Re: PATCH [mainline] Fix for long double (TARGET_LONG_DOUBLE_128) on ppc-darwin

[Geoffrey Keating <geoffk at geoffk dot org>]

Fariborz Jahanian <fjahanian@apple.com> writes:

> This is formal patch for an RFC I sent earlier.
> 
> Following test case fails with gcc3.5 on apple-ppc-darwin where 'long
> double' is 128 bits (TARGET_LONG_DOUBLE_128).
> 
> extern long double JUNK(long double ld);
> long double xdivcl()
> {
>     return JUNK(0.0L);
> }
> 
> Following pattern is generated to load 'long double' literal into two
> registers, using DImode:
> 
> (insn 8 26 27 0 (set (reg:DI 33 f1)
>  (mem/u/c:DI (lo_sum:SI (reg:SI 2 r2)
>  (const:SI (minus:SI (symbol_ref/u:SI ("*LC0") [flags 0x2])
>  (symbol_ref:SI ("<pic base>"))))) [0 S8 A64])) 327
> {*movdi_internal32} (nil)
>  (nil))
> 
> ...
> 
> (insn 9 27 10 0 (set (reg:DI 34 f2 [orig:33+8 ] [33])
>  (mem/u/c:DI (lo_sum:SI (reg:SI 2 r2)
>  (const:SI (minus:SI (symbol_ref/u:SI ("*LC0") [flags 0x2])
>  (symbol_ref:SI ("<pic base>"))))) [0 S8 A64])) 327
> {*movdi_internal32} (nil)
>  (nil))
> 
> Above pattern is generated in routine rs6000_emit_move and rejected in
> legitimate_lo_sum_address_p(...).
> 
> Attached patch bootstrapped and dejagnu tested on
> apple-ppc-darwin fixes the problem.
> 
> OK for FSF mainline?
> - Thanks, Fariborz (fjahanian@apple.com)

I think the second part of this patch won't work.  If you get into
rs6000_split_multireg_move with a non-offsettable address, there's no
code you can generate.  I'll look into this a bit more and come up
with a patch.

> ChangeLog:
> 
> 2004-07-24 Fariborz Jahanian <fjahanian@apple.com>
>         * config/rs6000/rs6000.c (legitimate_lo_sum_address_p):
>         DImode is legit.  mode with lo_sum pic address and when
>         long double is 128 bits.
>         (rs6000_split_multireg_move): Added case of LO_SUM when
>         register node is being obtained.
> 
> Patch:
> 
> Index: rs6000.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/config/rs6000/rs6000.c,v
> retrieving revision 1.671
> diff -c -p -r1.671 rs6000.c
> *** rs6000.c 23 Jul 2004 04:35:17 -0000 1.671
> --- rs6000.c 24 Jul 2004 18:32:19 -0000
> *************** legitimate_lo_sum_address_p (enum machin
> *** 3162,3168 ****
>         if (GET_MODE_NUNITS (mode) != 1)
>         return false;
>         if (GET_MODE_BITSIZE (mode) > 32
> !  && !(TARGET_HARD_FLOAT && TARGET_FPRS && mode == DFmode))
>         return false;
> 
>         return CONSTANT_P (x);
> --- 3162,3170 ----
>         if (GET_MODE_NUNITS (mode) != 1)
>         return false;
>         if (GET_MODE_BITSIZE (mode) > 32
> !  && !(TARGET_HARD_FLOAT && TARGET_FPRS
> !  && (mode == DFmode ||
> !  (TARGET_LONG_DOUBLE_128 && mode == DImode))))
>         return false;
> 
>         return CONSTANT_P (x);
> *************** rs6000_split_multireg_move (rtx dst, rtx
> *** 11077,11084 ****
>              we have change that register last.  */
> 
>           breg = (GET_CODE (XEXP (src, 0)) == PLUS
>                   ? XEXP (XEXP (src, 0), 0)
> !  : XEXP (src, 0));
> 
>           if (!REG_P (breg))
>               abort();
> --- 11079,11087 ----
>              we have change that register last.  */
> 
>           breg = (GET_CODE (XEXP (src, 0)) == PLUS
> + || GET_CODE (XEXP (src, 0)) == LO_SUM)
>                   ? XEXP (XEXP (src, 0), 0)
> !  : XEXP (src, 0);
> 
>           if (!REG_P (breg))
>               abort();