https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88788
prathamesh3492 at gcc dot gnu.org changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |prathamesh3492 at gcc
dot gnu.org
--- Comment #7 from prathamesh3492 at gcc dot gnu.org ---
Created attachment 45412
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45412&action=edit
Untested fix
Hi,
The issue seems to be recursively calling malloc_candidate_p_1 with duplicate
arguments, for example, with above test-case, it shows following trace:
https://pastebin.com/tF5Qg06X
We can see it is calling malloc_candidate_p_1 with resultobj_164=PHI<...>
thrice because resultobj_164 appears 3 times as a phi-arg in:
resultobj_165 = PHI <_12(12), resultobj_164(13), resultobj_164(14),
resultobj_164(15)>
I think it's more of a compile time hog rather than infinite recursion
happening. To avoid that, I simply skipped walking over duplicate args in the
phi in the attached patch:
+ bool skip_dup_arg = false;
+ for (unsigned j = i; j > 0; j--)
+ if (operand_equal_p (gimple_phi_arg_def (phi, j - 1), arg, 0))
+ {
+ skip_dup_arg = true;
+ break;
+ }
+ if (skip_dup_arg)
+ continue;
+
which appears to compile both the tests again.
I assume a phi stmt usually won't have more than 4 or 5 args, so the loop
shouldn't be too slow in practice ? I will be grateful for any other
suggestions. For the larger test-case it shows 164.08 wall seconds time for
compilation.
Thanks,
Prathamesh
