[PATCH] Fix complex lowering (PR middle-end/68146, PR tree-optimization/69155)

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

During complex lowering, we were walking bbs in bb index # order, which
means sometimes we could visit SSA_NAME uses before visiting definitions.
Also, even if we walk in rpo order as the following patch does, sometimes
we need to first use SSA_NAMEs before their definitions are lowered at least
for PHI arguments from the back edges.
This is problematic because the gimple folders can now just walk SSA_NAME
defs and aren't expecting NULL SSA_NAME_DEF_STMT.  This patch arranges
in those cases for the PHI to temporarily contain some VAR_DECL arguments
instead (which is arguably not valid SSA form either, but so is the case
when TODO_update_ssa is needed, so I hope the simplifiers just give up when
seeing those), and once we lower everything, fixes those PHIs up.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2016-01-14  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/68146
	PR tree-optimization/69155
	* tree-complex.c: Include cfganal.h.
	(phis_to_revisit): New variable.
	(extract_component): Add phiarg_p argument.  Assert that returned
	SSA_NAME has non-NULL SSA_NAME_DEF_STMT unless phiarg_p is true.
	(update_phi_components): Partly rewrite to use loop over real/imag
	components instead of code duplication.  If extract_component returns
	SSA_NAME with NULL SSA_NAME_DEF_STMT, store SSA_NAME_VAR or
	create_tmp_reg into the PHI node instead, and mention the phi triplet
	in phis_to_revisit.
	(tree_lower_complex): Walk bbs in rpo order.  Adjust phis recorded
	in phis_to_revisit at the end.

	* gfortran.dg/pr68146.f: New test.
	* gfortran.dg/pr69155.f90: New test.

--- gcc/tree-complex.c.jj	2016-01-13 20:19:34.415802325 +0100
+++ gcc/tree-complex.c	2016-01-14 12:32:58.563320679 +0100
@@ -39,6 +39,7 @@ along with GCC; see the file COPYING3.
 #include "tree-ssa-propagate.h"
 #include "tree-hasher.h"
 #include "cfgloop.h"
+#include "cfganal.h"
 
 
 /* For each complex ssa name, a lattice value.  We're interested in finding
@@ -69,6 +70,11 @@ static int_tree_htab_type *complex_varia
 /* For each complex SSA_NAME, a pair of ssa names for the components.  */
 static vec<tree> complex_ssa_name_components;
 
+/* Vector of PHI triplets (original complex PHI and corresponding real and
+   imag PHIs if real and/or imag PHIs contain temporarily
+   non-SSA_NAME/non-invariant args that need to be replaced by SSA_NAMEs.  */
+static vec<gphi *> phis_to_revisit;
+
 /* Lookup UID in the complex_variable_components hashtable and return the
    associated tree.  */
 static tree
@@ -588,7 +594,7 @@ set_component_ssa_name (tree ssa_name, b
 
 static tree
 extract_component (gimple_stmt_iterator *gsi, tree t, bool imagpart_p,
-		   bool gimple_p)
+		   bool gimple_p, bool phiarg_p = false)
 {
   switch (TREE_CODE (t))
     {
@@ -619,7 +625,10 @@ extract_component (gimple_stmt_iterator
       }
 
     case SSA_NAME:
-      return get_component_ssa_name (t, imagpart_p);
+      t = get_component_ssa_name (t, imagpart_p);
+      if (TREE_CODE (t) == SSA_NAME && SSA_NAME_DEF_STMT (t) == NULL)
+	gcc_assert (phiarg_p);
+      return t;
 
     default:
       gcc_unreachable ();
@@ -721,31 +730,48 @@ update_phi_components (basic_block bb)
 
       if (is_complex_reg (gimple_phi_result (phi)))
 	{
-	  tree lr, li;
-	  gimple *pr = NULL, *pi = NULL;
-	  unsigned int i, n;
-
-	  lr = get_component_ssa_name (gimple_phi_result (phi), false);
-	  if (TREE_CODE (lr) == SSA_NAME)
-	    pr = create_phi_node (lr, bb);
-
-	  li = get_component_ssa_name (gimple_phi_result (phi), true);
-	  if (TREE_CODE (li) == SSA_NAME)
-	    pi = create_phi_node (li, bb);
+	  gphi *p[2] = { NULL, NULL };
+	  unsigned int i, j, n;
+	  bool revisit_phi = false;
+
+	  for (j = 0; j < 2; j++)
+	    {
+	      tree l = get_component_ssa_name (gimple_phi_result (phi), j > 0);
+	      if (TREE_CODE (l) == SSA_NAME)
+		p[j] = create_phi_node (l, bb);
+	    }
 
 	  for (i = 0, n = gimple_phi_num_args (phi); i < n; ++i)
 	    {
 	      tree comp, arg = gimple_phi_arg_def (phi, i);
-	      if (pr)
-		{
-		  comp = extract_component (NULL, arg, false, false);
-		  SET_PHI_ARG_DEF (pr, i, comp);
-		}
-	      if (pi)
-		{
-		  comp = extract_component (NULL, arg, true, false);
-		  SET_PHI_ARG_DEF (pi, i, comp);
-		}
+	      for (j = 0; j < 2; j++)
+		if (p[j])
+		  {
+		    comp = extract_component (NULL, arg, j > 0, false, true);
+		    if (TREE_CODE (comp) == SSA_NAME
+			&& SSA_NAME_DEF_STMT (comp) == NULL)
+		      {
+			/* For the benefit of any gimple simplification during
+			   this pass that might walk SSA_NAME def stmts,
+			   don't add SSA_NAMEs without definitions into the
+			   PHI arguments, but put a decl in there instead
+			   temporarily, and revisit this PHI later on.  */
+			if (SSA_NAME_VAR (comp))
+			  comp = SSA_NAME_VAR (comp);
+			else
+			  comp = create_tmp_reg (TREE_TYPE (comp),
+						 get_name (comp));
+			revisit_phi = true;
+		      }
+		    SET_PHI_ARG_DEF (p[j], i, comp);
+		  }
+	    }
+
+	  if (revisit_phi)
+	    {
+	      phis_to_revisit.safe_push (phi);
+	      phis_to_revisit.safe_push (p[0]);
+	      phis_to_revisit.safe_push (p[1]);
 	    }
 	}
     }
@@ -1612,9 +1638,10 @@ expand_complex_operations_1 (gimple_stmt
 static unsigned int
 tree_lower_complex (void)
 {
-  int old_last_basic_block;
   gimple_stmt_iterator gsi;
   basic_block bb;
+  int n_bbs, i;
+  int *rpo;
 
   if (!init_dont_simulate_again ())
     return 0;
@@ -1632,18 +1659,40 @@ tree_lower_complex (void)
 
   update_parameter_components ();
 
-  /* ??? Ideally we'd traverse the blocks in breadth-first order.  */
-  old_last_basic_block = last_basic_block_for_fn (cfun);
-  FOR_EACH_BB_FN (bb, cfun)
+  rpo = XNEWVEC (int, last_basic_block_for_fn (cfun));
+  n_bbs = pre_and_rev_post_order_compute (NULL, rpo, false);
+  for (i = 0; i < n_bbs; i++)
     {
-      if (bb->index >= old_last_basic_block)
-	continue;
-
+      bb = BASIC_BLOCK_FOR_FN (cfun, rpo[i]);
       update_phi_components (bb);
       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 	expand_complex_operations_1 (&gsi);
     }
 
+  free (rpo);
+
+  if (!phis_to_revisit.is_empty ())
+    {
+      unsigned int n = phis_to_revisit.length ();
+      for (unsigned int j = 0; j < n; j += 3)
+	for (unsigned int k = 0; k < 2; k++)
+	  if (gphi *phi = phis_to_revisit[j + k + 1])
+	    {
+	      unsigned int m = gimple_phi_num_args (phi);
+	      for (unsigned int l = 0; l < m; ++l)
+		{
+		  tree op = gimple_phi_arg_def (phi, l);
+		  if (TREE_CODE (op) == SSA_NAME
+		      || is_gimple_min_invariant (op))
+		    continue;
+		  tree arg = gimple_phi_arg_def (phis_to_revisit[j], l);
+		  op = extract_component (NULL, arg, k > 0, false, false);
+		  SET_PHI_ARG_DEF (phi, l, op);
+		}
+	    }
+      phis_to_revisit.release ();
+    }
+
   gsi_commit_edge_inserts ();
 
   delete complex_variable_components;
--- gcc/testsuite/gfortran.dg/pr68146.f.jj	2016-01-14 12:39:33.876734654 +0100
+++ gcc/testsuite/gfortran.dg/pr68146.f	2016-01-14 12:40:43.418754450 +0100
@@ -0,0 +1,16 @@
+C PR middle-end/68146
+C { dg-do compile }
+C { dg-options "-O2 -w" }
+      SUBROUTINE CJYVB(V,Z,V0,CBJ,CDJ,CBY,CYY)
+      IMPLICIT DOUBLE PRECISION (A,B,G,O-Y)
+      IMPLICIT COMPLEX*16 (C,Z)
+      DIMENSION CBJ(0:*),CDJ(0:*),CBY(0:*)
+      N=INT(V)
+      CALL GAMMA2(VG,GA)
+      DO 65 K=1,N
+        CBY(K)=CYY
+65    CONTINUE
+      CDJ(0)=V0/Z*CBJ(0)-CBJ(1)
+      DO 70 K=1,N
+70      CDJ(K)=-(K+V0)/Z*CBJ(K)+CBJ(K-1)
+      END
--- gcc/testsuite/gfortran.dg/pr69155.f90.jj	2016-01-14 12:34:07.882335042 +0100
+++ gcc/testsuite/gfortran.dg/pr69155.f90	2016-01-14 12:33:31.000000000 +0100
@@ -0,0 +1,15 @@
+! PR tree-optimization/69155
+! { dg-do compile }
+
+function pr69155 (a, b)
+  complex(kind=8), value :: a, b
+  if (dimag (a) .lt. 10) then
+  1 continue
+    if (dble (a) .lt. 10) then
+      b = b - 1 / a
+      a = a + 1
+      goto 1
+    end if
+  end if
+  pr69155 = a + b
+end

	Jakub