Print out the location of expanded multiclass defs in TableGen errors.

When reporting an error for a defm, we would previously only report the
location of the outer defm, which is not always where the error is.

Now we also print the location of the expanded multiclass defs:

lib/Target/X86/X86InstrSSE.td:2902:12: error: foo
  defm ADD : basic_sse12_fp_binop_s<0x58, "add", fadd, SSE_ALU_ITINS_S>,
             ^
lib/Target/X86/X86InstrSSE.td:2801:11: note: instantiated from multiclass
  defm PD : sse12_fp_packed<opc, !strconcat(OpcodeStr, "pd"), OpNode, VR128,
            ^
lib/Target/X86/X86InstrSSE.td:194:5: note: instantiated from multiclass
    def rm : PI<opc, MRMSrcMem, (outs RC:$dst), (ins RC:$src1, x86memop:$src2),
        ^

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162409 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/TableGen/Error.cpp b/lib/TableGen/Error.cpp
index 1463b68..5dd688c 100644
--- a/lib/TableGen/Error.cpp
+++ b/lib/TableGen/Error.cpp
@@ -20,8 +20,19 @@
 
 SourceMgr SrcMgr;
 
-void PrintWarning(SMLoc WarningLoc, const Twine &Msg) {
-  SrcMgr.PrintMessage(WarningLoc, SourceMgr::DK_Warning, Msg);
+static void PrintMessage(ArrayRef<SMLoc> Loc, SourceMgr::DiagKind Kind,
+                         const Twine &Msg) {
+  SMLoc NullLoc;
+  if (Loc.empty())
+    Loc = NullLoc;
+  SrcMgr.PrintMessage(Loc.front(), Kind, Msg);
+  for (unsigned i = 1; i < Loc.size(); ++i)
+    SrcMgr.PrintMessage(Loc[i], SourceMgr::DK_Note,
+                        "instantiated from multiclass");
+}
+
+void PrintWarning(ArrayRef<SMLoc> WarningLoc, const Twine &Msg) {
+  PrintMessage(WarningLoc, SourceMgr::DK_Warning, Msg);
 }
 
 void PrintWarning(const char *Loc, const Twine &Msg) {
@@ -36,8 +47,8 @@
   PrintWarning(Warning.getLoc(), Warning.getMessage());
 }
 
-void PrintError(SMLoc ErrorLoc, const Twine &Msg) {
-  SrcMgr.PrintMessage(ErrorLoc, SourceMgr::DK_Error, Msg);
+void PrintError(ArrayRef<SMLoc> ErrorLoc, const Twine &Msg) {
+  PrintMessage(ErrorLoc, SourceMgr::DK_Error, Msg);
 }
 
 void PrintError(const char *Loc, const Twine &Msg) {