Add type attributes to LLVM C API

[lerno]

Summary

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

[arsenm]

As far as I know we don't have any C API unit tests, but sorely need them if you want to try adding the first

[lerno]

In D97763#2597047, @arsenm wrote:

As far as I know we don't have any C API unit tests, but sorely need them if you want to try adding the first

I see echo.cpp utilizing LLVMCreateEnumAttribute (but nothing using LLVMCreateStringAttribute), but I am not familiar with that code.

I submitted this change as there seemed little interest in https://bugs.llvm.org/show_bug.cgi?id=48249 from anyone else and there was a suggestion on the Discord that if I submitted a patch then maybe someone could have a look at it. The code is straightforward, but I don't know LLVM well enough to set up any tests. Both my project (C3) and the Odin Language is looking to use these functions as soon as they are included.

[lerno]

Just so I understand @arsenm: are API unit tests needed to approve this pull request? If so, who is planning on adding them? I mean the C API as it currently works cannot even correctly provide byval and sret according to spec.

[arsenm]

In D97763#2597318, @lerno wrote:

Just so I understand @arsenm: are API unit tests needed to approve this pull request? If so, who is planning on adding them? I mean the C API as it currently works cannot even correctly provide byval and sret according to spec.

No, but the C API is likely to keep breaking unless somebody adds them

[arsenm]

528f6f7d617757addac9b51dd5bcc1ab1352e9be

llvm/include/llvm-c/Core.h

 unsigned LLVMGetEnumAttributeKind(LLVMAttributeRef A);
 
 /**
  * Get the enum attribute's value. 0 is returned if none exists.
  */
 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.
  */
 LLVMAttributeRef LLVMCreateStringAttribute(LLVMContextRef C,
                                            const char *K, unsigned KLength,
                                            const char *V, unsigned VLength);
 
 /**
  * Get the string attribute's kind.
  */
 const char *LLVMGetStringAttributeKind(LLVMAttributeRef A, unsigned *Length);
 
 /**
  * Get the string attribute's value.
  */
 const char *LLVMGetStringAttributeValue(LLVMAttributeRef A, unsigned *Length);
 
 /**
  * Check for the different types of attributes.
  */
 LLVMBool LLVMIsEnumAttribute(LLVMAttributeRef A);
 LLVMBool LLVMIsStringAttribute(LLVMAttributeRef A);
+LLVMBool LLVMIsTypeAttribute(LLVMAttributeRef A);
 
 /**
  * Obtain a Type from a context by its registered name.
  */
 LLVMTypeRef LLVMGetTypeByName2(LLVMContextRef C, const char *Name);
 
 /**
  * @}

llvm/lib/IR/Core.cpp

 
 uint64_t LLVMGetEnumAttributeValue(LLVMAttributeRef A) {
   auto Attr = unwrap(A);
   if (Attr.isEnumAttribute())
     return 0;
   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) {
   return wrap(Attribute::get(*unwrap(C), StringRef(K, KLength),
                              StringRef(V, VLength)));
 }
 
 const char *LLVMGetStringAttributeKind(LLVMAttributeRef A,
LLVMBool LLVMIsEnumAttribute(LLVMAttributeRef A) {
   auto Attr = unwrap(A);
   return Attr.isEnumAttribute() || Attr.isIntAttribute();
 }
 
 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);
   DiagnosticPrinterRawOStream DP(Stream);
 
   unwrap(DI)->print(DP);
   Stream.flush();