Hi there, Ping. I'm seeking approval for this fix on trunk and 4_6-branch. Thanks!
Bill On Tue, 2011-09-13 at 17:55 -0500, William J. Schmidt wrote: > Greetings, > > The code to build scops (static control parts) for graphite first > rewrites loops into canonical loop-closed SSA form. PR50183 identifies > a scenario where the results do not fulfill all required invariants of > this form. In particular, a value defined inside a loop and used > outside that loop must reach exactly one definition, which must be a > single-argument PHI node called a close-phi. When nested loops exist, > it is possible that, following the rewrite, a definition may reach two > close-phis. This patch corrects that problem. > > The problem arises because loops are processed from outside in. While > processing a loop, duplicate close-phis are eliminated. However, > eliminating duplicate close-phis for an inner loop can sometimes create > duplicate close-phis for an already-processed outer loop. This patch > detects when this may have occurred and repeats the removal of duplicate > close-phis as necessary. > > The problem was noted on ibm/4_6-branch and 4_6-branch; it is apparently > latent on trunk. The same patch can be applied to all three branches. > > Bootstrapped and regression-tested on powerpc64-linux. OK to commit to > these three branches? > > Thanks, > Bill > > > 2011-09-13 Bill Schmidt <wschm...@linux.vnet.ibm.com> > > * graphite-scop-detection.c (make_close_phi_nodes_unique): New > forward declaration. > (remove_duplicate_close_phi): Detect and repair creation of > duplicate close-phis for a containing loop. > > > Index: gcc/graphite-scop-detection.c > =================================================================== > --- gcc/graphite-scop-detection.c (revision 178829) > +++ gcc/graphite-scop-detection.c (working copy) > @@ -30,6 +30,9 @@ along with GCC; see the file COPYING3. If not see > #include "tree-pass.h" > #include "sese.h" > > +/* Forward declarations. */ > +static void make_close_phi_nodes_unique (basic_block); > + > #ifdef HAVE_cloog > #include "ppl_c.h" > #include "graphite-ppl.h" > @@ -1231,6 +1234,13 @@ remove_duplicate_close_phi (gimple phi, gimple_stm > SET_USE (use_p, res); > > update_stmt (use_stmt); > + > + /* It is possible that we just created a duplicate close-phi > + for an already-processed containing loop. Check for this > + case and clean it up. */ > + if (gimple_code (use_stmt) == GIMPLE_PHI > + && gimple_phi_num_args (use_stmt) == 1) > + make_close_phi_nodes_unique (gimple_bb (use_stmt)); > } > > remove_phi_node (gsi, true); > >
