Add type attributes to LLVM C API

The LLVM C API is missing type attributes as is needed by attributes
such as sret and byval. This patch adds three missing wrapper
functions.

Bugzilla: https://bugs.llvm.org/show_bug.cgi?id=48249

https://reviews.llvm.org/D97763
(cherry picked from commit 528f6f7)

Author: lerno

llvm/include/llvm-c/Core.h

@@ -604,6 +604,17 @@ unsigned LLVMGetEnumAttributeKind(LLVMAttributeRef A);
  */
 uint64_t LLVMGetEnumAttributeValue(LLVMAttributeRef A);
 
+/**
+ * Create a type attribute
+ */
+LLVMAttributeRef LLVMCreateTypeAttribute(LLVMContextRef C, unsigned KindID,
+                                         LLVMTypeRef type_ref);
+
+/**
+ * Get the type attribute's value.
+ */
+LLVMTypeRef LLVMGetTypeAttributeValue(LLVMAttributeRef A);
+
 /**
  * Create a string attribute.
  */
@@ -626,6 +637,7 @@ const char *LLVMGetStringAttributeValue(LLVMAttributeRef A, unsigned *Length);
  */
 LLVMBool LLVMIsEnumAttribute(LLVMAttributeRef A);
 LLVMBool LLVMIsStringAttribute(LLVMAttributeRef A);
+LLVMBool LLVMIsTypeAttribute(LLVMAttributeRef A);
 
 /**
  * Obtain a Type from a context by its registered name.

llvm/lib/IR/Core.cpp

@@ -164,6 +164,18 @@ uint64_t LLVMGetEnumAttributeValue(LLVMAttributeRef A) {
   return Attr.getValueAsInt();
 }
 
+LLVMAttributeRef LLVMCreateTypeAttribute(LLVMContextRef C, unsigned KindID,
+                                         LLVMTypeRef type_ref) {
+  auto &Ctx = *unwrap(C);
+  auto AttrKind = (Attribute::AttrKind)KindID;
+  return wrap(Attribute::get(Ctx, AttrKind, unwrap(type_ref)));
+}
+
+LLVMTypeRef LLVMGetTypeAttributeValue(LLVMAttributeRef A) {
+  auto Attr = unwrap(A);
+  return wrap(Attr.getValueAsType());
+}
+
 LLVMAttributeRef LLVMCreateStringAttribute(LLVMContextRef C,
                                            const char *K, unsigned KLength,
                                            const char *V, unsigned VLength) {
@@ -194,6 +206,10 @@ LLVMBool LLVMIsStringAttribute(LLVMAttributeRef A) {
   return unwrap(A).isStringAttribute();
 }
 
+LLVMBool LLVMIsTypeAttribute(LLVMAttributeRef A) {
+  return unwrap(A).isTypeAttribute();
+}
+
 char *LLVMGetDiagInfoDescription(LLVMDiagnosticInfoRef DI) {
   std::string MsgStorage;
   raw_string_ostream Stream(MsgStorage);