http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58805
--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to vries from comment #10)
> I've tried out the example from comment 9.
>
> Tree-tail-merge considers the statements without effect because:
> ...
> (gdb) call debug_gimple_stmt (stmt)
> # .MEM_10 = VDEF <.MEM_3(D)>
> __asm__("movq $42, %0
> movq %0, %1
> " : "t" "=&r" t_8, "r" "=r" *x_4(D));
> (gdb) call gimple_has_side_effects (stmt)
> $2 = false
> ...
> and tree-ssa-tail-merge.c:stmt_local_def will return true.
>
> The side effect of the asm is in the expression for the output operand, so
> gimple_has_side_effects should return true.
No it shouldn't. It should return true if the stmt has side-effects that
are _not_ explicit in the statement. This side-effect is explicitely there.
