Ping -- the patch that depends on this one has been approved, but I am
still waiting for approval on these target-independent bits.
Thanks,
Bill
On Wed, 2014-08-13 at 18:01 -0500, Bill Schmidt wrote:
> Hi,
>
> I want to reuse some of the infrastructure in web.c (and df.h) for a
> target-specific RTL pass, particularly the union-find stuff. I could
> just copy it, I suppose, but it seems better to make the struct
> web_entry into a class so that I can inherit what I need. That's what
> this patch does.
>
> When I talked about this with some other folks, they mentioned that
> there has been talk of eliminating the web pass altogether, so that
> might be an argument in favor of just copying the logic. I am happy to
> do that if that's deemed preferable.
>
> I've taken the original struct and made it a base class that only
> retains the pred field from the original class, along with the
> union-find code. The reg field is something I don't need, so I've moved
> that into a subclass that the web code now uses. I've removed the
> extra_info field, which is not used and no longer makes sense with
> inheritance available. The rest of the changes are just adjusting to
> these modifications.
>
> I didn't overly "C++ify" anything, to keep the changes as non-invasive
> as possible.
>
> I'll post the PowerPC patch that makes use of the subclassing shortly.
>
> Bootstrapped and tested on powerpc64le-unknown-linux-gnu with no
> regressions. Is this ok for trunk?
>
> Thanks,
> Bill
>
>
> 2014-08-13 Bill Schmidt <wschm...@linux.vnet.ibm.com>
>
> * df.h (web_entry_base): Replace existing struct web_entry with a
> new class web_entry_base with only the predecessor member.
> (unionfind_root): Remove declaration and move to class member.
> (unionfind_union): Remove declaration and move to friend
> function.
> (union_defs): Remove declaration.
> * web.c (web_entry_base::unionfind_root): Modify to be member
> function and adjust accessors.
> (unionfind_union): Modify to be friend function and adjust
> accessors.
> (web_entry): New subclass of web_entry_base containing the reg
> member.
> (union_match_dups): Modify for struct -> class changes.
> (union_defs): Likewise.
> (entry_register): Likewise.
> (pass_web::execute): Likewise.
>
>
> Index: gcc/df.h
> ===================================================================
> --- gcc/df.h (revision 213923)
> +++ gcc/df.h (working copy)
> @@ -1184,20 +1184,22 @@ df_single_use (const df_insn_info *info)
>
> /* web */
>
> -/* This entry is allocated for each reference in the insn stream. */
> -struct web_entry
> +class web_entry_base
> {
> - /* Pointer to the parent in the union/find tree. */
> - struct web_entry *pred;
> - /* Newly assigned register to the entry. Set only for roots. */
> - rtx reg;
> - void* extra_info;
> + private:
> + /* Reference to the parent in the union/find tree. */
> + web_entry_base *pred_pvt;
> +
> + public:
> + /* Accessors. */
> + web_entry_base *pred () { return pred_pvt; }
> + void set_pred (web_entry_base *p) { pred_pvt = p; }
> +
> + /* Find representative in union-find tree. */
> + web_entry_base *unionfind_root ();
> +
> + /* Union with another set, returning TRUE if they are already unioned. */
> + friend bool unionfind_union (web_entry_base *first, web_entry_base
> *second);
> };
>
> -extern struct web_entry *unionfind_root (struct web_entry *);
> -extern bool unionfind_union (struct web_entry *, struct web_entry *);
> -extern void union_defs (df_ref, struct web_entry *,
> - unsigned int *used, struct web_entry *,
> - bool (*fun) (struct web_entry *, struct web_entry *));
> -
> #endif /* GCC_DF_H */
> Index: gcc/web.c
> ===================================================================
> --- gcc/web.c (revision 213923)
> +++ gcc/web.c (working copy)
> @@ -53,17 +53,17 @@ along with GCC; see the file COPYING3. If not see
>
> /* Find the root of unionfind tree (the representative of set). */
>
> -struct web_entry *
> -unionfind_root (struct web_entry *element)
> +web_entry_base *
> +web_entry_base::unionfind_root ()
> {
> - struct web_entry *element1 = element, *element2;
> + web_entry_base *element = this, *element1 = this, *element2;
>
> - while (element->pred)
> - element = element->pred;
> - while (element1->pred)
> + while (element->pred ())
> + element = element->pred ();
> + while (element1->pred ())
> {
> - element2 = element1->pred;
> - element1->pred = element;
> + element2 = element1->pred ();
> + element1->set_pred (element);
> element1 = element2;
> }
> return element;
> @@ -74,23 +74,32 @@ along with GCC; see the file COPYING3. If not see
> nothing is done. Otherwise, return false. */
>
> bool
> -unionfind_union (struct web_entry *first, struct web_entry *second)
> +unionfind_union (web_entry_base *first, web_entry_base *second)
> {
> - first = unionfind_root (first);
> - second = unionfind_root (second);
> + first = first->unionfind_root ();
> + second = second->unionfind_root ();
> if (first == second)
> return true;
> - second->pred = first;
> + second->set_pred (first);
> return false;
> }
>
> +class web_entry : public web_entry_base
> +{
> + private:
> + rtx reg_pvt;
> +
> + public:
> + rtx reg () { return reg_pvt; }
> + void set_reg (rtx r) { reg_pvt = r; }
> +};
> +
> /* For INSN, union all defs and uses that are linked by match_dup.
> FUN is the function that does the union. */
>
> static void
> -union_match_dups (rtx insn, struct web_entry *def_entry,
> - struct web_entry *use_entry,
> - bool (*fun) (struct web_entry *, struct web_entry *))
> +union_match_dups (rtx insn, web_entry *def_entry, web_entry *use_entry,
> + bool (*fun) (web_entry_base *, web_entry_base *))
> {
> struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
> df_ref use_link = DF_INSN_INFO_USES (insn_info);
> @@ -169,9 +178,9 @@ static void
> the values 0 and 1 are reserved for use by entry_register. */
>
> void
> -union_defs (df_ref use, struct web_entry *def_entry,
> - unsigned int *used, struct web_entry *use_entry,
> - bool (*fun) (struct web_entry *, struct web_entry *))
> +union_defs (df_ref use, web_entry *def_entry,
> + unsigned int *used, web_entry *use_entry,
> + bool (*fun) (web_entry_base *, web_entry_base *))
> {
> struct df_insn_info *insn_info = DF_REF_INSN_INFO (use);
> struct df_link *link = DF_REF_CHAIN (use);
> @@ -246,15 +255,15 @@ void
> /* Find the corresponding register for the given entry. */
>
> static rtx
> -entry_register (struct web_entry *entry, df_ref ref, unsigned int *used)
> +entry_register (web_entry *entry, df_ref ref, unsigned int *used)
> {
> - struct web_entry *root;
> + web_entry *root;
> rtx reg, newreg;
>
> /* Find the corresponding web and see if it has been visited. */
> - root = unionfind_root (entry);
> - if (root->reg)
> - return root->reg;
> + root = (web_entry *)entry->unionfind_root ();
> + if (root->reg ())
> + return root->reg ();
>
> /* We are seeing this web for the first time, do the assignment. */
> reg = DF_REF_REAL_REG (ref);
> @@ -278,7 +287,7 @@ static rtx
> REGNO (newreg));
> }
>
> - root->reg = newreg;
> + root->set_reg (newreg);
> return newreg;
> }
>
> @@ -332,8 +341,8 @@ class pass_web : public rtl_opt_pass
> unsigned int
> pass_web::execute (function *fun)
> {
> - struct web_entry *def_entry;
> - struct web_entry *use_entry;
> + web_entry *def_entry;
> + web_entry *use_entry;
> unsigned int max = max_reg_num ();
> unsigned int *used;
> basic_block bb;
> @@ -364,9 +373,9 @@ pass_web::execute (function *fun)
> }
>
> /* Record the number of uses and defs at the beginning of the
> optimization. */
> - def_entry = XCNEWVEC (struct web_entry, DF_DEFS_TABLE_SIZE ());
> + def_entry = XCNEWVEC (web_entry, DF_DEFS_TABLE_SIZE ());
> used = XCNEWVEC (unsigned, max);
> - use_entry = XCNEWVEC (struct web_entry, uses_num);
> + use_entry = XCNEWVEC (web_entry, uses_num);
>
> /* Produce the web. */
> FOR_ALL_BB_FN (bb, fun)
>
>
