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

  *                    specified)
  */
 LLVMMetadataRef LLVMDIBuilderCreateGlobalVariableExpression(
     LLVMDIBuilderRef Builder, LLVMMetadataRef Scope, const char *Name,
     size_t NameLen, const char *Linkage, size_t LinkLen, LLVMMetadataRef File,
     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.
  *
  * @see llvm::DIGlobalVariableExpression::getVariable()
  */
 LLVMMetadataRef LLVMDIGlobalVariableExpressionGetVariable(LLVMMetadataRef GVE);
 

llvm/lib/IR/DebugInfo.cpp

 }
 
 LLVMMetadataRef
 LLVMDIBuilderCreateArtificialType(LLVMDIBuilderRef Builder,
                                   LLVMMetadataRef Type) {
   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();
   return Str.data();
 }
 
 uint64_t LLVMDITypeGetSizeInBits(LLVMMetadataRef DType) {
   return unwrapDI<DIType>(DType)->getSizeInBits();

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

 /*===-- debuginfo.c - tool for testing libLLVM and llvm-c API -------------===*\
 |*                                                                            *|
 |* Part of the LLVM Project, under the Apache License v2.0 with LLVM          *|
 |* Exceptions.                                                                *|
 |* See https://llvm.org/LICENSE.txt for license information.                  *|
 |* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception                    *|
 |*                                                                            *|
 |*===----------------------------------------------------------------------===*|
 |*                                                                            *|
 |* Tests for the LLVM C DebugInfo API                                         *|
 |*                                                                            *|
 \*===----------------------------------------------------------------------===*/
 
 #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) {
   LLVMMetadataRef Decl = LLVMDIBuilderCreateStructType(DIB, File, "TestClass", 9, File, 42, 64, 0, LLVMDIFlagObjcClassComplete, NULL, NULL, 0, 0, NULL, NULL, 0);
   LLVMMetadataRef SuperDecl = LLVMDIBuilderCreateStructType(DIB, File, "TestSuperClass", 14, File, 42, 64, 0, LLVMDIFlagObjcClassComplete, NULL, NULL, 0, 0, NULL, NULL, 0);
   LLVMDIBuilderCreateInheritance(DIB, Decl, SuperDecl, 0, 0, 0);
   LLVMMetadataRef TestProperty =
       LLVMDIBuilderCreateObjCProperty(DIB, "test", 4, File, 42, "getTest", 7, "setTest", 7, 0x20 /*copy*/ | 0x40 /*nonatomic*/, SuperDecl);
int llvm_test_dibuilder(void) {
   puts(MStr);
   LLVMDisposeMessage(MStr);
 
   LLVMDisposeDIBuilder(DIB);
   LLVMDisposeModule(M);
 
   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

 // calc.c
 int llvm_calc(void);
 
 // disassemble.c
 int llvm_disassemble(void);
 
 // debuginfo.c
 int llvm_test_dibuilder(void);
+int llvm_get_di_tag(void);
 
 // metadata.c
 int llvm_add_named_metadata_operand(void);
 int llvm_set_metadata(void);
 int llvm_replace_md_operand(void);
 int llvm_is_a_value_as_metadata(void);
 
 // object.c

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

static void print_usage(void) {
   fprintf(stderr, "    Read object file from stdin - list sections\n\n");
   fprintf(stderr, "  * --object-list-symbols\n");
   fprintf(stderr,
           "    Read object file from stdin - list symbols (like nm)\n\n");
   fprintf(stderr, "  * --disassemble\n");
   fprintf(stderr, "    Read lines of triple, hex ascii machine code from stdin "
                   "- print disassembly\n\n");
   fprintf(stderr, "  * --calc\n");
+  fprintf(stderr, "  * --get-di-tag\n");
+  fprintf(stderr, "    Run test for getting MDNode dwarf tag\n");
   fprintf(stderr, "  * --replace-md-operand\n");
   fprintf(stderr, "    Run test for replacing MDNode operands\n");
   fprintf(stderr, "  * --is-a-value-as-metadata\n");
   fprintf(stderr,
           "    Run test for checking if LLVMValueRef is a ValueAsMetadata\n");
   fprintf(
       stderr,
       "    Read lines of name, rpn from stdin - print generated module\n\n");
int main(int argc, char **argv) {
   } else if (argc == 2 && !strcmp(argv[1], "--disassemble")) {
     return llvm_disassemble();
   } else if (argc == 2 && !strcmp(argv[1], "--calc")) {
     return llvm_calc();
   } else if (argc == 2 && !strcmp(argv[1], "--add-named-metadata-operand")) {
     return llvm_add_named_metadata_operand();
   } else if (argc == 2 && !strcmp(argv[1], "--set-metadata")) {
     return llvm_set_metadata();
+  } else if (argc == 2 && !strcmp(argv[1], "--get-di-tag")) {
+    return llvm_get_di_tag();
   } else if (argc == 2 && !strcmp(argv[1], "--replace-md-operand")) {
     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], "--test-function-attributes")) {
     return llvm_test_function_attributes();
   } else if (argc == 2 && !strcmp(argv[1], "--test-callsite-attributes")) {
     return llvm_test_callsite_attributes();