Better compatibility with LLVM < 13 (#319)

* Update wrapper to add type attribute on LLVM < 13

README.md

@@ -122,6 +122,7 @@ to C3 and compiled with the c3c compiler:
 - [x] Subarray initializers
 - [x] `$switch`
 - [x] Windows support
+- [x] Bitstructs
 - [ ] Anonymous structs
 - [ ] Complete C ABI conformance *in progress*
 - [ ] Debug info *in progress*
@@ -133,7 +134,6 @@ to C3 and compiled with the c3c compiler:
 - [ ] `global` / `shared` for globals 
 - [ ] Escape macros
 - [ ] Implicit capturing macros
-- [ ] Bitstructs
 - [ ] `asm` section *in progress*
 - [ ] `$for`
 - [ ] Pre-post conditions

src/compiler/llvm_codegen.c

@@ -1100,11 +1100,7 @@ void llvm_attribute_add_int(GenContext *context, LLVMValueRef value_to_add_attri
 
 void llvm_attribute_add_type(GenContext *c, LLVMValueRef value_to_add_attribute_to, unsigned attribute_id, LLVMTypeRef type, int index)
 {
-#if LLVM_VERSION_MAJOR < 13
-	LLVMAttributeRef llvm_attr = LLVMCreateEnumAttribute(c->context, attribute_id, 0);
-#else
 	LLVMAttributeRef llvm_attr = LLVMCreateTypeAttribute(c->context, attribute_id, type);
-#endif
 	LLVMAddAttributeAtIndex(value_to_add_attribute_to, index, llvm_attr);
 }
 
@@ -1115,11 +1111,7 @@ void llvm_attribute_add(GenContext *context, LLVMValueRef value_to_add_attribute
 
 void llvm_attribute_add_call_type(GenContext *c, LLVMValueRef call, unsigned attribute_id, int index, LLVMTypeRef type)
 {
-#if LLVM_VERSION_MAJOR < 13
-	LLVMAttributeRef llvm_attr = LLVMCreateEnumAttribute(c->context, attribute_id, 0);
-#else
 	LLVMAttributeRef llvm_attr = LLVMCreateTypeAttribute(c->context, attribute_id, type);
-#endif
 	LLVMAddCallSiteAttribute(call, index, llvm_attr);
 }
 

src/compiler/llvm_codegen_internal.h

@@ -187,6 +187,10 @@ void gencontext_end_file_emit(GenContext *c, Context *ast);
 void gencontext_end_module(GenContext *context);
 
 LLVMValueRef LLVMConstBswap(LLVMValueRef ConstantVal);
+#ifndef LLVMCreateTypeAttribute
+LLVMAttributeRef LLVMCreateTypeAttribute(LLVMContextRef C, unsigned KindID,
+										 LLVMTypeRef type_ref);
+#endif
 
 // BE value
 void llvm_value_addr(GenContext *c, BEValue *value);

wrapper/src/wrapper.cpp

@@ -111,6 +111,20 @@ static bool llvm_link(ObjFormat format, const char **args, int arg_count, const
 
 extern "C" {
 
+#if LLVM_VERSION_MAJOR < 13
+#if _MSC_VER
+	__declspec(selectany)
+#else
+	__attribute__((weak))
+#endif
+	LLVMAttributeRef LLVMCreateTypeAttribute(LLVMContextRef C, unsigned KindID,
+											 LLVMTypeRef type_ref)
+	{
+		auto &Ctx = *llvm::unwrap(C);
+		auto AttrKind = (llvm::Attribute::AttrKind)KindID;
+		return wrap(llvm::Attribute::get(Ctx, AttrKind, llvm::unwrap(type_ref)));
+	}
+#endif
 	LLVMValueRef LLVMConstBswap(LLVMValueRef ConstantVal)
 	{
 		llvm::Constant *Val = llvm::unwrap<llvm::Constant>(ConstantVal);