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Re: some seemingly redundant register uses in nios gcc compiled assembly code
- From: Ian Lance Taylor <ian at airs dot com>
- To: Liu Haibin <liu dot haibin at gmail dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: 06 Sep 2005 21:42:13 -0700
- Subject: Re: some seemingly redundant register uses in nios gcc compiled assembly code
- References: <e538aa3e05090621357d21694b@mail.gmail.com>
Liu Haibin <liu.haibin@gmail.com> writes:
> Does the following rtl implicitly indicate that r5 is used?
>
> (expr_list (use (reg:DF 6 r6))
> (expr_list (use (reg:DF 4 r4))
If DFmode requires two registers on your machine--which does appear to
be the case based on the assembly code which you showed--then (use
(reg:DF 4 r4)) does indeed indicate a case of r5. It indicates a use
of all registers from 4 up to but not including register number
4 + HARD_REGNO_NREGS (4, DFmode)
Ian