From a1950d1d2f2055f59fc63dd8c47fd933a7c6e81e Mon Sep 17 00:00:00 2001
From: MerryMage <git@mary.rs>
Date: Tue, 4 May 2021 14:19:05 +0100
Subject: [PATCH] backend/x64: Move save_host_MXCSR from JitState to stack

---
 src/backend/x64/a32_jitstate.h    | 1 -
 src/backend/x64/a64_jitstate.h    | 1 -
 src/backend/x64/block_of_code.cpp | 4 ++--
 src/backend/x64/jitstate_info.h   | 2 --
 src/backend/x64/stack_layout.h    | 2 ++
 5 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/src/backend/x64/a32_jitstate.h b/src/backend/x64/a32_jitstate.h
index 92271c73..80f2b3ef 100644
--- a/src/backend/x64/a32_jitstate.h
+++ b/src/backend/x64/a32_jitstate.h
@@ -42,7 +42,6 @@ struct A32JitState {
     // For internal use (See: BlockOfCode::RunCode)
     u32 guest_MXCSR = 0x00001f80;
     u32 asimd_MXCSR = 0x00009fc0;
-    u32 save_host_MXCSR = 0;
     s64 cycles_to_run = 0;
     s64 cycles_remaining = 0;
     bool halt_requested = false;
diff --git a/src/backend/x64/a64_jitstate.h b/src/backend/x64/a64_jitstate.h
index e94a88c6..d98dd572 100644
--- a/src/backend/x64/a64_jitstate.h
+++ b/src/backend/x64/a64_jitstate.h
@@ -45,7 +45,6 @@ struct A64JitState {
     // For internal use (See: BlockOfCode::RunCode)
     u32 guest_MXCSR = 0x00001f80;
     u32 asimd_MXCSR = 0x00009fc0;
-    u32 save_host_MXCSR = 0;
     s64 cycles_to_run = 0;
     s64 cycles_remaining = 0;
     bool halt_requested = false;
diff --git a/src/backend/x64/block_of_code.cpp b/src/backend/x64/block_of_code.cpp
index 8a19a7fb..f54d9a3a 100644
--- a/src/backend/x64/block_of_code.cpp
+++ b/src/backend/x64/block_of_code.cpp
@@ -230,13 +230,13 @@ void BlockOfCode::GenRunCode(std::function<void(BlockOfCode&)> rcp) {
 }
 
 void BlockOfCode::SwitchMxcsrOnEntry() {
-    stmxcsr(dword[r15 + jsi.offsetof_save_host_MXCSR]);
+    stmxcsr(dword[rsp + ABI_SHADOW_SPACE + offsetof(StackLayout, save_host_MXCSR)]);
     ldmxcsr(dword[r15 + jsi.offsetof_guest_MXCSR]);
 }
 
 void BlockOfCode::SwitchMxcsrOnExit() {
     stmxcsr(dword[r15 + jsi.offsetof_guest_MXCSR]);
-    ldmxcsr(dword[r15 + jsi.offsetof_save_host_MXCSR]);
+    ldmxcsr(dword[rsp + ABI_SHADOW_SPACE + offsetof(StackLayout, save_host_MXCSR)]);
 }
 
 void BlockOfCode::EnterStandardASIMD() {
diff --git a/src/backend/x64/jitstate_info.h b/src/backend/x64/jitstate_info.h
index e629a23c..711a218f 100644
--- a/src/backend/x64/jitstate_info.h
+++ b/src/backend/x64/jitstate_info.h
@@ -14,7 +14,6 @@ struct JitStateInfo {
     JitStateInfo(const JitStateType&)
         : offsetof_cycles_remaining(offsetof(JitStateType, cycles_remaining))
         , offsetof_cycles_to_run(offsetof(JitStateType, cycles_to_run))
-        , offsetof_save_host_MXCSR(offsetof(JitStateType, save_host_MXCSR))
         , offsetof_guest_MXCSR(offsetof(JitStateType, guest_MXCSR))
         , offsetof_asimd_MXCSR(offsetof(JitStateType, asimd_MXCSR))
         , offsetof_rsb_ptr(offsetof(JitStateType, rsb_ptr))
@@ -28,7 +27,6 @@ struct JitStateInfo {
 
     const size_t offsetof_cycles_remaining;
     const size_t offsetof_cycles_to_run;
-    const size_t offsetof_save_host_MXCSR;
     const size_t offsetof_guest_MXCSR;
     const size_t offsetof_asimd_MXCSR;
     const size_t offsetof_rsb_ptr;
diff --git a/src/backend/x64/stack_layout.h b/src/backend/x64/stack_layout.h
index 054fefab..e2a868c2 100644
--- a/src/backend/x64/stack_layout.h
+++ b/src/backend/x64/stack_layout.h
@@ -15,6 +15,8 @@ constexpr size_t SpillCount = 64;
 
 struct alignas(16) StackLayout {
     std::array<std::array<u64, 2>, SpillCount> spill;
+
+    u32 save_host_MXCSR;
 };
 
 static_assert(sizeof(StackLayout) % 16 == 0);