http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58253
--- Comment #1 from Martin Jambor <jamborm at gcc dot gnu.org> ---
I do not quite understand why the port needs to look at alignments of
scalars passed by value at all but I assume there is a reason.
When it comes to the IPA-SRA created formal parameter and actual
argument in the pr52402.c testcase, the following happens. The
decision in which register pair the parameter is passed is made in
epiphany_function_arg_boundary. This is reached in two different
ways:
1. When compiling foo.isra.0, indirectly from call to
targetm.calls.function_incoming_arg at function.c:2440. The type
is the type of the PARM_DECL which is aligned to 8 bits.
2. When expanding the call in main, indirectly from call to
targetm.calls.function_arg. The type passed is the type of the
actual argument, which is an anonymous SSA name which has the
natural alignment of the node which is 64.
Thus, epiphany_function_arg_boundary erroneously comes to two
different conclusions. Assuming there is nothing wrong with the
above, we can fix the problem in IPA-SRA by the patch below which sets
the type of the PARM_DECL to natural mode alignment (bootstrapped and
tested and tested on x86_64-linux, the same on ppc64 is underway).
But again, I am not really sure what the semantics of alignment of
scalar PARM_DECL is. Nevertheless, can you please check if the patch
indeed fixes the bug? If so, I'll post it to the mailing list for
review/further discussion. Thanks.
2013-11-28 Martin Jambor <mjam...@suse.cz>
PR ipa/58253
* ipa-prop.c (ipa_modify_formal_parameters): Create decls of
non-BLKmode in their naturally aligned type.
diff --git a/gcc/ipa-prop.c b/gcc/ipa-prop.c
index 6bdb0df..a26b11a 100644
--- a/gcc/ipa-prop.c
+++ b/gcc/ipa-prop.c
@@ -3443,7 +3443,15 @@ ipa_modify_formal_parameters (tree fndecl,
ipa_parm_adjustment_vec adjustments)
if (adj->by_ref)
ptype = build_pointer_type (adj->type);
else
- ptype = adj->type;
+ {
+ ptype = adj->type;
+ if (TYPE_MODE (ptype) != BLKmode)
+ {
+ unsigned malign = GET_MODE_ALIGNMENT (TYPE_MODE (ptype));
+ if (TYPE_ALIGN (ptype) < malign)
+ ptype = build_aligned_type (ptype, malign);
+ }
+ }
if (care_for_types)
new_arg_types = tree_cons (NULL_TREE, ptype, new_arg_types);
