pa reload problem

[John David Anglin]

> > stage1/xgcc -Bstage1/ -B/usr/local/hppa1.1-hp-hpux10.20/bin/ -c  -DIN_GCC    -g -O3 -fPIC -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wtraditional -pedantic -Wno-long-long  -DHAVE_CONFIG_H    -I. -I. -I../../gcc -I../../gcc/. -I../../gcc/config -I../../gcc/../include ../../gcc/c-typeck.c -o c-typeck.o
> > ../../gcc/c-typeck.c: In function `really_start_incremental_init':
> > ../../gcc/c-typeck.c:5180: output_operand: invalid expression as operand
> > ../../gcc/c-typeck.c:5180: Internal compiler error in output_operand_lossage, at final.c:3397
> > confused by earlier errors, bailing out
> 
> This error results from the following substitution which occurs in the
> "lreg" pass.  Here is the "lreg" rtl:
> 
> (insn 67 926 927 (set (reg/f:SI 107)
>         (mem/u:SI (lo_sum:SI (reg/f:SI 309)
>                 (unspec:SI[
>                         (symbol_ref:SI ("constructor_max_index"))
> 		    ]  0)) 0)) 82 {*pa.md:2352} (insn_list 65 (nil))
>     (expr_list:REG_EQUIV (mem/u:SI (lo_sum:SI (reg/f:SI 309)
> 		(unspec:SI[
> 			(symbol_ref:SI ("constructor_max_index"))
> 		    ]  0)) 0)
>         (expr_list:REG_DEAD (reg/f:SI 309)
>             (nil))))
> 
> ...
> 
> (insn 569 619 627 (set (reg/f:SI 232)
>         (reg/f:SI 107)) 69 {*pa.md:2099} (nil)
>     (expr_list:REG_DEAD (reg/f:SI 107)
>         (nil)))
> 
> Then, after the "greg" pass we get for insn 569:
> 
> (insn 569 619 627 (set (reg/f:SI 21 %r21)
>         (mem/u:SI (lo_sum:SI (reg/f:SI 8 %r8)
> 		(unspec:SI[
> 			(symbol_ref:SI ("constructor_max_index"))
> 		    ]  0)) 0)) 69 {*pa.md:2099} (nil)
>     (nil))

After further investigation, this appears to be a reload problem.  Reload
substitutes the mem for psuedo 107 because reg_equiv_mem[107] is set
to the above mem rtx and reg_renumber[107] = -1 (ie, there is no hard register
for the psuedo).  The function strict_memory_address_p is used to check
whether the the memory address is valid for the mode.  This uses
GO_IF_LEGITIMATE_ADDRESS.  The address is legit so reg_equiv_mem[107] gets
set.  The problem is reload doesn't appear to check if the insns resulting
from the substitution still match the conditions for the insn.  If it did,
it would find that the substituted mem is not a valid move_operand.

Any thoughts on what is the best approach to fix this?

Dave
-- 
J. David Anglin                                  dave.anglin@nrc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)