glcpp: Don't use infinite lookhead for #define differentiation.

Previously, we used lookahead patterns to differentiate:

   #define FOO(x)  function macro
   #define FOO (x) object macro

Unfortunately, our rule for function macros:

   {HASH}define{HSPACE}+/{IDENTIFIER}"("

relies on infinite lookahead, and apparently triggers a Flex bug where
the generated code overflows a state buffer (see YY_STATE_BUF_SIZE).

There's no need to use infinite lookahead.  We can simply change state,
match the identifier, and use a single character lookahead for the '('.
This apparently makes Flex not generate the giant state array, which
avoids the buffer overflow, and should be more efficient anyway.

Fixes piglit test 17000-consecutive-chars-identifier.frag.

NOTE: This is a candidate for every release branch ever.

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Carl Worth <[email protected]>

1 files changed, 14 insertions, 6 deletions

diff --git a/src/glsl/glcpp/glcpp-lex.l b/src/glsl/glcpp/glcpp-lex.l
index 7ab58cb288d..783c545495e 100644
--- a/src/glsl/glcpp/glcpp-lex.l
+++ b/src/glsl/glcpp/glcpp-lex.l
@@ -67,7 +67,7 @@ void glcpp_set_column (int  column_no , yyscan_t yyscanner);
 %option stack
 %option never-interactive
 
-%x DONE COMMENT UNREACHABLE SKIP
+%x DONE COMMENT UNREACHABLE SKIP DEFINE
 
 SPACE		[[:space:]]
 NONSPACE	[^[:space:]]
@@ -184,14 +184,22 @@ HEXADECIMAL_INTEGER	0[xX][0-9a-fA-F]+[uU]?
 	glcpp_error(yylloc, yyextra, "#error%s", p);
 }
 
-{HASH}define{HSPACE}+/{IDENTIFIER}"(" {
+{HASH}define{HSPACE}+ {
 	yyextra->space_tokens = 0;
-	return HASH_DEFINE_FUNC;
+	yy_push_state(DEFINE, yyscanner);
+	return HASH_DEFINE;
 }
 
-{HASH}define {
-	yyextra->space_tokens = 0;
-	return HASH_DEFINE_OBJ;
+<DEFINE>{IDENTIFIER}/"(" {
+	yy_pop_state(yyscanner);
+	yylval->str = ralloc_strdup (yyextra, yytext);
+	return FUNC_IDENTIFIER;
+}
+
+<DEFINE>{IDENTIFIER} {
+	yy_pop_state(yyscanner);
+	yylval->str = ralloc_strdup (yyextra, yytext);
+	return OBJ_IDENTIFIER;
 }
 
 {HASH}undef {