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Re: [PATCH] Reorganize rs6000_rtx_costs
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: Roger Sayle <roger at eyesopen dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Thu, 01 Jul 2004 22:20:04 -0400
- Subject: Re: [PATCH] Reorganize rs6000_rtx_costs
- References: <Pine.LNX.4.44.0407010948400.2046-100000@www.eyesopen.com>
>>>>> Roger Sayle writes:
> There should be no functional/parameter differences with this patch
> other than to report the size of multiplication and and division
> operations as a single instruction when optimizing for size. A
> minor difference to the x86 backend is that I introduce two "size"
> tables, one for 32bit code and the other for 64bit code, selected
> using TARGET_POWERPC64. This will allow us to record the fact that
> a 64-bit multiplication is significantly shorter on processors
> when compiling for a 64-bit CPU, than it is for a 32-bit CPU.
Do you mean that the table already records this information, or
that it can record the information? size32_cost and size64_cost both
uniformly contain the value 1, so I do not see how this provides any
distinction.
Also, the original code returned COSTS_N_INSNS(2), not
COSTS_N_INSNS(1), for optimize_size. Any reason for the change?
David