Add LLVMGlobalAddDebugInfo to Core.cpp

[demoitem]

This change allows globals to have multiple metadata attached. The GlobalSetMetadata function
only allows only one and is clobbered if more metadata is attempted to be added. The addDebugInfo
function calls addMetadata. This is needed because some languages have global structs containing lots of compiler-generated globals.

[llvmbot]

@llvm/pr-subscribers-debuginfo

@llvm/pr-subscribers-llvm-ir

Author: peter mckinna (demoitem)

Changes

This change allows globals to have multiple metadata attached. The GlobalSetMetadata function
only allows only one and is clobbered if more metadata is attempted to be added. The addDebugInfo
function calls addMetadata. This is needed because some languages have global structs containing lots of compiler-generated globals.

---

Full diff: https://github.com/llvm/llvm-project/pull/148747.diff

6 Files Affected:

• (modified) llvm/include/llvm-c/Core.h (+8)
• (modified) llvm/lib/IR/Core.cpp (+5)
• (added) llvm/test/Bindings/llvm-c/add_globaldebuginfo.ll (+2)
• (modified) llvm/tools/llvm-c-test/debuginfo.c (+34)
• (modified) llvm/tools/llvm-c-test/llvm-c-test.h (+1)
• (modified) llvm/tools/llvm-c-test/main.c (+2)

diff --git a/llvm/include/llvm-c/Core.h b/llvm/include/llvm-c/Core.h
index d645646289025..ec0c5e546fa8f 100644
--- a/llvm/include/llvm-c/Core.h
+++ b/llvm/include/llvm-c/Core.h
@@ -2707,6 +2707,14 @@ LLVM_C_ABI void LLVMGlobalEraseMetadata(LLVMValueRef Global, unsigned Kind);
  */
 LLVM_C_ABI void LLVMGlobalClearMetadata(LLVMValueRef Global);
 
+/**
+ * Add debuginfo metadata to this global.
+ *
+ * @see llvm::GlobalVariable::addDebugInfo()
+ */
+LLVM_C_ABI void LLVMGlobalAddDebugInfo(LLVMValueRef Global,
+                                       LLVMMetadataRef GVE);
+
 /**
  * Retrieves an array of metadata entries representing the metadata attached to
  * this value. The caller is responsible for freeing this array by calling
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
index f7ef4aa473ef5..988249ed23d9d 100644
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -2194,6 +2194,11 @@ void LLVMGlobalClearMetadata(LLVMValueRef Global) {
   unwrap<GlobalObject>(Global)->clearMetadata();
 }
 
+void LLVMGlobalAddDebugInfo(LLVMValueRef Global, LLVMMetadataRef GVE) {
+  unwrap<GlobalVariable>(Global)->addDebugInfo(
+      unwrap<DIGlobalVariableExpression>(GVE));
+}
+
 /*--.. Operations on global variables ......................................--*/
 
 LLVMValueRef LLVMAddGlobal(LLVMModuleRef M, LLVMTypeRef Ty, const char *Name) {
diff --git a/llvm/test/Bindings/llvm-c/add_globaldebuginfo.ll b/llvm/test/Bindings/llvm-c/add_globaldebuginfo.ll
new file mode 100644
index 0000000000000..da6536a9ce407
--- /dev/null
+++ b/llvm/test/Bindings/llvm-c/add_globaldebuginfo.ll
@@ -0,0 +1,2 @@
+; RUN: llvm-c-test --add-globaldebuginfo < /dev/null
+; This used to trigger an assertion
diff --git a/llvm/tools/llvm-c-test/debuginfo.c b/llvm/tools/llvm-c-test/debuginfo.c
index e73f69743805c..df70f6626ec14 100644
--- a/llvm/tools/llvm-c-test/debuginfo.c
+++ b/llvm/tools/llvm-c-test/debuginfo.c
@@ -416,3 +416,37 @@ int llvm_di_type_get_name(void) {
 
   return 0;
 }
+
+int llvm_add_globaldebuginfo(void) {
+  const char *Filename = "debuginfo.c";
+  LLVMModuleRef M = LLVMModuleCreateWithName(Filename);
+  LLVMDIBuilderRef Builder = LLVMCreateDIBuilder(M);
+  LLVMMetadataRef File =
+      LLVMDIBuilderCreateFile(Builder, Filename, strlen(Filename), ".", 1);
+
+  LLVMMetadataRef GlobalVarValueExpr =
+      LLVMDIBuilderCreateConstantValueExpression(Builder, 0);
+  LLVMMetadataRef Int64Ty =
+      LLVMDIBuilderCreateBasicType(Builder, "Int64", 5, 64, 0, LLVMDIFlagZero);
+  LLVMMetadataRef Int64TypeDef = LLVMDIBuilderCreateTypedef(
+      Builder, Int64Ty, "int64_t", 7, File, 42, File, 0);
+
+  LLVMMetadataRef GVE = LLVMDIBuilderCreateGlobalVariableExpression(
+      Builder, File, "global", 6, "", 0, File, 1, Int64TypeDef, true,
+      GlobalVarValueExpr, NULL, 0);
+
+  LLVMTypeRef RecType =
+      LLVMStructCreateNamed(LLVMGetModuleContext(M), "struct");
+  LLVMValueRef Global = LLVMAddGlobal(M, RecType, "global");
+
+  LLVMGlobalAddDebugInfo(Global, GVE);
+  size_t numEntries;
+  LLVMValueMetadataEntry *ME = LLVMGlobalCopyAllMetadata(Global, &numEntries);
+  assert(ME != NULL);
+  assert(numEntries == 1);
+
+  LLVMDisposeDIBuilder(Builder);
+  LLVMDisposeModule(M);
+
+  return 0;
+}
diff --git a/llvm/tools/llvm-c-test/llvm-c-test.h b/llvm/tools/llvm-c-test/llvm-c-test.h
index 1da6596cd5a8f..4c5a88ce0447e 100644
--- a/llvm/tools/llvm-c-test/llvm-c-test.h
+++ b/llvm/tools/llvm-c-test/llvm-c-test.h
@@ -45,6 +45,7 @@ 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);
+int llvm_add_globaldebuginfo(void);
 
 // object.c
 int llvm_object_list_sections(void);
diff --git a/llvm/tools/llvm-c-test/main.c b/llvm/tools/llvm-c-test/main.c
index badbe4b13b6ba..d1963b702888b 100644
--- a/llvm/tools/llvm-c-test/main.c
+++ b/llvm/tools/llvm-c-test/main.c
@@ -101,6 +101,8 @@ int main(int argc, char **argv) {
     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], "--add-globaldebuginfo")) {
+    return llvm_add_globaldebuginfo();
   } 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")) {

[nikic]

I think it would make more sense to expose LLVMGlobalAddMetadata as a primitive.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[demoitem]

Ok, I have exposed the GlobalAddMetadata but I think I still need the DebugInfo as users don't need to get the
kindId which could be problematic or perhaps overly complicated as one has to know the kindId needed
is for the "dbg" type.
As for the testing. Other tests seem to rely on an assert mechanism. If there is a better way to test this I would use it.

[demoitem]

Ping

[demoitem]

Are there any reviewers out there? Just asking.

[nikic]

LGTM

[demoitem]

Thanks @nikic I dont have commit access, could you merge this PR for me?

[demoitem]

Ping

[kstoimenov]

Looks like this broke sanitizer bots. Could you please take a look: https://lab.llvm.org/buildbot/#/builders/24/builds/11561

[mikaelholmen]

If compiling without asserts you get

../tools/llvm-c-test/debuginfo.c:447:27: error: unused variable 'ME' [-Werror,-Wunused-variable]
  447 |   LLVMValueMetadataEntry *ME = LLVMGlobalCopyAllMetadata(Global, &numEntries);
      |                           ^~
1 error generated.

here.

[mikaelholmen]

Looks like this broke sanitizer bots. Could you please take a look: https://lab.llvm.org/buildbot/#/builders/24/builds/11561

Yeah, for me, if I just build with ASAN and run lit tests then

Bindings/llvm-c/add_globaldebuginfo.ll

fails the same way as in the failed build bot.

Ping @demoitem

[nikic]

I think 5985620 should fix it.

[mikaelholmen]

I think 5985620 should fix it.

Yep, thanks!