From 5ab426a3020614dcc8640a4019c8d93c6c917ea0 Mon Sep 17 00:00:00 2001
From: Jacob Young <jacobly0@users.noreply.github.com>
Date: Mon, 13 Mar 2023 20:25:13 -0400
Subject: [PATCH] x86_64: fix store of undefined

---
 src/arch/x86_64/CodeGen.zig | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/arch/x86_64/CodeGen.zig b/src/arch/x86_64/CodeGen.zig
index a547b1222d..12c5071462 100644
--- a/src/arch/x86_64/CodeGen.zig
+++ b/src/arch/x86_64/CodeGen.zig
@@ -2861,7 +2861,13 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type
                 .unreach => unreachable,
                 .eflags => unreachable,
                 .undef => {
-                    try self.genSetReg(value_ty, reg, value);
+                    switch (abi_size) {
+                        1 => try self.store(ptr, .{ .immediate = 0xaa }, ptr_ty, value_ty),
+                        2 => try self.store(ptr, .{ .immediate = 0xaaaa }, ptr_ty, value_ty),
+                        4 => try self.store(ptr, .{ .immediate = 0xaaaaaaaa }, ptr_ty, value_ty),
+                        8 => try self.store(ptr, .{ .immediate = 0xaaaaaaaaaaaaaaaa }, ptr_ty, value_ty),
+                        else => try self.genInlineMemset(ptr, .{ .immediate = 0xaa }, .{ .immediate = abi_size }, .{}),
+                    }
                 },
                 .immediate => |imm| {
                     switch (abi_size) {