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Fix PR debug/49047
[pf3gnuchains/gcc-fork.git] / gcc / tree-ssa-forwprop.c
index ddc1ac4..56ba522 100644 (file)
@@ -392,9 +392,9 @@ combine_cond_expr_cond (location_t loc, enum tree_code code, tree type,
    were no simplifying combines.  */
 
 static tree
-forward_propagate_into_comparison (location_t loc,
-                                  enum tree_code code, tree type,
-                                  tree op0, tree op1)
+forward_propagate_into_comparison_1 (location_t loc,
+                                    enum tree_code code, tree type,
+                                    tree op0, tree op1)
 {
   tree tmp = NULL_TREE;
   tree rhs0 = NULL_TREE, rhs1 = NULL_TREE;
@@ -439,141 +439,31 @@ forward_propagate_into_comparison (location_t loc,
   return tmp;
 }
 
-/* Forward propagate the comparison defined in STMT like
-   cond_1 = x CMP y to uses of the form
-     a_1 = (T')cond_1
-     a_1 = !cond_1
-     a_1 = cond_1 != 0
-   Returns 1 if a transformation was done and 2 if the CFG should
-   be cleaned up.  Else returns 0.  */
+/* Propagate from the ssa name definition statements of the assignment
+   from a comparison at *GSI into the conditional if that simplifies it.
+   Returns true if the stmt was modified, false if not.  */
 
-static int 
-forward_propagate_comparison (gimple stmt)
+static bool
+forward_propagate_into_comparison (gimple_stmt_iterator *gsi)
 {
-  tree name = gimple_assign_lhs (stmt);
-  gimple use_stmt;
-  tree tmp = NULL_TREE;
-  int did_something = 0;
+  gimple stmt = gsi_stmt (*gsi);
+  tree tmp;
 
   /* Combine the comparison with defining statements.  */
-  do
+  tmp = forward_propagate_into_comparison_1 (gimple_location (stmt),
+                                            gimple_assign_rhs_code (stmt),
+                                            TREE_TYPE
+                                              (gimple_assign_lhs (stmt)),
+                                            gimple_assign_rhs1 (stmt),
+                                            gimple_assign_rhs2 (stmt));
+  if (tmp)
     {
-      tmp = forward_propagate_into_comparison (gimple_location (stmt),
-                                              gimple_assign_rhs_code (stmt),
-                                              TREE_TYPE (name),
-                                              gimple_assign_rhs1 (stmt),
-                                              gimple_assign_rhs2 (stmt));
-      if (tmp)
-       {
-         gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
-         bool inv = is_gimple_min_invariant (tmp);
-         gimple_assign_set_rhs_from_tree (&gsi, tmp);
-         gcc_assert (gsi_stmt (gsi) == stmt);
-         update_stmt (stmt);
-         did_something = MAX (did_something, inv ? 2 : 1);
-         if (TREE_CODE_CLASS (gimple_assign_rhs_code (stmt)) != tcc_comparison)
-           return did_something;
-       }
-    }
-  while (tmp);
-
-  /* Don't propagate ssa names that occur in abnormal phis.  */
-  if ((TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
-       && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt)))
-      || (TREE_CODE (gimple_assign_rhs2 (stmt)) == SSA_NAME
-        && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs2 (stmt))))
-    return did_something;
-
-  /* Do not un-cse comparisons.  But propagate through copies.  */
-  use_stmt = get_prop_dest_stmt (name, &name);
-  if (!use_stmt)
-    return did_something;
-
-  /* Conversion of the condition result to another integral type.  */
-  if (is_gimple_assign (use_stmt)
-      && (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (use_stmt))
-         || TREE_CODE_CLASS (gimple_assign_rhs_code (use_stmt))
-            == tcc_comparison
-          || gimple_assign_rhs_code (use_stmt) == TRUTH_NOT_EXPR)
-      && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_lhs (use_stmt))))
-    {
-      tree lhs = gimple_assign_lhs (use_stmt);
-
-      /* We can propagate the condition into a conversion.  */
-      if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (use_stmt)))
-       {
-         /* Avoid using fold here as that may create a COND_EXPR with
-            non-boolean condition as canonical form.  */
-         tmp = build2 (gimple_assign_rhs_code (stmt), TREE_TYPE (lhs),
-                        gimple_assign_rhs1 (stmt), gimple_assign_rhs2 (stmt));
-       }
-      /* We can propagate the condition into X op CST where op
-        is EQ_EXPR or NE_EXPR and CST is either one or zero.  */
-      else if (TREE_CODE_CLASS (gimple_assign_rhs_code (use_stmt))
-              == tcc_comparison
-             && TREE_CODE (gimple_assign_rhs1 (use_stmt)) == SSA_NAME
-             && TREE_CODE (gimple_assign_rhs2 (use_stmt)) == INTEGER_CST)
-      {
-        enum tree_code code = gimple_assign_rhs_code (use_stmt);
-        tree cst = gimple_assign_rhs2 (use_stmt);
-       tree cond;
-
-       cond = build2 (gimple_assign_rhs_code (stmt),
-                      TREE_TYPE (cst),
-                      gimple_assign_rhs1 (stmt),
-                      gimple_assign_rhs2 (stmt));
-
-        tmp = combine_cond_expr_cond (gimple_location (use_stmt),
-                                     code, TREE_TYPE (lhs),
-                                     cond, cst, false);
-        if (tmp == NULL_TREE)
-          return did_something;
-      }
-      /* We can propagate the condition into a statement that
-        computes the logical negation of the comparison result.  */
-      else if (gimple_assign_rhs_code (use_stmt) == TRUTH_NOT_EXPR)
-       {
-         tree type = TREE_TYPE (gimple_assign_rhs1 (stmt));
-         bool nans = HONOR_NANS (TYPE_MODE (type));
-         enum tree_code code;
-         code = invert_tree_comparison (gimple_assign_rhs_code (stmt), nans);
-         if (code == ERROR_MARK)
-           return did_something;
-
-         tmp = build2 (code, TREE_TYPE (lhs), gimple_assign_rhs1 (stmt),
-                        gimple_assign_rhs2 (stmt));
-       }
-      else
-       return did_something;
-
-      {
-       gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
-       bool inv = is_gimple_min_invariant (tmp);
-       gimple_assign_set_rhs_from_tree (&gsi, unshare_expr (tmp));
-       did_something = MAX (did_something, inv ? 2 : 1);
-       use_stmt = gsi_stmt (gsi);
-       update_stmt (use_stmt);
-      }
-
-      if (dump_file && (dump_flags & TDF_DETAILS))
-       {
-         tree old_rhs = rhs_to_tree (TREE_TYPE (gimple_assign_lhs (stmt)),
-                                      stmt);
-         fprintf (dump_file, "  Replaced '");
-         print_generic_expr (dump_file, old_rhs, dump_flags);
-         fprintf (dump_file, "' with '");
-         print_generic_expr (dump_file, tmp, dump_flags);
-         fprintf (dump_file, "'\n");
-       }
-
-      /* Remove defining statements.  */
-      if (remove_prop_source_from_use (name))
-       did_something = 2;
-      else
-       did_something = MAX (did_something, 1);
+      gimple_assign_set_rhs_from_tree (gsi, tmp);
+      update_stmt (stmt);
+      return true;
     }
 
-  return did_something;
+  return false;
 }
 
 /* Propagate from the ssa name definition statements of COND_EXPR
@@ -588,48 +478,41 @@ forward_propagate_into_gimple_cond (gimple stmt)
 {
   int did_something = 0;
   location_t loc = gimple_location (stmt);
+  tree tmp;
+  enum tree_code code = gimple_cond_code (stmt);
+
+  /* We can do tree combining on SSA_NAME and comparison expressions.  */
+  if (TREE_CODE_CLASS (gimple_cond_code (stmt)) != tcc_comparison)
+    return 0;
+
+  tmp = forward_propagate_into_comparison_1 (loc, code,
+                                            boolean_type_node,
+                                            gimple_cond_lhs (stmt),
+                                            gimple_cond_rhs (stmt));
+  if (tmp)
+    {
+      if (dump_file && tmp)
+       {
+         tree cond = build2 (gimple_cond_code (stmt),
+                             boolean_type_node,
+                             gimple_cond_lhs (stmt),
+                             gimple_cond_rhs (stmt));
+         fprintf (dump_file, "  Replaced '");
+         print_generic_expr (dump_file, cond, 0);
+         fprintf (dump_file, "' with '");
+         print_generic_expr (dump_file, tmp, 0);
+         fprintf (dump_file, "'\n");
+       }
 
-  do {
-    tree tmp = NULL_TREE;
-    enum tree_code code = gimple_cond_code (stmt);
-
-    /* We can do tree combining on SSA_NAME and comparison expressions.  */
-    if (TREE_CODE_CLASS (gimple_cond_code (stmt)) == tcc_comparison)
-      tmp = forward_propagate_into_comparison (loc, code,
-                                              boolean_type_node,
-                                              gimple_cond_lhs (stmt),
-                                              gimple_cond_rhs (stmt));
-
-    if (tmp)
-      {
-       if (dump_file && tmp)
-         {
-            tree cond = build2 (gimple_cond_code (stmt),
-                               boolean_type_node,
-                               gimple_cond_lhs (stmt),
-                               gimple_cond_rhs (stmt));
-           fprintf (dump_file, "  Replaced '");
-           print_generic_expr (dump_file, cond, 0);
-           fprintf (dump_file, "' with '");
-           print_generic_expr (dump_file, tmp, 0);
-           fprintf (dump_file, "'\n");
-         }
-
-        gimple_cond_set_condition_from_tree (stmt, unshare_expr (tmp));
-       update_stmt (stmt);
-
-       /* Remove defining statements.  */
-       if (is_gimple_min_invariant (tmp))
-         did_something = 2;
-       else if (did_something == 0)
-         did_something = 1;
-
-       /* Continue combining.  */
-       continue;
-      }
+      gimple_cond_set_condition_from_tree (stmt, unshare_expr (tmp));
+      update_stmt (stmt);
 
-    break;
-  } while (1);
+      /* Remove defining statements.  */
+      if (is_gimple_min_invariant (tmp))
+       did_something = 2;
+      else if (did_something == 0)
+       did_something = 1;
+    }
 
   return did_something;
 }
@@ -648,57 +531,49 @@ forward_propagate_into_cond (gimple_stmt_iterator *gsi_p)
   gimple stmt = gsi_stmt (*gsi_p);
   location_t loc = gimple_location (stmt);
   int did_something = 0;
+  tree tmp = NULL_TREE;
+  tree cond = gimple_assign_rhs1 (stmt);
 
-  do {
-    tree tmp = NULL_TREE;
-    tree cond = gimple_assign_rhs1 (stmt);
-
-    /* We can do tree combining on SSA_NAME and comparison expressions.  */
-    if (COMPARISON_CLASS_P (cond))
-      tmp = forward_propagate_into_comparison (loc, TREE_CODE (cond),
+  /* We can do tree combining on SSA_NAME and comparison expressions.  */
+  if (COMPARISON_CLASS_P (cond))
+    tmp = forward_propagate_into_comparison_1 (loc, TREE_CODE (cond),
                                               boolean_type_node,
                                               TREE_OPERAND (cond, 0),
                                               TREE_OPERAND (cond, 1));
-    else if (TREE_CODE (cond) == SSA_NAME)
-      {
-       tree name = cond, rhs0;
-       gimple def_stmt = get_prop_source_stmt (name, true, NULL);
-       if (!def_stmt || !can_propagate_from (def_stmt))
-         return did_something;
-
-       rhs0 = gimple_assign_rhs1 (def_stmt);
-       tmp = combine_cond_expr_cond (loc, NE_EXPR, boolean_type_node, rhs0,
-                                     build_int_cst (TREE_TYPE (rhs0), 0),
-                                     false);
-      }
-
-    if (tmp)
-      {
-       if (dump_file && tmp)
-         {
-           fprintf (dump_file, "  Replaced '");
-           print_generic_expr (dump_file, cond, 0);
-           fprintf (dump_file, "' with '");
-           print_generic_expr (dump_file, tmp, 0);
-           fprintf (dump_file, "'\n");
-         }
+  else if (TREE_CODE (cond) == SSA_NAME)
+    {
+      tree name = cond, rhs0;
+      gimple def_stmt = get_prop_source_stmt (name, true, NULL);
+      if (!def_stmt || !can_propagate_from (def_stmt))
+       return did_something;
 
-       gimple_assign_set_rhs_from_tree (gsi_p, unshare_expr (tmp));
-       stmt = gsi_stmt (*gsi_p);
-       update_stmt (stmt);
+      rhs0 = gimple_assign_rhs1 (def_stmt);
+      tmp = combine_cond_expr_cond (loc, NE_EXPR, boolean_type_node, rhs0,
+                                   build_int_cst (TREE_TYPE (rhs0), 0),
+                                   false);
+    }
 
-       /* Remove defining statements.  */
-       if (is_gimple_min_invariant (tmp))
-         did_something = 2;
-       else if (did_something == 0)
-         did_something = 1;
+  if (tmp)
+    {
+      if (dump_file && tmp)
+       {
+         fprintf (dump_file, "  Replaced '");
+         print_generic_expr (dump_file, cond, 0);
+         fprintf (dump_file, "' with '");
+         print_generic_expr (dump_file, tmp, 0);
+         fprintf (dump_file, "'\n");
+       }
 
-       /* Continue combining.  */
-       continue;
-      }
+      gimple_assign_set_rhs_from_tree (gsi_p, unshare_expr (tmp));
+      stmt = gsi_stmt (*gsi_p);
+      update_stmt (stmt);
 
-    break;
-  } while (1);
+      /* Remove defining statements.  */
+      if (is_gimple_min_invariant (tmp))
+       did_something = 2;
+      else if (did_something == 0)
+       did_something = 1;
+    }
 
   return did_something;
 }
@@ -1224,6 +1099,116 @@ forward_propagate_addr_expr (tree name, tree rhs)
   return all && has_zero_uses (name);
 }
 
+
+/* Forward propagate the comparison defined in STMT like
+   cond_1 = x CMP y to uses of the form
+     a_1 = (T')cond_1
+     a_1 = !cond_1
+     a_1 = cond_1 != 0
+   Returns true if stmt is now unused.  */
+
+static bool
+forward_propagate_comparison (gimple stmt)
+{
+  tree name = gimple_assign_lhs (stmt);
+  gimple use_stmt;
+  tree tmp = NULL_TREE;
+
+  /* Don't propagate ssa names that occur in abnormal phis.  */
+  if ((TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
+       && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt)))
+      || (TREE_CODE (gimple_assign_rhs2 (stmt)) == SSA_NAME
+        && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs2 (stmt))))
+    return false;
+
+  /* Do not un-cse comparisons.  But propagate through copies.  */
+  use_stmt = get_prop_dest_stmt (name, &name);
+  if (!use_stmt)
+    return false;
+
+  /* Conversion of the condition result to another integral type.  */
+  if (is_gimple_assign (use_stmt)
+      && (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (use_stmt))
+         || TREE_CODE_CLASS (gimple_assign_rhs_code (use_stmt))
+            == tcc_comparison
+          || gimple_assign_rhs_code (use_stmt) == TRUTH_NOT_EXPR)
+      && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_lhs (use_stmt))))
+    {
+      tree lhs = gimple_assign_lhs (use_stmt);
+
+      /* We can propagate the condition into a conversion.  */
+      if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (use_stmt)))
+       {
+         /* Avoid using fold here as that may create a COND_EXPR with
+            non-boolean condition as canonical form.  */
+         tmp = build2 (gimple_assign_rhs_code (stmt), TREE_TYPE (lhs),
+                        gimple_assign_rhs1 (stmt), gimple_assign_rhs2 (stmt));
+       }
+      /* We can propagate the condition into X op CST where op
+        is EQ_EXPR or NE_EXPR and CST is either one or zero.  */
+      else if (TREE_CODE_CLASS (gimple_assign_rhs_code (use_stmt))
+              == tcc_comparison
+             && TREE_CODE (gimple_assign_rhs1 (use_stmt)) == SSA_NAME
+             && TREE_CODE (gimple_assign_rhs2 (use_stmt)) == INTEGER_CST)
+      {
+        enum tree_code code = gimple_assign_rhs_code (use_stmt);
+        tree cst = gimple_assign_rhs2 (use_stmt);
+       tree cond;
+
+       cond = build2 (gimple_assign_rhs_code (stmt),
+                      TREE_TYPE (cst),
+                      gimple_assign_rhs1 (stmt),
+                      gimple_assign_rhs2 (stmt));
+
+        tmp = combine_cond_expr_cond (gimple_location (use_stmt),
+                                     code, TREE_TYPE (lhs),
+                                     cond, cst, false);
+        if (tmp == NULL_TREE)
+          return false;
+      }
+      /* We can propagate the condition into a statement that
+        computes the logical negation of the comparison result.  */
+      else if (gimple_assign_rhs_code (use_stmt) == TRUTH_NOT_EXPR)
+       {
+         tree type = TREE_TYPE (gimple_assign_rhs1 (stmt));
+         bool nans = HONOR_NANS (TYPE_MODE (type));
+         enum tree_code code;
+         code = invert_tree_comparison (gimple_assign_rhs_code (stmt), nans);
+         if (code == ERROR_MARK)
+           return false;
+
+         tmp = build2 (code, TREE_TYPE (lhs), gimple_assign_rhs1 (stmt),
+                        gimple_assign_rhs2 (stmt));
+       }
+      else
+       return false;
+
+      {
+       gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
+       gimple_assign_set_rhs_from_tree (&gsi, unshare_expr (tmp));
+       use_stmt = gsi_stmt (gsi);
+       update_stmt (use_stmt);
+      }
+
+      if (dump_file && (dump_flags & TDF_DETAILS))
+       {
+         tree old_rhs = rhs_to_tree (TREE_TYPE (gimple_assign_lhs (stmt)),
+                                      stmt);
+         fprintf (dump_file, "  Replaced '");
+         print_generic_expr (dump_file, old_rhs, dump_flags);
+         fprintf (dump_file, "' with '");
+         print_generic_expr (dump_file, tmp, dump_flags);
+         fprintf (dump_file, "'\n");
+       }
+
+      /* Remove defining statements.  */
+      return remove_prop_source_from_use (name);
+    }
+
+  return false;
+}
+
+
 /* If we have lhs = ~x (STMT), look and see if earlier we had x = ~y.
    If so, we can change STMT into lhs = y which can later be copy
    propagated.  Similarly for negation.
@@ -1236,9 +1221,11 @@ forward_propagate_addr_expr (tree name, tree rhs)
    there's less work to do for each NOT/NEG expression we find.
    Backwards propagation needs to look at the statement in a single
    backlink.  Forward propagation needs to look at potentially more
-   than one forward link.  */
+   than one forward link.
 
-static void
+   Returns true when the statement was changed.  */
+
+static bool 
 simplify_not_neg_expr (gimple_stmt_iterator *gsi_p)
 {
   gimple stmt = gsi_stmt (*gsi_p);
@@ -1258,14 +1245,17 @@ simplify_not_neg_expr (gimple_stmt_iterator *gsi_p)
          gimple_assign_set_rhs_from_tree (gsi_p, rhs_def_operand);
          stmt = gsi_stmt (*gsi_p);
          update_stmt (stmt);
+         return true;
        }
     }
+
+  return false;
 }
 
 /* STMT is a SWITCH_EXPR for which we attempt to find equivalent forms of
    the condition which we may be able to optimize better.  */
 
-static void
+static bool
 simplify_gimple_switch (gimple stmt)
 {
   tree cond = gimple_switch_index (stmt);
@@ -1311,10 +1301,13 @@ simplify_gimple_switch (gimple stmt)
                {
                  gimple_switch_set_index (stmt, def);
                  update_stmt (stmt);
+                 return true;
                }
            }
        }
     }
+
+  return false;
 }
 
 /* For pointers p2 and p1 return p2 - p1 if the
@@ -2206,10 +2199,11 @@ combine_conversions (gimple_stmt_iterator *gsi)
   return false;
 }
 
-/* Main entry point for the forward propagation optimizer.  */
+/* Main entry point for the forward propagation and statement combine
+   optimizer.  */
 
 static unsigned int
-tree_ssa_forward_propagate_single_use_vars (void)
+ssa_forward_propagate_and_combine (void)
 {
   basic_block bb;
   unsigned int todoflags = 0;
@@ -2220,166 +2214,187 @@ tree_ssa_forward_propagate_single_use_vars (void)
     {
       gimple_stmt_iterator gsi;
 
-      /* Note we update GSI within the loop as necessary.  */
+      /* Apply forward propagation to all stmts in the basic-block.
+        Note we update GSI within the loop as necessary.  */
       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
        {
          gimple stmt = gsi_stmt (gsi);
+         tree lhs, rhs;
+         enum tree_code code;
 
-         /* If this statement sets an SSA_NAME to an address,
-            try to propagate the address into the uses of the SSA_NAME.  */
-         if (is_gimple_assign (stmt))
+         if (!is_gimple_assign (stmt))
            {
-             tree lhs = gimple_assign_lhs (stmt);
-             tree rhs = gimple_assign_rhs1 (stmt);
-             enum tree_code code = gimple_assign_rhs_code (stmt);
+             gsi_next (&gsi);
+             continue;
+           }
 
-             if (TREE_CODE (lhs) != SSA_NAME
-                 || has_zero_uses (lhs))
-               {
-                 gsi_next (&gsi);
-                 continue;
-               }
+         lhs = gimple_assign_lhs (stmt);
+         rhs = gimple_assign_rhs1 (stmt);
+         code = gimple_assign_rhs_code (stmt);
+         if (TREE_CODE (lhs) != SSA_NAME
+             || has_zero_uses (lhs))
+           {
+             gsi_next (&gsi);
+             continue;
+           }
 
-             if (code == ADDR_EXPR
-                 /* Handle pointer conversions on invariant addresses
-                    as well, as this is valid gimple.  */
-                 || (CONVERT_EXPR_CODE_P (code)
-                     && TREE_CODE (rhs) == ADDR_EXPR
-                     && POINTER_TYPE_P (TREE_TYPE (lhs))))
-               {
-                 tree base = get_base_address (TREE_OPERAND (rhs, 0));
-                 if ((!base
-                      || !DECL_P (base)
-                      || decl_address_invariant_p (base))
-                     && !stmt_references_abnormal_ssa_name (stmt)
-                     && forward_propagate_addr_expr (lhs, rhs))
-                   {
-                     release_defs (stmt);
-                     todoflags |= TODO_remove_unused_locals;
-                     gsi_remove (&gsi, true);
-                   }
-                 else
-                   gsi_next (&gsi);
-               }
-             else if (code == POINTER_PLUS_EXPR
-                      && can_propagate_from (stmt))
-               {
-                 if (TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST
-                     /* ???  Better adjust the interface to that function
-                        instead of building new trees here.  */
-                     && forward_propagate_addr_expr
-                          (lhs,
-                           build1 (ADDR_EXPR,
-                                   TREE_TYPE (rhs),
-                                   fold_build2 (MEM_REF,
-                                                TREE_TYPE (TREE_TYPE (rhs)),
-                                                rhs,
-                                                fold_convert
-                                                  (ptr_type_node,
-                                                   gimple_assign_rhs2 (stmt))))))
-                   {
-                     release_defs (stmt);
-                     todoflags |= TODO_remove_unused_locals;
-                     gsi_remove (&gsi, true);
-                   }
-                 else if (is_gimple_min_invariant (rhs))
-                   {
-                     /* Make sure to fold &a[0] + off_1 here.  */
-                     fold_stmt_inplace (stmt);
-                     update_stmt (stmt);
-                     if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
-                       gsi_next (&gsi);
-                   }
-                 else
-                   gsi_next (&gsi);
-               }
-             else if ((code == BIT_NOT_EXPR
-                       || code == NEGATE_EXPR)
-                      && TREE_CODE (rhs) == SSA_NAME)
-               {
-                 simplify_not_neg_expr (&gsi);
-                 gsi_next (&gsi);
-               }
-             else if (code == COND_EXPR)
-                {
-                  /* In this case the entire COND_EXPR is in rhs1. */
-                 int did_something;
-                 fold_defer_overflow_warnings ();
-                  did_something = forward_propagate_into_cond (&gsi);
-                 stmt = gsi_stmt (gsi);
-                 if (did_something == 2)
-                   cfg_changed = true;
-                 fold_undefer_overflow_warnings (!TREE_NO_WARNING (rhs)
-                   && did_something, stmt, WARN_STRICT_OVERFLOW_CONDITIONAL);
-                 gsi_next (&gsi);
-                }
-             else if (TREE_CODE_CLASS (code) == tcc_comparison)
-               {
-                 bool no_warning = gimple_no_warning_p (stmt);
-                 int did_something;
-                 fold_defer_overflow_warnings ();
-                 did_something = forward_propagate_comparison (stmt);
-                 if (did_something == 2)
-                   cfg_changed = true;
-                 fold_undefer_overflow_warnings
-                   (!no_warning && did_something,
-                    stmt, WARN_STRICT_OVERFLOW_CONDITIONAL);
-                 gsi_next (&gsi);
-               }
-             else if (code == BIT_AND_EXPR
-                      || code == BIT_IOR_EXPR
-                      || code == BIT_XOR_EXPR)
+         /* If this statement sets an SSA_NAME to an address,
+            try to propagate the address into the uses of the SSA_NAME.  */
+         if (code == ADDR_EXPR
+             /* Handle pointer conversions on invariant addresses
+                as well, as this is valid gimple.  */
+             || (CONVERT_EXPR_CODE_P (code)
+                 && TREE_CODE (rhs) == ADDR_EXPR
+                 && POINTER_TYPE_P (TREE_TYPE (lhs))))
+           {
+             tree base = get_base_address (TREE_OPERAND (rhs, 0));
+             if ((!base
+                  || !DECL_P (base)
+                  || decl_address_invariant_p (base))
+                 && !stmt_references_abnormal_ssa_name (stmt)
+                 && forward_propagate_addr_expr (lhs, rhs))
                {
-                 if (!simplify_bitwise_binary (&gsi))
-                   gsi_next (&gsi);
+                 release_defs (stmt);
+                 todoflags |= TODO_remove_unused_locals;
+                 gsi_remove (&gsi, true);
                }
-             else if (code == PLUS_EXPR
-                      || code == MINUS_EXPR)
+             else
+               gsi_next (&gsi);
+           }
+         else if (code == POINTER_PLUS_EXPR
+                  && can_propagate_from (stmt))
+           {
+             if (TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST
+                 /* ???  Better adjust the interface to that function
+                    instead of building new trees here.  */
+                 && forward_propagate_addr_expr
+                 (lhs,
+                  build1 (ADDR_EXPR,
+                          TREE_TYPE (rhs),
+                          fold_build2 (MEM_REF,
+                                       TREE_TYPE (TREE_TYPE (rhs)),
+                                       rhs,
+                                       fold_convert
+                                       (ptr_type_node,
+                                        gimple_assign_rhs2 (stmt))))))
                {
-                 cfg_changed |= associate_plusminus (stmt);
-                 gsi_next (&gsi);
+                 release_defs (stmt);
+                 todoflags |= TODO_remove_unused_locals;
+                 gsi_remove (&gsi, true);
                }
-             else if (CONVERT_EXPR_CODE_P (code)
-                      || code == FLOAT_EXPR
-                      || code == FIX_TRUNC_EXPR)
+             else if (is_gimple_min_invariant (rhs))
                {
-                 if (!combine_conversions (&gsi))
+                 /* Make sure to fold &a[0] + off_1 here.  */
+                 fold_stmt_inplace (stmt);
+                 update_stmt (stmt);
+                 if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
                    gsi_next (&gsi);
                }
              else
                gsi_next (&gsi);
            }
-         else if (gimple_code (stmt) == GIMPLE_SWITCH)
+         else if (TREE_CODE_CLASS (code) == tcc_comparison)
            {
-             simplify_gimple_switch (stmt);
+             forward_propagate_comparison (stmt);
              gsi_next (&gsi);
            }
-         else if (gimple_code (stmt) == GIMPLE_COND)
-           {
-             int did_something;
-             fold_defer_overflow_warnings ();
-             did_something = forward_propagate_into_gimple_cond (stmt);
-             if (did_something == 2)
-               cfg_changed = true;
-             fold_undefer_overflow_warnings (did_something, stmt,
-                                             WARN_STRICT_OVERFLOW_CONDITIONAL);
-             gsi_next (&gsi);
-           }
-         else if (is_gimple_call (stmt))
-           {
-             tree callee = gimple_call_fndecl (stmt);
-             if (callee == NULL_TREE
-                 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
-                 || !simplify_builtin_call (&gsi, callee))
-               gsi_next (&gsi);
-           }
          else
            gsi_next (&gsi);
        }
+
+      /* Combine stmts with the stmts defining their operands.
+        Note we update GSI within the loop as necessary.  */
+      for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi);)
+       {
+         gimple stmt = gsi_stmt (gsi);
+         bool changed = false;
+
+         switch (gimple_code (stmt))
+           {
+           case GIMPLE_ASSIGN:
+             {
+               tree rhs1 = gimple_assign_rhs1 (stmt);
+               enum tree_code code = gimple_assign_rhs_code (stmt);
+
+               if ((code == BIT_NOT_EXPR
+                    || code == NEGATE_EXPR)
+                   && TREE_CODE (rhs1) == SSA_NAME)
+                 changed = simplify_not_neg_expr (&gsi);
+               else if (code == COND_EXPR)
+                 {
+                   /* In this case the entire COND_EXPR is in rhs1. */
+                   int did_something;
+                   fold_defer_overflow_warnings ();
+                   did_something = forward_propagate_into_cond (&gsi);
+                   stmt = gsi_stmt (gsi);
+                   if (did_something == 2)
+                     cfg_changed = true;
+                   fold_undefer_overflow_warnings
+                     (!TREE_NO_WARNING (rhs1) && did_something, stmt,
+                      WARN_STRICT_OVERFLOW_CONDITIONAL);
+                   changed = did_something != 0;
+                 }
+               else if (TREE_CODE_CLASS (code) == tcc_comparison)
+                 {
+                   bool no_warning = gimple_no_warning_p (stmt);
+                   fold_defer_overflow_warnings ();
+                   changed = forward_propagate_into_comparison (&gsi);
+                   fold_undefer_overflow_warnings
+                       (!no_warning && changed,
+                        stmt, WARN_STRICT_OVERFLOW_CONDITIONAL);
+                 }
+               else if (code == BIT_AND_EXPR
+                        || code == BIT_IOR_EXPR
+                        || code == BIT_XOR_EXPR)
+                 changed = simplify_bitwise_binary (&gsi);
+               else if (code == PLUS_EXPR
+                        || code == MINUS_EXPR)
+                 changed = associate_plusminus (stmt);
+               else if (CONVERT_EXPR_CODE_P (code)
+                        || code == FLOAT_EXPR
+                        || code == FIX_TRUNC_EXPR)
+                 changed = combine_conversions (&gsi);
+               break;
+             }
+
+           case GIMPLE_SWITCH:
+             changed = simplify_gimple_switch (stmt);
+             break;
+
+           case GIMPLE_COND:
+             {
+               int did_something;
+               fold_defer_overflow_warnings ();
+               did_something = forward_propagate_into_gimple_cond (stmt);
+               if (did_something == 2)
+                 cfg_changed = true;
+               fold_undefer_overflow_warnings
+                 (did_something, stmt, WARN_STRICT_OVERFLOW_CONDITIONAL);
+               changed = did_something != 0;
+               break;
+             }
+
+           case GIMPLE_CALL:
+             {
+               tree callee = gimple_call_fndecl (stmt);
+               if (callee != NULL_TREE
+                   && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
+                 changed = simplify_builtin_call (&gsi, callee);
+               break;
+             }
+
+           default:;
+           }
+
+         /* If the stmt changed try combining it again.  */
+         if (!changed)
+           gsi_prev (&gsi);
+       }
     }
 
   if (cfg_changed)
     todoflags |= TODO_cleanup_cfg;
+
   return todoflags;
 }
 
@@ -2396,7 +2411,7 @@ struct gimple_opt_pass pass_forwprop =
   GIMPLE_PASS,
   "forwprop",                  /* name */
   gate_forwprop,               /* gate */
-  tree_ssa_forward_propagate_single_use_vars,  /* execute */
+  ssa_forward_propagate_and_combine,   /* execute */
   NULL,                                /* sub */
   NULL,                                /* next */
   0,                           /* static_pass_number */