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

1 files changed, 19 insertions, 0 deletions

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;
+}