Support negative numbers in %human format

Author: bricknerb

clang/docs/InternalsManual.rst

@@ -324,8 +324,7 @@ Class:
 Description:
   This is a formatter which represents the argument number in a human readable
   format: the value ``123`` stays ``123``, ``12345`` becomes ``12.34k``,
-  ``6666666` becomes ``6.67M``, and so on for 'G' and 'T'.  Values less than
-  ``0`` are not supported.
+  ``6666666` becomes ``6.67M``, and so on for 'G' and 'T'.
 
 **"objcclass" format**
 

clang/lib/Basic/Diagnostic.cpp

@@ -658,15 +658,19 @@ static void HandleOrdinalModifier(unsigned ValNo,
 // 1234567 -> "1.23M".
 // 1234567890 -> "1.23G".
 // 1234567890123 -> "1.23T".
-static void HandleIntegerHumanModifier(unsigned ValNo,
+static void HandleIntegerHumanModifier(int64_t ValNo,
                                        SmallVectorImpl<char> &OutStr) {
-  static constexpr std::array<std::pair<uint64_t, char>, 4> Units = {
-      {{1'000'000'000'000UL, 'T'},
-       {1'000'000'000UL, 'G'},
-       {1'000'000UL, 'M'},
-       {1'000UL, 'k'}}};
+  static constexpr std::array<std::pair<int64_t, char>, 4> Units = {
+      {{1'000'000'000'000L, 'T'},
+       {1'000'000'000L, 'G'},
+       {1'000'000L, 'M'},
+       {1'000L, 'k'}}};
 
   llvm::raw_svector_ostream Out(OutStr);
+  if (ValNo < 0) {
+    Out << "-";
+    ValNo = -ValNo;
+  }
   for (const auto &[UnitSize, UnitSign] : Units) {
     if (ValNo >= UnitSize) {
       Out << llvm::format("%0.2f%c", ValNo / static_cast<double>(UnitSize),