On Thu, Jul 28, 2011 at 6:52 PM, Martin Jambor <mjam...@suse.cz> wrote:
> Hi,
>
> pass_split_functions is happy to split functions which have type
> attributes but cannot update them if the new clone has in any way
> different parameters than the original. This can lead to
> miscompilations in cases like the testcase.
>
> This patch solves it by 1) making the inliner set the
> can_change_signature flag to false for them because their signature
> cannot be changed (this step is also necessary to make IPA-CP operate
> on them and handle them correctly), and 2) make the splitting pass
> keep all parameters if the flag is set. The second step might involve
> inventing some default definitions if the parameters did not really
> have any.
>
> I spoke about this with Honza and he claimed that the new function is
> really an entirely different thing and that the parameters may
> correspond only very loosely and thus the type attributes should be
> cleared. I'm not sure I agree, but in any case I needed this to work
For sure some attributes may be worth to preserve/change for optimziation
purposes. Now, if a function is clonable then clearing all attributes from
the clone should be ok - there may be attributes that prevent cloning though
(or rather, need to be preserved).
Richard.
> to allow me continue with promised IPA-CP polishing and so I decided
> to do this because it was easier. (My own opinion is that the current
> representation of parameter-describing function type attributes is
> evil and will cause harm no matter hat we do.)
>
> A very similar patch has passed bootstrap and testsuite on
> x86_64-linux, the current one is undergoing both right now. OK for
> trunk if it passes?
>
> Thanks,
>
> Martin
>
>
>
> 2011-07-28 Martin Jambor <mjam...@suse.cz>
>
> PR middle-end/49886
> * ipa-inline-analysis.c (compute_inline_parameters): Set
> can_change_signature of noes with typde attributes.
> * ipa-split.c (split_function): Do not skip any arguments if
> can_change_signature is set.
>
> * testsuite/gcc.c-torture/execute/pr49886.c: New testcase.
>
> Index: src/gcc/ipa-inline-analysis.c
> ===================================================================
> --- src.orig/gcc/ipa-inline-analysis.c
> +++ src/gcc/ipa-inline-analysis.c
> @@ -1658,18 +1658,24 @@ compute_inline_parameters (struct cgraph
> /* Can this function be inlined at all? */
> info->inlinable = tree_inlinable_function_p (node->decl);
>
> - /* Inlinable functions always can change signature. */
> - if (info->inlinable)
> - node->local.can_change_signature = true;
> + /* Type attributes can use parameter indices to describe them. */
> + if (TYPE_ATTRIBUTES (TREE_TYPE (node->decl)))
> + node->local.can_change_signature = false;
> else
> {
> - /* Functions calling builtin_apply can not change signature. */
> - for (e = node->callees; e; e = e->next_callee)
> - if (DECL_BUILT_IN (e->callee->decl)
> - && DECL_BUILT_IN_CLASS (e->callee->decl) == BUILT_IN_NORMAL
> - && DECL_FUNCTION_CODE (e->callee->decl) == BUILT_IN_APPLY_ARGS)
> - break;
> - node->local.can_change_signature = !e;
> + /* Otherwise, inlinable functions always can change signature. */
> + if (info->inlinable)
> + node->local.can_change_signature = true;
> + else
> + {
> + /* Functions calling builtin_apply can not change signature. */
> + for (e = node->callees; e; e = e->next_callee)
> + if (DECL_BUILT_IN (e->callee->decl)
> + && DECL_BUILT_IN_CLASS (e->callee->decl) == BUILT_IN_NORMAL
> + && DECL_FUNCTION_CODE (e->callee->decl) ==
> BUILT_IN_APPLY_ARGS)
> + break;
> + node->local.can_change_signature = !e;
> + }
> }
> estimate_function_body_sizes (node, early);
>
> Index: src/gcc/ipa-split.c
> ===================================================================
> --- src.orig/gcc/ipa-split.c
> +++ src/gcc/ipa-split.c
> @@ -945,10 +945,10 @@ static void
> split_function (struct split_point *split_point)
> {
> VEC (tree, heap) *args_to_pass = NULL;
> - bitmap args_to_skip = BITMAP_ALLOC (NULL);
> + bitmap args_to_skip;
> tree parm;
> int num = 0;
> - struct cgraph_node *node;
> + struct cgraph_node *node, *cur_node = cgraph_get_node
> (current_function_decl);
> basic_block return_bb = find_return_bb ();
> basic_block call_bb;
> gimple_stmt_iterator gsi;
> @@ -968,17 +968,30 @@ split_function (struct split_point *spli
> dump_split_point (dump_file, split_point);
> }
>
> + if (cur_node->local.can_change_signature)
> + args_to_skip = BITMAP_ALLOC (NULL);
> + else
> + args_to_skip = NULL;
> +
> /* Collect the parameters of new function and args_to_skip bitmap. */
> for (parm = DECL_ARGUMENTS (current_function_decl);
> parm; parm = DECL_CHAIN (parm), num++)
> - if (!is_gimple_reg (parm)
> - || !gimple_default_def (cfun, parm)
> - || !bitmap_bit_p (split_point->ssa_names_to_pass,
> - SSA_NAME_VERSION (gimple_default_def (cfun, parm))))
> + if (args_to_skip
> + && (!is_gimple_reg (parm)
> + || !gimple_default_def (cfun, parm)
> + || !bitmap_bit_p (split_point->ssa_names_to_pass,
> + SSA_NAME_VERSION (gimple_default_def (cfun,
> + parm)))))
> bitmap_set_bit (args_to_skip, num);
> else
> {
> arg = gimple_default_def (cfun, parm);
> + if (!arg)
> + {
> + arg = make_ssa_name (parm, gimple_build_nop ());
> + set_default_def (parm, arg);
> + }
> +
> if (TYPE_MAIN_VARIANT (DECL_ARG_TYPE (parm))
> != TYPE_MAIN_VARIANT (TREE_TYPE (arg)))
> {
> @@ -1081,9 +1094,7 @@ split_function (struct split_point *spli
>
> /* Now create the actual clone. */
> rebuild_cgraph_edges ();
> - node = cgraph_function_versioning (cgraph_get_node (current_function_decl),
> - NULL, NULL,
> - args_to_skip,
> + node = cgraph_function_versioning (cur_node, NULL, NULL, args_to_skip,
> split_point->split_bbs,
> split_point->entry_bb, "part");
> /* For usual cloning it is enough to clear builtin only when signature
> @@ -1094,7 +1105,7 @@ split_function (struct split_point *spli
> DECL_BUILT_IN_CLASS (node->decl) = NOT_BUILT_IN;
> DECL_FUNCTION_CODE (node->decl) = (enum built_in_function) 0;
> }
> - cgraph_node_remove_callees (cgraph_get_node (current_function_decl));
> + cgraph_node_remove_callees (cur_node);
> if (!split_part_return_p)
> TREE_THIS_VOLATILE (node->decl) = 1;
> if (dump_file)
> Index: src/gcc/testsuite/gcc.c-torture/execute/pr49886.c
> ===================================================================
> --- /dev/null
> +++ src/gcc/testsuite/gcc.c-torture/execute/pr49886.c
> @@ -0,0 +1,100 @@
> +struct PMC {
> + unsigned flags;
> +};
> +
> +typedef struct Pcc_cell
> +{
> + struct PMC *p;
> + long bla;
> + long type;
> +} Pcc_cell;
> +
> +int gi;
> +int cond;
> +
> +extern void abort ();
> +extern void never_ever(int interp, struct PMC *pmc)
> + __attribute__((noinline,noclone));
> +
> +void never_ever (int interp, struct PMC *pmc)
> +{
> + abort ();
> +}
> +
> +static void mark_cell(int * interp, Pcc_cell *c)
> + __attribute__((__nonnull__(1)));
> +
> +static void
> +mark_cell(int * interp, Pcc_cell *c)
> +{
> + if (!cond)
> + return;
> +
> + if (c && c->type == 4 && c->p
> + && !(c->p->flags & (1<<18)))
> + never_ever(gi + 1, c->p);
> + if (c && c->type == 4 && c->p
> + && !(c->p->flags & (1<<17)))
> + never_ever(gi + 2, c->p);
> + if (c && c->type == 4 && c->p
> + && !(c->p->flags & (1<<16)))
> + never_ever(gi + 3, c->p);
> + if (c && c->type == 4 && c->p
> + && !(c->p->flags & (1<<15)))
> + never_ever(gi + 4, c->p);
> + if (c && c->type == 4 && c->p
> + && !(c->p->flags & (1<<14)))
> + never_ever(gi + 5, c->p);
> + if (c && c->type == 4 && c->p
> + && !(c->p->flags & (1<<13)))
> + never_ever(gi + 6, c->p);
> + if (c && c->type == 4 && c->p
> + && !(c->p->flags & (1<<12)))
> + never_ever(gi + 7, c->p);
> + if (c && c->type == 4 && c->p
> + && !(c->p->flags & (1<<11)))
> + never_ever(gi + 8, c->p);
> + if (c && c->type == 4 && c->p
> + && !(c->p->flags & (1<<10)))
> + never_ever(gi + 9, c->p);
> +}
> +
> +static void
> +foo(int * interp, Pcc_cell *c)
> +{
> + mark_cell(interp, c);
> +}
> +
> +static struct Pcc_cell *
> +__attribute__((noinline,noclone))
> +getnull(void)
> +{
> + return (struct Pcc_cell *) 0;
> +}
> +
> +
> +int main()
> +{
> + int i;
> +
> + cond = 1;
> + for (i = 0; i < 100; i++)
> + foo (&gi, getnull ());
> + return 0;
> +}
> +
> +
> +void
> +bar_1 (int * interp, Pcc_cell *c)
> +{
> + c->bla += 1;
> + mark_cell(interp, c);
> +}
> +
> +void
> +bar_2 (int * interp, Pcc_cell *c)
> +{
> + c->bla += 2;
> + mark_cell(interp, c);
> +}
> +
>
