Add support for sythetic operator dereference

Summary:
After this change a sythetic child provider can generate a special child
named "$$dereference$$" what if present is used when "operator*" or
"operator->" used on a ValueObject. The goal of the change is to make
expressions like "up->foo" work inside the "frame variable" command.

Reviewers: labath, jingham

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D31368

llvm-svn: 299251

diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/unique_ptr/TestDataFormatterStdUniquePtr.py b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/unique_ptr/TestDataFormatterStdUniquePtr.py
index eca690f94d874b5c59136ac484ad2b2d6ad48fcc..37adb28d7d591f618c5926e557986817e68df7ab 100644 (file)
--- a/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/unique_ptr/TestDataFormatterStdUniquePtr.py
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/unique_ptr/TestDataFormatterStdUniquePtr.py
@@ -42,13 +42,17 @@ class StdUniquePtrDataFormatterTestCase(TestBase):
         self.expect("frame variable sdp", substrs=['sdp = 0x', 'deleter = ', 'a = 3', 'b = 4'])
 
         self.assertEqual(123, frame.GetValueForVariablePath("iup.object").GetValueAsUnsigned())
+        self.assertEqual(123, frame.GetValueForVariablePath("*iup").GetValueAsUnsigned())
         self.assertFalse(frame.GetValueForVariablePath("iup.deleter").IsValid())
 
         self.assertEqual('"foobar"', frame.GetValueForVariablePath("sup.object").GetSummary())
+        self.assertEqual('"foobar"', frame.GetValueForVariablePath("*sup").GetSummary())
         self.assertFalse(frame.GetValueForVariablePath("sup.deleter").IsValid())
 
         self.assertEqual(456, frame.GetValueForVariablePath("idp.object").GetValueAsUnsigned())
+        self.assertEqual(456, frame.GetValueForVariablePath("*idp").GetValueAsUnsigned())
         self.assertEqual('"baz"', frame.GetValueForVariablePath("sdp.object").GetSummary())
+        self.assertEqual('"baz"', frame.GetValueForVariablePath("*sdp").GetSummary())
 
         idp_deleter = frame.GetValueForVariablePath("idp.deleter")
         self.assertTrue(idp_deleter.IsValid())
@@ -86,5 +90,7 @@ class StdUniquePtrDataFormatterTestCase(TestBase):
         frame = self.frame()
         self.assertTrue(frame.IsValid())
         self.assertEqual(2, frame.GetValueForVariablePath("f1->fp.object.data").GetValueAsUnsigned())
+        self.assertEqual(2, frame.GetValueForVariablePath("f1->fp->data").GetValueAsUnsigned())
         self.assertEqual(1, frame.GetValueForVariablePath("f1->fp.object.fp.object.data").GetValueAsUnsigned())
+        self.assertEqual(1, frame.GetValueForVariablePath("f1->fp->fp->data").GetValueAsUnsigned())
 

diff --git a/lldb/source/Core/ValueObject.cpp b/lldb/source/Core/ValueObject.cpp
index 3947551e2b2d38c57cef1cccb664cb40b721ef14..1c504a27a5b15e26a3e34399758bdec2515a824e 100644 (file)
--- a/lldb/source/Core/ValueObject.cpp
+++ b/lldb/source/Core/ValueObject.cpp
@@ -2889,6 +2889,11 @@ ValueObjectSP ValueObject::Dereference(Error &error) {
           child_is_base_class, child_is_deref_of_parent, eAddressTypeInvalid,
           language_flags);
     }
+  } else if (HasSyntheticValue()) {
+    m_deref_valobj =
+        GetSyntheticValue()
+            ->GetChildMemberWithName(ConstString("$$dereference$$"), true)
+            .get();
   }
 
   if (m_deref_valobj) {

diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
index 7af0a16ee19b978657821b07a4442343228c5da9..8d7ce6505a4fad762f30e1ccc070b0801ed7bc1b 100644 (file)
--- a/lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
@@ -114,7 +114,8 @@ size_t LibStdcppUniquePtrSyntheticFrontEnd::GetIndexOfChildWithName(
     return 0;
   if (name == ConstString("del") || name == ConstString("deleter"))
     return 1;
-  if (name == ConstString("obj") || name == ConstString("object"))
+  if (name == ConstString("obj") || name == ConstString("object") ||
+      name == ConstString("$$dereference$$"))
     return 2;
   return UINT32_MAX;
 }

diff --git a/lldb/source/Target/StackFrame.cpp b/lldb/source/Target/StackFrame.cpp
index d2278b4bc68bff7b3b2c618789277e7f75fcc2ed..fa86e57fdfa5a8b98cd971cc0db20f8de5bd6150 100644 (file)
--- a/lldb/source/Target/StackFrame.cpp
+++ b/lldb/source/Target/StackFrame.cpp
@@ -606,8 +606,10 @@ ValueObjectSP StackFrame::GetValueForVariableExpressionPath(
     // Calculate the next separator index ahead of time
     ValueObjectSP child_valobj_sp;
     const char separator_type = var_expr[0];
+    bool expr_is_ptr = false;
     switch (separator_type) {
     case '-':
+      expr_is_ptr = true;
       if (var_expr.size() >= 2 && var_expr[1] != '>')
         return ValueObjectSP();
 
@@ -624,11 +626,32 @@ ValueObjectSP StackFrame::GetValueForVariableExpressionPath(
           return ValueObjectSP();
         }
       }
+
+      // If we have a non pointer type with a sythetic value then lets check if
+      // we have an sythetic dereference specified.
+      if (!valobj_sp->IsPointerType() && valobj_sp->HasSyntheticValue()) {
+        Error deref_error;
+        if (valobj_sp->GetCompilerType().IsReferenceType()) {
+          valobj_sp = valobj_sp->GetSyntheticValue()->Dereference(deref_error);
+          if (error.Fail()) {
+            error.SetErrorStringWithFormatv(
+                "Failed to dereference reference type: %s", deref_error);
+            return ValueObjectSP();
+          }
+        }
+
+        valobj_sp = valobj_sp->Dereference(deref_error);
+        if (error.Fail()) {
+          error.SetErrorStringWithFormatv(
+              "Failed to dereference sythetic value: %s", deref_error);
+          return ValueObjectSP();
+        }
+        expr_is_ptr = false;
+      }
+
       var_expr = var_expr.drop_front(); // Remove the '-'
       LLVM_FALLTHROUGH;
     case '.': {
-      const bool expr_is_ptr = var_expr[0] == '>';
-
       var_expr = var_expr.drop_front(); // Remove the '.' or '>'
       separator_idx = var_expr.find_first_of(".-[");
       ConstString child_name(var_expr.substr(0, var_expr.find_first_of(".-[")));

diff --git a/lldb/www/varformats.html b/lldb/www/varformats.html
index 78c996e57ee7df5c8bba5d767e9beb3c417c38cd..c4c1d8efb568c3b5272112ec80bc24f7272ea2b7 100755 (executable)
--- a/lldb/www/varformats.html
+++ b/lldb/www/varformats.html
@@ -1068,6 +1068,7 @@ def function (valobj,internal_dict):<br/>
 <sup>[2]</sup> This method is optional (starting with SVN rev166495/LLDB-175). While implementing it in terms of <code>num_children</code> is acceptable, implementors are encouraged to look for optimized coding alternatives whenever reasonable.
 <br/>
 <sup>[3]</sup> This method is optional (starting with SVN revision 219330). The SBValue you return here will most likely be a numeric type (int, float, ...) as its value bytes will be used as-if they were the value of the root SBValue proper. As a shortcut for this, you can inherit from lldb.SBSyntheticValueProvider, and just define get_value as other methods are defaulted in the superclass as returning default no-children responses.
+<p>If a synthetic child provider supplies a special child named <code>$$dereference$$</code> then it will be used when evaluating <code>opertaor*</code> and <code>operator-&gt;</code> in the <code>frame variable</code> command and related SB API functions.</p>
                <p>For examples of how synthetic children are created, you are encouraged to look at <a href="http://llvm.org/svn/llvm-project/lldb/trunk/examples/synthetic/">examples/synthetic</a> in the LLDB trunk. Please, be aware that the code in those files (except bitfield/)
                        is legacy code and is not maintained.
                        You may especially want to begin looking at <a href="http://llvm.org/svn/llvm-project/lldb/trunk/examples/synthetic/bitfield">this example</a> to get