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[Bug target/35657] TDmode isn't aligned at 128bit when passing to a function
- From: "ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 21 Mar 2008 20:53:45 -0000
- Subject: [Bug target/35657] TDmode isn't aligned at 128bit when passing to a function
- References: <bug-35657-682@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #1 from ubizjak at gmail dot com 2008-03-21 20:53 -------
(In reply to comment #0)
> ix86_function_arg_boundary returns PARM_BOUNDARY for TDmode
> for ia32. Should it return 128bit? The psABI isn't clear on
> it. I think it should be aligned at 128bit.
Yes, because it is moved to/from XMM registers. Currently, this exact problem
is handled by a specialization code in ix86_expand_vector_move that forces
unaligned instructions for TDmode memory moves via
ix86_expand_vector_move_misalign.
Please note that we have to be compatible with SSE x86 and non-SSE x86 code, so
TDmode can't be passed in XMM registers on x86_32 targets.
I'd wait for psABI to clear situation w.r.t to alignment first.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35657