SUBREG Unrecognizable RTL

SUBREG Unrecognizable RTL

[daniel tian]

Hi:

Yeah. You are right. Here is another RTL unrecognized.  It happened
after reload.

(insn 749 156 147 22 (set (reg:HI 5 R5)
        (subreg:HI (mem/c:SI (plus:SI (reg/f:SI 15 R15)
                    (const_int 108 [0x6c])) [19 d0+0 S4 A32]) 0)) -1 (nil))

I traced the lots of functions like: reload, reload_as_needed,
emit_reload_insn, do_input_reload, emit_input_reload_insn in reload1.c
file. But I couldn't get any clue.
the gcc clashed in function: cleanup_subreg_operands. Because you can
see the RTL seems move reg to reg,  actually it load data from memory.
My target didn't accept this kind of RTL. The memory area is the
pseduo register.94. But the reg_renumber[i] < 0 &&
reg_equiv_memory_loc[i], then the pseduo register.94 was replaced with
memory location.

But I 've no idea about why it generates this kind of unrecognized RTL.
I have been hampered this problem for a while.

Any suggestion is appreciated.
Thanks very much.

Re: SUBREG Unrecognizable RTL

[daniel tian]

here are some information from the libgcc2.c.176r.greg. (BTY: the
error happened when cc1 build the libgcc2.c)

Reloads for insn # 147
Reload 0: reload_out (SI) = (reg/v:SI 99 [ __d0 ])
	GENERAL_REGS, RELOAD_FOR_OUTPUT (opnum = 0)
	reload_out_reg: (reg/v:SI 99 [ __d0 ])
	reload_reg_rtx: (reg:SI 5 R5)
Reload 1: reload_in (HI) = (subreg:HI (reg/v:SI 94 [ d0 ]) 0)
	GENERAL_REGS, RELOAD_FOR_INPUT (opnum = 1)
	reload_in_reg: (subreg:HI (reg/v:SI 94 [ d0 ]) 0)
	reload_reg_rtx: (reg:HI 5 R5)

So does it mean when the pseduo register 94 allocated fail, the memory
location will be substitute ?

Re: SUBREG Unrecognizable RTL

[Dave Korn]

daniel tian wrote:
> here are some information from the libgcc2.c.176r.greg. (BTY: the
> error happened when cc1 build the libgcc2.c)
> 
> Reloads for insn # 147
> Reload 0: reload_out (SI) = (reg/v:SI 99 [ __d0 ])
> 	GENERAL_REGS, RELOAD_FOR_OUTPUT (opnum = 0)
> 	reload_out_reg: (reg/v:SI 99 [ __d0 ])
> 	reload_reg_rtx: (reg:SI 5 R5)
> Reload 1: reload_in (HI) = (subreg:HI (reg/v:SI 94 [ d0 ]) 0)
> 	GENERAL_REGS, RELOAD_FOR_INPUT (opnum = 1)
> 	reload_in_reg: (subreg:HI (reg/v:SI 94 [ d0 ]) 0)
> 	reload_reg_rtx: (reg:HI 5 R5)
> 
> So does it mean when the pseduo register 94 allocated fail, the memory
> location will be substitute ?

  Yes, when the register allocator can't find a spare register for a variable,
it makes use of a stack slot instead.

> (insn 749 156 147 22 (set (reg:HI 5 R5)
>         (subreg:HI (mem/c:SI (plus:SI (reg/f:SI 15 R15)
>                     (const_int 108 [0x6c])) [19 d0+0 S4 A32]) 0)) -1 (nil))

  So, does your CPU support HImode sized load and store operations?

    cheers,
      DaveK

Re: SUBREG Unrecognizable RTL

[daniel tian]

Yeah. My target do have instructions support load/store HImode. And
the problem is fix. I just don't understand why.  Here is the
information I gotta: http://gcc.gnu.org/ml/gcc/2005-01/msg00788.html.
I defined a predicate function rice_memory_operand which calls the
function memory operand directly, and nothing else it do. I wrote it
because it's convenient to debug. This is the what make the RTL
unrecognizable.

This is weird. I have to hack it later.
Anyway, after fixed it, gcc is build success which means a great
forward step for me.

Thanks for your guys'help.
Best Wishes.

                daniel