Re: PING: PING: patch: ICE in legitimize_pic_address for x86_64 mingw target

[Jan Hubicka <hubicka@ucw.cz>]

> Hi,
> 
> there is an ICE for __declspec(dllimport) imported variables. The checking 
> of pic seems to be to early in legitimize_address. The check for 
> TARGET_DLLIMPORT_DECL_ATTRIBUTES should be done infront AFAICS. I 
> bootstraped it for x86_64-pc-mingw32 and i686-pc-mignew32 and it seems to 
> work fine for me.
> I tested this patch for i686-pc-cygwin and x86_64-pc-mingw32 and I saw no 
> regressions.

Hi,
the patch looks fine, however I think you need to check range of
CONST_INT operand:
      if (GET_CODE (x) == CONST
          && GET_CODE (XEXP (x, 0)) == PLUS
	  && GET_CODE (XEXP (XEXP (x, 0), 0)) == SYMBOL_REF
	  && SYMBOL_REF_DLLIMPORT_P (XEXP (XEXP (x, 0), 0)))

so the offset won't end up exceeding 32bit encoding. Does Windows ABI
guarantee some constant value?  (GCC can generate constant offset that
points off the symbol's object memory area itself when simplifying more
complex memory references)

SYSV ABI reserve 16MB for this that is checked at few places:
          if (!CONST_INT_P (op1) || INTVAL (op1) >= 16*1024*1024 || INTVAL (op1) < -16*1024*1024)
				       
Honza
> 
> ChangeLog:
> 
> 2007-03-30  Kai Tietz  <kai.tietz@onevision.com>
> 
>         * i386.c: (legitimize_address): Move dllimported variable check
>         infront of legitimizing pic address of CONST symbols.
> 
> Regards,
>  i.A. Kai Tietz
> 
> 
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> Index: gcc/gcc/config/i386/i386.c
> ===================================================================
> --- gcc.orig/gcc/config/i386/i386.c
> +++ gcc/gcc/config/i386/i386.c
> @@ -7673,9 +7673,6 @@ legitimize_address (rtx x, rtx oldx ATTR
>        return gen_rtx_PLUS (Pmode, t, XEXP (XEXP (x, 0), 1));
>      }
>  
> -  if (flag_pic && SYMBOLIC_CONST (x))
> -    return legitimize_pic_address (x, 0);
> -
>    if (TARGET_DLLIMPORT_DECL_ATTRIBUTES)
>      {
>        if (GET_CODE (x) == SYMBOL_REF && SYMBOL_REF_DLLIMPORT_P (x))
> @@ -7690,6 +7687,9 @@ legitimize_address (rtx x, rtx oldx ATTR
>  	}
>      }
>  
> +  if (flag_pic && SYMBOLIC_CONST (x))
> +    return legitimize_pic_address (x, 0);
> +
>    /* Canonicalize shifts by 0, 1, 2, 3 into multiply */
>    if (GET_CODE (x) == ASHIFT
>        && CONST_INT_P (XEXP (x, 1))
> =