* Pointer analysis in GCC-4.3.0 - Getting spurious pointsTo pair. [not found] <ee5d809b0905270045u4775e419q3da30a3e3b8157e8@mail.gmail.com> @ 2009-06-15 10:33 ` Seema Ravandale 2009-06-15 11:19 ` Richard Guenther 0 siblings, 1 reply; 2+ messages in thread From: Seema Ravandale @ 2009-06-15 10:33 UTC (permalink / raw) To: gcc, gcc-help Hi. Gimple code of the program I have tried to get the pointsTo information is as follow: A = 0; B = &A; C = &B; D = &C; D.1255 = *D; D = (int * * *) D.1255; The expected pointsTo pairs are, B = { A } , A = { }, C = { B }, D.1255 = { B }, D = { B C } But with GCC-4.3.0, and command line options -fdump-ipa-all -funit-at-a-time -fipa-pta, we are getting spurious pointsTo pairs as, D.1255 = { B A } , D = { B C A } Is the current analysis Flow-insensitive? Even if It is, the sperious information, D -> A should not occur. Please, Can someone clarify on this? - Seema ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Pointer analysis in GCC-4.3.0 - Getting spurious pointsTo pair. 2009-06-15 10:33 ` Pointer analysis in GCC-4.3.0 - Getting spurious pointsTo pair Seema Ravandale @ 2009-06-15 11:19 ` Richard Guenther 0 siblings, 0 replies; 2+ messages in thread From: Richard Guenther @ 2009-06-15 11:19 UTC (permalink / raw) To: Seema Ravandale; +Cc: gcc, gcc-help On Mon, Jun 15, 2009 at 12:33 PM, Seema Ravandale<ravandaless@gmail.com> wrote: > Hi. > > Gimple code of the program I have tried to get the pointsTo > information is as follow: > > A = 0; > B = &A; > C = &B; > D = &C; > D.1255 = *D; > D = (int * * *) D.1255; > > The expected pointsTo pairs are, > B = { A } , A = { }, C = { B }, D.1255 = { B }, D = { B C } > > But with GCC-4.3.0, and command line options -fdump-ipa-all > -funit-at-a-time -fipa-pta, we are getting spurious pointsTo pairs > as, > D.1255 = { B A } , D = { B C A } > > Is the current analysis Flow-insensitive? Even if It is, the sperious > information, D -> A should not occur. > Please, Can someone clarify on this? IPA-PTA is completely bogus (and its results are unused). Further GCC 4.3 has a very large number of known oddities with computing points-to information, GCC 4.4 is a lot better here but only GCC 4.5 has fixes for all (known) bugs. Richard. > - Seema > ^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] <ee5d809b0905270045u4775e419q3da30a3e3b8157e8@mail.gmail.com>
2009-06-15 10:33 ` Pointer analysis in GCC-4.3.0 - Getting spurious pointsTo pair Seema Ravandale
2009-06-15 11:19 ` Richard Guenther
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