From a722e1fc0bcbae55c6a143ece9f20db8a3212818 Mon Sep 17 00:00:00 2001
From: joachimschmidt557 <joachim.schmidt557@outlook.com>
Date: Sat, 1 Jan 2022 12:51:29 +0100
Subject: [PATCH] stage2 codegen: Add generateSymbol for optional stub

---
 src/arch/arm/CodeGen.zig | 13 +++++++------
 src/codegen.zig          |  8 ++++++++
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/arch/arm/CodeGen.zig b/src/arch/arm/CodeGen.zig
index d1c7c7ecf0..e90c0ad5e4 100644
--- a/src/arch/arm/CodeGen.zig
+++ b/src/arch/arm/CodeGen.zig
@@ -3180,17 +3180,18 @@ fn genSetStack(self: *Self, ty: Type, stack_offset: u32, mcv: MCValue) InnerErro
                 // TODO optimize the register allocation
                 const regs = try self.register_manager.allocRegs(5, .{ null, null, null, null, null }, &.{});
                 const src_reg = regs[0];
-                const dst_reg = regs[2];
+                const dst_reg = regs[1];
                 const len_reg = regs[2];
                 const count_reg = regs[3];
                 const tmp_reg = regs[4];
 
-                // add src_reg, fp, #off
-                const src_offset_op: Instruction.Operand = if (Instruction.Operand.fromU32(off)) |x| x else {
+                // sub src_reg, fp, #off
+                const adj_src_offset = off + @intCast(u32, ty.abiSize(self.target.*));
+                const src_offset_op: Instruction.Operand = if (Instruction.Operand.fromU32(adj_src_offset)) |x| x else {
                     return self.fail("TODO load: set reg to stack offset with all possible offsets", .{});
                 };
                 _ = try self.addInst(.{
-                    .tag = .add,
+                    .tag = .sub,
                     .cond = .al,
                     .data = .{ .rr_op = .{
                         .rd = src_reg,
@@ -3200,8 +3201,8 @@ fn genSetStack(self: *Self, ty: Type, stack_offset: u32, mcv: MCValue) InnerErro
                 });
 
                 // sub dst_reg, fp, #stack_offset
-                const adj_stack_offset = stack_offset + @intCast(u32, ty.abiSize(self.target.*));
-                const dst_offset_op: Instruction.Operand = if (Instruction.Operand.fromU32(adj_stack_offset)) |x| x else {
+                const adj_dst_offset = stack_offset + @intCast(u32, ty.abiSize(self.target.*));
+                const dst_offset_op: Instruction.Operand = if (Instruction.Operand.fromU32(adj_dst_offset)) |x| x else {
                     return self.fail("TODO load: set reg to stack offset with all possible offsets", .{});
                 };
                 _ = try self.addInst(.{
diff --git a/src/codegen.zig b/src/codegen.zig
index fdbdb7d5c1..9de13ee657 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -400,6 +400,14 @@ pub fn generateSymbol(
 
             return Result{ .appended = {} };
         },
+        .Optional => {
+            // TODO generateSymbol for optionals
+            const target = bin_file.options.target;
+            const abi_size = try math.cast(usize, typed_value.ty.abiSize(target));
+            try code.writer().writeByteNTimes(0xaa, abi_size);
+
+            return Result{ .appended = {} };
+        },
         else => |t| {
             return Result{
                 .fail = try ErrorMsg.create(