Re: Importance of transformations that turn data dependencies into control dependencies?

2016-03-01 Thread Paul E. McKenney
On Tue, Mar 01, 2016 at 05:55:07PM +0100, Michael Matz wrote: > Hi, > > On Tue, 1 Mar 2016, Richard Biener wrote: > > > > What about the example I gave above? Is it unrealistic for compilers > > > do ever do something like this, or is it just unlikely to gain much > > > performance, or is it

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-03-01 Thread Michael Matz
Hi, On Tue, 1 Mar 2016, Richard Biener wrote: > > What about the example I gave above? Is it unrealistic for compilers > > do ever do something like this, or is it just unlikely to gain much > > performance, or is it just that GCC does not do this today? > > GCC does not do this today with

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-03-01 Thread Richard Biener
On Fri, Feb 26, 2016 at 8:10 PM, Torvald Riegel wrote: > On Fri, 2016-02-26 at 11:49 +0100, Richard Biener wrote: >> On Thu, Feb 25, 2016 at 6:33 PM, Torvald Riegel wrote: >> > On Wed, 2016-02-24 at 13:14 +0100, Richard Biener wrote: >> >> On Tue, Feb 23,

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-02-29 Thread Torvald Riegel
On Fri, 2016-02-26 at 20:10 +0100, Torvald Riegel wrote: > On Fri, 2016-02-26 at 11:49 +0100, Richard Biener wrote: > > On Thu, Feb 25, 2016 at 6:33 PM, Torvald Riegel wrote: > > > On Wed, 2016-02-24 at 13:14 +0100, Richard Biener wrote: > > >> On Tue, Feb 23, 2016 at 8:38 PM,

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-02-29 Thread Torvald Riegel
On Fri, 2016-02-26 at 11:49 +0100, Richard Biener wrote: > On Thu, Feb 25, 2016 at 6:33 PM, Torvald Riegel wrote: > > On Wed, 2016-02-24 at 13:14 +0100, Richard Biener wrote: > >> On Tue, Feb 23, 2016 at 8:38 PM, Torvald Riegel wrote: > >> > I'd like to

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-02-26 Thread Jeff Law
On 02/24/2016 05:14 AM, Richard Biener wrote: Note that if a user writes if (p == d) { ... do lots of stuff via p ... } GCC might rewrite accesses to p as accesses to d and thus expose those opportunities. Is that a transform that isn't valid then or is the code written by

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-02-26 Thread Paul E. McKenney
On Fri, Feb 26, 2016 at 11:49:29AM +0100, Richard Biener wrote: > On Thu, Feb 25, 2016 at 6:33 PM, Torvald Riegel wrote: > > On Wed, 2016-02-24 at 13:14 +0100, Richard Biener wrote: > >> On Tue, Feb 23, 2016 at 8:38 PM, Torvald Riegel wrote: > >> > I'd

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-02-26 Thread Richard Biener
On Thu, Feb 25, 2016 at 6:33 PM, Torvald Riegel wrote: > On Wed, 2016-02-24 at 13:14 +0100, Richard Biener wrote: >> On Tue, Feb 23, 2016 at 8:38 PM, Torvald Riegel wrote: >> > I'd like to know, based on the GCC experience, how important we consider >> >

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-02-25 Thread Torvald Riegel
On Thu, 2016-02-25 at 18:33 +0100, Torvald Riegel wrote: > On Wed, 2016-02-24 at 13:14 +0100, Richard Biener wrote: > > On Tue, Feb 23, 2016 at 8:38 PM, Torvald Riegel wrote: > > > I'd like to know, based on the GCC experience, how important we consider > > > optimizations

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-02-25 Thread Torvald Riegel
On Wed, 2016-02-24 at 13:14 +0100, Richard Biener wrote: > On Tue, Feb 23, 2016 at 8:38 PM, Torvald Riegel wrote: > > I'd like to know, based on the GCC experience, how important we consider > > optimizations that may turn data dependencies of pointers into control > >

Re: Importance of transformations that turn data dependencies into control dependencies?

2016-02-24 Thread Richard Biener
On Tue, Feb 23, 2016 at 8:38 PM, Torvald Riegel wrote: > I'd like to know, based on the GCC experience, how important we consider > optimizations that may turn data dependencies of pointers into control > dependencies. I'm thinking about all optimizations or transformations >

Importance of transformations that turn data dependencies into control dependencies?

2016-02-23 Thread Torvald Riegel
I'd like to know, based on the GCC experience, how important we consider optimizations that may turn data dependencies of pointers into control dependencies. I'm thinking about all optimizations or transformations that guess that a pointer might have a specific value, and then create