Update LLVM backend to begin work on a generic ABI system

1 files changed, 762 insertions, 0 deletions

diff --git a/src/llvm_abi.cpp b/src/llvm_abi.cpp
new file mode 100644
index 000000000..2bede5822
--- /dev/null
+++ b/src/llvm_abi.cpp
@@ -0,0 +1,762 @@
+enum lbArgKind {
+	lbArg_Direct,
+	lbArg_Indirect,
+	lbArg_Ignore,
+};
+
+struct lbArgType {
+	lbArgKind kind;
+	LLVMTypeRef type;
+	LLVMTypeRef cast_type;      // Optional
+	LLVMTypeRef pad_type;       // Optional
+	LLVMAttributeRef attribute; // Optional
+};
+
+lbArgType lb_arg_type_direct(LLVMTypeRef type, LLVMTypeRef cast_type, LLVMTypeRef pad_type, LLVMAttributeRef attr) {
+	return lbArgType{lbArg_Direct, type, cast_type, pad_type, attr};
+}
+lbArgType lb_arg_type_direct(LLVMTypeRef type) {
+	return lb_arg_type_direct(type, nullptr, nullptr, nullptr);
+}
+
+lbArgType lb_arg_type_indirect(LLVMTypeRef type, LLVMAttributeRef attr) {
+	return lbArgType{lbArg_Indirect, type, nullptr, nullptr, attr};
+}
+
+lbArgType lb_arg_type_ignore(LLVMTypeRef type) {
+	return lbArgType{lbArg_Ignore, type, nullptr, nullptr, nullptr};
+}
+
+struct lbFunctionType {
+	LLVMContextRef   ctx;
+	ProcCallingConvention calling_convention;
+	Array<lbArgType> args;
+	lbArgType        ret;
+};
+
+
+bool lb_is_type_kind(LLVMTypeRef type, LLVMTypeKind kind) {
+	return LLVMGetTypeKind(type) == kind;
+}
+
+LLVMTypeRef lb_function_type_to_llvm_ptr(lbFunctionType *ft, bool is_var_arg) {
+	unsigned arg_count = cast(unsigned)ft->args.count;
+	unsigned offset = 0;
+
+	LLVMTypeRef ret = nullptr;
+	if (ft->ret.kind == lbArg_Direct) {
+		if (ft->ret.cast_type != nullptr) {
+			ret = ft->ret.cast_type;
+		} else {
+			ret = ft->ret.type;
+		}
+	} else if (ft->ret.kind == lbArg_Indirect) {
+		offset += 1;
+		ret = LLVMVoidTypeInContext(ft->ctx);
+	} else if (ft->ret.kind == lbArg_Ignore) {
+		ret = LLVMVoidTypeInContext(ft->ctx);
+	}
+	GB_ASSERT_MSG(ret != nullptr, "%d", ft->ret.kind);
+
+	unsigned maximum_arg_count = offset+arg_count;
+	LLVMTypeRef *args = gb_alloc_array(heap_allocator(), LLVMTypeRef, maximum_arg_count);
+	if (offset == 1) {
+		GB_ASSERT(ft->ret.kind == lbArg_Indirect);
+		args[0] = ft->ret.type;
+	}
+
+	unsigned arg_index = offset;
+	for (unsigned i = 0; i < arg_count; i++) {
+		lbArgType *arg = &ft->args[i];
+		if (arg->kind == lbArg_Direct) {
+			LLVMTypeRef arg_type = nullptr;
+			if (ft->args[i].cast_type != nullptr) {
+				arg_type = arg->cast_type;
+			} else {
+				arg_type = arg->type;
+			}
+			args[arg_index++] = arg_type;
+		} else if (arg->kind == lbArg_Indirect) {
+			GB_ASSERT(!lb_is_type_kind(arg->type, LLVMPointerTypeKind));
+			args[arg_index++] = LLVMPointerType(arg->type, 0);
+		} else if (arg->kind == lbArg_Ignore) {
+			// ignore
+		}
+	}
+	unsigned total_arg_count = arg_index;
+	LLVMTypeRef func_type = LLVMFunctionType(ret, args, total_arg_count, is_var_arg);
+	return LLVMPointerType(func_type, 0);
+}
+
+
+void lb_add_function_type_attributes(LLVMValueRef fn, lbFunctionType *ft, ProcCallingConvention calling_convention) {
+	if (ft == nullptr) {
+		return;
+	}
+	unsigned arg_count = cast(unsigned)ft->args.count;
+	unsigned offset = 0;
+	if (ft->ret.kind == lbArg_Indirect) {
+		offset += 1;
+	}
+
+	unsigned arg_index = offset;
+	for (unsigned i = 0; i < arg_count; i++) {
+		lbArgType *arg = &ft->args[i];
+		if (arg->kind == lbArg_Ignore) {
+			continue;
+		}
+
+		if (arg->attribute) {
+			LLVMAddAttributeAtIndex(fn, arg_index+1, arg->attribute);
+		}
+
+		arg_index++;
+	}
+
+	if (offset != 0 && ft->ret.kind == lbArg_Indirect && ft->ret.attribute != nullptr) {
+		LLVMAddAttributeAtIndex(fn, offset, ft->ret.attribute);
+	}
+
+	lbCallingConventionKind cc_kind = lbCallingConvention_C;
+	// TODO(bill): Clean up this logic
+	if (build_context.metrics.os != TargetOs_js)  {
+		cc_kind = lb_calling_convention_map[calling_convention];
+	}
+	LLVMSetFunctionCallConv(fn, cc_kind);
+	if (calling_convention == ProcCC_Odin) {
+		unsigned context_index = offset+arg_count;
+		LLVMContextRef c = ft->ctx;
+		LLVMAddAttributeAtIndex(fn, context_index, lb_create_enum_attribute(c, "noalias", true));
+		LLVMAddAttributeAtIndex(fn, context_index, lb_create_enum_attribute(c, "nonnull", true));
+		LLVMAddAttributeAtIndex(fn, context_index, lb_create_enum_attribute(c, "nocapture", true));
+	}
+
+}
+
+i64 lb_sizeof(LLVMTypeRef type);
+i64 lb_alignof(LLVMTypeRef type);
+
+i64 lb_sizeof(LLVMTypeRef type) {
+	LLVMTypeKind kind = LLVMGetTypeKind(type);
+	switch (kind) {
+	case LLVMVoidTypeKind:
+		return 0;
+	case LLVMIntegerTypeKind:
+		{
+			unsigned w = LLVMGetIntTypeWidth(type);
+			return (w + 7)/8;
+		}
+	case LLVMFloatTypeKind:
+		return 4;
+	case LLVMDoubleTypeKind:
+		return 8;
+	case LLVMPointerTypeKind:
+		return build_context.word_size;
+	case LLVMStructTypeKind:
+		{
+			unsigned field_count = LLVMCountStructElementTypes(type);
+			i64 offset = 0;
+			if (LLVMIsPackedStruct(type)) {
+				for (unsigned i = 0; i < field_count; i++) {
+					LLVMTypeRef field = LLVMStructGetTypeAtIndex(type, i);
+					offset += lb_sizeof(field);
+				}
+			} else {
+				for (unsigned i = 0; i < field_count; i++) {
+					LLVMTypeRef field = LLVMStructGetTypeAtIndex(type, i);
+					i64 align = lb_alignof(field);
+					offset = align_formula(offset, align);
+					offset += lb_sizeof(field);
+				}
+			}
+			offset = align_formula(offset, lb_alignof(type));
+			return offset;
+		}
+		break;
+	case LLVMArrayTypeKind:
+		{
+			LLVMTypeRef elem = LLVMGetElementType(type);
+			i64 elem_size = lb_sizeof(elem);
+			i64 count = LLVMGetVectorSize(type);
+			i64 size = count * elem_size;
+			return size;
+		}
+		break;
+
+	case LLVMX86_MMXTypeKind:
+		return 8;
+	case LLVMVectorTypeKind:
+		{
+			LLVMTypeRef elem = LLVMGetElementType(type);
+			i64 elem_size = lb_sizeof(elem);
+			i64 count = LLVMGetVectorSize(type);
+			i64 size = count * elem_size;
+			return gb_clamp(next_pow2(size), 1, build_context.max_align);
+		}
+
+	}
+	GB_PANIC("Unhandled type for lb_sizeof -> %s", LLVMPrintTypeToString(type));
+
+	// LLVMValueRef v = LLVMSizeOf(type);
+	// GB_ASSERT(LLVMIsConstant(v));
+	// return cast(i64)LLVMConstIntGetSExtValue(v);
+	return 0;
+}
+
+i64 lb_alignof(LLVMTypeRef type) {
+	LLVMTypeKind kind = LLVMGetTypeKind(type);
+	switch (kind) {
+	case LLVMVoidTypeKind:
+		return 1;
+	case LLVMIntegerTypeKind:
+		{
+			unsigned w = LLVMGetIntTypeWidth(type);
+			return gb_clamp((w + 7)/8, 1, build_context.max_align);
+		}
+	case LLVMFloatTypeKind:
+		return 4;
+	case LLVMDoubleTypeKind:
+		return 8;
+	case LLVMPointerTypeKind:
+		return build_context.word_size;
+	case LLVMStructTypeKind:
+		{
+			if (LLVMIsPackedStruct(type)) {
+				return 1;
+			} else {
+				unsigned field_count = LLVMCountStructElementTypes(type);
+				i64 max_align = 1;
+				for (unsigned i = 0; i < field_count; i++) {
+					LLVMTypeRef field = LLVMStructGetTypeAtIndex(type, i);
+					i64 field_align = lb_alignof(field);
+					max_align = gb_max(max_align, field_align);
+				}
+				return max_align;
+			}
+		}
+		break;
+	case LLVMArrayTypeKind:
+		{
+			LLVMTypeRef elem = LLVMGetElementType(type);
+			i64 elem_size = lb_sizeof(elem);
+			i64 count = LLVMGetVectorSize(type);
+			i64 size = count * elem_size;
+			return size;
+		}
+		break;
+
+	case LLVMX86_MMXTypeKind:
+		return 8;
+	case LLVMVectorTypeKind:
+		{
+			LLVMTypeRef elem = LLVMGetElementType(type);
+			i64 elem_size = lb_sizeof(elem);
+			i64 count = LLVMGetVectorSize(type);
+			i64 size = count * elem_size;
+			return gb_clamp(next_pow2(size), 1, build_context.max_align);
+		}
+
+	}
+	GB_PANIC("Unhandled type for lb_sizeof -> %s", LLVMPrintTypeToString(type));
+
+	// LLVMValueRef v = LLVMAlignOf(type);
+	// GB_ASSERT(LLVMIsConstant(v));
+	// return LLVMConstIntGetSExtValue(v);
+	return 1;
+}
+
+Type *lb_abi_to_odin_type(LLVMTypeRef type) {
+	LLVMTypeKind kind = LLVMGetTypeKind(type);
+	switch (kind) {
+	case LLVMVoidTypeKind:
+		return nullptr;
+	case LLVMIntegerTypeKind:
+		{
+			unsigned w = LLVMGetIntTypeWidth(type);
+			if (w == 1) {
+				return t_llvm_bool;
+			}
+			unsigned bytes = (w + 7)/8;
+			switch (bytes) {
+			case 1: return t_u8;
+			case 2: return t_u16;
+			case 4: return t_u32;
+			case 8: return t_u64;
+			case 16: return t_u128;
+			}
+			GB_PANIC("Unhandled integer type");
+		}
+	case LLVMFloatTypeKind:
+		return t_f32;
+	case LLVMDoubleTypeKind:
+		return t_f64;
+	case LLVMPointerTypeKind:
+		return t_rawptr;
+	case LLVMStructTypeKind:
+		{
+			GB_PANIC("HERE");
+		}
+		break;
+	case LLVMArrayTypeKind:
+		{
+
+			i64 count = LLVMGetVectorSize(type);
+			Type *elem = lb_abi_to_odin_type(LLVMGetElementType(type));
+			return alloc_type_array(elem, count);
+		}
+		break;
+
+	case LLVMX86_MMXTypeKind:
+		return t_vector_x86_mmx;
+	case LLVMVectorTypeKind:
+		{
+			i64 count = LLVMGetVectorSize(type);
+			Type *elem = lb_abi_to_odin_type(LLVMGetElementType(type));
+			return alloc_type_simd_vector(count, elem);
+		}
+
+	}
+	GB_PANIC("Unhandled type for lb_abi_to_odin_type -> %s", LLVMPrintTypeToString(type));
+
+	// LLVMValueRef v = LLVMSizeOf(type);
+	// GB_ASSERT(LLVMIsConstant(v));
+	// return cast(i64)LLVMConstIntGetSExtValue(v);
+	return 0;
+}
+
+
+
+#define LB_ABI_INFO(name) lbFunctionType *name(LLVMContextRef c, LLVMTypeRef *arg_types, unsigned arg_count, LLVMTypeRef return_type, bool return_is_defined, ProcCallingConvention calling_convention)
+typedef LB_ABI_INFO(lbAbiInfoType);
+
+
+// NOTE(bill): I hate `namespace` in C++ but this is just because I don't want to prefix everything
+namespace lbAbi386 {
+	Array<lbArgType> compute_arg_types(LLVMContextRef c, LLVMTypeRef *arg_types, unsigned arg_count);
+	lbArgType compute_return_type(LLVMContextRef c, LLVMTypeRef return_type, bool return_is_defined);
+
+	LB_ABI_INFO(abi_info) {
+		lbFunctionType *ft = gb_alloc_item(heap_allocator(), lbFunctionType);
+		ft->ctx = c;
+		ft->args = compute_arg_types(c, arg_types, arg_count);
+		ft->ret = compute_return_type(c, return_type, return_is_defined);
+		ft->calling_convention = calling_convention;
+		return ft;
+	}
+
+	lbArgType non_struct(LLVMContextRef c, LLVMTypeRef type) {
+		if (build_context.metrics.os == TargetOs_windows &&
+		           build_context.word_size == 8 &&
+		           lb_is_type_kind(type, LLVMIntegerTypeKind) &&
+		           lb_sizeof(type) == 16) {
+
+			LLVMTypeRef cast_type = LLVMVectorType(LLVMInt64TypeInContext(c), 2);
+			return lb_arg_type_direct(type, cast_type, nullptr, nullptr);
+		}
+
+
+
+		LLVMAttributeRef attr = nullptr;
+		LLVMTypeRef i1 = LLVMInt1TypeInContext(c);
+		if (type == i1) {
+			// attr = lb_create_enum_attribute(c, "zext", true);
+			// return lb_arg_type_direct(type, i1, nullptr, attr);
+		}
+		return lb_arg_type_direct(type, nullptr, nullptr, attr);
+	}
+
+	Array<lbArgType> compute_arg_types(LLVMContextRef c, LLVMTypeRef *arg_types, unsigned arg_count) {
+		auto args = array_make<lbArgType>(heap_allocator(), arg_count);
+
+		for (unsigned i = 0; i < arg_count; i++) {
+			LLVMTypeRef t = arg_types[i];
+			LLVMTypeKind kind = LLVMGetTypeKind(t);
+			if (kind == LLVMStructTypeKind) {
+				i64 sz = lb_sizeof(t);
+				if (sz == 0) {
+					args[i] = lb_arg_type_ignore(t);
+				} else {
+					args[i] = lb_arg_type_indirect(t, lb_create_enum_attribute(c, "byval", true));
+				}
+			} else {
+				args[i] = non_struct(c, t);
+			}
+		}
+		return args;
+	}
+
+	lbArgType compute_return_type(LLVMContextRef c, LLVMTypeRef return_type, bool return_is_defined) {
+		if (!return_is_defined) {
+			return lb_arg_type_direct(LLVMVoidTypeInContext(c));
+		} else if (lb_is_type_kind(return_type, LLVMStructTypeKind) || lb_is_type_kind(return_type, LLVMArrayTypeKind)) {
+			i64 sz = lb_sizeof(return_type);
+			switch (sz) {
+			case 1: return lb_arg_type_direct(return_type, LLVMIntTypeInContext(c,  8), nullptr, nullptr);
+			case 2: return lb_arg_type_direct(return_type, LLVMIntTypeInContext(c, 16), nullptr, nullptr);
+			case 4: return lb_arg_type_direct(return_type, LLVMIntTypeInContext(c, 32), nullptr, nullptr);
+			case 8: return lb_arg_type_direct(return_type, LLVMIntTypeInContext(c, 64), nullptr, nullptr);
+			}
+			return lb_arg_type_indirect(LLVMPointerType(return_type, 0), lb_create_enum_attribute(c, "sret", true));
+		}
+		return non_struct(c, return_type);
+	}
+};
+
+namespace lbAbiAmd64Win64 {
+	Array<lbArgType> compute_arg_types(LLVMContextRef c, LLVMTypeRef *arg_types, unsigned arg_count);
+
+
+	LB_ABI_INFO(abi_info) {
+		lbFunctionType *ft = gb_alloc_item(heap_allocator(), lbFunctionType);
+		ft->ctx = c;
+		ft->args = compute_arg_types(c, arg_types, arg_count);
+		ft->ret = lbAbi386::compute_return_type(c, return_type, return_is_defined);
+		ft->calling_convention = calling_convention;
+		return ft;
+	}
+
+	Array<lbArgType> compute_arg_types(LLVMContextRef c, LLVMTypeRef *arg_types, unsigned arg_count) {
+		auto args = array_make<lbArgType>(heap_allocator(), arg_count);
+
+		for (unsigned i = 0; i < arg_count; i++) {
+			LLVMTypeRef t = arg_types[i];
+			LLVMTypeKind kind = LLVMGetTypeKind(t);
+			if (kind == LLVMStructTypeKind) {
+				i64 sz = lb_sizeof(t);
+				switch (sz) {
+				case 1:
+				case 2:
+				case 4:
+				case 8:
+					args[i] = lb_arg_type_direct(t, LLVMIntTypeInContext(c, 8*cast(unsigned)sz), nullptr, nullptr);
+					break;
+				default:
+					args[i] = lb_arg_type_indirect(t, nullptr);
+					break;
+				}
+			} else {
+				args[i] = lbAbi386::non_struct(c, t);
+			}
+		}
+		return args;
+	}
+};
+
+// NOTE(bill): I hate `namespace` in C++ but this is just because I don't want to prefix everything
+namespace lbAbiAmd64SysV {
+	enum RegClass {
+		RegClass_NoClass,
+		RegClass_Int,
+		RegClass_SSEFs,
+		RegClass_SSEFv,
+		RegClass_SSEDs,
+		RegClass_SSEDv,
+		RegClass_SSEInt,
+		RegClass_SSEUp,
+		RegClass_X87,
+		RegClass_X87Up,
+		RegClass_ComplexX87,
+		RegClass_Memory,
+	};
+
+	bool is_sse(RegClass reg_class) {
+		switch (reg_class) {
+		case RegClass_SSEFs:
+		case RegClass_SSEFv:
+		case RegClass_SSEDv:
+			return true;
+		}
+		return false;
+	}
+
+	void all_mem(Array<RegClass> *cs) {
+		for_array(i, *cs) {
+			(*cs)[i] = RegClass_Memory;
+		}
+	}
+
+	Array<lbArgType> compute_arg_types(LLVMContextRef c, LLVMTypeRef *arg_types, unsigned arg_count);
+	lbArgType compute_return_type(LLVMContextRef c, LLVMTypeRef return_type, bool return_is_defined);
+	void classify_with(LLVMTypeRef t, Array<RegClass> *cls, i64 ix, i64 off);
+	void fixup(LLVMTypeRef t, Array<RegClass> *cls);
+
+	LB_ABI_INFO(abi_info) {
+		lbFunctionType *ft = gb_alloc_item(heap_allocator(), lbFunctionType);
+		ft->ctx = c;
+		// TODO(bill): THIS IS VERY VERY WRONG!
+		ft->args = compute_arg_types(c, arg_types, arg_count);
+		ft->ret = compute_return_type(c, return_type, return_is_defined);
+		ft->calling_convention = calling_convention;
+		return ft;
+	}
+
+	lbArgType non_struct(LLVMContextRef c, LLVMTypeRef type) {
+		LLVMAttributeRef attr = nullptr;
+		LLVMTypeRef i1 = LLVMInt1TypeInContext(c);
+		if (type == i1) {
+			attr = lb_create_enum_attribute(c, "zext", true);
+		}
+		return lb_arg_type_direct(type, nullptr, nullptr, attr);
+	}
+
+	Array<RegClass> classify(LLVMTypeRef t) {
+		i64 sz = lb_sizeof(t);
+		i64 words = (sz + 7)/8;
+		auto reg_classes = array_make<RegClass>(heap_allocator(), cast(isize)words);
+		if (words > 4) {
+			all_mem(&reg_classes);
+		} else {
+			classify_with(t, &reg_classes, 0, 0);
+			fixup(t, &reg_classes);
+		}
+		return reg_classes;
+	}
+
+	void classify_struct(LLVMTypeRef *fields, unsigned field_count, Array<RegClass> *cls, i64 i, i64 off, LLVMBool packed) {
+		i64 field_off = off;
+		for (unsigned i = 0; i < field_count; i++) {
+			LLVMTypeRef t = fields[i];
+			if (!packed) {
+				field_off = align_formula(field_off, lb_alignof(t));
+			}
+			classify_with(t, cls, i, field_off);
+			field_off += lb_sizeof(t);
+		}
+	}
+
+	void unify(Array<RegClass> *cls, i64 i, RegClass newv) {
+		RegClass &oldv = (*cls)[i];
+		if (oldv == newv) {
+			return;
+		} else if (oldv == RegClass_NoClass) {
+			oldv = newv;
+		} else if (newv == RegClass_NoClass) {
+			return;
+		} else if (oldv == RegClass_Memory || newv == RegClass_Memory) {
+			return;
+		} else if (oldv == RegClass_Int || newv	== RegClass_Int) {
+			return;
+		} else if (oldv == RegClass_X87 || oldv == RegClass_X87Up || oldv == RegClass_ComplexX87 ||
+		           newv == RegClass_X87 || newv == RegClass_X87Up || newv == RegClass_ComplexX87) {
+			oldv = RegClass_Memory;
+		} else {
+			oldv = newv;
+		}
+	}
+
+	void fixup(LLVMTypeRef t, Array<RegClass> *cls) {
+		i64 i = 0;
+		i64 e = cls->count;
+		if (e > 2 && (lb_is_type_kind(t, LLVMStructTypeKind) || lb_is_type_kind(t, LLVMArrayTypeKind))) {
+			RegClass &oldv = (*cls)[i];
+			if (is_sse(oldv)) {
+				for (i++; i < e; i++) {
+					if (oldv != RegClass_SSEUp) {
+						all_mem(cls);
+						return;
+					}
+				}
+			} else {
+				all_mem(cls);
+				return;
+			}
+		} else {
+			while (i < e) {
+				RegClass &oldv = (*cls)[i];
+				if (oldv == RegClass_Memory) {
+					all_mem(cls);
+					return;
+				} else if (oldv == RegClass_X87Up) {
+					// NOTE(bill): Darwin
+					all_mem(cls);
+					return;
+				} else if (oldv == RegClass_SSEUp) {
+					oldv = RegClass_SSEDv;
+				} else if (is_sse(oldv)) {
+					i++;
+					while (i != e && oldv == RegClass_SSEUp) {
+						i++;
+					}
+				} else if (oldv == RegClass_X87) {
+					i++;
+					while (i != e && oldv == RegClass_X87Up) {
+						i++;
+					}
+				} else {
+					i++;
+				}
+			}
+		}
+	}
+
+	unsigned llvec_len(Array<RegClass> const &reg_classes) {
+		unsigned len = 1;
+		for_array(i, reg_classes) {
+			if (reg_classes[i] != RegClass_SSEUp) {
+				break;
+			}
+			len++;
+		}
+		return len;
+	}
+
+
+	LLVMTypeRef llreg(LLVMContextRef c, Array<RegClass> const &reg_classes) {;
+		auto types = array_make<LLVMTypeRef>(heap_allocator(), 0, reg_classes.count);
+		for_array(i, reg_classes) {
+			switch (reg_classes[i]) {
+			case RegClass_Int:
+				array_add(&types, LLVMIntTypeInContext(c, 64));
+				break;
+			case RegClass_SSEFv:
+				{
+					unsigned vec_len = llvec_len(array_slice(reg_classes, i+1, reg_classes.count));
+					LLVMTypeRef vec_type = LLVMVectorType(LLVMFloatTypeInContext(c), vec_len);
+					array_add(&types, vec_type);
+					i += vec_len;
+					continue;
+				}
+				break;
+			case RegClass_SSEFs:
+				array_add(&types, LLVMFloatTypeInContext(c));
+				break;
+			case RegClass_SSEDs:
+				array_add(&types, LLVMDoubleTypeInContext(c));
+				break;
+			default:
+				GB_PANIC("Unhandled RegClass");
+			}
+		}
+
+		return LLVMStructTypeInContext(c, types.data, cast(unsigned)types.count, false);
+	}
+
+	void classify_with(LLVMTypeRef t, Array<RegClass> *cls, i64 ix, i64 off) {
+		i64 t_align = lb_alignof(t);
+		i64 t_size  = lb_sizeof(t);
+
+		i64 mis_align = off % t_align;
+		if (mis_align != 0) {
+			i64 e = (off + t_size + 7) / 8;
+			for (i64 i = off / 8; i < e; i++) {
+				unify(cls, ix+1, RegClass_Memory);
+			}
+			return;
+		}
+
+		switch (LLVMGetTypeKind(t)) {
+		case LLVMIntegerTypeKind:
+		case LLVMPointerTypeKind:
+			unify(cls, ix+off / 8, RegClass_Int);
+			break;
+		case LLVMFloatTypeKind:
+			unify(cls, ix+off / 8, (off%8 == 4) ? RegClass_SSEFv : RegClass_SSEFs);
+			break;
+		case LLVMDoubleTypeKind:
+			unify(cls, ix+off / 8,  RegClass_SSEDs);
+			break;
+		case LLVMStructTypeKind:
+			{
+				unsigned field_count = LLVMCountStructElementTypes(t);
+				LLVMTypeRef *fields = gb_alloc_array(heap_allocator(), LLVMTypeRef, field_count); // HACK(bill): LEAK
+				defer (gb_free(heap_allocator(), fields));
+
+				LLVMGetStructElementTypes(t, fields);
+
+				classify_struct(fields, field_count, cls, ix, off, LLVMIsPackedStruct(t));
+			}
+			break;
+		case LLVMArrayTypeKind:
+			{
+				i64 len = LLVMGetArrayLength(t);
+				LLVMTypeRef elem = LLVMGetElementType(t);
+				i64 elem_sz = lb_sizeof(elem);
+				for (i64 i = 0; i < len; i++) {
+					classify_with(elem, cls, ix, off + i*elem_sz);
+				}
+			}
+			break;
+		default:
+			GB_PANIC("Unhandled type");
+			break;
+		}
+	}
+
+	Array<lbArgType> compute_arg_types(LLVMContextRef c, LLVMTypeRef *arg_types, unsigned arg_count) {
+		auto args = array_make<lbArgType>(heap_allocator(), arg_count);
+
+		for (unsigned i = 0; i < arg_count; i++) {
+			LLVMTypeRef t = arg_types[i];
+			LLVMTypeKind kind = LLVMGetTypeKind(t);
+			if (kind == LLVMStructTypeKind) {
+				i64 sz = lb_sizeof(t);
+				if (sz == 0) {
+					args[i] = lb_arg_type_ignore(t);
+				} else {
+					args[i] = lb_arg_type_indirect(t, lb_create_enum_attribute(c, "byval", true));
+				}
+			} else {
+				args[i] = non_struct(c, t);
+			}
+		}
+		return args;
+	}
+
+	lbArgType compute_return_type(LLVMContextRef c, LLVMTypeRef return_type, bool return_is_defined) {
+		if (!return_is_defined) {
+			return lb_arg_type_direct(LLVMVoidTypeInContext(c));
+		} else if (lb_is_type_kind(return_type, LLVMStructTypeKind)) {
+			i64 sz = lb_sizeof(return_type);
+			switch (sz) {
+			case 1: return lb_arg_type_direct(return_type, LLVMIntTypeInContext(c,  8), nullptr, nullptr);
+			case 2: return lb_arg_type_direct(return_type, LLVMIntTypeInContext(c, 16), nullptr, nullptr);
+			case 4: return lb_arg_type_direct(return_type, LLVMIntTypeInContext(c, 32), nullptr, nullptr);
+			case 8: return lb_arg_type_direct(return_type, LLVMIntTypeInContext(c, 64), nullptr, nullptr);
+			}
+			return lb_arg_type_indirect(LLVMPointerType(return_type, 0), lb_create_enum_attribute(c, "sret", true));
+		} else if (build_context.metrics.os == TargetOs_windows && lb_is_type_kind(return_type, LLVMIntegerTypeKind) && lb_sizeof(return_type) == 16) {
+			return lb_arg_type_direct(return_type, LLVMIntTypeInContext(c, 128), nullptr, nullptr);
+		}
+		return non_struct(c, return_type);
+	}
+};
+
+
+
+
+LB_ABI_INFO(lb_get_abi_info) {
+	switch (calling_convention) {
+	case ProcCC_None:
+	case ProcCC_PureNone:
+	case ProcCC_InlineAsm:
+		{
+			lbFunctionType *ft = gb_alloc_item(heap_allocator(), lbFunctionType);
+			ft->ctx = c;
+			ft->args = array_make<lbArgType>(heap_allocator(), arg_count);
+			for (unsigned i = 0; i < arg_count; i++) {
+				ft->args[i] = lb_arg_type_direct(arg_types[i]);
+			}
+			if (return_is_defined) {
+				ft->ret = lb_arg_type_direct(return_type);
+			} else {
+				ft->ret = lb_arg_type_direct(LLVMVoidTypeInContext(c));
+			}
+			ft->calling_convention = calling_convention;
+			return ft;
+		}
+	}
+
+	if (build_context.metrics.arch == TargetArch_amd64) {
+		if (build_context.metrics.os == TargetOs_windows) {
+			return lbAbiAmd64Win64::abi_info(c, arg_types, arg_count, return_type, return_is_defined, calling_convention);
+		} else {
+			return lbAbiAmd64SysV::abi_info(c, arg_types, arg_count, return_type, return_is_defined, calling_convention);
+		}
+	} else if (build_context.metrics.arch == TargetArch_386) {
+		return lbAbi386::abi_info(c, arg_types, arg_count, return_type, return_is_defined, calling_convention);
+	} else if (build_context.metrics.arch == TargetArch_wasm32) {
+		return lbAbi386::abi_info(c, arg_types, arg_count, return_type, return_is_defined, calling_convention);
+	}
+	GB_PANIC("Unsupported ABI");
+	return {};
+}