[gcc r12-728] Replace unreachable code with an assert.

[gcc r12-728] Replace unreachable code with an assert.

[Martin Sebor]

https://gcc.gnu.org/g:de09c0ddb81e2dc0e35c2e362532e93ca417200c

commit r12-728-gde09c0ddb81e2dc0e35c2e362532e93ca417200c
Author: Martin Sebor <msebor@redhat.com>
Date:   Tue May 11 13:58:48 2021 -0600

    Replace unreachable code with an assert.
    
    Resolves:
    PR middle-end/21433 - The COMPONENT_REF case of expand_expr_real_1 is probably wrong
    
    gcc/ChangeLog:
    
            PR middle-end/21433
            * expr.c (expand_expr_real_1): Replace unreachable code with an assert.

Diff:
---
 gcc/expr.c | 57 ++-------------------------------------------------------
 1 file changed, 2 insertions(+), 55 deletions(-)

diff --git a/gcc/expr.c b/gcc/expr.c
index 1b65f6b3245..d09ee42e262 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -10949,61 +10949,8 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
       goto normal_inner_ref;
 
     case COMPONENT_REF:
-      /* If the operand is a CONSTRUCTOR, we can just extract the
-	 appropriate field if it is present.  */
-      if (TREE_CODE (treeop0) == CONSTRUCTOR)
-	{
-	  unsigned HOST_WIDE_INT idx;
-	  tree field, value;
-	  scalar_int_mode field_mode;
-
-	  FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (treeop0),
-				    idx, field, value)
-	    if (field == treeop1
-		/* We can normally use the value of the field in the
-		   CONSTRUCTOR.  However, if this is a bitfield in
-		   an integral mode that we can fit in a HOST_WIDE_INT,
-		   we must mask only the number of bits in the bitfield,
-		   since this is done implicitly by the constructor.  If
-		   the bitfield does not meet either of those conditions,
-		   we can't do this optimization.  */
-		&& (! DECL_BIT_FIELD (field)
-		    || (is_int_mode (DECL_MODE (field), &field_mode)
-			&& (GET_MODE_PRECISION (field_mode)
-			    <= HOST_BITS_PER_WIDE_INT))))
-	      {
-		if (DECL_BIT_FIELD (field)
-		    && modifier == EXPAND_STACK_PARM)
-		  target = 0;
-		op0 = expand_expr (value, target, tmode, modifier);
-		if (DECL_BIT_FIELD (field))
-		  {
-		    HOST_WIDE_INT bitsize = TREE_INT_CST_LOW (DECL_SIZE (field));
-		    scalar_int_mode imode
-		      = SCALAR_INT_TYPE_MODE (TREE_TYPE (field));
-
-		    if (TYPE_UNSIGNED (TREE_TYPE (field)))
-		      {
-			op1 = gen_int_mode ((HOST_WIDE_INT_1 << bitsize) - 1,
-					    imode);
-			op0 = expand_and (imode, op0, op1, target);
-		      }
-		    else
-		      {
-			int count = GET_MODE_PRECISION (imode) - bitsize;
-
-			op0 = expand_shift (LSHIFT_EXPR, imode, op0, count,
-					    target, 0);
-			op0 = expand_shift (RSHIFT_EXPR, imode, op0, count,
-					    target, 0);
-		      }
-		  }
-
-		return op0;
-	      }
-	}
-      goto normal_inner_ref;
-
+      gcc_assert (TREE_CODE (treeop0) != CONSTRUCTOR);
+      /* Fall through.  */
     case BIT_FIELD_REF:
     case ARRAY_RANGE_REF:
     normal_inner_ref: