[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 Richard Biener changed: What|Removed |Added CC||hubicka at gcc dot gnu.org Target Milestone|--- |10.0
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 Martin Liška changed: What|Removed |Added Status|UNCONFIRMED |ASSIGNED Last reconfirmed||2020-01-28 CC||marxin at gcc dot gnu.org Assignee|unassigned at gcc dot gnu.org |hubicka at gcc dot gnu.org Ever confirmed|0 |1
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 Richard Biener changed: What|Removed |Added Priority|P3 |P1
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 Martin Liška changed: What|Removed |Added Status|ASSIGNED|WAITING CC||marxin at gcc dot gnu.org --- Comment #1 from Martin Liška --- I've just run the test-case on aarch64 and it works fine (-O2, -O2 -flto, -O3 -flto -fno-early-inlining). And lto.exp testsuite works fine on aarch64. @Wilco: Can you please double-check?
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 Wilco changed: What|Removed |Added CC||wdijkstr at arm dot com --- Comment #2 from Wilco --- (In reply to Martin Liška from comment #1) > I've just run the test-case on aarch64 and it works fine (-O2, -O2 -flto, > -O3 -flto -fno-early-inlining). And lto.exp testsuite works fine on aarch64. > @Wilco: Can you please double-check? Yes it now works on AArch64, but I still see failures on Arm.
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 --- Comment #3 from Martin Liška --- (In reply to Wilco from comment #2) > (In reply to Martin Liška from comment #1) > > I've just run the test-case on aarch64 and it works fine (-O2, -O2 -flto, > > -O3 -flto -fno-early-inlining). And lto.exp testsuite works fine on aarch64. > > @Wilco: Can you please double-check? > > Yes it now works on AArch64, but I still see failures on Arm. Can you please analyze (or bisect that) what happens?
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 Martin Liška changed: What|Removed |Added CC||avieira at gcc dot gnu.org, ||clyon at gcc dot gnu.org --- Comment #4 from Martin Liška --- I'm adding ARM guys, I hope they can try to reproduce that.
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 --- Comment #5 from Christophe Lyon --- Created attachment 48183 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48183&action=edit executable asm from objdump
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 --- Comment #6 from Christophe Lyon --- Created attachment 48184 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48184&action=edit GCC passes dumps
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 --- Comment #7 from Christophe Lyon --- Created attachment 48185 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48185&action=edit qemu execution trace
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 --- Comment #8 from Jan Hubicka --- Do we have compile farm machine where this can be reproduced?
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 --- Comment #9 from Martin Liška --- (In reply to Jan Hubicka from comment #8) > Do we have compile farm machine where this can be reproduced? I guess we don't have any.
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 --- Comment #10 from Wilco --- (In reply to Christophe Lyon from comment #6) > Created attachment 48184 [details] > GCC passes dumps So according to that, in 105t.vrp1 it removes the branch and unconditionally calls abort: Folding statement: _4 = _3 == 0B; Matching expression match.pd:1737, gimple-match.c:708 Matching expression match.pd:1740, gimple-match.c:772 Matching expression match.pd:1747, gimple-match.c:826 Not folded Folding statement: if (_5 == 0) gimple_simplified to if (1 != 0) Folded into: if (1 != 0) Folding statement: return; Not folded Folding statement: __builtin_abort (); Not folded Removing dead stmt _5 = __builtin_constant_p (_4); It doesn't make sense, these are the VRP ranges: _1: short int * * VARYING _2: short int * * VARYING _3: short int * VARYING _4: bool VARYING _5: int [0, 0] _10: struct a * VARYING So somehow it decides that __builtin_constant_p (VARYING) == [0,0]???
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322
--- Comment #11 from Jan Hubicka ---
The problem is that on ARM sizeof (short) == sizeof (int)
and LTO will glob all short and int pointers together. So this is missed
optimization only.
We do this globing sort of by design. For GCC11 I plan to refine type merging
again a bit but until then we could either xfail this testcase or change int to
long which is 4 bytes.
Not a release blocker though.
I would welcome if someone could test the testcase adjustment (I was doing LTO
by hand)
diff --git a/gcc/testsuite/g++.dg/lto/alias-4_0.C
b/gcc/testsuite/g++.dg/lto/alias-4_0.C
index 410c3140baf..0ab12adef5b 100644
--- a/gcc/testsuite/g++.dg/lto/alias-4_0.C
+++ b/gcc/testsuite/g++.dg/lto/alias-4_0.C
@@ -5,7 +5,7 @@ short *ptr_init, **ptr=&ptr_init;
__attribute__ ((used))
struct a {
- int *aptr;
+ long *aptr;
} a, *aptr=&a;
void
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 Jakub Jelinek changed: What|Removed |Added CC||jakub at gcc dot gnu.org --- Comment #12 from Jakub Jelinek --- Which ARM target has 16-bit int? I don't see INT_TYPE_SIZE nor SHORT_TYPE_SIZE defined in config/arm/*, neither BITS_PER_WORD, so all depends on UNITS_PER_WORD, which is 4 and thus short is 16-bit and int is 32-bit.
[Bug tree-optimization/91322] [10 regression] alias-4 test failure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91322 --- Comment #13 from Jan Hubicka --- > Which ARM target has 16-bit int? > I don't see INT_TYPE_SIZE nor SHORT_TYPE_SIZE defined in config/arm/*, neither > BITS_PER_WORD, so all depends on UNITS_PER_WORD, which is 4 and thus short is > 16-bit and int is 32-bit. Hmm, you are right - I messed up target triplets. With arm-linux-gnueabi I see 4 byte int and the testcase calls abort. However it is still missed optimization. I will check why we end up with different code than x86 LTO. Honza
Re: [Bug tree-optimization/91322] [10 regression] alias-4 test failure
> Which ARM target has 16-bit int? > I don't see INT_TYPE_SIZE nor SHORT_TYPE_SIZE defined in config/arm/*, neither > BITS_PER_WORD, so all depends on UNITS_PER_WORD, which is 4 and thus short is > 16-bit and int is 32-bit. Hmm, you are right - I messed up target triplets. With arm-linux-gnueabi I see 4 byte int and the testcase calls abort. However it is still missed optimization. I will check why we end up with different code than x86 LTO. Honza
