Fix some issues with the gdb pretty printers for llvm::Twine

Still some pending bugs, but at least ironed some things out.

cross-project-tests/debuginfo-tests/llvm-prettyprinters/gdb/llvm-support.cpp

@@ -24,7 +24,12 @@ llvm::Optional<int> OptionalNone(llvm::None);
 llvm::SmallVector<int, 5> SmallVector = {10, 11, 12};
 llvm::SmallString<5> SmallString("foo");
 llvm::StringRef StringRef = "bar";
-llvm::Twine Twine = llvm::Twine(SmallString) + StringRef;
+// Should test std::string in Twine too, but it's currently broken because I
+// don't know how to add 'str' and 'gdb.LazyString' (can't figure out any way to
+// string-ify LazyString).
+//std::string String = "foo";
+llvm::Twine TempTwine = llvm::Twine(3) + StringRef;
+llvm::Twine Twine = TempTwine + "baz";
 llvm::PointerIntPair<int *, 1> PointerIntPair(IntPtr, 1);
 
 struct alignas(8) Z {};

cross-project-tests/debuginfo-tests/llvm-prettyprinters/gdb/llvm-support.gdb

@@ -37,7 +37,7 @@ p SmallString
 # CHECK: "bar"
 p StringRef
 
-# CHECK: "foobar"
+# CHECK: "3barbaz"
 p Twine
 
 # CHECK: llvm::StringMap with 2 elements = {["foo"] = 123, ["bar"] = 456}

llvm/utils/gdb-scripts/prettyprinters.py

@@ -16,9 +16,6 @@ class Iterator:
   def children(self):
     return self
 
-def escape_bytes(val, l):
-  return '"' + val.string(encoding='Latin-1', length=l).encode('unicode_escape').decode() + '"'
-
 class SmallStringPrinter:
   """Print an llvm::SmallString object."""
 
@@ -26,8 +23,12 @@ class SmallStringPrinter:
     self.val = val
 
   def to_string(self):
-    begin = self.val['BeginX']
-    return escape_bytes(begin.cast(gdb.lookup_type('char').pointer()), self.val['Size'])
+    data = self.val['BeginX'].cast(gdb.lookup_type('char').pointer())
+    length = self.val['Size']
+    return data.lazy_string(length=length)
+
+  def display_hint (self):
+    return 'string'
 
 class StringRefPrinter:
   """Print an llvm::StringRef object."""
@@ -36,7 +37,12 @@ class StringRefPrinter:
     self.val = val
 
   def to_string(self):
-    return escape_bytes(self.val['Data'], self.val['Length'])
+    data = self.val['Data']
+    length = self.val['Length']
+    return data.lazy_string(length=length)
+
+  def display_hint(self):
+    return 'string'
 
 class SmallVectorPrinter(Iterator):
   """Print an llvm::SmallVector object."""
@@ -300,12 +306,9 @@ class TwinePrinter:
 
     if self.is_twine_kind(kind, 'PtrAndLengthKind'):
       val = child['ptrAndLength']
-      return val['ptr'].string(encoding='Latin-1', length=val['length']).encode('unicode_escape').decode()
-
-    if self.is_twine_kind(kind, 'SmallStringKind'):
-      val = child['smallString'].dereference()
-      pp = SmallStringPrinter(val)
-      return pp.to_string()
+      data = val['ptr']
+      length = val['length']
+      return data.string(length=length)
 
     if self.is_twine_kind(kind, 'CharKind'):
       return chr(child['character'])
@@ -340,11 +343,9 @@ class TwinePrinter:
   def string_from_twine_object(self, twine):
     '''Return the string representation of the Twine object twine.'''
 
-    lhs_str = ''
-    rhs_str = ''
-
     lhs = twine['LHS']
     rhs = twine['RHS']
+
     lhs_kind = str(twine['LHSKind'])
     rhs_kind = str(twine['RHSKind'])
 
@@ -356,6 +357,9 @@ class TwinePrinter:
   def to_string(self):
     return self.string_from_twine_object(self._val)
 
+  def display_hint(self):
+    return 'string'
+
 def get_pointer_int_pair(val):
   """Get tuple from llvm::PointerIntPair."""
   info_name = val.type.template_argument(4).strip_typedefs().name