This is the mail archive of the
`gcc@gcc.gnu.org`
mailing list for the GCC project.

Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|

Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |

Other format: | [Raw text] |

*From*: Richard Guenther <richard dot guenther at gmail dot com>*To*: Tobias Grosser <grosser at fim dot uni-passau dot de>*Cc*: gcc at gcc dot gnu dot org, Sebastian Pop <sebpop at gmail dot com>, Li Feng <nemokingdom at gmail dot com>, gcc-graphite <gcc-graphite at googlegroups dot com>*Date*: Thu, 16 Jul 2009 10:39:00 +0200*Subject*: Re: How could I get alias set information from data_reference_p*References*: <f18356030907132301n2306cd0ah3929575851d5cdff@mail.gmail.com> <cb9d34b20907140903y3a9e067g81d35a7f4ab3d58@mail.gmail.com> <cb9d34b20907140908l2f1a2eb2r1be98670ac62d86e@mail.gmail.com> <84fc9c000907141434n18721235oddafd9ff5489ff72@mail.gmail.com> <1247655619.1418.179.camel@localhost> <84fc9c000907150426w69f13cebv4a36e834d1e3c9f1@mail.gmail.com> <1247685312.87884.417.camel@localhost> <84fc9c000907151346r58239f06u318b55fe72ae0038@mail.gmail.com> <15137_1247690941_4A5E40BC_15137_586_1_84fc9c000907151348s41395cc5u6cfacb60cde78bfa@mail.gmail.com> <1247699704.87884.423.camel@localhost>

On Thu, Jul 16, 2009 at 1:15 AM, Tobias Grosser<grosser@fim.uni-passau.de> wrote: > On Wed, 2009-07-15 at 22:48 +0200, Richard Guenther wrote: >> On Wed, Jul 15, 2009 at 10:46 PM, Richard >> Guenther<richard.guenther@gmail.com> wrote: >> > On Wed, Jul 15, 2009 at 9:15 PM, Tobias >> > Grosser<grosser@fim.uni-passau.de> wrote: >> >>> A note on Lis final graph algorithm. ?I don't understand why you want >> >>> to allow data-references to be part of multiple alias-sets? ?(Of course >> >>> I don't know how you are going to use the alias-sets ...) >> >> >> >> Just to pass more information to Graphite. The easiest example might be >> >> something like >> >> >> >> A -- B -- C >> >> >> >> if we have >> >> >> >> AS1 = {A,B} >> >> AS2 = {B,C} >> >> >> >> we know that A and C do not alias and therefore do not have any >> > >> > No, from the above you _don't_ know that. ?How would you arrive >> > at that conclusion? >> >> What I want to say is that, if ?A -- B -- C is supposed to be the alias graph >> resulting from querying the alias oracle for the pairs (A, B), (A, C), (B, C) >> then this is a result that will never occur. ?Because if (A, B) is true >> and (B, C) is true then (A, C) will be true as well. > > What for example for this case: > > void foo (*b) { > ?int *a > ?int *c > > ?if (bar()) > ? ? ? ?a = b; > ?else > ? ? ? ?c = b; > } > > I thought this may give us the example above, but it seems I am wrong. > If the alias oracle is transitive that would simplify the algorithm a > lot. Can we rely on the transitivity? Actually I was too fast (or rather it was too late), an example with A -- B -- C would be int a, c; void foo(int *p) with B == (*p). B may alias a and c but a may not alias c. So, back to my first question then, which is still valid. Just to pass more information to Graphite. The easiest example might be something like A -- B -- C if we have AS1 = {A,B} AS2 = {B,C} we know that A and C do not alias and therefore do not have any dependencies. How do you derive at 'A and C do not alias' from looking at the alias set numbers for AS1 and AS2. How do you still figure out that B aliases A and C just from looking at the alias set numbers? Or rather, what single alias set number does B get? Richard. > Tobi > > > >

**Follow-Ups**:

**References**:**How could I get alias set information from data_reference_p***From:*Li Feng

**Re: How could I get alias set information from data_reference_p***From:*Sebastian Pop

**Re: How could I get alias set information from data_reference_p***From:*Sebastian Pop

**Re: How could I get alias set information from data_reference_p***From:*Richard Guenther

**Re: How could I get alias set information from data_reference_p***From:*Tobias Grosser

**Re: How could I get alias set information from data_reference_p***From:*Richard Guenther

**Re: How could I get alias set information from data_reference_p***From:*Tobias Grosser

**Re: How could I get alias set information from data_reference_p***From:*Richard Guenther

**Re: How could I get alias set information from data_reference_p***From:*Tobias Grosser

Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|

Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |