From 2c3fcba6dc56f848a07332ff005e2db9054dca26 Mon Sep 17 00:00:00 2001
From: Zack Weinberg <zack@gcc.gnu.org>
Date: Mon, 10 Sep 2001 22:34:03 +0000
Subject: [PATCH] cpplex.c (parse_identifier): Fast-path optimize.
* cpplex.c (parse_identifier): Fast-path optimize. Avoid
copying identifier when we're just going to throw it away.
(parse_identifier_slow): New routine to handle abnormal cases.
(_cpp_lex_token): Update call site.
* hashtable.c (ht_lookup): Don't assume that the string we've
been given is NUL-terminated.
* system.h: #define __builtin_expect(a, b) to (a) if not
GCC >=3.0.
From-SVN: r45529
---
gcc/ChangeLog | 18 +++++--
gcc/cpplex.c | 128 +++++++++++++++++++++++++++++++++---------------
gcc/hashtable.c | 2 +-
gcc/system.h | 7 +++
4 files changed, 111 insertions(+), 44 deletions(-)
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b2edebd3533c..fed56b5f5d36 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,15 @@
+2001-09-10 Zack Weinberg <zackw@panix.com>
+
+ * cpplex.c (parse_identifier): Fast-path optimize. Avoid
+ copying identifier when we're just going to throw it away.
+ (parse_identifier_slow): New routine to handle abnormal cases.
+ (_cpp_lex_token): Update call site.
+
+ * hashtable.c (ht_lookup): Don't assume that the string we've
+ been given is NUL-terminated.
+ * system.h: #define __builtin_expect(a, b) to (a) if not
+ GCC >=3.0.
+
2001-09-10 Michael Meissner <meissner@redhat.com>
* config.gcc (sparc64-*-solaris2): Add alias to be compatible with
@@ -16,7 +28,7 @@ Mon Sep 10 16:26:44 2001 Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
* dwarf2out.c (incomplete_types, decl_scope_table): Make them
into varray's and register them as roots with the garbage
- collector so they are not collected too soon.
+ collector so they are not collected too soon.
Mon Sep 10 14:21:26 CEST 2001 Jan Hubicka <jh@suse.cz>
@@ -31,7 +43,7 @@ Mon Sep 10 14:21:26 CEST 2001 Jan Hubicka <jh@suse.cz>
(basic_block_for_insn, label_value_list): Move from flow.c; make global.
(n_basic_blocks, n_edges, basic_block_info, entry_exit_blocks,
init_flow, clear_edges, can_delete_note_p, can_delete_label_p,
- flow_delete_insn, flow_delete_insn_chain, create_basic_block,
+ flow_delete_insn, flow_delete_insn_chain, create_basic_block,
expunge_block, flow_delete_block, compute_bb_for_insn,
update_bb_for_insn, set_block_for_insn, set_block_for_new_insns,
make_edge, remove_edge, redirect_edge_succ, redirect_edge_succ_nodup,
@@ -40,7 +52,7 @@ Mon Sep 10 14:21:26 CEST 2001 Jan Hubicka <jh@suse.cz>
redirect_edge_and_branch, redirect_edge_and_branch_force,
tidy_fallthru_edge, tidy_fallthru_edges, back_edge_of_syntactic_loop_p,
split_edge, insert_insn_on_edge, commit_one_edge_insertion,
- commit_edge_insertions, dump_flow_info, debug_flow_info,
+ commit_edge_insertions, dump_flow_info, debug_flow_info,
dump_edge_info, dump_bb, debug_bb, debug_bb_n, print_rtl_with_bb,
verify_flow_info, purge_dead_edges, purge_all_dead_edges):
Move here from flow.c
diff --git a/gcc/cpplex.c b/gcc/cpplex.c
index 03bd85516cc4..071cdca0c4dc 100644
--- a/gcc/cpplex.c
+++ b/gcc/cpplex.c
@@ -88,7 +88,9 @@ static int skip_block_comment PARAMS ((cpp_reader *));
static int skip_line_comment PARAMS ((cpp_reader *));
static void adjust_column PARAMS ((cpp_reader *));
static void skip_whitespace PARAMS ((cpp_reader *, cppchar_t));
-static cpp_hashnode *parse_identifier PARAMS ((cpp_reader *, cppchar_t));
+static cpp_hashnode *parse_identifier PARAMS ((cpp_reader *));
+static cpp_hashnode *parse_identifier_slow PARAMS ((cpp_reader *,
+ const U_CHAR *));
static void parse_number PARAMS ((cpp_reader *, cpp_string *, cppchar_t, int));
static int unescaped_terminator_p PARAMS ((cpp_reader *, const U_CHAR *));
static void parse_string PARAMS ((cpp_reader *, cpp_token *, cppchar_t));
@@ -470,40 +472,101 @@ name_p (pfile, string)
return 1;
}
-/* Parse an identifier, skipping embedded backslash-newlines.
- Calculate the hash value of the token while parsing, for improved
- performance. The hashing algorithm *must* match cpp_lookup(). */
+/* Parse an identifier, skipping embedded backslash-newlines. This is
+ a critical inner loop. The common case is an identifier which has
+ not been split by backslash-newline, does not contain a dollar
+ sign, and has already been scanned (roughly 10:1 ratio of
+ seen:unseen identifiers in normal code; the distribution is
+ Poisson-like). Second most common case is a new identifier, not
+ split and no dollar sign. The other possibilities are rare and
+ have been relegated to parse_identifier_slow. */
static cpp_hashnode *
-parse_identifier (pfile, c)
+parse_identifier (pfile)
cpp_reader *pfile;
- cppchar_t c;
{
cpp_hashnode *result;
+ const U_CHAR *cur, *rlimit;
+
+ /* Fast-path loop. Skim over a normal identifier.
+ N.B. ISIDNUM does not include $. */
+ cur = pfile->buffer->cur - 1;
+ rlimit = pfile->buffer->rlimit;
+ do
+ cur++;
+ while (cur < rlimit && ISIDNUM (*cur));
+
+ /* Check for slow-path cases. */
+ if (cur < rlimit && (*cur == '?' || *cur == '\\' || *cur == '$'))
+ result = parse_identifier_slow (pfile, cur);
+ else
+ {
+ const U_CHAR *base = pfile->buffer->cur - 1;
+ result = (cpp_hashnode *)
+ ht_lookup (pfile->hash_table, base, cur - base, HT_ALLOC);
+ pfile->buffer->cur = cur;
+ }
+
+ /* Rarely, identifiers require diagnostics when lexed.
+ XXX Has to be forced out of the fast path. */
+ if (__builtin_expect ((result->flags & NODE_DIAGNOSTIC)
+ && !pfile->state.skipping, 0))
+ {
+ /* It is allowed to poison the same identifier twice. */
+ if ((result->flags & NODE_POISONED) && !pfile->state.poisoned_ok)
+ cpp_error (pfile, "attempt to use poisoned \"%s\"",
+ NODE_NAME (result));
+
+ /* Constraint 6.10.3.5: __VA_ARGS__ should only appear in the
+ replacement list of a variadic macro. */
+ if (result == pfile->spec_nodes.n__VA_ARGS__
+ && !pfile->state.va_args_ok)
+ cpp_pedwarn (pfile,
+ "__VA_ARGS__ can only appear in the expansion of a C99 variadic macro");
+ }
+
+ return result;
+}
+
+/* Slow path. This handles identifiers which have been split, and
+ identifiers which contain dollar signs. The part of the identifier
+ from PFILE->buffer->cur-1 to CUR has already been scanned. */
+static cpp_hashnode *
+parse_identifier_slow (pfile, cur)
+ cpp_reader *pfile;
+ const U_CHAR *cur;
+{
cpp_buffer *buffer = pfile->buffer;
- unsigned int saw_dollar = 0, len;
+ const U_CHAR *base = buffer->cur - 1;
struct obstack *stack = &pfile->hash_table->stack;
+ unsigned int c, saw_dollar = 0, len;
+
+ /* Copy the part of the token which is known to be okay. */
+ obstack_grow (stack, base, cur - base);
+ /* Now process the part which isn't. We are looking at one of
+ '$', '\\', or '?' on entry to this loop. */
+ c = *cur++;
+ buffer->cur = cur;
do
{
- do
- {
- obstack_1grow (stack, c);
+ while (is_idchar (c))
+ {
+ obstack_1grow (stack, c);
- if (c == '$')
- saw_dollar++;
+ if (c == '$')
+ saw_dollar++;
- c = EOF;
- if (buffer->cur == buffer->rlimit)
- break;
+ c = EOF;
+ if (buffer->cur == buffer->rlimit)
+ break;
- c = *buffer->cur++;
- }
- while (is_idchar (c));
+ c = *buffer->cur++;
+ }
/* Potential escaped newline? */
if (c != '?' && c != '\\')
- break;
+ break;
c = skip_escaped_newlines (pfile, c);
}
while (is_idchar (c));
@@ -521,26 +584,8 @@ parse_identifier (pfile, c)
len = obstack_object_size (stack);
obstack_1grow (stack, '\0');
- /* This routine commits the memory if necessary. */
- result = (cpp_hashnode *)
+ return (cpp_hashnode *)
ht_lookup (pfile->hash_table, obstack_finish (stack), len, HT_ALLOCED);
-
- /* Some identifiers require diagnostics when lexed. */
- if (result->flags & NODE_DIAGNOSTIC && !pfile->state.skipping)
- {
- /* It is allowed to poison the same identifier twice. */
- if ((result->flags & NODE_POISONED) && !pfile->state.poisoned_ok)
- cpp_error (pfile, "attempt to use poisoned \"%s\"",
- NODE_NAME (result));
-
- /* Constraint 6.10.3.5: __VA_ARGS__ should only appear in the
- replacement list of a variadic macro. */
- if (result == pfile->spec_nodes.n__VA_ARGS__
- && !pfile->state.va_args_ok)
- cpp_pedwarn (pfile, "__VA_ARGS__ can only appear in the expansion of a C99 variadic macro");
- }
-
- return result;
}
/* Parse a number, skipping embedded backslash-newlines. */
@@ -1003,14 +1048,17 @@ _cpp_lex_token (pfile, result)
case 'S': case 'T': case 'U': case 'V': case 'W': case 'X':
case 'Y': case 'Z':
result->type = CPP_NAME;
- result->val.node = parse_identifier (pfile, c);
+ result->val.node = parse_identifier (pfile);
/* 'L' may introduce wide characters or strings. */
if (result->val.node == pfile->spec_nodes.n_L)
{
- c = buffer->read_ahead; /* For make_string. */
+ c = buffer->read_ahead;
+ if (c == EOF && buffer->cur < buffer->rlimit)
+ c = *buffer->cur;
if (c == '\'' || c == '"')
{
+ buffer->cur++;
ACCEPT_CHAR (c == '"' ? CPP_WSTRING: CPP_WCHAR);
goto make_string;
}
diff --git a/gcc/hashtable.c b/gcc/hashtable.c
index 7d0359a2c613..bd2b13727bb8 100644
--- a/gcc/hashtable.c
+++ b/gcc/hashtable.c
@@ -162,7 +162,7 @@ ht_lookup (table, str, len, insert)
HT_LEN (node) = len;
if (insert == HT_ALLOC)
- HT_STR (node) = obstack_copy (&table->stack, str, len + 1);
+ HT_STR (node) = obstack_copy0 (&table->stack, str, len);
else
HT_STR (node) = str;
diff --git a/gcc/system.h b/gcc/system.h
index 6b580830e486..7938fb6bdf29 100644
--- a/gcc/system.h
+++ b/gcc/system.h
@@ -490,6 +490,13 @@ extern void abort PARAMS ((void));
#endif /* ! __FUNCTION__ */
#endif
+/* __builtin_expect(A, B) evaluates to A, but notifies the compiler that
+ the most likely value of A is B. This feature was added at some point
+ between 2.95 and 3.0. Let's use 3.0 as the lower bound for now. */
+#if (GCC_VERSION < 3000)
+#define __builtin_expect(a, b) (a)
+#endif
+
/* Provide some sort of boolean type. We use stdbool.h if it's
available. This must be after all inclusion of system headers,
as some of them will mess us up. */
--
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