From 2468645bf2211788c4ad9b3c02d6b94ea027bb1c Mon Sep 17 00:00:00 2001
From: Ben Vanik <ben.vanik@gmail.com>
Date: Thu, 2 Jan 2014 23:53:18 -0800
Subject: [PATCH] Making functions naked for now, as it makes life way easier.

---
 src/alloy/backend/x64/x64_code_cache.cc | 12 +++++++++---
 src/alloy/backend/x64/x64_emitter.cc    | 14 ++++++++++----
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/alloy/backend/x64/x64_code_cache.cc b/src/alloy/backend/x64/x64_code_cache.cc
index aa14ad0ea..854e6f699 100644
--- a/src/alloy/backend/x64/x64_code_cache.cc
+++ b/src/alloy/backend/x64/x64_code_cache.cc
@@ -213,12 +213,17 @@ void X64CodeChunk::AddTableEntry(uint8_t* code, size_t code_size) {
   size_t unwind_info_offset = offset;
   offset += UNWIND_INFO_SIZE;
 
+  // TODO(benvanik): take as parameters?
+  bool has_prolog = false;
+  uint8_t prolog_size = 4;
+  uint8_t stack_bytes = 16;
+
   // http://msdn.microsoft.com/en-us/library/ddssxxy8.aspx
   UNWIND_INFO* unwind_info = (UNWIND_INFO*)(buffer + unwind_info_offset);
   unwind_info->Version = 1;
   unwind_info->Flags = 0;
-  unwind_info->SizeOfProlog = 4;
-  unwind_info->CountOfCodes = 1;
+  unwind_info->SizeOfProlog = has_prolog ? prolog_size : 0;
+  unwind_info->CountOfCodes = has_prolog ? 1 : 0;
   unwind_info->FrameRegister = 0;
   unwind_info->FrameOffset = 0;
 
@@ -226,7 +231,8 @@ void X64CodeChunk::AddTableEntry(uint8_t* code, size_t code_size) {
   auto& code_0 = unwind_info->UnwindCode[0];
   code_0.CodeOffset = 4; // end of instruction + 1 == offset of next instruction
   code_0.UnwindOp = UWOP_ALLOC_SMALL;
-  code_0.OpInfo = 16;
+  code_0.OpInfo = stack_bytes;
+  XEASSERT(stack_bytes < 128);
 
   // Add entry.
   auto& fn_entry = fn_table[fn_table_count++];
diff --git a/src/alloy/backend/x64/x64_emitter.cc b/src/alloy/backend/x64/x64_emitter.cc
index 2eed311e3..7d865b915 100644
--- a/src/alloy/backend/x64/x64_emitter.cc
+++ b/src/alloy/backend/x64/x64_emitter.cc
@@ -103,7 +103,7 @@ void* XbyakGenerator::Emplace(X64CodeCache* code_cache) {
 int XbyakGenerator::Emit(LIRBuilder* builder) {
   // Function prolog.
   // Must be 16b aligned.
-  // Windows is very strict about the form of this and the eiplog:
+  // Windows is very strict about the form of this and the epilog:
   // http://msdn.microsoft.com/en-us/library/tawsa7cb.aspx
   // TODO(benvanik): save off non-volatile registers so we can use them:
   //     RBX, RBP, RDI, RSI, RSP, R12, R13, R14, R15
@@ -112,8 +112,12 @@ int XbyakGenerator::Emit(LIRBuilder* builder) {
   // IMPORTANT: any changes to the prolog must be kept in sync with
   //     X64CodeCache, which dynamically generates exception information.
   //     Adding or changing anything here must be matched!
+  const bool emit_prolog = false;
   const size_t stack_size = 16;
-  sub(rsp, stack_size);
+  if (emit_prolog) {
+    sub(rsp, stack_size);
+    // TODO(benvanik): save registers.
+  }
 
   // Body.
   auto block = builder->first_block();
@@ -145,8 +149,10 @@ int XbyakGenerator::Emit(LIRBuilder* builder) {
 
   // Function epilog.
   L("epilog");
-  add(rsp, stack_size);
-  // TODO(benvanik): restore registers.
+  if (emit_prolog) {
+    add(rsp, stack_size);
+    // TODO(benvanik): restore registers.
+  }
   ret();
 
   return 0;