[LLVM-C] Deprecate the LLVMValueRef-returning metadata creation functions

[CodaFi]

Summary

There is still some value in using these functions while the remaining LLVMValueRef-based accessors are still around, but LLVMMDNodeInContext in particular has some wonky semantics that make it worth replacing outright.

[whitequark]

LGTM

llvm/include/llvm-c/Core.h

 
 /**
  * @defgroup LLVMCCoreValueMetadata Metadata
  *
  * @{
  */
 
 /**
- * Obtain a MDString value from a context.
+ * Create an MDString value from a given string value.
  *
- * The returned instance corresponds to the llvm::MDString class.
+ * The MDString value does not take ownership of the given string, it remains
+ * the responsibility of the caller to free it.
  *
- * The instance is specified by string data of a specified length. The
- * string content is copied, so the backing memory can be freed after
- * this function returns.
+ * @see llvm::MDString::get()
  */
-LLVMValueRef LLVMMDStringInContext(LLVMContextRef C, const char *Str,
-                                   unsigned SLen);
-
-/**
- * Obtain a MDString value from the global context.
- */
-LLVMValueRef LLVMMDString(const char *Str, unsigned SLen);
+LLVMMetadataRef LLVMMDStringInContext2(LLVMContextRef C, const char *Str,
+                                       size_t SLen);
 
 /**
- * Obtain a MDNode value from a context.
+ * Create an MDNode value with the given array of operands.
  *
- * The returned value corresponds to the llvm::MDNode class.
+ * @see llvm::MDNode::get()
  */
-LLVMValueRef LLVMMDNodeInContext(LLVMContextRef C, LLVMValueRef *Vals,
-                                 unsigned Count);
-
-/**
- * Obtain a MDNode value from the global context.
- */
-LLVMValueRef LLVMMDNode(LLVMValueRef *Vals, unsigned Count);
+LLVMMetadataRef LLVMMDNodeInContext2(LLVMContextRef C, LLVMMetadataRef *MDs,
+                                     size_t Count);
 
 /**
  * Obtain a Metadata as a Value.
  */
 LLVMValueRef LLVMMetadataAsValue(LLVMContextRef C, LLVMMetadataRef MD);
 
 /**
  * Obtain a Value as a Metadata.

  * LLVMValueRefs. This memory will be populated with the LLVMValueRefs of the
  * MDNode's operands.
  *
  * @param V MDNode to get the operands from.
  * @param Dest Destination array for operands.
  */
 void LLVMGetMDNodeOperands(LLVMValueRef V, LLVMValueRef *Dest);
 
+/** Deprecated: Use LLVMMDStringInContext2 instead. */
+LLVMValueRef LLVMMDStringInContext(LLVMContextRef C, const char *Str,
+                                   unsigned SLen);
+/** Deprecated: Use LLVMMDStringInContext2 instead. */
+LLVMValueRef LLVMMDString(const char *Str, unsigned SLen);
+/** Deprecated: Use LLVMMDNodeInContext2 instead. */
+LLVMValueRef LLVMMDNodeInContext(LLVMContextRef C, LLVMValueRef *Vals,
+                                 unsigned Count);
+/** Deprecated: Use LLVMMDNodeInContext2 instead. */
+LLVMValueRef LLVMMDNode(LLVMValueRef *Vals, unsigned Count);
+
 /**
  * @}
  */
 
 /**
  * @defgroup LLVMCCoreValueBasicBlock Basic Block
  *
  * A basic block represents a single entry single exit section of code.

llvm/lib/IR/Core.cpp

 }
 
 LLVMValueRef LLVMConstPointerNull(LLVMTypeRef Ty) {
   return wrap(ConstantPointerNull::get(unwrap<PointerType>(Ty)));
 }
 
 /*--.. Operations on metadata nodes ........................................--*/
 
+LLVMMetadataRef LLVMMDStringInContext2(LLVMContextRef C, const char *Str,
+                                       size_t SLen) {
+  return wrap(MDString::get(*unwrap(C), StringRef(Str, SLen)));
+}
+
+LLVMMetadataRef LLVMMDNodeInContext2(LLVMContextRef C, LLVMMetadataRef *MDs,
+                                     size_t Count) {
+  return wrap(MDNode::get(*unwrap(C), ArrayRef<Metadata*>(unwrap(MDs), Count)));
+}
+
 LLVMValueRef LLVMMDStringInContext(LLVMContextRef C, const char *Str,
                                    unsigned SLen) {
   LLVMContext &Context = *unwrap(C);
   return wrap(MetadataAsValue::get(
       Context, MDString::get(Context, StringRef(Str, SLen))));
 }
 
 LLVMValueRef LLVMMDString(const char *Str, unsigned SLen) {