[PATCH] correct parameter alignment for library calls in calls.c

[Hariharan]

Hi Ian,
Can you please review the patch below? It is related to the issue that 
you raised before. Please see 
http://gcc.gnu.org/ml/gcc-patches/2007-02/msg00716.html

Regards
Hari

Hariharan wrote:
> Hi,
> I found a bug while testing latest gcc sources in the picochip port. 
> It was small enough that i thought i could fix it myself.
>
> In expr.c, function emit_push_insn, with strict_alignment, if "align" 
> was not as strong as what is needed for the mode, we now try move the 
> value to a properly aligned temp (gathered using assign_temp). When 
> this change was made, calls to emit_push_insn from calls.c have been 
> changed to properly emit "align". But, there is still a place in 
> calls.c, in function emit_library_call_value_1, lines ~3720, where we 
> have a call to emit_push_insn with PARM_BOUNDARY as the alignment. 
> Note that we pass a NULL_TREE as well. In usual targets, 
> PARM_BOUNDARY(generally 4 bytes) would probably suffice for parameters 
> passed on stack. Ours is a bit unusual in that we only *require* 2 
> byte alignment, but we enforce STRICT_ALIGNMENT.
>
> In my opinion, the call to emit_push_insn should get the proper 
> alignment for the parameter and then use that for the parameter 
> "align", instead of the current PARM_BOUNDARY.
>
> I see that Ian raised this issue when the original change was made. 
> http://gcc.gnu.org/ml/gcc-patches/2007-02/msg00716.html
>
> I am submitting a patch with the change. I have tested it on our port 
> (which is quite unusual in its own respects) and i686-pc-linux-gnu 
> bootstrap and tested it.
>
> Regards
> Hari
>
> Index: gcc/calls.c
> ===================================================================
> --- gcc/calls.c (revision 132323)
> +++ gcc/calls.c (working copy)
> @@ -3660,6 +3660,7 @@
>       rtx val = argvec[argnum].value;
>       rtx reg = argvec[argnum].reg;
>       int partial = argvec[argnum].partial;
> +      unsigned int parm_align = argvec[argnum].locate.boundary;
>       int lower_bound = 0, upper_bound = 0, i;
>
>       if (! (reg != 0 && partial == 0))
> @@ -3721,7 +3722,7 @@
>                }
>            }
>
> -         emit_push_insn (val, mode, NULL_TREE, NULL_RTX, PARM_BOUNDARY,
> +         emit_push_insn (val, mode, NULL_TREE, NULL_RTX, parm_align,
>                          partial, reg, 0, argblock,
>                          GEN_INT (argvec[argnum].locate.offset.constant),
>                          reg_parm_stack_space,
>
>