https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104117
--- Comment #15 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Vladimir Makarov from comment #13)
> I think there are two code spots whose pitfalls resulted in the PR.
>
> The first one is in rs6000.cc::legitimate_lo_sum_address_p which permits
> wrong pic low-sum address.
Ack,
> Another one is in lra-constraints.cc::process_address_1 which permits put
> wrong low-sum address in reg and use the reg in memory.
>
> The following patch solves the problem:
>
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index 5404fb18755..306f67f26c4 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -8202,7 +8202,7 @@ legitimate_lo_sum_address_p (machine_mode mode, rtx x,
> int strict)
> {
> bool large_toc_ok;
>
> - if (DEFAULT_ABI == ABI_V4 && flag_pic)
> + if ((DEFAULT_ABI == ABI_V4 || DEFAULT_ABI == ABI_DARWIN) && flag_pic)
> return false;
> /* LRA doesn't use LEGITIMIZE_RELOAD_ADDRESS as it usually calls
> push_reload from reload pass code. LEGITIMIZE_RELOAD_ADDRESS
I have a somewhat wider fix which accounts for the case that UNSPEC [
SYMBOL_REF ] MACHOPIC_UNSPEC_OFFSET *is* valid, where SYMBOL_REF is not (but
the change you have made could be sufficient - will try to get that into a
retest soon).
> diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
> index 30d088afbca..998e82be54f 100644
> --- a/gcc/lra-constraints.c
> +++ b/gcc/lra-constraints.c
> @@ -3517,21 +3517,8 @@ process_address_1 (int nop, bool check_only_p,
> *ad.inner = gen_rtx_LO_SUM (Pmode, new_reg, addr);
> if (!valid_address_p (op, &ad, cn))
> {
> - /* Try to put lo_sum into register. */
> - insn = emit_insn (gen_rtx_SET
> - (new_reg,
> - gen_rtx_LO_SUM (Pmode, new_reg,
> addr)));
> - code = recog_memoized (insn);
> - if (code >= 0)
> - {
> - *ad.inner = new_reg;
> - if (!valid_address_p (op, &ad, cn))
> - {
> - *ad.inner = addr;
> - code = -1;
> - }
> - }
> -
> + *ad.inner = addr;
> + code = -1;
> }
> }
> if (code < 0)
>
> The patch was successfully tested on x86-64/ppc64 under Linux.
The second part of the patch is the same as what I was testing.
How to proceed on this (testing an LRA change widely enough)?
