From 865258432a1a335a2858b74e07e3e2c69db025af Mon Sep 17 00:00:00 2001
From: Matthias Braun <matze@braunis.de>
Date: Mon, 22 Sep 2008 18:42:50 +0000
Subject: [PATCH] possibility to disable builtin functions

[r22178]
---
 builtins/builtins.c | 37 +++++++++++++++++++++++++++++++++++++
 main.c              |  4 +++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/builtins/builtins.c b/builtins/builtins.c
index 3342563..026f8e2 100644
--- a/builtins/builtins.c
+++ b/builtins/builtins.c
@@ -27,6 +27,7 @@ static inline int strcmp(const char *s1, const char *s2)
 	return (unsigned char)*s1 - (unsigned char)*s2;
 }
 
+/*
 static inline __SIZE_TYPE__ strlen(const char *s)
 {
 	__SIZE_TYPE__ result = 0;
@@ -34,6 +35,42 @@ static inline __SIZE_TYPE__ strlen(const char *s)
 		result++;
 	return result;
 }
+*/
+
+static inline __SIZE_TYPE__ strlen(const char *str)
+{
+	const char          *char_ptr;
+	const unsigned long *long_ptr;
+	unsigned long int longword, magic_bits, himagic, lomagic;
+	int abort(void);
+
+	for (char_ptr = str; ((unsigned long int) char_ptr & (sizeof(longword)-1)) != 0; ++char_ptr) {
+		if (*char_ptr == '\0')
+			return char_ptr - str;
+	}
+
+	long_ptr = (unsigned long int*) char_ptr;
+	magic_bits = 0x7efefeffL;
+	himagic    = 0x80808080L;
+	lomagic    = 0x01010101L;
+	if (sizeof(longword) > 4)
+		abort();
+
+	for(;;) {
+		longword = *long_ptr++;
+		if (((longword - lomagic) & himagic) != 0) {
+			const char *cp = (const char*) (long_ptr - 1);
+			if (cp[0] == 0)
+				return cp-str;
+			if (cp[1] == 0)
+				return cp-str+1;
+			if (cp[2] == 0)
+				return cp-str+2;
+			if (cp[3] == 0)
+				return cp-str+3;
+		}
+	}
+}
 
 static inline char *strcpy(char *dest, const char *source)
 {
diff --git a/main.c b/main.c
index 2497541..b137518 100644
--- a/main.c
+++ b/main.c
@@ -567,11 +567,11 @@ int main(int argc, char **argv)
 	default:
 	case 4:
 		set_option("strict-aliasing");
+		use_builtins = true;
 		/* fallthrough */
 	case 3:
 		set_option("cond-eval");
 		set_option("if-conv");
-		use_builtins = true;
 		/* fallthrough */
 	case 2:
 		set_option("inline");
@@ -677,6 +677,8 @@ int main(int argc, char **argv)
 
 					if (streq(opt, "dollars-in-identifiers")) {
 						allow_dollar_in_symbol = truth_value;
+					} if (streq(opt, "builtins")) {
+						use_builtins = truth_value;
 					} else if (streq(opt, "short-wchar")) {
 						opt_short_wchar_t = truth_value;
 					} else if (streq(opt, "syntax-only")) {
-- 
2.20.1