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From: "iains at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/110044] [10, 11, 12, 13, 14 Regression] #pragma
 pack(push, 1) may not force packing, while __attribute__((packed,
 aligned(1))) works
Date: Wed, 31 May 2023 13:34:25 +0000
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X-Bugzilla-Component: target
X-Bugzilla-Version: 12.2.0
X-Bugzilla-Keywords: ABI, wrong-code
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110044

--- Comment #6 from Iain Sandoe <iains at gcc dot gnu.org> ---
I'm going to test the following (which will take some time since the hardwa=
re
is needed for testing releases too).

The test for AGGREGATE_TYPE_P() could actually be changed to
RECORD_OR_UNION_TYPE_P () - since the case that we might have an array is
handled for non-empty structs (but we do need to guard the empty struct cas=
e).=20
The problem seems to be we were ignoring that the field type could be packe=
d or
that there was a cap on the max alignment.

If it works as expected then I will apply to the open branches (hopefully
before 10.5 is spun).

----

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 5b3b8b52e7e..e1c038da305 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -8209,7 +8209,8 @@ darwin_rs6000_special_round_type_align (tree type,
unsigned int computed,
       type =3D TREE_TYPE (type);
   } while (AGGREGATE_TYPE_P (type));

-  if (! AGGREGATE_TYPE_P (type) && type !=3D error_mark_node)
+  if (type !=3D error_mark_node && ! AGGREGATE_TYPE_P (type)
+      ! TYPE_PACKED(type) && maximum_field_alignment =3D=3D 0)
     align =3D MAX (align, TYPE_ALIGN (type));

   return align;=