[Bug target/20094] gcc.dg/transparent-union-* fail on ia64-hpux

["wilson at specifixinc dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From wilson at specifixinc dot com  2005-02-19 23:15 -------
Subject: Re:  gcc.dg/transparent-union-* fail on ia64-hpux

pinskia at gcc dot gnu dot org wrote:
> ------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-19 21:24 -------
> Hmm, Does anyone know how these union are supposed to be passed on ia64-*-hpux, if by referrence 
> then the warning is correct and the testcase should not be tested on this target.  This is an ABI Issue.

unions get passed right-aligned little-endian and left-aligned 
big-endian.  Since linux is little-endian, and HPUX is big-endian, only 
HPUX has a problem here.  HPUX defines MEMBER_TYPE_FORCES_BLK to make 
this work.  There are other ways to solve this problem used by other 
targets, for instance, defining BLOCK_REG_PADDING for HPUX.  Getting 
BLOCK_REG_PADDING to work can be tricky though.

It looks like the ia64/hpux.h is the only one that defines 
MEMBER_TYPE_FORCES_BLK that can trigger this problem, since the others 
don't trigger on pointer or integer types.

It appears that MEMBER_TYPE_FORCES_BLK should not be used for a 
transparent union, or should be used differently.  This check could 
perhaps be done unconditionally in stor-layout.c.  This might be a 
simple solution.

Or maybe we can pass the union/structure type to MEMBER_TYPE_FORCES_BLK 
and modify the ia64/hpux.h version of the macro to check for the 
transparent_union attribute.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20094