Quoting Richard Guenther <richard.guent...@gmail.com>:
Something smaller (but pointless) woudl be nice.
I have attached the patch with the example added to the documentation.
Again, bootstrapped on i686-pc-linux-gnu.
2011-09-19 J"orn Rennecke <joern.renne...@arc.com>
* genoutput.c (process_template): Process '*' in '@' alternatives.
* doc/md.texi (node Output Statement): Provide example for the above.
Index: doc/md.texi
===================================================================
--- doc/md.texi (revision 191429)
+++ doc/md.texi (working copy)
@@ -665,6 +665,22 @@ (define_insn ""
@end group
@end smallexample
+If you just need a little bit of C code in one (or a few) alternatives,
+you can use @samp{*} inside of a @samp{@@} multi-alternative template:
+
+@smallexample
+@group
+(define_insn ""
+ [(set (match_operand:SI 0 "general_operand" "=r,<,m")
+ (const_int 0))]
+ ""
+ "@@
+ clrreg %0
+ * return stack_mem_p (operands[0]) ? \"push 0" : \"clrmem %0\";
+ clrmem %0")
+@end group
+@end smallexample
+
@node Predicates
@section Predicates
@cindex predicates
Index: genoutput.c
===================================================================
--- genoutput.c (revision 191429)
+++ genoutput.c (working copy)
@@ -662,19 +662,55 @@ process_template (struct data *d, const
list of assembler code templates, one for each alternative. */
else if (template_code[0] == '@')
{
- d->template_code = 0;
- d->output_format = INSN_OUTPUT_FORMAT_MULTI;
+ int found_star = 0;
- printf ("\nstatic const char * const output_%d[] = {\n", d->code_number);
+ for (cp = &template_code[1]; *cp; )
+ {
+ while (ISSPACE (*cp))
+ cp++;
+ if (*cp == '*')
+ found_star = 1;
+ while (!IS_VSPACE (*cp) && *cp != '\0')
+ ++cp;
+ }
+ d->template_code = 0;
+ if (found_star)
+ {
+ d->output_format = INSN_OUTPUT_FORMAT_FUNCTION;
+ puts ("\nstatic const char *");
+ printf ("output_%d (rtx *operands ATTRIBUTE_UNUSED, "
+ "rtx insn ATTRIBUTE_UNUSED)\n", d->code_number);
+ puts ("{");
+ puts (" switch (which_alternative)\n {");
+ }
+ else
+ {
+ d->output_format = INSN_OUTPUT_FORMAT_MULTI;
+ printf ("\nstatic const char * const output_%d[] = {\n",
+ d->code_number);
+ }
for (i = 0, cp = &template_code[1]; *cp; )
{
- const char *ep, *sp;
+ const char *ep, *sp, *bp;
while (ISSPACE (*cp))
cp++;
- printf (" \"");
+ bp = cp;
+ if (found_star)
+ {
+ printf (" case %d:", i);
+ if (*cp == '*')
+ {
+ printf ("\n ");
+ cp++;
+ }
+ else
+ printf (" return \"");
+ }
+ else
+ printf (" \"");
for (ep = sp = cp; !IS_VSPACE (*ep) && *ep != '\0'; ++ep)
if (!ISSPACE (*ep))
@@ -690,7 +726,18 @@ process_template (struct data *d, const
cp++;
}
- printf ("\",\n");
+ if (!found_star)
+ puts ("\",");
+ else if (*bp != '*')
+ puts ("\";");
+ else
+ {
+ /* The usual action will end with a return.
+ If there is neither break or return at the end, this is
+ assumed to be intentional; this allows to have multiple
+ consecutive alternatives share some code. */
+ puts ("");
+ }
i++;
}
if (i == 1)
@@ -700,7 +747,10 @@ process_template (struct data *d, const
error_with_line (d->lineno,
"wrong number of alternatives in the output template");
- printf ("};\n");
+ if (found_star)
+ puts (" default: gcc_unreachable ();\n }\n}");
+ else
+ printf ("};\n");
}
else
{
