Fix PR94043 by making vect_live_op generate lc-phi

As PR94043 shows, my commit r10-4524 exposed one issue in
vectorizable_live_operation, which inserts one extra BB
before the single exit, leading unexpected operand expansion
and unexpected loop depth assertion.  As Richi suggested,
this patch is to teach vectorizable_live_operation to
generate loop closed phi for vec_lhs, it looks like:
     loop;
     # lhs' = PHI <lhs>
=>
     loop;
     # vec_lhs' = PHI <vec_lhs>
     new_tree = BIT_FIELD_REF <vec_lhs', ...>;
     lhs' = new_tree;

I noticed that there are some SLP cases that have same lhs
and vec_lhs but different offsets, which can make us have
more PHIs for the same vec_lhs there.  But I think it would
be fine since only one of them is actually live, the others
should be eliminated by the following dce.  So the patch
doesn't check whether there is one phi for vec_lhs, just
create one directly instead.

Bootstrapped/regtested on powerpc64le-linux-gnu (LE) P8.

2020-04-01  Kewen Lin  <linkw@gcc.gnu.org>

gcc/ChangeLog

    PR tree-optimization/94043
    * tree-vect-loop.c (vectorizable_live_operation): Generate loop-closed
    phi for vec_lhs and use it for lane extraction.

gcc/testsuite/ChangeLog

    PR tree-optimization/94043
    * gfortran.dg/graphite/vect-pr94043.f90: New test.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5bd72ccddd9ca792b9eeacc5db7755197ed59131..fc836b83e171944bbb9e8a788113149db5ea2999 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-04-01  Kewen Lin  <linkw@gcc.gnu.org>
+
+       PR tree-optimization/94043
+       * tree-vect-loop.c (vectorizable_live_operation): Generate loop-closed
+       phi for vec_lhs and use it for lane extraction.
+
 2020-03-31  Felix Yang  <felix.yang@huawei.com>
 
        PR tree-optimization/94398

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index adfbdb01af77f955a18f96ac628a32e79002b18e..6f41ffbb048735e555b907b8b78ab4cd160a1d85 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-01  Kewen Lin  <linkw@gcc.gnu.org>
+
+       PR tree-optimization/94043
+       * gfortran.dg/graphite/vect-pr94043.f90: New test.
+
 2020-04-01  Iain Buclaw  <ibuclaw@gdcproject.org>
 
        PR d/90136

diff --git a/gcc/testsuite/gfortran.dg/graphite/vect-pr94043.f90 b/gcc/testsuite/gfortran.dg/graphite/vect-pr94043.f90
new file mode 100644 (file)
index 0000000..744c0f3
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/graphite/vect-pr94043.f90
@@ -0,0 +1,18 @@
+! { dg-do compile }
+! { dg-additional-options "-O3 -ftree-parallelize-loops=2 -fno-tree-dce" }
+
+! As PR94043, test it to be compiled successfully without ICE.
+
+program yw
+      integer :: hx(6, 6)
+      integer :: ps = 1, e2 = 1
+
+      do ps = 1, 6
+        do e2 = 1, 6
+            hx(e2, ps) = 0
+            if (ps >= 5 .and. e2 >= 5) then
+                hx(e2, ps) = hx(1, 1)
+            end if
+        end do
+      end do
+end program

diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index 73e092c1d6c5b953444e6a5b83841ef441afcf44..c9b653491f73879e300526918a5533ee0e627c1d 100644 (file)
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -7998,6 +7998,25 @@ vectorizable_live_operation (stmt_vec_info stmt_info,
       bitstart = int_const_binop (MINUS_EXPR, vec_bitsize, bitsize);
     }
 
+  /* Ensure the VEC_LHS for lane extraction stmts satisfy loop-closed PHI
+     requirement, insert one phi node for it.  It looks like:
+        loop;
+       BB:
+        # lhs' = PHI <lhs>
+     ==>
+        loop;
+       BB:
+        # vec_lhs' = PHI <vec_lhs>
+        new_tree = lane_extract <vec_lhs', ...>;
+        lhs' = new_tree;  */
+
+  basic_block exit_bb = single_exit (loop)->dest;
+  gcc_assert (single_pred_p (exit_bb));
+
+  tree vec_lhs_phi = copy_ssa_name (vec_lhs);
+  gimple *phi = create_phi_node (vec_lhs_phi, exit_bb);
+  SET_PHI_ARG_DEF (phi, single_exit (loop)->dest_idx, vec_lhs);
+
   gimple_seq stmts = NULL;
   tree new_tree;
   if (LOOP_VINFO_FULLY_MASKED_P (loop_vinfo))
@@ -8010,10 +8029,10 @@ vectorizable_live_operation (stmt_vec_info stmt_info,
         the loop mask for the final iteration.  */
       gcc_assert (ncopies == 1 && !slp_node);
       tree scalar_type = TREE_TYPE (STMT_VINFO_VECTYPE (stmt_info));
-      tree mask = vect_get_loop_mask (gsi, &LOOP_VINFO_MASKS (loop_vinfo),
-                                     1, vectype, 0);
-      tree scalar_res = gimple_build (&stmts, CFN_EXTRACT_LAST,
-                                     scalar_type, mask, vec_lhs);
+      tree mask = vect_get_loop_mask (gsi, &LOOP_VINFO_MASKS (loop_vinfo), 1,
+                                     vectype, 0);
+      tree scalar_res = gimple_build (&stmts, CFN_EXTRACT_LAST, scalar_type,
+                                     mask, vec_lhs_phi);
 
       /* Convert the extracted vector element to the required scalar type.  */
       new_tree = gimple_convert (&stmts, lhs_type, scalar_res);
@@ -8023,13 +8042,32 @@ vectorizable_live_operation (stmt_vec_info stmt_info,
       tree bftype = TREE_TYPE (vectype);
       if (VECTOR_BOOLEAN_TYPE_P (vectype))
        bftype = build_nonstandard_integer_type (tree_to_uhwi (bitsize), 1);
-      new_tree = build3 (BIT_FIELD_REF, bftype, vec_lhs, bitsize, bitstart);
+      new_tree = build3 (BIT_FIELD_REF, bftype, vec_lhs_phi, bitsize, bitstart);
       new_tree = force_gimple_operand (fold_convert (lhs_type, new_tree),
                                       &stmts, true, NULL_TREE);
     }
 
   if (stmts)
-    gsi_insert_seq_on_edge_immediate (single_exit (loop), stmts);
+    {
+      gimple_stmt_iterator exit_gsi = gsi_after_labels (exit_bb);
+      gsi_insert_before (&exit_gsi, stmts, GSI_CONTINUE_LINKING);
+
+      /* Remove existing phi from lhs and create one copy from new_tree.  */
+      tree lhs_phi = NULL_TREE;
+      gimple_stmt_iterator gsi;
+      for (gsi = gsi_start_phis (exit_bb); !gsi_end_p (gsi); gsi_next (&gsi))
+       {
+         gimple *phi = gsi_stmt (gsi);
+         if ((gimple_phi_arg_def (phi, 0) == lhs))
+           {
+             remove_phi_node (&gsi, false);
+             lhs_phi = gimple_phi_result (phi);
+             gimple *copy = gimple_build_assign (lhs_phi, new_tree);
+             gsi_insert_after (&exit_gsi, copy, GSI_CONTINUE_LINKING);
+             break;
+           }
+       }
+    }
 
   /* Replace use of lhs with newly computed result.  If the use stmt is a
      single arg PHI, just replace all uses of PHI result.  It's necessary