[DebugInfo] Add bit size to _BitInt name in debug info (llvm#165583)

Follow on from llvm#164372

This changes the DW_AT_name for `_BitInt(N)` from `_BitInt` to `_BitInt(N)`

(cherry picked from commit 30579c0)

Author: OCHyams

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -1146,7 +1146,10 @@ llvm::DIType *CGDebugInfo::CreateType(const BuiltinType *BT) {
 }
 
 llvm::DIType *CGDebugInfo::CreateType(const BitIntType *Ty) {
-  StringRef Name = Ty->isUnsigned() ? "unsigned _BitInt" : "_BitInt";
+  SmallString<32> Name;
+  llvm::raw_svector_ostream OS(Name);
+  OS << (Ty->isUnsigned() ? "unsigned _BitInt(" : "_BitInt(")
+     << Ty->getNumBits() << ")";
   llvm::dwarf::TypeKind Encoding = Ty->isUnsigned()
                                        ? llvm::dwarf::DW_ATE_unsigned
                                        : llvm::dwarf::DW_ATE_signed;

clang/test/CodeGen/bit-int.c

@@ -4,5 +4,5 @@
 unsigned _BitInt(17) a;
 _BitInt(2) b;
 
-// CHECK: !DIBasicType(name: "_BitInt", size: 8, dataSize: 2, encoding: DW_ATE_signed)
-// CHECK: !DIBasicType(name: "unsigned _BitInt", size: 32,  dataSize: 17, encoding: DW_ATE_unsigned)
+// CHECK: !DIBasicType(name: "_BitInt(2)", size: 8, dataSize: 2, encoding: DW_ATE_signed)
+// CHECK: !DIBasicType(name: "unsigned _BitInt(17)", size: 32,  dataSize: 17, encoding: DW_ATE_unsigned)