From 31ac93d051be5be78419ed16da9fcae9783eb4e6 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Tue, 23 Feb 2021 14:13:57 +0100
Subject: [PATCH] AK: Optimize StringView::operator==(const char*) a little bit

Don't compute the strlen() of the string we're comparing against first.
This can save a lot of time if we're comparing against something that
already fails to match in the first few characters.
---
 AK/StringView.h | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/AK/StringView.h b/AK/StringView.h
index 7ff37437c3..6f6f9058de 100644
--- a/AK/StringView.h
+++ b/AK/StringView.h
@@ -144,11 +144,15 @@ public:
             return !cstring;
         if (!cstring)
             return false;
-        size_t other_length = __builtin_strlen(cstring);
-        if (m_length != other_length)
-            return false;
-        return !__builtin_memcmp(m_characters, cstring, m_length);
+        // NOTE: `m_characters` is not guaranteed to be null-terminated, but `cstring` is.
+        const char* cp = cstring;
+        for (size_t i = 0; i < m_length; ++i) {
+            if (m_characters[i] != *(cp++))
+                return false;
+        }
+        return !*cp;
     }
+
     bool operator!=(const char* cstring) const
     {
         return !(*this == cstring);