expr.c line 8139 has this:
/* Attempt to return something suitable for generating an
indexed address, for machines that support that. */
if (modifier == EXPAND_SUM && mode == ptr_mode
&& host_integerp (treeop1, 0))
{
tree exp1 = treeop1;
op0 = expand_expr (treeop0, subtarget, VOIDmode,
EXPAND_SUM);
if (!REG_P (op0))
op0 = force_operand (op0, NULL_RTX);
if (!REG_P (op0))
op0 = copy_to_mode_reg (mode, op0);
return REDUCE_BIT_FIELD (gen_rtx_MULT (mode, op0,
gen_int_mode (tree_low_cst (exp1, 0),
TYPE_MODE (TREE_TYPE (exp1)))));
}
Why isn't there a check to see if the machine actually supports that
MULT before blindly generating it? The expand_mult() that follows is
able to handle that case if the machine doesn't have indexed addresses
or a real MUL insn.
