[x64] Fix up offset of stack alloc in prolog for unwind info.

- [x64] Track offset of stack alloc in prolog within emitted functions.
- [x64] Don't use hardcoded offset of stack alloc in prolog in generated
  unwind info.

src/xenia/cpu/backend/x64/x64_backend.cc

@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2013 Ben Vanik. All rights reserved.                             *
+ * Copyright 2019 Ben Vanik. All rights reserved.                             *
  * Released under the BSD license - see LICENSE in the root for more details. *
  ******************************************************************************
  */
@@ -409,6 +409,7 @@ HostToGuestThunk X64ThunkEmitter::EmitHostToGuestThunk() {
 
   struct _code_offsets {
     size_t prolog;
+    size_t prolog_stack_alloc;
     size_t body;
     size_t epilog;
     size_t tail;
@@ -424,6 +425,7 @@ HostToGuestThunk X64ThunkEmitter::EmitHostToGuestThunk() {
   mov(qword[rsp + 8 * 1], rcx);
   sub(rsp, stack_size);
 
+  code_offsets.prolog_stack_alloc = getSize();
   code_offsets.body = getSize();
 
   // Save nonvolatile registers.
@@ -453,6 +455,8 @@ HostToGuestThunk X64ThunkEmitter::EmitHostToGuestThunk() {
   func_info.code_size.body = code_offsets.epilog - code_offsets.body;
   func_info.code_size.epilog = code_offsets.tail - code_offsets.epilog;
   func_info.code_size.tail = getSize() - code_offsets.tail;
+  func_info.prolog_stack_alloc_offset =
+      code_offsets.prolog_stack_alloc - code_offsets.prolog;
   func_info.stack_size = stack_size;
 
   void* fn = Emplace(func_info);
@@ -467,6 +471,7 @@ GuestToHostThunk X64ThunkEmitter::EmitGuestToHostThunk() {
 
   struct _code_offsets {
     size_t prolog;
+    size_t prolog_stack_alloc;
     size_t body;
     size_t epilog;
     size_t tail;
@@ -479,6 +484,7 @@ GuestToHostThunk X64ThunkEmitter::EmitGuestToHostThunk() {
   // rsp + 0 = return address
   sub(rsp, stack_size);
 
+  code_offsets.prolog_stack_alloc = getSize();
   code_offsets.body = getSize();
 
   // Save off volatile registers.
@@ -504,6 +510,8 @@ GuestToHostThunk X64ThunkEmitter::EmitGuestToHostThunk() {
   func_info.code_size.body = code_offsets.epilog - code_offsets.body;
   func_info.code_size.epilog = code_offsets.tail - code_offsets.epilog;
   func_info.code_size.tail = getSize() - code_offsets.tail;
+  func_info.prolog_stack_alloc_offset =
+      code_offsets.prolog_stack_alloc - code_offsets.prolog;
   func_info.stack_size = stack_size;
 
   void* fn = Emplace(func_info);
@@ -519,6 +527,7 @@ ResolveFunctionThunk X64ThunkEmitter::EmitResolveFunctionThunk() {
 
   struct _code_offsets {
     size_t prolog;
+    size_t prolog_stack_alloc;
     size_t body;
     size_t epilog;
     size_t tail;
@@ -531,6 +540,7 @@ ResolveFunctionThunk X64ThunkEmitter::EmitResolveFunctionThunk() {
   // rsp + 0 = return address
   sub(rsp, stack_size);
 
+  code_offsets.prolog_stack_alloc = getSize();
   code_offsets.body = getSize();
 
   // Save volatile registers
@@ -557,6 +567,8 @@ ResolveFunctionThunk X64ThunkEmitter::EmitResolveFunctionThunk() {
   func_info.code_size.body = code_offsets.epilog - code_offsets.body;
   func_info.code_size.epilog = code_offsets.tail - code_offsets.epilog;
   func_info.code_size.tail = getSize() - code_offsets.tail;
+  func_info.prolog_stack_alloc_offset =
+      code_offsets.prolog_stack_alloc - code_offsets.prolog;
   func_info.stack_size = stack_size;
 
   void* fn = Emplace(func_info);

src/xenia/cpu/backend/x64/x64_code_cache.cc

@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2013 Ben Vanik. All rights reserved.                             *
+ * Copyright 2019 Ben Vanik. All rights reserved.                             *
  * Released under the BSD license - see LICENSE in the root for more details. *
  ******************************************************************************
  */

src/xenia/cpu/backend/x64/x64_code_cache.h

@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2013 Ben Vanik. All rights reserved.                             *
+ * Copyright 2019 Ben Vanik. All rights reserved.                             *
  * Released under the BSD license - see LICENSE in the root for more details. *
  ******************************************************************************
  */
@@ -33,6 +33,7 @@ struct EmitFunctionInfo {
     size_t tail;
     size_t total;
   } code_size;
+  size_t prolog_stack_alloc_offset;  // offset of instruction after stack alloc
   size_t stack_size;
 };
 

src/xenia/cpu/backend/x64/x64_code_cache_win.cc

@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2015 Ben Vanik. All rights reserved.                             *
+ * Copyright 2019 Ben Vanik. All rights reserved.                             *
  * Released under the BSD license - see LICENSE in the root for more details. *
  ******************************************************************************
  */
@@ -248,6 +248,10 @@ void Win32X64CodeCache::InitializeUnwindEntry(
 
   assert_true(func_info.code_size.prolog < 256);  // needs to fit into a uint8_t
   auto prolog_size = static_cast<uint8_t>(func_info.code_size.prolog);
+  assert_true(func_info.prolog_stack_alloc_offset <
+              256);  // needs to fit into a uint8_t
+  auto prolog_stack_alloc_offset =
+      static_cast<uint8_t>(func_info.prolog_stack_alloc_offset);
 
   if (!func_info.stack_size) {
     // https://docs.microsoft.com/en-us/cpp/build/exception-handling-x64#struct-unwind_info
@@ -268,8 +272,7 @@ void Win32X64CodeCache::InitializeUnwindEntry(
 
     // https://docs.microsoft.com/en-us/cpp/build/exception-handling-x64#struct-unwind_code
     unwind_code = &unwind_info->UnwindCode[unwind_info->CountOfCodes++];
-    unwind_code->CodeOffset =
+    unwind_code->CodeOffset = prolog_stack_alloc_offset;
-        14;  // end of instruction + 1 == offset of next instruction
     unwind_code->UnwindOp = UWOP_ALLOC_SMALL;
     unwind_code->OpInfo = func_info.stack_size / 8 - 1;
   } else {
@@ -285,8 +288,7 @@ void Win32X64CodeCache::InitializeUnwindEntry(
 
     // https://docs.microsoft.com/en-us/cpp/build/exception-handling-x64#struct-unwind_code
     unwind_code = &unwind_info->UnwindCode[unwind_info->CountOfCodes++];
-    unwind_code->CodeOffset =
+    unwind_code->CodeOffset = prolog_stack_alloc_offset;
-        7;  // end of instruction + 1 == offset of next instruction
     unwind_code->UnwindOp = UWOP_ALLOC_LARGE;
     unwind_code->OpInfo = 0;  // One slot for size
 

src/xenia/cpu/backend/x64/x64_emitter.cc

@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2013 Ben Vanik. All rights reserved.                             *
+ * Copyright 2019 Ben Vanik. All rights reserved.                             *
  * Released under the BSD license - see LICENSE in the root for more details. *
  ******************************************************************************
  */
@@ -163,6 +163,7 @@ bool X64Emitter::Emit(HIRBuilder* builder, EmitFunctionInfo& func_info) {
 
   struct _code_offsets {
     size_t prolog;
+    size_t prolog_stack_alloc;
     size_t body;
     size_t epilog;
     size_t tail;
@@ -183,6 +184,9 @@ bool X64Emitter::Emit(HIRBuilder* builder, EmitFunctionInfo& func_info) {
   stack_size_ = stack_size;
 
   sub(rsp, (uint32_t)stack_size);
+
+  code_offsets.prolog_stack_alloc = getSize();
+
   mov(qword[rsp + StackLayout::GUEST_CTX_HOME], GetContextReg());
   mov(qword[rsp + StackLayout::GUEST_RET_ADDR], rcx);
   mov(qword[rsp + StackLayout::GUEST_CALL_RET_ADDR], 0);
@@ -275,6 +279,8 @@ bool X64Emitter::Emit(HIRBuilder* builder, EmitFunctionInfo& func_info) {
   func_info.code_size.body = code_offsets.epilog - code_offsets.body;
   func_info.code_size.epilog = code_offsets.tail - code_offsets.epilog;
   func_info.code_size.tail = getSize() - code_offsets.tail;
+  func_info.prolog_stack_alloc_offset =
+      code_offsets.prolog_stack_alloc - code_offsets.prolog;
 
   return true;
 }

src/xenia/cpu/backend/x64/x64_emitter.h

@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2013 Ben Vanik. All rights reserved.                             *
+ * Copyright 2019 Ben Vanik. All rights reserved.                             *
  * Released under the BSD license - see LICENSE in the root for more details. *
  ******************************************************************************
  */