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Re: [PATCH] Speedup/remove uses of is_gimple_reg (PHI_RESULT)
- From: Daniel Jacobowitz <drow at false dot org>
- To: Andrew Pinski <pinskia at physics dot uc dot edu>
- Cc: "gcc-patches at gcc dot gnu dot org Patches" <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 15 Nov 2004 22:15:40 -0500
- Subject: Re: [PATCH] Speedup/remove uses of is_gimple_reg (PHI_RESULT)
- References: <6919D2CD-376F-11D9-89EF-000A95D692F4@physics.uc.edu>
On Mon, Nov 15, 2004 at 08:32:42PM -0500, Andrew Pinski wrote:
> I noticed that a huge amount of time was being spent in is_gimple_reg.
> We were calling it on the result of a PHI_NODE to figure out if it was
> a virtual PHI node or not. This patch "steals" the static bit to
> indicate if the PHI node is a virtual node. This speeds up the compiler
> but I did not measure how much. The is_gimple_reg on a profile using
> Shark goes down to below the 25th top function on the profile.
> OK? Bootstrapped and tested on powerpc-darwin.
It sounds reasonable but...
Please, if you're submitting patches to improve performance, make some
comprehensive measurement to indicate you're doing the right thing.
This kind of micro-optimization can easily backfire.