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Re: Incorrect use of anti-dependency to order instructions in the DFA scheduler
- From: Richard Henderson <rth at redhat dot com>
- To: Daniel Towner <daniel dot towner at picochip dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Thu, 1 Sep 2005 10:49:48 -0700
- Subject: Re: Incorrect use of anti-dependency to order instructions in the DFA scheduler
- References: <4316D423.4010804@picochip.com>
On Thu, Sep 01, 2005 at 11:12:51AM +0100, Daniel Towner wrote:
> Why is an anti-dependence used to enforce the ordering of the branch and
> the subsequent instruction?
Because gcc doesn't target true vliw machines, and given strict
program ordering of insn, anti-dependence is correct.
> ... and if I changed it, would this break other ports?
Yes.
You need to be special-casing branches in your backend's bundling hooks.
r~