From 16d6ed4174d49ca0c1d070fd9a9922fa2603fc80 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Fri, 31 Jul 2026 13:55:02 +0300
Subject: [PATCH] x86_64 backend: support returning structs & arrays

---
 .../jit/source/arch/linux_x86_64/compiler.cpp | 53 ++++++++++++++-----
 1 file changed, 39 insertions(+), 14 deletions(-)

diff --git a/libs/jit/source/arch/linux_x86_64/compiler.cpp b/libs/jit/source/arch/linux_x86_64/compiler.cpp
index 4053a88..58e5950 100644
--- a/libs/jit/source/arch/linux_x86_64/compiler.cpp
+++ b/libs/jit/source/arch/linux_x86_64/compiler.cpp
@@ -34,6 +34,11 @@ namespace pslang::jit::linux_x86_64
 			reg::r9,
 		};
 
+		static std::array<reg, 2> integer_ret_reg = {
+			reg::rax,
+			reg::rdx,
+		};
+
 		struct small_struct_data
 		{
 			struct octet
@@ -760,7 +765,27 @@ namespace pslang::jit::linux_x86_64
 					{}
 					else if (struct_type || array_type)
 					{
-						throw std::runtime_error("Not implemented");
+						if (auto small_struct = classify_small_struct(lcontext, type))
+						{
+							auto address = node_address(*node.value);
+
+							std::uint8_t reg_index = 0;
+							std::uint8_t fp_reg = 0;
+							for (int o : {0, 1})
+							{
+								auto & octet = small_struct->octets[o];
+								if (!octet) break;
+
+								if (octet->has_integer)
+									load(*node.value, integer_ret_reg[reg_index++], 8 * o);
+								else if (octet->has_floating_point)
+									load_xmm(*node.value, (reg)(fp_reg++), 8, 8 * o);
+							}
+						}
+						else
+						{
+							copy_memory(node_address(*node.value), {reg::rdi, 0}, size);
+						}
 					}
 					else if (types::is_integer_like_type(*type))
 						load(*node.value, reg::rax);
@@ -851,7 +876,7 @@ namespace pslang::jit::linux_x86_64
 							for (std::size_t o : {0, 1})
 							{
 								auto & octet = small_struct->octets[o];
-								if (!octet) continue;
+								if (!octet) break;
 								if (octet->has_integer)
 									builder.mov_write(integer_arg_reg[reg_index++], reg::rsp, stack_size - argument_position[i] + 8 * o);
 								else if (octet->has_floating_point)
@@ -933,25 +958,25 @@ namespace pslang::jit::linux_x86_64
 					return {.base = reg::rsp, .offset = stack_size - stack_position.at(it)};
 			}
 
-			void load(ir::node_ref it, reg reg_dst)
+			void load(ir::node_ref it, reg reg_dst, std::int32_t offset = 0)
 			{
 				auto const address = node_address(it);
 				if (address.base)
-					builder.mov_read(*address.base, address.offset, reg_dst);
+					builder.mov_read(*address.base, address.offset + offset, reg_dst);
 				else
-					builder.mov_read_rip_prev(address.offset, reg_dst);
+					builder.mov_read_rip_prev(address.offset + offset, reg_dst);
 			}
 
-			void store(ir::node_ref it, reg reg_src)
+			void store(ir::node_ref it, reg reg_src, std::int32_t offset = 0)
 			{
 				auto const address = node_address(it);
 				if (address.base)
-					builder.mov_write(reg_src, *address.base, address.offset);
+					builder.mov_write(reg_src, *address.base, address.offset + offset);
 				else
-					builder.mov_write_rip_prev(reg_src, address.offset);
+					builder.mov_write_rip_prev(reg_src, address.offset + offset);
 			}
 
-			void load_xmm(ir::node_ref it, reg reg_dst, std::uint8_t size)
+			void load_xmm(ir::node_ref it, reg reg_dst, std::uint8_t size, std::int32_t offset = 0)
 			{
 				if (size != 4 && size != 8)
 					throw std::runtime_error("Bad type size for load_xmm");
@@ -960,15 +985,15 @@ namespace pslang::jit::linux_x86_64
 				if (address.base)
 				{
 					if (size == 4)
-						builder.mov_read_xmm_32(*address.base, address.offset, reg_dst);
+						builder.mov_read_xmm_32(*address.base, address.offset + offset, reg_dst);
 					else
-						builder.mov_read_xmm(*address.base, address.offset, reg_dst);
+						builder.mov_read_xmm(*address.base, address.offset + offset, reg_dst);
 				}
 				else
 					throw std::runtime_error("RIP-relative XMM read is not supported");
 			}
 
-			void store_xmm(ir::node_ref it, reg reg_src, std::uint8_t size)
+			void store_xmm(ir::node_ref it, reg reg_src, std::uint8_t size, std::int32_t offset = 0)
 			{
 				if (size != 4 && size != 8)
 					throw std::runtime_error("Bad type size for store_xmm");
@@ -977,9 +1002,9 @@ namespace pslang::jit::linux_x86_64
 				if (address.base)
 				{
 					if (size == 4)
-						builder.mov_write_xmm_32(reg_src, *address.base, address.offset);
+						builder.mov_write_xmm_32(reg_src, *address.base, address.offset + offset);
 					else
-						builder.mov_write_xmm(reg_src, *address.base, address.offset);
+						builder.mov_write_xmm(reg_src, *address.base, address.offset + offset);
 				}
 				else
 					throw std::runtime_error("RIP-relative XMM write is not supported");