Re: [PATCH] add gdbarch_in_function_epilogue_p hook for sparc64

[Mark Kettenis <mark dot kettenis at xs4all dot nl>]

> From: jose.marchesi@oracle.com (Jose E. Marchesi)
> Date: Mon, 10 Feb 2014 13:40:23 +0100
> 
> 2013-10-16  Jose E. Marchesi  <jose.marchesi@oracle.com>
> 
> 	* sparc-tdep.c (sparc_in_function_epilogue_p): New function.
> 	(X_RETTURN): New macro.
> 	* sparc-tdep.h: sparc_in_function_epilogue_p prototype.
> 
> 	* sparc64-tdep.c (sparc64_init_abi): Hook
> 	sparc_in_function_epilogue_p.

Finally managed to test this on OpenBSD/sparc64.  Seems to fix an
XFAIL and a FAIL in mi-watch.exp for me.  Although those are a bit
suspect since (software) watchpoints are currently a bit broken on
OpenBSD/sparc64.  Pretty sure this doesn't cause any regressions
though, so please go ahaed.



> diff --git a/gdb/sparc-tdep.c b/gdb/sparc-tdep.c
> index 38b345b..311a156 100644
> --- a/gdb/sparc-tdep.c
> +++ b/gdb/sparc-tdep.c
> @@ -88,6 +88,9 @@ struct regset;
>  #define X_DISP19(i) ((((i) & 0x7ffff) ^ 0x40000) - 0x40000)
>  #define X_DISP10(i) ((((((i) >> 11) && 0x300) | (((i) >> 5) & 0xff)) ^ 0x200) - 0x200)
>  #define X_SIMM13(i) ((((i) & 0x1fff) ^ 0x1000) - 0x1000)
> +/* Macros to identify some instructions.  */
> +/* RETURN (RETT in V8) */
> +#define X_RETTURN(i) ((X_OP (i) == 0x2) && (X_OP3 (i) == 0x39))
>  
>  /* Fetch the instruction at PC.  Instructions are always big-endian
>     even if the processor operates in little-endian mode.  */
> @@ -452,6 +455,29 @@ sparc32_pseudo_register_write (struct gdbarch *gdbarch,
>    regcache_raw_write (regcache, regnum + 1, buf + 4);
>  }
>  
> +/* Implement "in_function_epilogue_p".  */
> +
> +int
> +sparc_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc)
> +{
> +  /* This function must return true if we are one instruction after an
> +     instruction that destroyed the stack frame of the current
> +     function.  The SPARC instructions used to restore the callers
> +     stack frame are RESTORE and RETURN/RETT.
> +
> +     Of these RETURN/RETT is a branch instruction and thus we return
> +     true if we are in its delay slot.
> +
> +     RESTORE is almost always found in the delay slot of a branch
> +     instruction that transfers control to the caller, such as JMPL.
> +     Thus the next instruction is in the caller frame and we don't
> +     need to do anything about it.  */
> +
> +  unsigned int insn = sparc_fetch_instruction (pc - 4);
> +
> +  return X_RETTURN (insn);
> +}
> +
>  
>  static CORE_ADDR
>  sparc32_frame_align (struct gdbarch *gdbarch, CORE_ADDR address)
> diff --git a/gdb/sparc-tdep.h b/gdb/sparc-tdep.h
> index b83d711..a065ebe 100644
> --- a/gdb/sparc-tdep.h
> +++ b/gdb/sparc-tdep.h
> @@ -193,6 +193,9 @@ extern struct sparc_frame_cache *
>  extern struct sparc_frame_cache *
>    sparc32_frame_cache (struct frame_info *this_frame, void **this_cache);
>  
> +extern int
> +  sparc_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc);
> +
>  
>  
>  extern int sparc_software_single_step (struct frame_info *frame);
> diff --git a/gdb/sparc64-tdep.c b/gdb/sparc64-tdep.c
> index 52958df..9e4db3a 100644
> --- a/gdb/sparc64-tdep.c
> +++ b/gdb/sparc64-tdep.c
> @@ -1196,6 +1196,7 @@ sparc64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
>      (gdbarch, default_stabs_argument_has_addr);
>  
>    set_gdbarch_skip_prologue (gdbarch, sparc64_skip_prologue);
> +  set_gdbarch_in_function_epilogue_p (gdbarch, sparc_in_function_epilogue_p);
>  
>    /* Hook in the DWARF CFI frame unwinder.  */
>    dwarf2_frame_set_init_reg (gdbarch, sparc64_dwarf2_frame_init_reg);
>