From: Rupert Swarbrick <rswarbrick@gmail.com>
Date: Tue, 26 May 2020 10:51:06 +0000 (+0100)
Subject: Use c_str(), not str() for IdString/std::string == and != operators
X-Git-Tag: working-ls180~535^2
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8f87ccec9b6ed3c9bb8280830b506b28324a60d8;p=yosys.git

Use c_str(), not str() for IdString/std::string == and != operators

These operators work by fetching the string from the global string
table and then comparing with the std::string that was passed in as
rhs.

Using str() means that we create a std::string (strlen; malloc;
memcpy), compare for equality (another memcmp if they have the same
length) and then finally free the string.

Using c_str() means that we pass the const char* straight to
std::string's equality operator. This ends up as a call to
std::string::compare (the const char* flavour), which is essentially
strcmp.
---

diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 11c45bbec..10bfc13f2 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -296,8 +296,8 @@ namespace RTLIL
 
 		// The methods below are just convenience functions for better compatibility with std::string.
 
-		bool operator==(const std::string &rhs) const { return str() == rhs; }
-		bool operator!=(const std::string &rhs) const { return str() != rhs; }
+		bool operator==(const std::string &rhs) const { return c_str() == rhs; }
+		bool operator!=(const std::string &rhs) const { return c_str() != rhs; }
 
 		bool operator==(const char *rhs) const { return strcmp(c_str(), rhs) == 0; }
 		bool operator!=(const char *rhs) const { return strcmp(c_str(), rhs) != 0; }