On Sun, Dec 23, 2012 at 10:43 AM, Richard Sandiford
<rdsandif...@googlemail.com> wrote:
> Some of the maths builtins can expand to a call followed by a bit
> of postprocessing. With 4.8's PARALLEL return optimisations, these
> embedded calls might return a PARALLEL of pseudos, but the postprocessing
> isn't prepared to deal with that. This leads to an ICE in builtins-53.c
> on n32 and n64 mips64-linux-gnu.
>
> One fix might have been to pass an explicit register target to the
> expand routines, but that target's only a hint. This patch instead
> adds an avoid_group_rtx function (named after gen_group_rtx) to convert
> PARALLELs to pseudos where necessary.
>
> I wondered whether it was really safe for expand_builtin_int_roundingfn_2
> to pass "target == const0_rtx" as the "ignore" parameter to expand_call,
> given that we don't actually ignore the return value ourselves
> (even if the caller does). I suppose it is safe though,
> since expand_call will always return const0_rtx in that case,
> and this code is dealing with integer return values.
>
> Tested on mips64-linux-gnu. OK to install? Or is there a better way?
You didn't add a testcase so I can't check myself - but why isn't
using force_reg enough here? I can imagine other cases than PARALLELs
that are not well handled, no?
Thanks,
Richard.
> Richard
>
>
> gcc/
> * expr.h (avoid_group_rtx): Declare.
> * expr.c (avoid_group_rtx): New function.
> * builtins.c (expand_builtin_int_roundingfn): Call it.
> (expand_builtin_int_roundingfn_2): Likewise.
>
> Index: gcc/expr.h
> ===================================================================
> --- gcc/expr.h 2012-12-23 09:21:21.969086853 +0000
> +++ gcc/expr.h 2012-12-23 09:32:03.487440220 +0000
> @@ -334,6 +334,8 @@ extern rtx emit_group_move_into_temps (r
> PARALLEL. */
> extern void emit_group_store (rtx, rtx, tree, int);
>
> +extern rtx avoid_group_rtx (rtx, tree);
> +
> /* Copy BLKmode object from a set of registers. */
> extern void copy_blkmode_from_reg (rtx, rtx, tree);
>
> Index: gcc/expr.c
> ===================================================================
> --- gcc/expr.c 2012-12-23 09:21:21.980086911 +0000
> +++ gcc/expr.c 2012-12-23 09:32:03.485440208 +0000
> @@ -2079,6 +2079,23 @@ emit_group_store (rtx orig_dst, rtx src,
> emit_move_insn (orig_dst, dst);
> }
>
> +/* Return a form of X that does not use a PARALLEL. TYPE is the type
> + of the value stored in X. */
> +
> +rtx
> +avoid_group_rtx (rtx x, tree type)
> +{
> + enum machine_mode mode = TYPE_MODE (type);
> + gcc_checking_assert (GET_MODE (x) == VOIDmode || GET_MODE (x) == mode);
> + if (GET_CODE (x) == PARALLEL)
> + {
> + rtx result = gen_reg_rtx (mode);
> + emit_group_store (result, x, type, int_size_in_bytes (type));
> + return result;
> + }
> + return x;
> +}
> +
> /* Copy a BLKmode object of TYPE out of a register SRCREG into TARGET.
>
> This is used on targets that return BLKmode values in registers. */
> Index: gcc/builtins.c
> ===================================================================
> --- gcc/builtins.c 2012-12-23 09:21:21.981086916 +0000
> +++ gcc/builtins.c 2012-12-23 09:34:47.813323158 +0000
> @@ -2757,6 +2757,7 @@ expand_builtin_int_roundingfn (tree exp,
> exp = build_call_nofold_loc (EXPR_LOCATION (exp), fallback_fndecl, 1, arg);
>
> tmp = expand_normal (exp);
> + tmp = avoid_group_rtx (tmp, TREE_TYPE (exp));
>
> /* Truncate the result of floating point optab to integer
> via expand_fix (). */
> @@ -2860,6 +2861,7 @@ expand_builtin_int_roundingfn_2 (tree ex
> fallback_fndecl, 1, arg);
>
> target = expand_call (exp, NULL_RTX, target == const0_rtx);
> + target = avoid_group_rtx (target, TREE_TYPE (exp));
> return convert_to_mode (mode, target, 0);
> }
>
