Fix ICE in factor_out_conditional_conversion

[Eric Botcazou]

This is a regression present on the mainline and 6 branch and introduced by 
the new factor_out_conditional_conversion function:

eric@polaris:~/build/gcc/native> gcc/xgcc -Bgcc -S opt55.adb -O 
+===========================GNAT BUG DETECTED==============================+
| 7.0.0 20160523 (experimental) [trunk revision 236576] (x86_64-suse-linux) 
GCC error:|
| in make_ssa_name_fn, at tree-ssanames.c:266                              |
| Error detected around opt55.adb:15:4             

The function is trying to create a SSA_NAME of a RECORD_TYPE because it just 
stripped a VIEW_CONVERT_EXPR created by SRA:

  _1 = VIEW_CONVERT_EXPR<float>(VIEW_CONVERT_EXPR<struct 
opt55__f__S3b>(*c_4(D)).d1);

Fixed by bailing out if the new type is not is_gimple_reg_type.  The patch 
also removes a test which is trivially redundant (is_gimple_assign is subsumed 
into gimple_assign_cast_p).

Tested on x86_64-suse-linux, applied on the mainline and 6 branch as obvious.


2016-05-25  Eric Botcazou  <ebotca...@adacore.com>

        * tree-ssa-phiopt.c (factor_out_conditional_conversion): Remove
        redundant test and bail out if the type of the new operand is not
        a GIMPLE register type after stripping a VIEW_CONVERT_EXPR.


2016-05-25  Eric Botcazou  <ebotca...@adacore.com>

        * gnat.dg/opt55.ad[sb]: New test.

-- 
Eric Botcazou
Index: tree-ssa-phiopt.c
===================================================================
--- tree-ssa-phiopt.c	(revision 236576)
+++ tree-ssa-phiopt.c	(working copy)
@@ -438,15 +438,18 @@ factor_out_conditional_conversion (edge
   /* Check if arg0 is an SSA_NAME and the stmt which defines arg0 is
      a conversion.  */
   arg0_def_stmt = SSA_NAME_DEF_STMT (arg0);
-  if (!is_gimple_assign (arg0_def_stmt)
-      || !gimple_assign_cast_p (arg0_def_stmt))
+  if (!gimple_assign_cast_p (arg0_def_stmt))
     return NULL;
 
   /* Use the RHS as new_arg0.  */
   convert_code = gimple_assign_rhs_code (arg0_def_stmt);
   new_arg0 = gimple_assign_rhs1 (arg0_def_stmt);
   if (convert_code == VIEW_CONVERT_EXPR)
-    new_arg0 = TREE_OPERAND (new_arg0, 0);
+    {
+      new_arg0 = TREE_OPERAND (new_arg0, 0);
+      if (!is_gimple_reg_type (TREE_TYPE (new_arg0)))
+	return NULL;
+    }
 
   if (TREE_CODE (arg1) == SSA_NAME)
     {

-- { dg-do compile }
-- { dg-options "-O" }

package body Opt55 is

   function Cond (B : Boolean; If_True, If_False : Date) return Date is
   begin
      if B then
         return If_True;
      else
         return If_False;
      end if;
   end;

   function F (C : Rec2; B : Boolean) return Date is
   begin
      return Cond (B, C.D1, C.D2);
   end;

end Opt55;

package Opt55 is

   type Date is record
      D : Float;
   end record;

   type Rec1 (Kind : Boolean := False) is record
      case Kind is
         when True => N : Natural;
         when False => null;
      end case;
   end record;

   type Rec2 (D : Positive) is record
      R  : Rec1;
      D1 : Date;
      D2 : Date;
   end record;

   function F (C : Rec2; B : Boolean) return Date;

end Opt55;