DI: Add Function::getSubprogram()

Add `Function::setSubprogram()` and `Function::getSubprogram()`,
convenience methods to forward to `setMetadata()` and `getMetadata()`,
respectively, and deal in `DISubprogram` instead of `MDNode`.

Also add a verifier check to enforce that `!dbg` attachments are always
subprograms.

Originally (when I had the llvm-dev discussion back in April) I thought
I'd store a pointer directly on `llvm::Function` for these attachments
-- we frequently have debug info, and that's much cheaper than using map
in the context if there are no other function-level attachments -- but
for now I'm just using the generic infrastructure.  Let's add the extra
complexity only if this shows up in a profile.

llvm-svn: 246339

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/test/Verifier/metadata-function-dbg.ll b/llvm/test/Verifier/metadata-function-dbg.ll
new file mode 100644
index 00000000000..43c632babda
--- /dev/null
+++ b/llvm/test/Verifier/metadata-function-dbg.ll
@@ -0,0 +1,23 @@
+; RUN: not llvm-as %s -disable-output 2>&1 | FileCheck %s
+
+define void @foo() !dbg !4 {
+  unreachable
+}
+
+; CHECK-NOT:  !dbg
+; CHECK:      function !dbg attachment must be a subprogram
+; CHECK-NEXT: void ()* @bar
+; CHECK-NEXT: !{{[0-9]+}} = !{}
+define void @bar() !dbg !6 {
+  unreachable
+}
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+
+!llvm.dbg.cu = !{!1}
+!1 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, subprograms: !3)
+!2 = !DIFile(filename: "t.c", directory: "/path/to/dir")
+!3 = !{!4}
+!4 = distinct !DISubprogram(name: "foo", scope: !1, file: !2, function: void ()* @foo)
+!6 = !{}