[llvm-c] Add bindings for DbgRecord

[arthaud]

In the LLVM-C library, there is currently no way to get information about a DbgRecord - which is the new way to attach debug information to llvm instructions.
We can only iterate on debug records with LLVMGetFirstDbgRecord/LLVMGetLastDbgRecord/LLVMGetNextDbgRecord, but there is no way to read information.

This PR adds utility functions to read DbgRecord information.

[llvmbot]

@llvm/pr-subscribers-debuginfo

@llvm/pr-subscribers-llvm-ir

Author: Maxime Arthaud (arthaud)

Changes

In the LLVM-C library, there is currently no way to get information about a DbgRecord - which is the new way to attach debug information to llvm instructions.
We can only iterate on debug records with LLVMGetFirstDbgRecord/LLVMGetLastDbgRecord/LLVMGetNextDbgRecord, but there is no way to read information.

This PR adds utility functions to read DbgRecord information.

---

Full diff: https://github.com/llvm/llvm-project/pull/166383.diff

3 Files Affected:

• (modified) llvm/include/llvm-c/Core.h (+38)
• (modified) llvm/lib/IR/Core.cpp (+34)
• (modified) llvm/tools/llvm-c-test/debuginfo.c (+19)

diff --git a/llvm/include/llvm-c/Core.h b/llvm/include/llvm-c/Core.h
index 4e380d9bd5969..83dd1eba876e6 100644
--- a/llvm/include/llvm-c/Core.h
+++ b/llvm/include/llvm-c/Core.h
@@ -531,6 +531,13 @@ enum {
  */
 typedef unsigned LLVMGEPNoWrapFlags;
 
+typedef enum {
+  LLVMDbgRecordLabel,
+  LLVMDbgRecordDeclare,
+  LLVMDbgRecordValue,
+  LLVMDbgRecordAssign,
+} LLVMDbgRecordKind;
+
 /**
  * @}
  */
@@ -3896,6 +3903,37 @@ LLVM_C_ABI LLVMDbgRecordRef LLVMGetNextDbgRecord(LLVMDbgRecordRef DbgRecord);
 LLVM_C_ABI LLVMDbgRecordRef
 LLVMGetPreviousDbgRecord(LLVMDbgRecordRef DbgRecord);
 
+/**
+ * Get the debug location attached to the debug record.
+ *
+ * @see llvm::DbgRecord::getDebugLoc()
+ */
+LLVMMetadataRef LLVMDbgRecordGetDebugLoc(LLVMDbgRecordRef Rec);
+
+LLVMDbgRecordKind LLVMDbgRecordGetKind(LLVMDbgRecordRef Rec);
+
+/**
+ * Get the value of the DbgVariableRecord.
+ *
+ * @see llvm::DbgVariableRecord::getValue()
+ */
+LLVMValueRef LLVMDbgVariableRecordGetValue(LLVMDbgRecordRef Rec,
+                                           unsigned OpIdx);
+
+/**
+ * Get the debug info variable of the DbgVariableRecord.
+ *
+ * @see llvm::DbgVariableRecord::getVariable()
+ */
+LLVMMetadataRef LLVMDbgVariableRecordGetVariable(LLVMDbgRecordRef Rec);
+
+/**
+ * Get the debug info expression of the DbgVariableRecord.
+ *
+ * @see llvm::DbgVariableRecord::getExpression()
+ */
+LLVMMetadataRef LLVMDbgVariableRecordGetExpression(LLVMDbgRecordRef Rec);
+
 /**
  * @defgroup LLVMCCoreValueInstructionCall Call Sites and Invocations
  *
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
index 27d8294b01264..fd9630ea2abe7 100644
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -3036,6 +3036,40 @@ LLVMDbgRecordRef LLVMGetPreviousDbgRecord(LLVMDbgRecordRef Rec) {
   return wrap(&*--I);
 }
 
+LLVMMetadataRef LLVMDbgRecordGetDebugLoc(LLVMDbgRecordRef Rec) {
+  return wrap(unwrap<DbgRecord>(Rec)->getDebugLoc().getAsMDNode());
+}
+
+LLVMDbgRecordKind LLVMDbgRecordGetKind(LLVMDbgRecordRef Rec) {
+  DbgRecord *Record = unwrap<DbgRecord>(Rec);
+  if (isa<DbgLabelRecord>(Record)) {
+    return LLVMDbgRecordLabel;
+  }
+  DbgVariableRecord *VariableRecord = dyn_cast<DbgVariableRecord>(Record);
+  assert(VariableRecord && "unexpected record");
+  if (VariableRecord->isDbgDeclare()) {
+    return LLVMDbgRecordDeclare;
+  }
+  if (VariableRecord->isDbgValue()) {
+    return LLVMDbgRecordValue;
+  }
+  assert(VariableRecord->isDbgAssign() && "unexpected record");
+  return LLVMDbgRecordAssign;
+}
+
+LLVMValueRef LLVMDbgVariableRecordGetValue(LLVMDbgRecordRef Rec,
+                                           unsigned OpIdx) {
+  return wrap(unwrap<DbgVariableRecord>(Rec)->getValue(OpIdx));
+}
+
+LLVMMetadataRef LLVMDbgVariableRecordGetVariable(LLVMDbgRecordRef Rec) {
+  return wrap(unwrap<DbgVariableRecord>(Rec)->getRawVariable());
+}
+
+LLVMMetadataRef LLVMDbgVariableRecordGetExpression(LLVMDbgRecordRef Rec) {
+  return wrap(unwrap<DbgVariableRecord>(Rec)->getRawExpression());
+}
+
 unsigned LLVMGetNumArgOperands(LLVMValueRef Instr) {
   if (FuncletPadInst *FPI = dyn_cast<FuncletPadInst>(unwrap(Instr))) {
     return FPI->arg_size();
diff --git a/llvm/tools/llvm-c-test/debuginfo.c b/llvm/tools/llvm-c-test/debuginfo.c
index 9db7aa0929aab..ec45f75de4c89 100644
--- a/llvm/tools/llvm-c-test/debuginfo.c
+++ b/llvm/tools/llvm-c-test/debuginfo.c
@@ -364,6 +364,25 @@ int llvm_test_dibuilder(void) {
   assert(AddDbgRecordUnderTheRange == NULL);
   (void)AddDbgRecordUnderTheRange;
 
+  // Test that we can read the first debug record.
+  LLVMMetadataRef AddDbgRecordFirstDebugLoc = LLVMDbgRecordGetDebugLoc(AddDbgRecordFirst);
+  assert(LLVMDILocationGetLine(AddDbgRecordFirstDebugLoc) == 43);
+  assert(LLVMDbgRecordGetKind(AddDbgRecordFirst) == LLVMDbgRecordValue);
+  LLVMValueRef AddDbgRecordFirstValue = LLVMDbgVariableRecordGetValue(AddDbgRecordFirst, 0);
+  assert(LLVMGetValueKind(AddDbgRecordFirstValue) == LLVMConstantIntValueKind);
+  assert(LLVMConstIntGetZExtValue(AddDbgRecordFirstValue) == 0);
+  LLVMMetadataRef AddDbgRecordFirstVariable = LLVMDbgVariableRecordGetVariable(AddDbgRecordFirst);
+  assert(LLVMGetMetadataKind(AddDbgRecordFirstVariable) == LLVMDILocalVariableMetadataKind);
+  // TODO: For now, there is no way to get the name.
+  LLVMMetadataRef AddDbgRecordFirstVariableScope = LLVMDIVariableGetScope(AddDbgRecordFirstVariable);
+  assert(LLVMGetMetadataKind(AddDbgRecordFirstVariableScope) == LLVMDILexicalBlockMetadataKind);
+  LLVMMetadataRef AddDbgRecordFirstVariableFile = LLVMDIScopeGetFile(AddDbgRecordFirstVariableScope);
+  assert(LLVMGetMetadataKind(AddDbgRecordFirstVariableFile) == LLVMDIFileMetadataKind);
+  unsigned FileLen = 0;
+  assert(strcmp(LLVMDIFileGetFilename(AddDbgRecordFirstVariableFile, &FileLen), "debuginfo.c") == 0);
+  LLVMMetadataRef AddDbgRecordFirstExpr = LLVMDbgVariableRecordGetExpression(AddDbgRecordFirst);
+  assert(LLVMGetMetadataKind(AddDbgRecordFirstExpr) == LLVMDIExpressionMetadataKind);
+
   char *MStr = LLVMPrintModuleToString(M);
   puts(MStr);
   LLVMDisposeMessage(MStr);

[github-actions]

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

[arthaud]

@OCHyams @nikic could I please get a review?

[OCHyams]

LGTM with a style nit. Test looks good, thanks

[OCHyams]

boring nit pick: please can we drop the braces on the single-line ifs? (style guide)

[arthaud]

Done

[OCHyams]

Do you have commit access or would you like me to merge this?

[arthaud]

I need this to be merged, thank you.

[OCHyams]

No problem. I just spotted that I think a few of the variables you added to the test will cause unused variable warnings in release builds. I can't remember that being a requirement but I think some bots run with Werror. I could be making that up, but I can see other assert-only variables in the test have a (void)MyVar; so possibly best to follow suit here?

(On the other hand, we could land it and see if any bots complain...)

[arthaud]

Sure, done.