[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 --- Comment #17 from hubicka at kam dot mff.cuni.cz --- > Fixed (Honza, hope you don't mind the backports I've done, did that so that it > is on time for 10.4). Thanks. I don't mind: I was planning to do them this week anyway and also extra VOLATILE check shoud not be very risky.
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 Jakub Jelinek changed: What|Removed |Added Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #16 from Jakub Jelinek --- Fixed (Honza, hope you don't mind the backports I've done, did that so that it is on time for 10.4).
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 --- Comment #15 from CVS Commits --- The releases/gcc-10 branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:62148f13c6427edd256072b3196a01b3d5ed2805 commit r10-10856-g62148f13c6427edd256072b3196a01b3d5ed2805 Author: Jan Hubicka Date: Tue Jun 14 14:05:53 2022 +0200 Fix ipa-cp wrt volatile loads Check for volatile flag to ipa_load_from_parm_agg. gcc/ChangeLog: 2022-06-10 Jan Hubicka PR ipa/105739 * ipa-prop.c (ipa_load_from_parm_agg): Punt on volatile loads. gcc/testsuite/ChangeLog: 2022-06-10 Jan Hubicka * gcc.dg/ipa/pr105739.c: New test. (cherry picked from commit 8f6c317b3a16350698f3c9e0accb43a9b4acb4ae)
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 --- Comment #14 from CVS Commits --- The releases/gcc-11 branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:49aa637488053223bc04e59aac411d4a92ebcf7b commit r11-10080-g49aa637488053223bc04e59aac411d4a92ebcf7b Author: Jan Hubicka Date: Tue Jun 14 14:05:53 2022 +0200 Fix ipa-cp wrt volatile loads Check for volatile flag to ipa_load_from_parm_agg. gcc/ChangeLog: 2022-06-10 Jan Hubicka PR ipa/105739 * ipa-prop.c (ipa_load_from_parm_agg): Punt on volatile loads. gcc/testsuite/ChangeLog: 2022-06-10 Jan Hubicka * gcc.dg/ipa/pr105739.c: New test. (cherry picked from commit 8f6c317b3a16350698f3c9e0accb43a9b4acb4ae)
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 --- Comment #13 from CVS Commits --- The releases/gcc-12 branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:bf4ba940673b80961c5979078f9d37a7bef2f5ff commit r12-8493-gbf4ba940673b80961c5979078f9d37a7bef2f5ff Author: Jan Hubicka Date: Tue Jun 14 14:05:53 2022 +0200 Fix ipa-cp wrt volatile loads Check for volatile flag to ipa_load_from_parm_agg. gcc/ChangeLog: 2022-06-10 Jan Hubicka PR ipa/105739 * ipa-prop.cc (ipa_load_from_parm_agg): Punt on volatile loads. gcc/testsuite/ChangeLog: 2022-06-10 Jan Hubicka * gcc.dg/ipa/pr105739.c: New test. (cherry picked from commit 8f6c317b3a16350698f3c9e0accb43a9b4acb4ae)
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 --- Comment #12 from Jakub Jelinek --- Thanks, I have verified that on the #c0 testcase on 10 branch it makes both __builtin_unreachable calls go away.
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 --- Comment #11 from CVS Commits --- The master branch has been updated by Jan Hubicka : https://gcc.gnu.org/g:8f6c317b3a16350698f3c9e0accb43a9b4acb4ae commit r13-1089-g8f6c317b3a16350698f3c9e0accb43a9b4acb4ae Author: Jan Hubicka Date: Tue Jun 14 14:05:53 2022 +0200 Fix ipa-cp wrt volatile loads Check for volatile flag to ipa_load_from_parm_agg. gcc/ChangeLog: 2022-06-10 Jan Hubicka PR ipa/105739 * ipa-prop.cc (ipa_load_from_parm_agg): Punt on volatile loads. gcc/testsuite/ChangeLog: 2022-06-10 Jan Hubicka * gcc.dg/ipa/pr105739.c: New test.
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739
--- Comment #10 from Jan Hubicka ---
I am testing
diff --git a/gcc/ipa-prop.cc b/gcc/ipa-prop.cc
index afd9222b5a2..c037668e7d8 100644
--- a/gcc/ipa-prop.cc
+++ b/gcc/ipa-prop.cc
@@ -1112,6 +1112,10 @@ ipa_load_from_parm_agg (struct ipa_func_body_info *fbi,
if (!base)
return false;
+ /* We can not propagate across volatile loads. */
+ if (TREE_THIS_VOLATILE (op))
+return false;
+
if (DECL_P (base))
{
int index = ipa_get_param_decl_index_1 (descriptors, base);
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739
--- Comment #9 from Jan Hubicka ---
Indeed volatile checks seems to be missing across ipa-prop code. Here is
smaller testcase:
__attribute__((noinline))
static int
test2(int a)
{
if (__builtin_constant_p (a))
__builtin_abort ();
return a;
}
/*__attribute__((noinline))*/
static int
test(int *a)
{
int val = *(volatile int *)a;
if (__builtin_constant_p (val))
__builtin_abort ();
if (val)
return test2(val);
return 0;
}
int a;
int
main()
{
a = 0;
return test ();
}
is optimized to
main:
.LFB2:
.cfi_startproc
movl$0, a(%rip)
movla(%rip), %eax
xorl%eax, %eax
ret
.cfi_endproc
which I don't think is correct. The volatile load can be non-0 and thus we can
return non-0.
It does not trigger unreachable as I hoped for since vrp and fab passes seems
to jump to same conclusion as ipa-cp.
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 --- Comment #8 from Jan Hubicka --- After inlning I see: IPA function summary for rcu_tasks_trace_pertask/5350 inlinable global time: 13.535950 self size: 11 global size: 16 min size: 11 self stack: 0 global stack:0 estimated growth:5 size:8.00, time:5.807250 size:3.00, time:2.00, executed if:(not inlined) size:2.00, time:2.00, nonconst if:(op0 changed) calls: rcu_tasks_trace_pertask.part.0/5788 inlined freq:0.62 Stack frame offset 0, callee self size 0 trc_wait_for_one_reader/5799 inlined freq:0.62 Stack frame offset 0, callee self size 0 __builtin_unreachable/5800 unreachable freq:0.00 loop depth: 0 size: 0 time: 0 predicate: (false) op0 is compile time invariant op1 is compile time invariant trc_wait_for_one_reader.part.0/5784 --param max-inline-insns-auto limit reached freq:0.31 loop depth: 0 size: 3 time: 12 callee size:100 stack: 0 __builtin_expect/5421 function body not available freq:1.00 loop depth: 0 size: 0 time: 0 op1 is compile time invariant So it seems that we determine call in trc_wait_for_one_reader unreachable. It originally calls printk: IPA function summary for trc_wait_for_one_reader/5348 inlinable global time: 13.50 self size: 20 global size: 20 min size: 1 self stack: 0 global stack:0 size:1.00, time:1.00 size:3.00, time:2.00, executed if:(not inlined) size:0.50, time:0.50, executed if:(not inlined), nonconst if:(op0[ref offset: 8672] changed) && (not inlined) size:2.50, time:2.50, nonconst if:(op0[ref offset: 8672] changed) size:1.50, time:0.25, executed if:(op0[ref offset: 8672] != -1) && (not inlined) size:3.50, time:1.25, executed if:(op0[ref offset: 8672] != -1) calls: trc_wait_for_one_reader.part.0/5784 function not considered for inlining freq:0.50 loop depth: 0 size: 3 time: 12 callee size:55 stack: 0 predicate: (op0[ref offset: 8672] == -1) _printk/5452 function body not available freq:0.00 loop depth: 0 size: 5 time: 14 predicate: (op0[ref offset: 8672] != -1) op0 is compile time invariant So we somehow figure out (op0[ref offset: 8672] != -1) here: Enqueueing calls in rcu_tasks_trace_pertask.part.0/5788. Estimating body: trc_wait_for_one_reader/5348 Known to be false: not inlined, op0[ref offset: 8672] != -1, op0[ref offset: 8672] changed size:4 time:7.00 nonspec time:12.00 This seems to be based on: Jump functions: Jump functions of caller rcu_tasks_trace_pertask.part.0/5788: callsite rcu_tasks_trace_pertask.part.0/5788 -> trc_wait_for_one_reader/5348 : param 0: PASS THROUGH: 0, op nop_expr Aggregate passed by reference: offset: 8672, type: int, CONST: -1 value: 0x0, mask:
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 --- Comment #7 from hubicka at kam dot mff.cuni.cz --- > Honza, any estimate how long this could take? I'd prefer to wait with 10.4 > for > it if it isn't going to take too long. I am at a conference this week with talk at Wednesday. I will try to debug this during the event. Honza
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 --- Comment #6 from Jakub Jelinek --- Honza, any estimate how long this could take? I'd prefer to wait with 10.4 for it if it isn't going to take too long.
[Bug tree-optimization/105739] [10 Regression] Miscompilation of Linux kernel update.c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105739 Richard Biener changed: What|Removed |Added Target Milestone|9.5 |10.4 --- Comment #5 from Richard Biener --- GCC 9 branch is being closed
