[DEBUG_INFO][NVPTX] Generate DW_AT_address_class to get the values in debugger.

Summary:
According to
https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf,
the compiler should emit the DW_AT_address_class attribute for all
variable and parameter. It means, that DW_AT_address_class attribute
should be used in the non-standard way to support compatibility with the
cuda-gdb debugger.
Clang is able to generate the information about the variable address
class. This information is emitted as the expression sequence
`DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef`. The patch
tries to find all such expressions and transform them into
`DW_AT_address_class <DWARF Address Space>` if target is NVPTX and the debugger is gdb.
If the expression is not found, then default values are used. For the
local variables <DWARF Address Space> is set to ADDR_local_space(6), for
the globals <DWARF Address Space> is set to ADDR_global_space(5). The
values are taken from the table in the same section 5.2. CUDA-Specific
DWARF Definitions.

Reviewers: echristo, probinson

Subscribers: jholewinski, aprantl, llvm-commits

Differential Revision: https://reviews.llvm.org/D57157

llvm-svn: 353203

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/include/llvm/IR/DebugInfoMetadata.h b/llvm/include/llvm/IR/DebugInfoMetadata.h
index 40e6873eba7..385f6e7a65f 100644
--- a/llvm/include/llvm/IR/DebugInfoMetadata.h
+++ b/llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -2510,6 +2510,12 @@ public:
   /// return true with an offset of zero.
   bool extractIfOffset(int64_t &Offset) const;
 
+  /// Checks if the last 4 elements of the expression are DW_OP_constu <DWARF
+  /// Address Space> DW_OP_swap DW_OP_xderef and extracts the <DWARF Address
+  /// Space>.
+  static const DIExpression *extractAddressClass(const DIExpression *Expr,
+                                                 unsigned &AddrClass);
+
   /// Constants for DIExpression::prepend.
   enum { NoDeref = false, WithDeref = true, WithStackValue = true };