Re: [PR64164] drop copyrename, integrate into expand

[Richard Biener <richard.guenther@gmail.com>]

On Wed, Aug 19, 2015 at 8:45 AM, Alexandre Oliva <aoliva@redhat.com> wrote:
> On Aug 18, 2015, Alexandre Oliva <aoliva@redhat.com> wrote:
>
>>>> On Aug 17, 2015, Christophe Lyon <christophe.lyon@linaro.org> wrote:
>>>>> Since this was committed (r226901), I can see that the compiler build
>>>>> fails for armeb targets, when building libgcc:
>
>> This patch fixes this particular case.  I'll also add this configuration
>> to the cross build tests I'm going to rerun shortly, before submitting a
>> followup formally, to see whether other non-MEM mems need to be handled
>> explicitly.
>
> On Aug 17, 2015, Andreas Schwab <schwab@linux-m68k.org> wrote:
>
>> Andreas Schwab <schwab@linux-m68k.org> writes:
>
>>> Alexandre Oliva <aoliva@redhat.com> writes:
>>>
>>>> Would you be so kind as to give it a spin on a m68k native?  TIA,
>>>
>>> I tried it on ia64, and it falls flat on the floor.
>
>> It fixes the m68k failures, though.
>
> On Aug 17, 2015, Alexandre Oliva <aoliva@redhat.com> wrote:
>
>>> I tried it on ia64, and it falls flat on the floor.
>
>> Doh, I see a logic flaw in the patch I posted.
>
> There were other shortcomings in the snippets I posted before, revealed
> by testing on on various other targets: remaining BLKmode asserts,
> failure to deal with parms without a default def and split complex args
> with an unassigned stack address.  This patch fixes them all.
>
> It was regstrapped on x86_64-linux-gnu, i686-linux-gnu, ppc64-linux-gnu,
> ppc64el-linux-gnu, and further tested with a compile-only 'make all' on
> a binutils+gcc+newlib tree on all tens of cross targets mentioned
> before, plus the armeb configuration Christophe mentioned.
>
> Ok to install?

Ok.

Thanks,
Richard.

>
> [PR64164] fix regressions reported on m68k and armeb
>
> From: Alexandre Oliva <aoliva@redhat.com>
>
> Defer stack slot address assignment for all parms that can't live in
> pseudos, and accept pseudos assignments in assign_param_setup_block.
>
> for  gcc/ChangeLog
>
>         PR rtl-optimization/64164
>         * cfgexpand.c (parm_maybe_byref_p): Renamed to...
>         (parm_in_stack_slot_p): ... this.  Disregard mode, what
>         matters is whether the parm will live in a pseudo or a stack
>         slot.
>         (expand_one_ssa_partition): Deal with params without a default
>         def.  Disregard mode.
>         * cfgexpand.h: Renamed function declaration.
>         * tree-ssa-coalesce.c: Adjust.
>         * function.c (split_complex_args): Allocate stack slot for
>         unassigned parms before splitting.
>         (parm_in_unassigned_mem_p): New.  Use it instead of
>         parm_maybe_byref_p throughout this file.
>         (assign_parm_setup_block): Use it.  Accept pseudos in the
>         expand-assigned rtl.
>         (assign_parm_setup_reg): Drop BLKmode requirement.
>         (assign_parm_setup_stack): Allocate and fill in the address of
>         unassigned MEM parms.
> ---
>  gcc/cfgexpand.c         |   44 ++++++++++++++++++++++------
>  gcc/cfgexpand.h         |    2 +
>  gcc/function.c          |   74 ++++++++++++++++++++++++++++++++++++++++-------
>  gcc/tree-ssa-coalesce.c |    4 +--
>  4 files changed, 100 insertions(+), 24 deletions(-)
>
> diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
> index 0bc20f6..d567a87 100644
> --- a/gcc/cfgexpand.c
> +++ b/gcc/cfgexpand.c
> @@ -172,17 +172,23 @@ leader_merge (tree cur, tree next)
>    return cur;
>  }
>
> -/* Return true if VAR is a PARM_DECL or a RESULT_DECL of type BLKmode.
> +/* Return true if VAR is a PARM_DECL or a RESULT_DECL that ought to be
> +   assigned to a stack slot.  We can't have expand_one_ssa_partition
> +   choose their address: the pseudo holding the address would be set
> +   up too late for assign_params to copy the parameter if needed.
> +
>     Such parameters are likely passed as a pointer to the value, rather
>     than as a value, and so we must not coalesce them, nor allocate
>     stack space for them before determining the calling conventions for
> -   them.  For their SSA_NAMEs, expand_one_ssa_partition emits RTL as
> -   MEMs with pc_rtx as the address, and then it replaces the pc_rtx
> -   with NULL so as to make sure the MEM is not used before it is
> -   adjusted in assign_parm_setup_reg.  */
> +   them.
> +
> +   For their SSA_NAMEs, expand_one_ssa_partition emits RTL as MEMs
> +   with pc_rtx as the address, and then it replaces the pc_rtx with
> +   NULL so as to make sure the MEM is not used before it is adjusted
> +   in assign_parm_setup_reg.  */
>
>  bool
> -parm_maybe_byref_p (tree var)
> +parm_in_stack_slot_p (tree var)
>  {
>    if (!var || VAR_P (var))
>      return false;
> @@ -190,7 +196,7 @@ parm_maybe_byref_p (tree var)
>    gcc_assert (TREE_CODE (var) == PARM_DECL
>               || TREE_CODE (var) == RESULT_DECL);
>
> -  return TYPE_MODE (TREE_TYPE (var)) == BLKmode;
> +  return !use_register_for_decl (var);
>  }
>
>  /* Return the partition of the default SSA_DEF for decl VAR.  */
> @@ -1343,17 +1349,35 @@ expand_one_ssa_partition (tree var)
>
>    if (!use_register_for_decl (var))
>      {
> -      if (parm_maybe_byref_p (SSA_NAME_VAR (var))
> -         && ssa_default_def_partition (SSA_NAME_VAR (var)) == part)
> +      /* We can't risk having the parm assigned to a MEM location
> +        whose address references a pseudo, for the pseudo will only
> +        be set up after arguments are copied to the stack slot.
> +
> +        If the parm doesn't have a default def (e.g., because its
> +        incoming value is unused), then we want to let assign_params
> +        do the allocation, too.  In this case we want to make sure
> +        SSA_NAMEs associated with the parm don't get assigned to more
> +        than one partition, lest we'd create two unassigned stac
> +        slots for the same parm, thus the assert at the end of the
> +        block.  */
> +      if (parm_in_stack_slot_p (SSA_NAME_VAR (var))
> +         && (ssa_default_def_partition (SSA_NAME_VAR (var)) == part
> +             || !ssa_default_def (cfun, SSA_NAME_VAR (var))))
>         {
>           expand_one_stack_var_at (var, pc_rtx, 0, 0);
>           rtx x = SA.partition_to_pseudo[part];
>           gcc_assert (GET_CODE (x) == MEM);
> -         gcc_assert (GET_MODE (x) == BLKmode);
>           gcc_assert (XEXP (x, 0) == pc_rtx);
>           /* Reset the address, so that any attempt to use it will
>              ICE.  It will be adjusted in assign_parm_setup_reg.  */
>           XEXP (x, 0) = NULL_RTX;
> +         /* If the RTL associated with the parm is not what we have
> +            just created, the parm has been split over multiple
> +            partitions.  In order for this to work, we must have a
> +            default def for the parm, otherwise assign_params won't
> +            know what to do.  */
> +         gcc_assert (DECL_RTL_IF_SET (SSA_NAME_VAR (var)) == x
> +                     || ssa_default_def (cfun, SSA_NAME_VAR (var)));
>         }
>        else if (defer_stack_allocation (var, true))
>         add_stack_var (var);
> diff --git a/gcc/cfgexpand.h b/gcc/cfgexpand.h
> index 987cf356..d168672 100644
> --- a/gcc/cfgexpand.h
> +++ b/gcc/cfgexpand.h
> @@ -22,7 +22,7 @@ along with GCC; see the file COPYING3.  If not see
>
>  extern tree gimple_assign_rhs_to_tree (gimple);
>  extern HOST_WIDE_INT estimated_stack_frame_size (struct cgraph_node *);
> -extern bool parm_maybe_byref_p (tree);
> +extern bool parm_in_stack_slot_p (tree);
>  extern rtx get_rtl_for_parm_ssa_default_def (tree var);
>
>
> diff --git a/gcc/function.c b/gcc/function.c
> index 715c19f..222c76f 100644
> --- a/gcc/function.c
> +++ b/gcc/function.c
> @@ -153,6 +153,7 @@ static void do_clobber_return_reg (rtx, void *);
>  static void do_use_return_reg (rtx, void *);
>  static rtx rtl_for_parm (struct assign_parm_data_all *, tree);
>  static void maybe_reset_rtl_for_parm (tree);
> +static bool parm_in_unassigned_mem_p (tree, rtx);
>
>
>  /* Stack of nested functions.  */
> @@ -2326,6 +2327,22 @@ split_complex_args (struct assign_parm_data_all *all, vec<tree> *args)
>               rtx rtl = rtl_for_parm (all, cparm);
>               if (rtl)
>                 {
> +                 /* If this is parm is unassigned, assign it now: the
> +                    newly-created decls wouldn't expect the need for
> +                    assignment, and if they were assigned
> +                    independently, they might not end up in adjacent
> +                    slots, so unsplit wouldn't be able to fill in the
> +                    unassigned address of the complex MEM.  */
> +                 if (parm_in_unassigned_mem_p (cparm, rtl))
> +                   {
> +                     int align = STACK_SLOT_ALIGNMENT
> +                       (TREE_TYPE (cparm), GET_MODE (rtl), MEM_ALIGN (rtl));
> +                     rtx loc = assign_stack_local
> +                       (GET_MODE (rtl), GET_MODE_SIZE (GET_MODE (rtl)),
> +                        align);
> +                     XEXP (rtl, 0) = XEXP (loc, 0);
> +                   }
> +
>                   SET_DECL_RTL (p, read_complex_part (rtl, false));
>                   SET_DECL_RTL (decl, read_complex_part (rtl, true));
>
> @@ -2934,6 +2951,27 @@ assign_parm_setup_block_p (struct assign_parm_data_one *data)
>    return false;
>  }
>
> +/* Return true if FROM_EXPAND is a MEM with an address to be filled in
> +   by assign_params.  This should be the case if, and only if,
> +   parm_in_stack_slot_p holds for the parm DECL that expanded to
> +   FROM_EXPAND, so we check that, too.  */
> +
> +static bool
> +parm_in_unassigned_mem_p (tree decl, rtx from_expand)
> +{
> +  bool result = MEM_P (from_expand) && !XEXP (from_expand, 0);
> +
> +  gcc_assert (result == parm_in_stack_slot_p (decl)
> +             /* Maybe it was already assigned.  That's ok, especially
> +                for split complex args.  */
> +             || (!result && MEM_P (from_expand)
> +                 && (XEXP (from_expand, 0) == virtual_stack_vars_rtx
> +                     || (GET_CODE (XEXP (from_expand, 0)) == PLUS
> +                         && XEXP (XEXP (from_expand, 0), 0) == virtual_stack_vars_rtx))));
> +
> +  return result;
> +}
> +
>  /* A subroutine of assign_parms.  Arrange for the parameter to be
>     present and valid in DATA->STACK_RTL.  */
>
> @@ -2956,8 +2994,7 @@ assign_parm_setup_block (struct assign_parm_data_all *all,
>      {
>        DECL_ALIGN (parm) = MAX (DECL_ALIGN (parm), BITS_PER_WORD);
>        rtx from_expand = rtl_for_parm (all, parm);
> -      if (from_expand && (!parm_maybe_byref_p (parm)
> -                         || XEXP (from_expand, 0) != NULL_RTX))
> +      if (from_expand && !parm_in_unassigned_mem_p (parm, from_expand))
>         stack_parm = copy_rtx (from_expand);
>        else
>         {
> @@ -2968,8 +3005,7 @@ assign_parm_setup_block (struct assign_parm_data_all *all,
>           if (from_expand)
>             {
>               gcc_assert (GET_CODE (stack_parm) == MEM);
> -             gcc_assert (GET_CODE (from_expand) == MEM);
> -             gcc_assert (XEXP (from_expand, 0) == NULL_RTX);
> +             gcc_assert (parm_in_unassigned_mem_p (parm, from_expand));
>               XEXP (from_expand, 0) = XEXP (stack_parm, 0);
>               PUT_MODE (from_expand, GET_MODE (stack_parm));
>               stack_parm = copy_rtx (from_expand);
> @@ -3017,6 +3053,11 @@ assign_parm_setup_block (struct assign_parm_data_all *all,
>        else if (size == 0)
>         ;
>
> +      /* MEM may be a REG if coalescing assigns the param's partition
> +        to a pseudo.  */
> +      else if (REG_P (mem))
> +       emit_move_insn (mem, entry_parm);
> +
>        /* If SIZE is that of a mode no bigger than a word, just use
>          that mode's store operation.  */
>        else if (size <= UNITS_PER_WORD)
> @@ -3121,7 +3162,7 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
>        if (GET_MODE (parmreg) != promoted_nominal_mode)
>         parmreg = gen_lowpart (promoted_nominal_mode, parmreg);
>      }
> -  else if (!from_expand || parm_maybe_byref_p (parm))
> +  else if (!from_expand || parm_in_unassigned_mem_p (parm, from_expand))
>      {
>        parmreg = gen_reg_rtx (promoted_nominal_mode);
>        if (!DECL_ARTIFICIAL (parm))
> @@ -3131,7 +3172,6 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
>         {
>           gcc_assert (data->passed_pointer);
>           gcc_assert (GET_CODE (from_expand) == MEM
> -                     && GET_MODE (from_expand) == BLKmode
>                       && XEXP (from_expand, 0) == NULL_RTX);
>           XEXP (from_expand, 0) = parmreg;
>         }
> @@ -3349,7 +3389,7 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
>           did_conversion = true;
>         }
>        else if (GET_MODE (parmreg) == BLKmode)
> -       gcc_assert (parm_maybe_byref_p (parm));
> +       gcc_assert (parm_in_stack_slot_p (parm));
>        else
>         emit_move_insn (parmreg, src);
>
> @@ -3455,12 +3495,15 @@ assign_parm_setup_stack (struct assign_parm_data_all *all, tree parm,
>    if (data->entry_parm != data->stack_parm)
>      {
>        rtx src, dest;
> +      rtx from_expand = NULL_RTX;
>
>        if (data->stack_parm == 0)
>         {
> -         rtx x = data->stack_parm = rtl_for_parm (all, parm);
> -         if (x)
> -           gcc_assert (GET_MODE (x) == GET_MODE (data->entry_parm));
> +         from_expand = rtl_for_parm (all, parm);
> +         if (from_expand)
> +           gcc_assert (GET_MODE (from_expand) == GET_MODE (data->entry_parm));
> +         if (from_expand && !parm_in_unassigned_mem_p (parm, from_expand))
> +           data->stack_parm = from_expand;
>         }
>
>        if (data->stack_parm == 0)
> @@ -3472,7 +3515,16 @@ assign_parm_setup_stack (struct assign_parm_data_all *all, tree parm,
>             = assign_stack_local (GET_MODE (data->entry_parm),
>                                   GET_MODE_SIZE (GET_MODE (data->entry_parm)),
>                                   align);
> -         set_mem_attributes (data->stack_parm, parm, 1);
> +         if (!from_expand)
> +           set_mem_attributes (data->stack_parm, parm, 1);
> +         else
> +           {
> +             gcc_assert (GET_CODE (data->stack_parm) == MEM);
> +             gcc_assert (parm_in_unassigned_mem_p (parm, from_expand));
> +             XEXP (from_expand, 0) = XEXP (data->stack_parm, 0);
> +             PUT_MODE (from_expand, GET_MODE (data->stack_parm));
> +             data->stack_parm = copy_rtx (from_expand);
> +           }
>         }
>
>        dest = validize_mem (copy_rtx (data->stack_parm));
> diff --git a/gcc/tree-ssa-coalesce.c b/gcc/tree-ssa-coalesce.c
> index 08ce72c..6468012 100644
> --- a/gcc/tree-ssa-coalesce.c
> +++ b/gcc/tree-ssa-coalesce.c
> @@ -1386,8 +1386,8 @@ gimple_can_coalesce_p (tree name1, tree name2)
>          because it may be passed by reference.  */
>        return ((!var1 || VAR_P (var1)) && (!var2 || VAR_P (var2)))
>         || (/* The case var1 == var2 is already covered above.  */
> -           !parm_maybe_byref_p (var1)
> -           && !parm_maybe_byref_p (var2)
> +           !parm_in_stack_slot_p (var1)
> +           && !parm_in_stack_slot_p (var2)
>             && promote_ssa_mode (name1, NULL) == promote_ssa_mode (name2, NULL));
>      }
>
>
>
> --
> Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
> You must be the change you wish to see in the world. -- Gandhi
> Be Free! -- http://FSFLA.org/   FSF Latin America board member
> Free Software Evangelist|Red Hat Brasil GNU Toolchain Engineer