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Re: Turn on -funroll-loops at -O3?

From: "Andi Kleen" <andi at firstfloor dot org>
To: gcc at gcc dot gnu dot org
Date: Sat, 22 Jan 2011 14:55:26 -0800
Subject: Re: Turn on -funroll-loops at -O3?
References: <AANLkTikBLR2Tx=yNL5w7-u6u0FBkKq4wOPzaS=XgRGS4@mail.gmail.com>

"H.J. Lu" <hjl.tools@gmail.com> writes:

> Hi,
>
> SInce -O3 turns on vectorizer, should it also turn on
> -funroll-loops?

In my experience gcc already unrolls very aggressively at -O3,
due to the vector unroller which is enabled by default.

-Andi

References:
- Turn on -funroll-loops at -O3?
  - From: H.J. Lu

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