Revert "PR14569: Omit debug info for thunks"

This reverts commit r189320.

Alexey Samsonov and Dmitry Vyukov presented some arguments for keeping
these around - though it still seems like those tasks could be solved by
a tool just using the symbol table. In a very small number of cases,
thunks may be inlined & debug info might be able to save profilers &
similar tools from misclassifying those cases as part of the caller.

The extra changes here plumb through the VarDecl for various cases to
CodeGenFunction - this provides better fidelity through a few APIs but
generally just causes the CGF::StartFunction to fallback to using the
name of the IR function as the name in the debug info.

The changes to debug-info-global-ctor-dtor.cpp seem like goodness. The
two names that go missing (in favor of only emitting those names as
linkage names) are names that can be demangled - emitting them only as
the linkage name should encourage tools to do just that.

Again, thanks to Dinesh Dwivedi for investigation/work on this issue.

llvm-svn: 189421

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/test/CodeGenCXX/debug-info-thunk.cpp b/clang/test/CodeGenCXX/debug-info-thunk.cpp
index b2bb5a9e39f..2a508957253 100644
--- a/clang/test/CodeGenCXX/debug-info-thunk.cpp
+++ b/clang/test/CodeGenCXX/debug-info-thunk.cpp
@@ -14,4 +14,4 @@ struct C : A, B {
 
 void C::f() { }
 
-// CHECK-NOT: [ DW_TAG_subprogram ] [line 15] [def] [_ZThn{{4|8}}_N1C1fEv]
+// CHECK: metadata !"_ZThn{{4|8}}_N1C1fEv", i32 15, {{.*}} ; [ DW_TAG_subprogram ] [line 15] [def]{{$}}