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Re: RFA: Fix rtl-optimization/22258
- From: Bernd Schmidt <bernds_cb1 at t-online dot de>
- To: Joern RENNECKE <joern dot rennecke at st dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Thu, 30 Jun 2005 21:47:39 +0200
- Subject: Re: RFA: Fix rtl-optimization/22258
- References: <42C44729.1070207@st.com>
Joern RENNECKE wrote:
The problem in rtl-optimization/22258 is that we combine an instruction
that
requires a spill into a return value copy to a likely spilled register.
If any part of the return value is live during i1, i2 and/or i3, it will be
live in i3. It is therefore sufficient to check liveness for i3.
For a value that can be held in a single machine mode, a HARD_REG_SET
would be overkill, so I use a bitmask in a single int, which the GNU coding
standard says can be assumed to contain at least 32 bits on any of our host
platforms.
Example? Why isn't this caught by cant_combine_insn_p?
Bernd