Use the DWARF linkage name when importing C++ methods.

When importing C++ methods into clang AST nodes from the DWARF symbol
table, preserve the DW_AT_linkage_name and use it as the linker
("asm") name for the symbol.

Concretely, this enables `expression` to call into names that use the
GNU `abi_tag` extension, and enables lldb to call into code using
std::string or std::list from recent versions of libstdc++. See
https://bugs.llvm.org/show_bug.cgi?id=35310 . It also seems broadly
more robust than relying on the DWARF->clang->codegen pipeline to
roundtrip properly, but I'm not immediately aware of any other cases
in which it makes a difference.

Patch by Nelson Elhage!

Differential Revision:  https://reviews.llvm.org/D40283

llvm-svn: 328658

3 files changed, 63 insertions, 0 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/expression_command/pr35310/Makefile b/lldb/packages/Python/lldbsuite/test/expression_command/pr35310/Makefile
new file mode 100644
index 00000000000..8a7102e347a
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/expression_command/pr35310/Makefile
@@ -0,0 +1,5 @@
+LEVEL = ../../make
+
+CXX_SOURCES := main.cpp
+
+include $(LEVEL)/Makefile.rules
diff --git a/lldb/packages/Python/lldbsuite/test/expression_command/pr35310/TestExprsBug35310.py b/lldb/packages/Python/lldbsuite/test/expression_command/pr35310/TestExprsBug35310.py
new file mode 100644
index 00000000000..6cc479401de
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/expression_command/pr35310/TestExprsBug35310.py
@@ -0,0 +1,39 @@
+from __future__ import print_function
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+class ExprBug35310(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+
+        self.main_source = "main.cpp"
+        self.main_source_spec = lldb.SBFileSpec(self.main_source)
+
+    def test_issue35310(self):
+        """Test invoking functions with non-standard linkage names.
+
+        The GNU abi_tag extension used by libstdc++ is a common source
+        of these, but they could originate from other reasons as well.
+        """
+        self.build()
+
+        (target, process, thread, bkpt) = lldbutil.run_to_source_breakpoint(self, 
+                                          '// Break here', self.main_source_spec)
+        frame = thread.GetFrameAtIndex(0)
+
+        value = frame.EvaluateExpression("a.test_abi_tag()")
+        self.assertTrue(value.IsValid())
+        self.assertTrue(value.GetError().Success())
+        self.assertEqual(value.GetValueAsSigned(0), 1)
+
+        value = frame.EvaluateExpression("a.test_asm_name()")
+        self.assertTrue(value.IsValid())
+        self.assertTrue(value.GetError().Success())
+        self.assertEqual(value.GetValueAsSigned(0), 2)
diff --git a/lldb/packages/Python/lldbsuite/test/expression_command/pr35310/main.cpp b/lldb/packages/Python/lldbsuite/test/expression_command/pr35310/main.cpp
new file mode 100644
index 00000000000..a8e8a5c737a
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/expression_command/pr35310/main.cpp
@@ -0,0 +1,19 @@
+#include <stdio.h>
+
+class A {
+public:
+  int __attribute__((abi_tag("cxx11"))) test_abi_tag() {
+      return 1;
+  }
+  int test_asm_name() asm("A_test_asm") {
+      return 2;
+  }
+};
+
+int main(int argc, char **argv) {
+  A a;
+  // Break here
+  a.test_abi_tag();
+  a.test_asm_name();
+  return 0;
+}