[lldb] Enable debugging of binaries with mixed (splitted/regular) dwarf

Initialize the default value of SymbolFileDWARF uuid with 
the appropriately shifted DW_INVALID_OFFSET constant.
This change fixes the collision in the computation of DIE uid 
(inside DIERef::GetUID) and incorrect CompileUnit lookup
(because of the misleading cu_offset value).

Test plan: make check-lldb

Differential revision: https://reviews.llvm.org/D42563

llvm-svn: 323832

5 files changed, 74 insertions, 3 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/Makefile b/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/Makefile
new file mode 100644
index 00000000000..7cfad32f827
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/Makefile
@@ -0,0 +1,10 @@
+LEVEL := ../../make
+
+C_SOURCES := a.c b.c
+a.o: CFLAGS_EXTRAS += -gsplit-dwarf
+
+include $(LEVEL)/Makefile.rules
+
+.PHONY: clean
+clean::
+	$(RM) -f a.dwo a.o b.o main
diff --git a/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/TestMixedDwarfBinary.py b/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/TestMixedDwarfBinary.py
new file mode 100644
index 00000000000..0266be62c25
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/TestMixedDwarfBinary.py
@@ -0,0 +1,46 @@
+""" Testing debugging of a binary with "mixed" dwarf (with/without fission). """
+import os
+import lldb
+import sys
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestMixedDwarfBinary(TestBase):
+    mydir = TestBase.compute_mydir(__file__)
+
+    def setUp(self):
+        TestBase.setUp(self)
+
+    @no_debug_info_test  # Prevent the genaration of the dwarf version of this test
+    @add_test_categories(["dwo"])
+    @skipUnlessPlatform(["linux"])
+    def test_mixed_dwarf(self):
+        """Test that 'frame variable' works
+        for the executable built from two source files compiled
+        with/whithout -gsplit-dwarf correspondingly."""
+
+        self.build()
+        exe = os.path.join(os.getcwd(), "a.out")
+
+        self.target = self.dbg.CreateTarget(exe)
+        self.assertTrue(self.target, VALID_TARGET)
+
+        main_bp = self.target.BreakpointCreateByName("g", "a.out")
+        self.assertTrue(main_bp, VALID_BREAKPOINT)
+
+        self.process = self.target.LaunchSimple(
+            None, None, self.get_process_working_directory())
+        self.assertTrue(self.process, PROCESS_IS_VALID)
+
+        # The stop reason of the thread should be breakpoint.
+        self.assertTrue(self.process.GetState() == lldb.eStateStopped,
+                        STOPPED_DUE_TO_BREAKPOINT)
+
+        frame = self.process.GetThreadAtIndex(0).GetFrameAtIndex(0)
+        x = frame.FindVariable("x")
+        self.assertTrue(x.IsValid(), "x is not valid")
+        y = frame.FindVariable("y")
+        self.assertTrue(y.IsValid(), "y is not valid")
+
diff --git a/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/a.c b/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/a.c
new file mode 100644
index 00000000000..047e78a9b29
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/a.c
@@ -0,0 +1,3 @@
+int f() {
+  return 1;
+}
diff --git a/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/b.c b/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/b.c
new file mode 100644
index 00000000000..d79970e13d4
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/linux/mix-dwo-and-regular-objects/b.c
@@ -0,0 +1,11 @@
+extern int f();
+
+void g() {
+  int y = 14;
+  int x = f();
+}
+
+int main() {
+  g();
+  return 0;
+}
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index c132889a7ba..d37837cd212 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -392,9 +392,10 @@ SymbolFileDWARF::GetParentSymbolContextDIE(const DWARFDIE &child_die) {
 }
 
 SymbolFileDWARF::SymbolFileDWARF(ObjectFile *objfile)
-    : SymbolFile(objfile), UserID(0), // Used by SymbolFileDWARFDebugMap to when
-                                      // this class parses .o files to contain
-                                      // the .o file index/ID
+    : SymbolFile(objfile),
+      UserID(uint64_t(DW_INVALID_OFFSET) << 32), // Used by SymbolFileDWARFDebugMap to when
+                                                 // this class parses .o files to contain
+                                                 // the .o file index/ID
       m_debug_map_module_wp(), m_debug_map_symfile(NULL), m_data_debug_abbrev(),
       m_data_debug_aranges(), m_data_debug_frame(), m_data_debug_info(),
       m_data_debug_line(), m_data_debug_macro(), m_data_debug_loc(),