Re: [PATCH] Fix ix86_split_long_move collision handling with TLS (PR target/66470)

[Jakub Jelinek <jakub@redhat.com>]

On Tue, Jun 09, 2015 at 03:21:55PM +0200, Uros Bizjak wrote:
> I'm afraid that simple scan loop won't work correctly on x32. There
> are some issues with UNSPEC_TP for this target, so we have to generate
> zero_extend of SImode UNSPEC, e.g.:
> 
> (plus:DI (zero_extend:DI (unspec:SI [...] UNSPEC_TP) (reg:DI ...))
> 
> as can be seen in get_thread_pointer to construct the address. It
> looks that your loop won't find the UNSPEC_TP tag in the above case.

You're right, for -m32 it would need to start with
   rtx *x = &addr;
+  while (GET_CODE (*x) == ZERO_EXTEND
+	 || GET_CODE (*x) == AND
+	 || GET_CODE (*x) == SUBREG)
+    x = &XEXP (*x, 0);
to get at the PLUS.  Now, with either the original patch with the above
ammendment, or with the iterators, the question is what to do
with the UNSPEC_TP for -m32.  Is it ok to just use addr32 on the
lea and use normal Pmode (== DImode) addressing for the memory reads
(if I read the code well, that is what it does right now for the non-TLS
ones:
          if (GET_MODE (base) != Pmode)
            base = gen_rtx_REG (Pmode, REGNO (base));
)?  Then we'd need to change tls_base mode to Pmode.

	Jakub