[backport from gcc-4.8/trunk r195301 <mikpe@it.uu.se>]

gcc/

2013-01-18  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/56015
	* expr.c (expand_expr_real_2) <case COMPLEX_EXPR>: Handle
	the case where writing real complex part of target modifies
	op1.

gcc/testsuite/

2013-01-18  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/56015
	* gfortran.dg/pr56015.f90: New test.

--- gcc-4.7.2/gcc/expr.c.~1~	2012-08-06 16:34:27.000000000 +0200
+++ gcc-4.7.2/gcc/expr.c	2013-01-20 11:29:40.410261693 +0100
@@ -8696,6 +8696,54 @@ expand_expr_real_2 (sepops ops, rtx targ
 
       if (!target)
 	target = gen_reg_rtx (TYPE_MODE (type));
+      else
+	/* If target overlaps with op1, then either we need to force
+	   op1 into a pseudo (if target also overlaps with op0),
+	   or write the complex parts in reverse order.  */
+	switch (GET_CODE (target))
+	  {
+	  case CONCAT:
+	    if (reg_overlap_mentioned_p (XEXP (target, 0), op1))
+	      {
+		if (reg_overlap_mentioned_p (XEXP (target, 1), op0))
+		  {
+		  complex_expr_force_op1:
+		    temp = gen_reg_rtx (GET_MODE_INNER (GET_MODE (target)));
+		    emit_move_insn (temp, op1);
+		    op1 = temp;
+		    break;
+		  }
+	      complex_expr_swap_order:
+		/* Move the imaginary (op1) and real (op0) parts to their
+		   location.  */
+		write_complex_part (target, op1, true);
+		write_complex_part (target, op0, false);
+
+		return target;
+	      }
+	    break;
+	  case MEM:
+	    temp = adjust_address_nv (target,
+				      GET_MODE_INNER (GET_MODE (target)), 0);
+	    if (reg_overlap_mentioned_p (temp, op1))
+	      {
+		enum machine_mode imode = GET_MODE_INNER (GET_MODE (target));
+		temp = adjust_address_nv (target, imode,
+					  GET_MODE_SIZE (imode));
+		if (reg_overlap_mentioned_p (temp, op0))
+		  goto complex_expr_force_op1;
+		goto complex_expr_swap_order;
+	      }
+	    break;
+	  default:
+	    if (reg_overlap_mentioned_p (target, op1))
+	      {
+		if (reg_overlap_mentioned_p (target, op0))
+		  goto complex_expr_force_op1;
+		goto complex_expr_swap_order;
+	      }
+	    break;
+	  }
 
       /* Move the real (op0) and imaginary (op1) parts to their location.  */
       write_complex_part (target, op0, false);
--- gcc-4.7.2/gcc/testsuite/gfortran.dg/pr56015.f90.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.7.2/gcc/testsuite/gfortran.dg/pr56015.f90	2013-01-20 11:29:40.400261510 +0100
@@ -0,0 +1,16 @@
+! PR middle-end/56015
+! { dg-do run }
+! { dg-options "-Ofast -fno-inline" }
+
+program pr56015
+  implicit none
+  complex*16 p(10)
+  p(:) = (0.1d0, 0.2d0)
+  p(:) = (0.0d0, 1.0d0) * p(:)
+  call foo (p)
+contains
+  subroutine foo (p)
+    complex*16 p(10)
+    if (any (p .ne. (-0.2d0, 0.1d0))) call abort
+  end subroutine
+end program pr56015