[SymbolFilePDB] Add support for resolving variable symbols

Summary:
Implement FindGlobalVariables and ParseVariableContext methods.

Compile unit information is necessary for resolving variable context, however some PDB symbols do not have this information. For now an empty DWARFExpression is used to construct a lldb::Variable instance with the limitation that using lldb to lookup the value of a global or local variable is not available.

This commit may slow down lit/SymbolFile/PDB/compilands.test since the test includes MS specific modules that spend more time parsing variables.

Reviewers: rnk, zturner, lldb-commits

Subscribers: aprantl, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D45224

llvm-svn: 333049

lldb/lit/SymbolFile/PDB/Inputs/VariablesTest.cpp

@@ -0,0 +1,50 @@
+typedef int IntTypedef;
+IntTypedef g_IntVar;  // Testing globals.
+
+typedef enum Enum { // Testing constants.
+  RED,
+  GREEN,
+  BLUE
+} EnumTypedef;
+EnumTypedef g_EnumVar;  // Testing members.
+
+// FIXME: `sg_IntVar` appears both in global scope's children and compiland's
+// children but with different symbol's id.
+static int sg_IntVar = -1;  // Testing file statics.
+
+// FIXME: `g_Const` appears both in global scope's children and compiland's
+// children but with different symbol's id.
+const int g_Const = 0x88;  // Testing constant data.
+const int *g_pConst = &g_Const; // Avoid optimizing the const away
+
+thread_local int g_tls = 0;  // Testing thread-local storage.
+
+class Class {
+  static int m_StaticClassMember;
+public:
+  explicit Class(int a) {}
+  void Func() {}
+};
+int Class::m_StaticClassMember = 10; // Testing static class members.
+Class ClassVar(1);
+
+int f(int var_arg1, int var_arg2) {  // Testing parameters.
+  long same_name_var = -1;
+  return 1;
+}
+
+int same_name_var = 100;
+int main() {
+  int same_name_var = 0;  // Testing locals.
+  const char local_const = 0x1;
+
+  // FIXME: 'local_CString` is not found through compiland's children.
+  const char local_CString[] = "abc";  // Testing constant string.
+  const char *local_pCString = local_CString; // Avoid optimizing the const away
+
+  int a = 10;
+  a++;
+
+  ClassVar.Func();
+  return 0;
+}

lldb/lit/SymbolFile/PDB/variables.test

@@ -0,0 +1,58 @@
+REQUIRES: windows
+RUN: clang-cl /Z7 /c %S/Inputs/VariablesTest.cpp /o %T/VariablesTest.cpp.obj
+RUN: link %T/VariablesTest.cpp.obj /DEBUG /nodefaultlib /ENTRY:main /OUT:%T/VariablesTest.cpp.exe
+RUN: lldb-test symbols %T/VariablesTest.cpp.exe | FileCheck %s
+
+CHECK: Module [[MOD:.*]]
+CHECK: SymbolVendor ([[MOD]])
+CHECK:     CompileUnit{{.*}}, language = "c++", file = '{{.*}}\VariablesTest.cpp'
+CHECK-DAG:   Variable{{.*}}, name = "g_IntVar"
+CHECK-SAME:  scope = global, external
+CHECK-DAG:   Variable{{.*}}, name = "m_StaticClassMember"
+CHECK-SAME:  scope = global, external
+CHECK-DAG:   Variable{{.*}}, name = "g_pConst"
+CHECK-SAME:  scope = global, external
+CHECK-DAG:   Variable{{.*}}, name = "same_name_var"
+CHECK-SAME:  scope = global, external
+CHECK-DAG:   Variable{{.*}}, name = "g_EnumVar"
+CHECK-SAME:  scope = global, external
+CHECK-DAG:   Variable{{.*}}, name = "g_tls"
+CHECK-SAME:  scope = thread local, external
+CHECK-DAG:   Variable{{.*}}, name = "ClassVar"
+CHECK-SAME:  scope = global, external
+CHECK-DAG:   Variable{{.*}}, name = "g_Const"
+CHECK-SAME:  scope = ??? (2)
+
+CHECK-DAG:   Function{[[FID1:.*]]}, mangled = ?f@@YAHHH@Z
+CHECK-NEXT:  Block{[[FID1]]}
+CHECK-DAG:     Variable{{.*}}, name = "var_arg1"
+CHECK-SAME:    scope = parameter
+CHECK-DAG:     Variable{{.*}}, name = "var_arg2"
+CHECK-SAME:    scope = parameter
+CHECK-DAG:     Variable{{.*}}, name = "same_name_var"
+CHECK-SAME:    scope = local
+
+CHECK-DAG:   Function{[[FID2:.*]]}, mangled = main
+CHECK-NEXT:  Block{[[FID2]]}
+CHECK-DAG:     Variable{{.*}}, name = "same_name_var"
+CHECK-SAME:    scope = local
+CHECK-DAG:     Variable{{.*}}, name = "local_const"
+CHECK-SAME:    scope = local
+CHECK-DAG:     Variable{{.*}}, name = "local_pCString"
+CHECK-SAME:    scope = local
+CHECK-DAG:     Variable{{.*}}, name = "a"
+CHECK-SAME:    scope = local
+
+CHECK-DAG:   Function{[[FID3:.*]]}, mangled = ??0Class@@QEAA@H@Z
+CHECK-NEXT:  Block{[[FID3]]}
+CHECK-DAG:     Variable{{.*}}, name = "this"
+CHECK-SAME:    scope = parameter
+CHECK-SAME:    artificial
+CHECK-DAG:     Variable{{.*}}, name = "a"
+CHECK-SAME:    scope = parameter
+
+CHECK-DAG:   Function{[[FID4:.*]]}, mangled = ?Func@Class@@QEAAXXZ
+CHECK-NEXT:  Block{[[FID4]]}
+CHECK-DAG:     Variable{{.*}}, name = "this"
+CHECK-SAME:    scope = parameter
+CHECK-SAME:    artificial