fix PR68453: recursively add phi nodes to merge points

The patch adds close phi nodes to every outer loop exit, and to every loop
guard.  For loop guards it computes an initial value that determines where we
stop inserting phi nodes.  When the initial value is a constant, the initial
value is considered to be defined in the entry of the code gen region.

Co-Authored-By: Sebastian Pop <s.pop@samsung.com>

From-SVN: r230918

gcc/ChangeLog

+2015-11-25  Aditya Kumar  <aditya.k7@samsung.com>
+	    Sebastian Pop  <s.pop@samsung.com>
+
+	PR tree-optimization/68453
+	* graphite-isl-ast-to-gimple.c (translate_isl_ast_for_loop): Do
+	not redirect edges already pointing to their destination.
+	(translate_isl_ast_node_for): Split edges after loops to create
+	basic blocks for close phi nodes.  Save merge points at the end of
+	a loop guard.
+	(translate_isl_ast_node_if): Save merge points at the end of the
+	if region.
+	(add_close_phis_to_outer_loops): New.
+	(add_close_phis_to_merge_points): New.
+	(copy_loop_close_phi_args): Call add_close_phis_to_merge_points.
+	(copy_bb_and_scalar_dependences): Do not split basic blocks on
+	loop close phi locations.
+
 2015-11-25  Jan Hubicka  <jh@suse.cz>
 
 	* ipa-visibility.c (cgraph_externally_visible_p,

gcc/testsuite/ChangeLog

+2015-11-25  Aditya Kumar  <aditya.k7@samsung.com>
+	    Sebastian Pop  <s.pop@samsung.com>
+
+	PR tree-optimization/68453
+	* gfortran.dg/graphite/pr68453.f90: New.
+
 2015-11-25  Martin Sebor  <msebor@redhat.com>
 
 	PR c/66516

gcc/testsuite/gfortran.dg/graphite/pr68453.f90

+! { dg-options "-floop-nest-optimize -O2" }
+
+MODULE dbcsr_geev
+  INTEGER, PARAMETER :: real_8=8
+CONTAINS
+  SUBROUTINE dbcsr_dgeev(jobvl,jobvr,matrix,ndim,evals,revec,levec)
+    CHARACTER(1)                             :: jobvl, jobvr
+    REAL(real_8), DIMENSION(:, :)            :: matrix
+    INTEGER                                  :: ndim
+    COMPLEX(real_8), DIMENSION(:)            :: evals
+    COMPLEX(real_8), DIMENSION(:, :)         :: revec, levec
+    INTEGER                                  :: i, info, lwork
+    REAL(real_8)                             :: norm, tmp_array(ndim,ndim), &
+                                                work(20*ndim)
+    REAL(real_8), DIMENSION(ndim)            :: eval1, eval2
+    REAL(real_8), DIMENSION(ndim, ndim)      :: evec_l, evec_r
+    DO WHILE (i.le.ndim)
+      IF(ABS(eval2(i)).LT.EPSILON(REAL(0.0,real_8)))THEN
+        norm=SQRT(SUM(evec_r(:,i)**2.0_real_8)+SUM(evec_r(:,i+1)**2.0_real_8))
+        revec(:,i)=CMPLX(evec_r(:,i),evec_r(:,i+1),real_8)/norm
+      END IF
+    END DO
+  END SUBROUTINE  dbcsr_dgeev
+END MODULE dbcsr_geev