[PATCH RFA] tree-iterator: C++11 range-for and tree_stmt_iterator
Jason Merrill
jason@redhat.com
Fri May 14 01:50:03 GMT 2021
On 5/13/21 7:21 PM, Martin Sebor wrote:
> On 5/13/21 1:26 PM, Jason Merrill via Gcc-patches wrote:
>> Ping.
>>
>> On 5/1/21 12:29 PM, Jason Merrill wrote:
>>> Like my recent patch to add ovl_range and lkp_range in the C++ front
>>> end,
>>> this patch adds the tsi_range adaptor for using C++11 range-based
>>> 'for' with
>>> a STATEMENT_LIST, e.g.
>>>
>>> for (tree stmt : tsi_range (stmt_list)) { ... }
>>>
>>> This also involves adding some operators to tree_stmt_iterator that are
>>> needed for range-for iterators, and should also be useful in code
>>> that uses
>>> the iterators directly.
>>>
>>> The patch updates the suitable loops in the C++ front end, but does not
>>> touch any loops elsewhere in the compiler.
>
> I like the modernization of the loops.
>
> I can't find anything terribly wrong with the iterator but let me
> at least pick on some nits ;)
>
>>>
>>> gcc/ChangeLog:
>>>
>>> * tree-iterator.h (struct tree_stmt_iterator): Add operator++,
>>> operator--, operator*, operator==, and operator!=.
>>> (class tsi_range): New.
>>>
>>> gcc/cp/ChangeLog:
>>>
>>> * constexpr.c (build_data_member_initialization): Use tsi_range.
>>> (build_constexpr_constructor_member_initializers): Likewise.
>>> (constexpr_fn_retval, cxx_eval_statement_list): Likewise.
>>> (potential_constant_expression_1): Likewise.
>>> * coroutines.cc (await_statement_expander): Likewise.
>>> (await_statement_walker): Likewise.
>>> * module.cc (trees_out::core_vals): Likewise.
>>> * pt.c (tsubst_expr): Likewise.
>>> * semantics.c (set_cleanup_locs): Likewise.
>>> ---
>>> gcc/tree-iterator.h | 28 +++++++++++++++++++++++-----
>>> gcc/cp/constexpr.c | 42 ++++++++++++++----------------------------
>>> gcc/cp/coroutines.cc | 10 ++++------
>>> gcc/cp/module.cc | 5 ++---
>>> gcc/cp/pt.c | 5 ++---
>>> gcc/cp/semantics.c | 5 ++---
>>> 6 files changed, 47 insertions(+), 48 deletions(-)
>>>
>>> diff --git a/gcc/tree-iterator.h b/gcc/tree-iterator.h
>>> index 076fff8644c..f57456bb473 100644
>>> --- a/gcc/tree-iterator.h
>>> +++ b/gcc/tree-iterator.h
>>> @@ -1,4 +1,4 @@
>>> -/* Iterator routines for manipulating GENERIC tree statement list.
>>> +/* Iterator routines for manipulating GENERIC tree statement list.
>>> -*- C++ -*-
>>> Copyright (C) 2003-2021 Free Software Foundation, Inc.
>>> Contributed by Andrew MacLeod <amacleod@redhat.com>
>>> @@ -32,6 +32,13 @@ along with GCC; see the file COPYING3. If not see
>>> struct tree_stmt_iterator {
>>> struct tree_statement_list_node *ptr;
>>> tree container;
>
> I assume the absence of ctors is intentional. If so, I suggest
> to add a comment explaing why. Otherwise, I would provide one
> (or as many as needed).
>
>>> +
>>> + bool operator== (tree_stmt_iterator b) const
>>> + { return b.ptr == ptr && b.container == container; }
>>> + bool operator!= (tree_stmt_iterator b) const { return !(*this ==
>>> b); }
>>> + tree_stmt_iterator &operator++ () { ptr = ptr->next; return *this; }
>>> + tree_stmt_iterator &operator-- () { ptr = ptr->prev; return *this; }
>
> I would suggest to add postincrement and postdecrement.
>
>>> + tree &operator* () { return ptr->stmt; }
>
> Given the pervasive lack of const-safety in GCC and the by-value
> semantics of the iterator this probably isn't worth it but maybe
> add a const overload. operator-> would probably never be used.
>
>>> };
>>> static inline tree_stmt_iterator
>>> @@ -71,27 +78,38 @@ tsi_one_before_end_p (tree_stmt_iterator i)
>>> static inline void
>>> tsi_next (tree_stmt_iterator *i)
>>> {
>>> - i->ptr = i->ptr->next;
>>> + ++(*i);
>>> }
>>> static inline void
>>> tsi_prev (tree_stmt_iterator *i)
>>> {
>>> - i->ptr = i->ptr->prev;
>>> + --(*i);
>>> }
>>> static inline tree *
>>> tsi_stmt_ptr (tree_stmt_iterator i)
>>> {
>>> - return &i.ptr->stmt;
>>> + return &(*i);
>>> }
>>> static inline tree
>>> tsi_stmt (tree_stmt_iterator i)
>>> {
>>> - return i.ptr->stmt;
>>> + return *i;
>>> }
>>> +/* Make tree_stmt_iterator work as a C++ range, e.g.
>>> + for (tree stmt : tsi_range (stmt_list)) { ... } */
>>> +class tsi_range
>>> +{
>>> + tree t;
>>> + public:
>>> + tsi_range (tree t): t(t) { }
>>> + tree_stmt_iterator begin() { return tsi_start (t); }
>>> + tree_stmt_iterator end() { return { nullptr, t }; }
>
> Those member functions could be made const.
Sure:
>>> +};
>>> +
>>> enum tsi_iterator_update
>>> {
>>> TSI_NEW_STMT, /* Only valid when single statement is
>>> added, move
>>> diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
>>> index 9481a5bfd3c..260b0122f59 100644
>>> --- a/gcc/cp/constexpr.c
>>> +++ b/gcc/cp/constexpr.c
>>> @@ -330,12 +330,9 @@ build_data_member_initialization (tree t,
>>> vec<constructor_elt, va_gc> **vec)
>>> return false;
>>> if (TREE_CODE (t) == STATEMENT_LIST)
>>> {
>>> - tree_stmt_iterator i;
>>> - for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
>>> - {
>>> - if (! build_data_member_initialization (tsi_stmt (i), vec))
>>> - return false;
>>> - }
>>> + for (tree stmt : tsi_range (t))
>>> + if (! build_data_member_initialization (stmt, vec))
>>> + return false;
>>> return true;
>>> }
>>> if (TREE_CODE (t) == CLEANUP_STMT)
>>> @@ -577,10 +574,9 @@ build_constexpr_constructor_member_initializers
>>> (tree type, tree body)
>>> break;
>>> case STATEMENT_LIST:
>>> - for (tree_stmt_iterator i = tsi_start (body);
>>> - !tsi_end_p (i); tsi_next (&i))
>>> + for (tree stmt : tsi_range (body))
>>> {
>>> - body = tsi_stmt (i);
>>> + body = stmt;
>>> if (TREE_CODE (body) == BIND_EXPR)
>>> break;
>>> }
>>> @@ -617,10 +613,9 @@ build_constexpr_constructor_member_initializers
>>> (tree type, tree body)
>>> }
>>> else if (TREE_CODE (body) == STATEMENT_LIST)
>>> {
>>> - tree_stmt_iterator i;
>>> - for (i = tsi_start (body); !tsi_end_p (i); tsi_next (&i))
>>> + for (tree stmt : tsi_range (body))
>>> {
>>> - ok = build_data_member_initialization (tsi_stmt (i), &vec);
>>> + ok = build_data_member_initialization (stmt, &vec);
>>> if (!ok)
>>> break;
>>> }
>>> @@ -675,11 +670,10 @@ constexpr_fn_retval (tree body)
>>> {
>>> case STATEMENT_LIST:
>>> {
>>> - tree_stmt_iterator i;
>>> tree expr = NULL_TREE;
>>> - for (i = tsi_start (body); !tsi_end_p (i); tsi_next (&i))
>>> + for (tree stmt : tsi_range (body))
>>> {
>>> - tree s = constexpr_fn_retval (tsi_stmt (i));
>>> + tree s = constexpr_fn_retval (stmt);
>>> if (s == error_mark_node)
>>> return error_mark_node;
>>> else if (s == NULL_TREE)
>>> @@ -5772,7 +5766,6 @@ cxx_eval_statement_list (const constexpr_ctx
>>> *ctx, tree t,
>>> bool *non_constant_p, bool *overflow_p,
>>> tree *jump_target)
>>> {
>>> - tree_stmt_iterator i;
>>> tree local_target;
>>> /* In a statement-expression we want to return the last value.
>>> For empty statement expression return void_node. */
>>> @@ -5782,9 +5775,8 @@ cxx_eval_statement_list (const constexpr_ctx
>>> *ctx, tree t,
>>> local_target = NULL_TREE;
>>> jump_target = &local_target;
>>> }
>>> - for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
>>> + for (tree stmt : tsi_range (t))
>>> {
>>> - tree stmt = tsi_stmt (i);
>>> /* We've found a continue, so skip everything until we reach
>>> the label its jumping to. */
>>> if (continues (jump_target))
>>> @@ -8283,16 +8275,10 @@ potential_constant_expression_1 (tree t, bool
>>> want_rval, bool strict, bool now,
>>> }
>>> case STATEMENT_LIST:
>>> - {
>>> - tree_stmt_iterator i;
>>> - for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
>>> - {
>>> - if (!RECUR (tsi_stmt (i), any))
>>> - return false;
>>> - }
>>> - return true;
>>> - }
>>> - break;
>>> + for (tree stmt : tsi_range (t))
>>> + if (!RECUR (stmt, any))
>>> + return false;
>>> + return true;
>>> case MODIFY_EXPR:
>>> if (cxx_dialect < cxx14)
>>> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
>>> index dbd703a67cc..9b498f9d0b4 100644
>>> --- a/gcc/cp/coroutines.cc
>>> +++ b/gcc/cp/coroutines.cc
>>> @@ -1771,10 +1771,9 @@ await_statement_expander (tree *stmt, int
>>> *do_subtree, void *d)
>>> return NULL_TREE; /* Just process the sub-trees. */
>>> else if (TREE_CODE (*stmt) == STATEMENT_LIST)
>>> {
>>> - tree_stmt_iterator i;
>>> - for (i = tsi_start (*stmt); !tsi_end_p (i); tsi_next (&i))
>>> + for (tree &s : tsi_range (*stmt))
>>> {
>>> - res = cp_walk_tree (tsi_stmt_ptr (i), await_statement_expander,
>>> + res = cp_walk_tree (&s, await_statement_expander,
>>> d, NULL);
>>> if (res)
>>> return res;
>>> @@ -3523,10 +3522,9 @@ await_statement_walker (tree *stmt, int
>>> *do_subtree, void *d)
>>> }
>>> else if (TREE_CODE (*stmt) == STATEMENT_LIST)
>>> {
>>> - tree_stmt_iterator i;
>>> - for (i = tsi_start (*stmt); !tsi_end_p (i); tsi_next (&i))
>>> + for (tree &s : tsi_range (*stmt))
>>> {
>>> - res = cp_walk_tree (tsi_stmt_ptr (i), await_statement_walker,
>>> + res = cp_walk_tree (&s, await_statement_walker,
>>> d, NULL);
>>> if (res)
>>> return res;
>>> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
>>> index 02c19f55548..f0fb0144706 100644
>>> --- a/gcc/cp/module.cc
>>> +++ b/gcc/cp/module.cc
>>> @@ -6094,9 +6094,8 @@ trees_out::core_vals (tree t)
>>> break;
>>> case STATEMENT_LIST:
>>> - for (tree_stmt_iterator iter = tsi_start (t);
>>> - !tsi_end_p (iter); tsi_next (&iter))
>>> - if (tree stmt = tsi_stmt (iter))
>>> + for (tree stmt : tsi_range (t))
>>> + if (stmt)
>>> WT (stmt);
>>> WT (NULL_TREE);
>>> break;
>>> diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
>>> index 116bdd2e42a..ad140cfd586 100644
>>> --- a/gcc/cp/pt.c
>>> +++ b/gcc/cp/pt.c
>>> @@ -18234,9 +18234,8 @@ tsubst_expr (tree t, tree args,
>>> tsubst_flags_t complain, tree in_decl,
>>> {
>>> case STATEMENT_LIST:
>>> {
>>> - tree_stmt_iterator i;
>>> - for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
>>> - RECUR (tsi_stmt (i));
>>> + for (tree stmt : tsi_range (t))
>>> + RECUR (stmt);
>>> break;
>>> }
>>> diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
>>> index 6224f49f189..2912efad9be 100644
>>> --- a/gcc/cp/semantics.c
>>> +++ b/gcc/cp/semantics.c
>>> @@ -613,9 +613,8 @@ set_cleanup_locs (tree stmts, location_t loc)
>>> set_cleanup_locs (CLEANUP_BODY (stmts), loc);
>>> }
>>> else if (TREE_CODE (stmts) == STATEMENT_LIST)
>>> - for (tree_stmt_iterator i = tsi_start (stmts);
>>> - !tsi_end_p (i); tsi_next (&i))
>>> - set_cleanup_locs (tsi_stmt (i), loc);
>>> + for (tree stmt : tsi_range (stmts))
>>> + set_cleanup_locs (stmt, loc);
>>> }
>>> /* Finish a scope. */
>>>
>>> base-commit: 3c65858787dc52b65b26fa7018587c01510f442c
>>> prerequisite-patch-id: 7ce9dff1f7d449f4a13fb882bf7b1a962a56de95
>>>
>>
>
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