[Bug target/26743] gcc generates unreachable branch

["dave at hiauly1 dot hia dot nrc dot ca" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #4 from dave at hiauly1 dot hia dot nrc dot ca  2006-03-19 17:09 -------
Subject: Re:  gcc generates unreachable branch

> ------- Comment #3 from tausq at debian dot org  2006-03-19 15:52 -------
> I think this is a bit different, the bit of code that causes the problem is:
> 
>  339796         .loc 1 38663 0
>  339797         or,<> %r28,%r0,%r3
>  339798         b .L25049
>  339799         copy %r4,%r19
> 
> This bit of code is (I think) generated by output_movb() in pa.c, which doesn't
> check if the branch target is reachable.

Looks like the same issue.

I'm somewhat swamped at the moment.  The code in output_cbranch provides
an example of how to fix this bug.  It was fixed in this patch:

2003-03-18  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>

        PR 10062
        * config/pa/pa-hpux.h (TARGET_HPUX_UNWIND_LIBRARY): Redefine.
        * pa-protos.h (output_lbranch): New prototype.
        * pa.c (compute_frame_size): Change size of the frame marker on the
        64-bit ports to 48 bytes.
        (pa_output_function_prologue): Document why SAVE_SP is set.
        (hppa_expand_prologue): Save previous stack pointer into frame marker
        on targets which use the hpux unwind library.
        (output_cbranch): Use output_lbranch.
        (output_lbranch): New function to output long unconditional branches.
        * pa.h (TARGET_HPUX_UNWIND_LIBRARY): Define.
        (STACK_POINTER_OFFSET): Update offset for 48-byte frame marker on
        64-bit ports.
        * pa.md (jump): Use output_lbranch.
        (allocate_stack): New expander for dynamic stack allocation.

A new length alternative may need to be needed to the patterns that
use output_movb.

Dave


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26743