@ -1228,7 +1228,7 @@ substitute_and_fold_dom_walker::before_dom_children (basic_block bb) } } - substitute_and_fold_engine->propagate_into_phi_args (bb); + //substitute_and_fold_engine->propagate_into_phi_args (bb); return NULL; }
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 Aldy Hernandez changed: What|Removed |Added CC||zsojka at seznam dot cz --- Comment #4 from Aldy Hernandez --- *** Bug 95653 has been marked as a duplicate of this bug. ***
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649
Aldy Hernandez changed:
What|Removed |Added
Assignee|unassigned at gcc dot gnu.org |aldyh at gcc dot gnu.org
--- Comment #2 from Aldy Hernandez ---
Here is another testcase pulled from pr95653 which I'm marking as a duplicate
of this one.
This one needs -O2 -fno-tree-scev-cprop to reproduce.
char b (void);
char *d;
int e;
int f;
void
g (char *h)
{
while (d)
{
long i = b ();
if (h + i > d)
break;
if (f > 0 || e)
do
*h++ = *h;
while (--i);
}
}
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 Aldy Hernandez changed: What|Removed |Added Status|NEW |ASSIGNED --- Comment #3 from Aldy Hernandez --- Mine.
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 Bill Seurer changed: What|Removed |Added CC||seurer at linux dot vnet.ibm.com --- Comment #1 from Bill Seurer --- I am seeing something slightly different that started with the same revision on powerpc64 as well. It is preventing several of the spec2006 tests from compiling. See pr95662.
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 Richard Biener changed: What|Removed |Added Target Milestone|--- |11.0 Priority|P3 |P1
[Bug tree-optimization/95649] [11 Regression] ICE during GIMPLE pass: cunroll since r11-1146-g1396fa5b91cfa0b3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95649 Martin Liška changed: What|Removed |Added Ever confirmed|0 |1 Known to fail||11.0 CC||aldyh at gcc dot gnu.org, ||marxin at gcc dot gnu.org Summary|ICE during GIMPLE pass: |[11 Regression] ICE during |cunroll |GIMPLE pass: cunroll since ||r11-1146-g1396fa5b91cfa0b3 Known to work||10.1.0 Last reconfirmed||2020-06-12 Status|UNCONFIRMED |NEW
