lookup_constraint is also an out-of-line switch-based function.
Since most constraints are still single-letter ones, it should be
more efficient to have a lookup array for the single-character case
and an out-of-line function for the more complicated ones. This becomes
even more important with the latter half of the series (which isn't as
much of a win otherwise).
Richard
gcc/
* genpreds.c (write_lookup_constraint): Rename to...
(write_lookup_constraint_1): ...this.
(write_lookup_constraint_array): New function.
(write_tm_preds_h): Define lookup_constraint as an inline function
that uses write_lookup_constraint_array where possible.
(write_insn_preds_c): Update for the changes above.
Index: gcc/genpreds.c
===================================================================
--- gcc/genpreds.c 2014-06-05 21:05:45.308958640 +0100
+++ gcc/genpreds.c 2014-06-05 21:05:45.972964371 +0100
@@ -966,11 +966,11 @@ write_enum_constraint_num (void)
/* Write out a function which looks at a string and determines what
constraint name, if any, it begins with. */
static void
-write_lookup_constraint (void)
+write_lookup_constraint_1 (void)
{
unsigned int i;
puts ("enum constraint_num\n"
- "lookup_constraint (const char *str)\n"
+ "lookup_constraint_1 (const char *str)\n"
"{\n"
" switch (str[0])\n"
" {");
@@ -1005,6 +1005,29 @@ write_lookup_constraint (void)
"}\n");
}
+/* Write out an array that maps single-letter characters to their
+ constraints (if that fits in a character) or 255 if lookup_constraint_1
+ must be called. */
+static void
+write_lookup_constraint_array (void)
+{
+ unsigned int i;
+ printf ("const unsigned char lookup_constraint_array[] = {\n ");
+ for (i = 0; i < ARRAY_SIZE (constraints_by_letter_table); i++)
+ {
+ if (i != 0)
+ printf (",\n ");
+ struct constraint_data *c = constraints_by_letter_table[i];
+ if (!c)
+ printf ("CONSTRAINT__UNKNOWN");
+ else if (c->namelen == 1)
+ printf ("MIN ((int) CONSTRAINT_%s, (int) UCHAR_MAX)", c->c_name);
+ else
+ printf ("UCHAR_MAX");
+ }
+ printf ("\n};\n\n");
+}
+
/* Write out a function which looks at a string and determines what
the constraint name length is. */
static void
@@ -1245,7 +1268,22 @@ #define GCC_TM_PREDS_H\n\
if (constraint_max_namelen > 0)
{
write_enum_constraint_num ();
- puts ("extern enum constraint_num lookup_constraint (const char *);");
+ puts ("extern enum constraint_num lookup_constraint_1 (const char *);\n"
+ "extern const unsigned char lookup_constraint_array[];\n"
+ "\n"
+ "/* Return the constraint at the beginning of P, or"
+ " CONSTRAINT__UNKNOWN if it\n"
+ " isn't recognized. */\n"
+ "\n"
+ "static inline enum constraint_num\n"
+ "lookup_constraint (const char *p)\n"
+ "{\n"
+ " unsigned int index = lookup_constraint_array"
+ "[(unsigned char) *p];\n"
+ " return (index == UCHAR_MAX\n"
+ " ? lookup_constraint_1 (p)\n"
+ " : (enum constraint_num) index);\n"
+ "}\n");
if (satisfied_start == num_constraints)
puts ("/* Return true if X satisfies constraint C. */\n"
"\n"
@@ -1383,7 +1421,8 @@ write_insn_preds_c (void)
if (constraint_max_namelen > 0)
{
- write_lookup_constraint ();
+ write_lookup_constraint_1 ();
+ write_lookup_constraint_array ();
if (have_register_constraints)
write_reg_class_for_constraint_1 ();
write_constraint_satisfied_p_1 ();
