[ADT] Forward some StringRef::find overloads to std::string_view

These are identical in terms of functionality and performance (checked
libc++ and libstdc++). We could do the same for rfind, but that actually
has a off-by one on its position argument.

StringRef::find(StringRef) seems to be quite a bit more optimized than
the standard library one, so leave it alone.

1 files changed, 2 insertions, 13 deletions

diff --git a/llvm/lib/Support/StringRef.cpp b/llvm/lib/Support/StringRef.cpp
index f9fa511..fb93940 100644
--- a/llvm/lib/Support/StringRef.cpp
+++ b/llvm/lib/Support/StringRef.cpp
@@ -215,15 +215,7 @@ size_t StringRef::rfind_insensitive(char C, size_t From) const {
 /// \return - The index of the last occurrence of \arg Str, or npos if not
 /// found.
 size_t StringRef::rfind(StringRef Str) const {
-  size_t N = Str.size();
-  if (N > Length)
-    return npos;
-  for (size_t i = Length - N + 1, e = 0; i != e;) {
-    --i;
-    if (substr(i, N).equals(Str))
-      return i;
-  }
-  return npos;
+  return std::string_view(*this).rfind(Str);
 }
 
 size_t StringRef::rfind_insensitive(StringRef Str) const {
@@ -257,10 +249,7 @@ StringRef::size_type StringRef::find_first_of(StringRef Chars,
 /// find_first_not_of - Find the first character in the string that is not
 /// \arg C or npos if not found.
 StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {
-  for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
-    if (Data[i] != C)
-      return i;
-  return npos;
+  return std::string_view(*this).find_first_not_of(C, From);
 }
 
 /// find_first_not_of - Find the first character in the string that is not