From cf86ae6b657c9eadbe2c8bbe2d695e6830879f31 Mon Sep 17 00:00:00 2001
From: Ryan Houdek <Sonicadvance1@gmail.com>
Date: Sun, 17 Dec 2023 18:24:00 -0800
Subject: [PATCH] FEXCore: Describe exit function linking object with a
 structure

Instead of just poking raw uint64_t data values, describe it with a
struct.

This will be a read-only in the future.
---
 FEXCore/Source/Interface/Context/Context.h      |  9 +++++++--
 FEXCore/Source/Interface/Core/JIT/Arm64/JIT.cpp | 14 +++++++-------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/FEXCore/Source/Interface/Context/Context.h b/FEXCore/Source/Interface/Context/Context.h
index f4a9d9512..0d4b9bafa 100644
--- a/FEXCore/Source/Interface/Context/Context.h
+++ b/FEXCore/Source/Interface/Context/Context.h
@@ -277,12 +277,17 @@ namespace FEXCore::Context {
     static void ThreadRemoveCodeEntry(FEXCore::Core::InternalThreadState *Thread, uint64_t GuestRIP);
     static void ThreadAddBlockLink(FEXCore::Core::InternalThreadState *Thread, uint64_t GuestDestination, uintptr_t HostLink, const std::function<void()> &delinker);
 
+    struct ExitFunctionLinkData {
+      uint64_t HostBranch;
+      uint64_t GuestRIP;
+    };
+
     template<auto Fn>
-    static uint64_t ThreadExitFunctionLink(FEXCore::Core::CpuStateFrame *Frame, uint64_t *record) {
+    static uint64_t ThreadExitFunctionLink(FEXCore::Core::CpuStateFrame *Frame, ExitFunctionLinkData *Record) {
       auto Thread = Frame->Thread;
       auto lk = GuardSignalDeferringSection<std::shared_lock>(static_cast<ContextImpl*>(Thread->CTX)->CodeInvalidationMutex, Thread);
 
-      return Fn(Frame, record);
+      return Fn(Frame, Record);
     }
 
     // Wrapper which takes CpuStateFrame instead of InternalThreadState and unique_locks CodeInvalidationMutex
diff --git a/FEXCore/Source/Interface/Core/JIT/Arm64/JIT.cpp b/FEXCore/Source/Interface/Core/JIT/Arm64/JIT.cpp
index 104cc6ae8..980a931e8 100644
--- a/FEXCore/Source/Interface/Core/JIT/Arm64/JIT.cpp
+++ b/FEXCore/Source/Interface/Core/JIT/Arm64/JIT.cpp
@@ -480,9 +480,9 @@ void Arm64JITCore::Op_Unhandled(IR::IROp_Header const *IROp, IR::NodeID Node) {
 }
 
 
-static uint64_t Arm64JITCore_ExitFunctionLink(FEXCore::Core::CpuStateFrame *Frame, uint64_t *record) {
+static uint64_t Arm64JITCore_ExitFunctionLink(FEXCore::Core::CpuStateFrame *Frame, FEXCore::Context::ContextImpl::ExitFunctionLinkData *Record) {
   auto Thread = Frame->Thread;
-  auto GuestRip = record[1];
+  auto GuestRip = Record->GuestRIP;
 
   auto HostCode = Thread->LookupCache->FindBlock(GuestRip);
 
@@ -491,7 +491,7 @@ static uint64_t Arm64JITCore_ExitFunctionLink(FEXCore::Core::CpuStateFrame *Fram
     return Frame->Pointers.Common.DispatcherLoopTop;
   }
 
-  uintptr_t branch = (uintptr_t)(record) - 8;
+  uintptr_t branch = (uintptr_t)(Record) - 8;
   auto LinkerAddress = Frame->Pointers.Common.ExitFunctionLinker;
 
   auto offset = HostCode/4 - branch/4;
@@ -503,7 +503,7 @@ static uint64_t Arm64JITCore_ExitFunctionLink(FEXCore::Core::CpuStateFrame *Fram
     FEXCore::ARMEmitter::Emitter::ClearICache((void*)branch, 24);
 
     // Add de-linking handler
-    Thread->LookupCache->AddBlockLink(GuestRip, (uintptr_t)record, [branch, LinkerAddress]{
+    Thread->LookupCache->AddBlockLink(GuestRip, (uintptr_t)Record, [branch, LinkerAddress]{
       FEXCore::ARMEmitter::Emitter emit((uint8_t*)(branch), 24);
       FEXCore::ARMEmitter::ForwardLabel l_BranchHost;
       emit.ldr(FEXCore::ARMEmitter::XReg::x0, &l_BranchHost);
@@ -514,11 +514,11 @@ static uint64_t Arm64JITCore_ExitFunctionLink(FEXCore::Core::CpuStateFrame *Fram
     });
   } else {
     // fallback case - do a soft-er link by patching the pointer
-    record[0] = HostCode;
+    Record->HostBranch = HostCode;
 
     // Add de-linking handler
-    Thread->LookupCache->AddBlockLink(GuestRip, (uintptr_t)record, [record, LinkerAddress]{
-      record[0] = LinkerAddress;
+    Thread->LookupCache->AddBlockLink(GuestRip, (uintptr_t)Record, [Record, LinkerAddress]{
+      Record->HostBranch = LinkerAddress;
     });
   }