[Ada] Fix ICE on multi-dimensional array

[Eric Botcazou <ebotcazou@adacore.com>]

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This is a regression present on the mainline, 7 and 6 branches, in the form of 
an ICE during tree-sra, which is confused by an unconstrained array type.

Tested on x86_64-suse-linux, applied on mainline, 7 and 6 branches.


2017-09-05  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc-interface/trans.c (pos_to_constructor): Skip conversions to an
	unconstrained array type.


2017-09-05  Eric Botcazou  <ebotcazou@adacore.com>

	* testsuite/gnat.dg/array29.ad[sb]: New test.

-- 
Eric Botcazou

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Index: gcc-interface/trans.c
===================================================================
--- gcc-interface/trans.c	(revision 251553)
+++ gcc-interface/trans.c	(working copy)
@@ -9826,7 +9826,14 @@ pos_to_constructor (Node_Id gnat_expr, t
 				       gnat_component_type);
       else
 	{
-	  gnu_expr = gnat_to_gnu (gnat_expr);
+	  /* If the expression is a conversion to an unconstrained array type,
+	     skip it to avoid spilling to memory.  */
+	  if (Nkind (gnat_expr) == N_Type_Conversion
+	      && Is_Array_Type (Etype (gnat_expr))
+	      && !Is_Constrained (Etype (gnat_expr)))
+	    gnu_expr = gnat_to_gnu (Expression (gnat_expr));
+	  else
+	    gnu_expr = gnat_to_gnu (gnat_expr);
 
 	  /* Before assigning the element to the array, make sure it is
 	     in range.  */

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

package body Array29 is

  procedure Copy (Src : in Matrix; Dst : out Matrix) is
  begin
    for I in Src'Range (1) loop
      for J in Src'Range (2) loop
        Dst (I, J) := Src (I, J);
      end loop;
    end loop;
  end;

  procedure Proc is
    N : constant := 2;
    FM1 : constant Matrix (1 .. N, 1 .. N) := ((1.0, 2.0), (3.0, 4.0));
    FM2 : constant Matrix (1 .. N, 1 .. N) := ((1.0, 2.0), (3.0, 4.0));
    A : constant array (1 .. 2) of Matrix (1 .. N, 1 .. N)
      := (Matrix (FM1), Matrix (FM2));
    Final : Matrix (1 .. N, 1 .. N);
  begin
    Copy (Src => A (1), Dst => Final);
  end;

end Array29;

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package Array29 is

  type Matrix is array (Integer range <>, Integer range <>) of Long_Float;

  procedure Proc;

end Array29;