From 6f0ff9e54b15cd6e2e2cd27d3a0d6c92a13e6692 Mon Sep 17 00:00:00 2001
From: Wunkolo <Wunkolo@gmail.com>
Date: Fri, 10 May 2024 08:05:28 -0700
Subject: [PATCH] [a64] Preserve X0 when resolving functions

Fixes indirect branches
---
 src/xenia/cpu/backend/a64/a64_backend.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/xenia/cpu/backend/a64/a64_backend.cc b/src/xenia/cpu/backend/a64/a64_backend.cc
index f95ae43d5..ee24766af 100644
--- a/src/xenia/cpu/backend/a64/a64_backend.cc
+++ b/src/xenia/cpu/backend/a64/a64_backend.cc
@@ -437,7 +437,7 @@ ResolveFunctionThunk A64ThunkEmitter::EmitResolveFunctionThunk() {
 
   code_offsets.prolog = offset();
 
-  // rsp + 0 = return address
+  STP(ZR, X0, SP, PRE_INDEXED, -16);
   SUB(SP, SP, stack_size);
 
   code_offsets.prolog_stack_alloc = offset();
@@ -453,6 +453,7 @@ ResolveFunctionThunk A64ThunkEmitter::EmitResolveFunctionThunk() {
   MOV(W1, W17);
   MOV(X16, reinterpret_cast<uint64_t>(&ResolveFunction));
   BLR(X16);
+  MOV(X16, X0);
 
   EmitLoadVolatileRegs();
 
@@ -461,7 +462,8 @@ ResolveFunctionThunk A64ThunkEmitter::EmitResolveFunctionThunk() {
   // add(rsp, stack_size);
   // jmp(rax);
   ADD(SP, SP, stack_size);
-  BR(X0);
+  LDP(ZR, X0, SP, POST_INDEXED, 16);
+  BR(X16);
 
   code_offsets.tail = offset();