[parisc-linux] [PATCH] gcc/config/pa/ftpr.c fixes for new TRAMPOLINE_TEMPLATE in hppa's glibc.

[Carlos O'Donell]

> I'm not quite sure what the "-4" is intended to accomplish, I figure I
> could have prefixed the TREAMPOLINE_TEMPLATE with another jump that
> gives the right address? That still makes for an extra jump, and I'd
> rather have gcc just look in the right place first.
 
The easier fix is to change dl-machine.h to read:

    505 #define TRAMPOLINE_TEMPLATE(tramp_name, fixup_name)                     \
    506   extern void tramp_name (void);                                        \
    507   asm (                                                                 \
    508  "      .text\n"                                                        \
    509         /* FAKE bl to provide gcc's __cffc with fixup's address */      \
    510  "      bl      " #fixup_name ",%r2\n" /* Runtime address of fixup */   \
    511  "      .globl " #tramp_name "\n"                                       \
    512  "      .type " #tramp_name ", at function\n"                              \
    513   #tramp_name ":\n"                                                     \
    514         /* Save return pointer */                                       \
    515  "      stw     %r2,-20(%sp)\n"                                         \

The addition of the *fake* bl in that .text before the function allows gcc
to use the "-4" lookup to find the right 17-bit displacement towards "fixup"

The patch below *can* still go into gcc, and will speedup __cffc when running
with the new glibc.

The above changes are added into the latest glibc patches at:
http://www.parisc-linux.org/~carlos/glibc-hppa-patches-latest.tar.gz


> 2004-01-31  Carlos O'Donell  <carlos at baldric.uwo.ca>
> 
> 	* gcc/config/pa/fptr.c (__canonicalize_funcptr_for_compare): Add
> 	extra offset check for new glibc TRAMPOLINE_TEMPLATE.
> 
> Index: gcc/config/pa/fptr.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/config/pa/fptr.c,v
> retrieving revision 1.2
> diff -u -p -r1.2 fptr.c
> --- gcc/config/pa/fptr.c	9 Dec 2002 19:16:14 -0000	1.2
> +++ gcc/config/pa/fptr.c	31 Jan 2004 22:18:27 -0000
> @@ -35,7 +35,7 @@ Boston, MA 02111-1307, USA.  */
>     the template should it be necessary to change the current branch
>     position.  */
>  #define NOFFSETS 2
> -static int fixup_branch_offset[NOFFSETS] = { 32, -4 };
> +static int fixup_branch_offset[NOFFSETS] = { 36, 32, -4 };
>  
>  #define GET_FIELD(X, FROM, TO) \
>    ((X) >> (31 - (TO)) & ((1 << ((TO) - (FROM) + 1)) - 1))