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Re: Question of the LOG_LINKS field
- From: Ian Lance Taylor <iant at google dot com>
- To: "Ling-hua Tseng" <uranus at it dot muds dot net>
- Cc: <gcc at gcc dot gnu dot org>
- Date: 16 Jul 2006 09:15:58 -0700
- Subject: Re: Question of the LOG_LINKS field
- References: <000901c6a869$c12a38c0$0100a8c0@uranus>
"Ling-hua Tseng" <uranus@it.muds.net> writes:
> The algorithm is highly dependent on the information of LOG_LINKS(insn).
> But I found that there are not any dependecy info for `reload instructions'
> because the register allocation pass and reloading pass are peformed after
> the first insn scheduling pass.
Right. The LOG_LINKS field is not reliable after reload.
> Should I write a violent algorithm to scan these data dependencies?
Yes.
> Are there any better solutions for this problem?
At present, there is not.
mips_avoid_hazard in config/mips/mips.c is an example of how the MIPS
backend addresses a similar issue. Note the use of DELAYED_REG.
Ian