I think the subject says what causes the problem and the reason why
we don't fold *&a into a[0] is because fold does not handle it
but fold_stmt does.  So what I did was to patch remove_useless_stmts_1
to do the folding for us (this is already done for the second testcase
in the PR, for MODIFY_EXPR).  I also removed the case for SWITCH_EXPR
in remove_useless_stmts_1 because it was not needed at all and just
slowed us down.

OK? Bootstrapped and tested on powerpc-darwin.



ChangeLog:

	* tree-cfg.c (remove_useless_stmts_1) <case SWITCH_EXPR>:
	Don't fold statement.
	<case ASM_EXPR>: Fold the statement.

testsuite/ChangeLog:
	* gcc.c-torture/compile/pr17529.c: Remove the xfail.