add LLVMGetDINodeTag

[davibe]

Summary

Hello!

I'm working on a tool that visits debug info it using the llvm-c API. I noticed that there is no way to get the dwarf::Tag of a DINode, so I added LLVMGetDINodeTag

[davibe]

Rebased on the main branch

[davibe]

I don't have commit access, could someone please commit this for me?

[davibe]

This comment was removed by davibe.

[davibe]

@aprantl this is the other one

[chapuni]

Warnings in Release build.

llvm/tools/llvm-c-test/debuginfo.c

211

Could you fold it into assert?

222

ditto.

[aprantl]

Looks like this was fixed in

commit 2700d66a054327c2dbb90d8b44b1d5cf3b0043b8
Author: Kazu Hirata <[e-mail]>
Date:   Wed Feb 8 21:00:45 2023 -0800

    [llvm-c-test] Fix unused variable warnings

Thanks!

llvm/include/llvm-c/DebugInfo.h

     unsigned LineNo, LLVMMetadataRef Ty, LLVMBool LocalToUnit,
     LLVMMetadataRef Expr, LLVMMetadataRef Decl, uint32_t AlignInBits);
 
+
+/**
+ * Get the dwarf::Tag of a DINode
+ */
+uint16_t LLVMGetDINodeTag(LLVMMetadataRef MD);
+
 /**
  * Retrieves the \c DIVariable associated with this global variable expression.
  * \param GVE    The global variable expression.

llvm/lib/IR/DebugInfo.cpp

   return wrap(unwrap(Builder)->createArtificialType(unwrapDI<DIType>(Type)));
 }
 
+uint16_t LLVMGetDINodeTag(LLVMMetadataRef MD) {
+  return unwrapDI<DINode>(MD)->getTag();
+}
+
 const char *LLVMDITypeGetName(LLVMMetadataRef DType, size_t *Length) {
   StringRef Str = unwrap<DIType>(DType)->getName();
   *Length = Str.size();

llvm/test/Bindings/llvm-c/get-md-tag.ll

+; RUN: llvm-c-test --get-di-tag < /dev/null
+; This used to trigger an assertion

llvm/tools/llvm-c-test/debuginfo.c

 \*===----------------------------------------------------------------------===*/
 
 #include "llvm-c-test.h"
-#include "llvm-c/Core.h"
 #include "llvm-c/DebugInfo.h"
 #include <stdio.h>
 #include <string.h>
+#include <assert.h>
 
 static LLVMMetadataRef
 declare_objc_class(LLVMDIBuilderRef DIB, LLVMMetadataRef File) {

 
   return 0;
 }
+
+int llvm_get_di_tag(void) {
+  LLVMModuleRef m = LLVMModuleCreateWithName("Mod");
+  LLVMContextRef context = LLVMGetModuleContext(m);
+
+  LLVMMetadataRef metas[] = {LLVMMDStringInContext2(context, "foo", 3)};
+  LLVMMetadataRef md = LLVMMDNodeInContext2(context, metas, 1);
+  uint16_t tag0 = LLVMGetDINodeTag(md);
+
+  assert(tag0 == 0);
+
+  const char *filename = "metadata.c";
+  LLVMDIBuilderRef builder = LLVMCreateDIBuilder(m);
+  LLVMMetadataRef file =
+      LLVMDIBuilderCreateFile(builder, filename, strlen(filename), ".", 1);
+  LLVMMetadataRef decl = LLVMDIBuilderCreateStructType(
+      builder, file, "TestClass", 9, file, 42, 64, 0,
+      LLVMDIFlagObjcClassComplete, NULL, NULL, 0, 0, NULL, NULL, 0);
+  uint16_t tag1 = LLVMGetDINodeTag(decl);
+
+  assert(tag1 == 0x13);
+
+  LLVMDisposeModule(m);
+
+  return 0;
+}

llvm/tools/llvm-c-test/llvm-c-test.h

 
 // debuginfo.c
 int llvm_test_dibuilder(void);
+int llvm_get_di_tag(void);
 
 // metadata.c
 int llvm_add_named_metadata_operand(void);

llvm/tools/llvm-c-test/main.c

   fprintf(stderr, "  * --is-a-value-as-metadata\n");
   fprintf(stderr,
           "    Run test for checking if LLVMValueRef is a ValueAsMetadata\n");
+  fprintf(stderr, "  * --get-di-tag\n");
+  fprintf(stderr, "    Run test for getting MDNode dwarf tag\n");
   fprintf(
       stderr,
       "    Read lines of name, rpn from stdin - print generated module\n\n");

     return llvm_replace_md_operand();
   } else if (argc == 2 && !strcmp(argv[1], "--is-a-value-as-metadata")) {
     return llvm_is_a_value_as_metadata();
+  } else if (argc == 2 && !strcmp(argv[1], "--get-di-tag")) {
+    return llvm_get_di_tag();
   } else if (argc == 2 && !strcmp(argv[1], "--test-function-attributes")) {
     return llvm_test_function_attributes();
   } else if (argc == 2 && !strcmp(argv[1], "--test-callsite-attributes")) {