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List:       gcc
Subject:    Re: Code Motion after Machine Dependent Reorganization??
From:       "Steven Bosscher" <stevenb.gcc () gmail ! com>
Date:       2008-12-30 20:34:57
Message-ID: 571f6b510812301234m217eaa96n277f8c86f54defce () mail ! gmail ! com
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On Tue, Dec 30, 2008 at 8:38 PM, Ian Lance Taylor <iant@google.com> wrote:
> "Balaji V. Iyer" <bviyer@ncsu.edu> writes:
>
>>       Thanks for your help. What I mainly want to do is to make some
>> hardware decisions by looking at the instructions inside a Basic block.
>> Ths is why I was using the "FOR_EACH_BB" function.
>>
>>       When and where can I intercept the RTL such that I can get the
>> RTL that matches the output assembly equivalents? I am willing to add my
>> own hook if necessary.
>
> If you want to look at RTL which precisely matches the output
> assembly, then you should use FINAL_PRESCAN_INSN.  You won't get basic
> block markers, though.
>
> If you want to look at RTL which is pretty close to the output
> assembly, and for which the basic blocks are reasonably valid, then
> you should write a pass which runs somewhere after the second
> scheduling pass.

You can also just resurrect the CFG when you enter your machine reorg
pass.  See how ia64 does that, for example (grep for
compute_bb_for_insn).

Gr.
Steven
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