On Tue, Jun 9, 2015 at 3:39 PM, Jakub Jelinek <ja...@redhat.com> wrote: > 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.
(I assume you referred to -mx32 above. Please also note that -mx32 uses Pmode == SImode by default). Yes, please emit zero-extended address load to a DImode register, and use this register with UNSPEC_TP to form final DImode address. The LEA that will be generated from address load will use DImode inputs due to %H operand modifier and will output to (implicitly zero-extended) SImode register. FYI, you just hit two special cases here: - addresses that mention %fs and %gs are always in DImode - LEA input operands are also always in DImode, but compiler already takes care of it. Uros.
