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Re: [PATCH] SPARC psABI fix, callee returns struct checking.
- From: "David S. Miller" <davem at davemloft dot net>
- To: carlos at codesourcery dot com
- Cc: gcc-patches at gcc dot gnu dot org, ebotcazou at libertysurf dot fr, rth at redhat dot com, davem at redhat dot com, jakub at redhat dot com
- Date: Wed, 08 Mar 2006 14:41:36 -0800 (PST)
- Subject: Re: [PATCH] SPARC psABI fix, callee returns struct checking.
- References: <20060308223803.GA11591@lios>
From: Carlos O'Donell <carlos@codesourcery.com>
Date: Wed, 8 Mar 2006 17:38:04 -0500
> GCC assumes that the caller would always allocate this save area and
> does not implement the requirements on the callee side. For the sake of
> interoperability, gcc must implement the callee side checking. GCC must
> make sure the callee looks for an unimp insn, and that the size encoded
> therein matches the size of the return. Only after the checks can the
> callee use the pointer to the save area.
Please don't enable this new check by default.
On processors having independant instruction and data TLB's (basically
all UltraSPARC chips), this is going to cause performance problems.