Remove memory allocation with string

[hiraditya]

Rebase

[hiraditya]

remove consume

[hiraditya]

the following failures reported by buildbot are unrelated to this change:

https://buildkite.com/llvm-project/premerge-checks/builds/18911#c2f85ee7-80d4-418b-9913-a553c2bd256e
Failed Tests (2):

AddressSanitizer-x86_64-linux :: TestCases/Linux/odr-vtable.cpp
AddressSanitizer-x86_64-linux-dynamic :: TestCases/Linux/odr-vtable.cpp

llvm/lib/Option/OptTable.cpp

if (Str.startswith(Prefix)) {
         return Prefix.size() + StringRef(I->Name).size();
     }
   }
   return 0;
 }
 
 // Returns true if one of the Prefixes + In.Names matches Option
 static bool optionMatches(const OptTable::Info &In, StringRef Option) {
-  if (In.Prefixes)
+  if (In.Prefixes) {
+    StringRef InName(In.Name);
     for (size_t I = 0; In.Prefixes[I]; I++)
-      if (Option.endswith(In.Name))
-        if (Option == std::string(In.Prefixes[I]) + In.Name)
+      if (Option.endswith(InName))
+        if (Option.slice(0, Option.size() - InName.size()) == In.Prefixes[I])
           return true;
+  }
   return false;
 }
 
 // This function is for flag value completion.
 // Eg. When "-stdlib=" and "l" was passed to this function, it will return
 // appropiriate values for stdlib, which starts with l.
 std::vector<std::string>
 OptTable::suggestValueCompletions(StringRef Option, StringRef Arg) const {