Add support for DW_TAG_thrown_type.

For Swift we would like to be able to encode the error types that a
function may throw, so the debugger can display them alongside the
function's return value when finish-ing a function.

DWARF defines DW_TAG_thrown_type (intended to be used for C++ throw()
declarations) that is a perfect fit for this purpose. This patch wires
up support for DW_TAG_thrown_type in LLVM by adding a list of thrown
types to DISubprogram.

To offset the cost of the extra pointer, there is a follow-up patch
that turns DISubprogram into a variable-length node.

rdar://problem/29481673

Differential Revision: https://reviews.llvm.org/D32559

llvm-svn: 301489

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 4e04020f206..5f60774c302 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -1050,6 +1050,14 @@ void Verifier::visitDISubprogram(const DISubprogram &N) {
     // Subprogram declarations (part of the type hierarchy).
     AssertDI(!Unit, "subprogram declarations must not have a compile unit", &N);
   }
+
+  if (auto *RawThrownTypes = N.getRawThrownTypes()) {
+    auto *ThrownTypes = dyn_cast<MDTuple>(RawThrownTypes);
+    AssertDI(ThrownTypes, "invalid thrown types list", &N, RawThrownTypes);
+    for (Metadata *Op : ThrownTypes->operands())
+      AssertDI(Op && isa<DIType>(Op), "invalid thrown type", &N, ThrownTypes,
+               Op);
+  }
 }
 
 void Verifier::visitDILexicalBlockBase(const DILexicalBlockBase &N) {