Introducing LLVMMetadataRef

Summary:
This seems like an uncontroversial first step toward providing access to the metadata hierarchy that now exists in LLVM. This should allow for good debug info support from C.

Future plans are to deprecate API that take mixed bags of values and metadata (mainly the LLVMMDNode family of functions) and migrate the rest toward the use of LLVMMetadataRef.

Once this is in place, mapping of DIBuilder will be able to start.

Reviewers: mehdi_amini, echristo, whitequark, jketema, Wallbraker

Reviewed By: Wallbraker

Subscribers: Eugene.Zelenko, axw, mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D19448

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300447 91177308-0d34-0410-b5e6-96231b3b80d8

bindings/go/llvm/IRBindings.h

@@ -26,7 +26,6 @@
 extern "C" {
 #endif
 
-typedef struct LLVMOpaqueMetadata *LLVMMetadataRef;
 struct LLVMDebugLocMetadata{
     unsigned Line;
     unsigned Col;
@@ -59,16 +58,6 @@ void LLVMSetSubprogram(LLVMValueRef Fn, LLVMMetadataRef SP);
 #ifdef __cplusplus
 }
 
-namespace llvm {
-
-DEFINE_ISA_CONVERSION_FUNCTIONS(Metadata, LLVMMetadataRef)
-
-inline Metadata **unwrap(LLVMMetadataRef *Vals) {
-  return reinterpret_cast<Metadata**>(Vals);
-}
-
-}
-
 #endif
 
 #endif

include/llvm-c/Core.h

@@ -2130,6 +2130,16 @@ LLVMValueRef LLVMMDNodeInContext(LLVMContextRef C, LLVMValueRef *Vals,
  */
 LLVMValueRef LLVMMDNode(LLVMValueRef *Vals, unsigned Count);
 
+/**
+ * Obtain a Metadata as a Value.
+ */
+LLVMValueRef LLVMMetadataAsValue(LLVMContextRef C, LLVMMetadataRef MD);
+
+/**
+ * Obtain a Value as a Metadata.
+ */
+LLVMMetadataRef LLVMValueAsMetadata(LLVMValueRef Val);
+
 /**
  * Obtain the underlying string from a MDString value.
  *

include/llvm-c/Types.h

@@ -82,6 +82,13 @@ typedef struct LLVMOpaqueValue *LLVMValueRef;
  */
 typedef struct LLVMOpaqueBasicBlock *LLVMBasicBlockRef;
 
+/**
+ * Represents an LLVM Metadata.
+ *
+ * This models llvm::Metadata.
+ */
+typedef struct LLVMOpaqueMetadata *LLVMMetadataRef;
+
 /**
  * Represents an LLVM basic block builder.
  *

include/llvm/IR/Metadata.h

@@ -30,6 +30,7 @@
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/Casting.h"
+#include "llvm/Support/CBindingWrapping.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <cassert>
 #include <cstddef>
@@ -133,6 +134,14 @@ class Metadata {
   /// @}
 };
 
+// Create wrappers for C Binding types (see CBindingWrapping.h).
+DEFINE_ISA_CONVERSION_FUNCTIONS(Metadata, LLVMMetadataRef)
+
+// Specialized opaque metadata conversions.
+inline Metadata **unwrap(LLVMMetadataRef *MDs) {
+  return reinterpret_cast<Metadata**>(MDs);
+}
+
 #define HANDLE_METADATA(CLASS) class CLASS;
 #include "llvm/IR/Metadata.def"
 

lib/IR/Core.cpp

@@ -863,6 +863,19 @@ LLVMValueRef LLVMMDNode(LLVMValueRef *Vals, unsigned Count) {
   return LLVMMDNodeInContext(LLVMGetGlobalContext(), Vals, Count);
 }
 
+LLVMValueRef LLVMMetadataAsValue(LLVMContextRef C, LLVMMetadataRef MD) {
+  return wrap(MetadataAsValue::get(*unwrap(C), unwrap(MD)));
+}
+
+LLVMMetadataRef LLVMValueAsMetadata(LLVMValueRef Val) {
+  auto *V = unwrap(Val);
+  if (auto *C = dyn_cast<Constant>(V))
+    return wrap(ConstantAsMetadata::get(C));
+  if (auto *MAV = dyn_cast<MetadataAsValue>(V))
+    return wrap(MAV->getMetadata());
+  return wrap(ValueAsMetadata::get(V));
+}
+
 const char *LLVMGetMDString(LLVMValueRef V, unsigned *Length) {
   if (const auto *MD = dyn_cast<MetadataAsValue>(unwrap(V)))
     if (const MDString *S = dyn_cast<MDString>(MD->getMetadata())) {