Add an override to StringRef::getAsInteger which parses into an APInt.

It gets its own implementation totally divorced from the (presumably
performance-sensitive) routines which parse into a uint64_t.

Add APInt::operator|=(uint64_t), which is situationally much better than
using a full APInt.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97381 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/StringRef.h

@@ -18,6 +18,7 @@
 namespace llvm {
   template<typename T>
   class SmallVectorImpl;
+  class APInt;
 
   /// StringRef - Represent a constant reference to a string, i.e. a character
   /// array and a length, which need not be null terminated.
@@ -273,6 +274,19 @@ namespace llvm {
 
     // TODO: Provide overloads for int/unsigned that check for overflow.
 
+    /// getAsInteger - Parse the current string as an integer of the
+    /// specified radix, or of an autosensed radix if the radix given
+    /// is 0.  The current value in Result is discarded, and the
+    /// storage is changed to be wide enough to store the parsed
+    /// integer.
+    ///
+    /// Returns true if the string does not solely consist of a valid
+    /// non-empty number in the appropriate base.
+    ///
+    /// APInt::fromString is superficially similar but assumes the
+    /// string is well-formed in the given radix.
+    bool getAsInteger(unsigned Radix, APInt &Result) const;
+
     /// @}
     /// @name Substring Operations
     /// @{