From 970874ad627f07491528a2e4407e26a78e009947 Mon Sep 17 00:00:00 2001
From: "whesse@chromium.org"
 <whesse@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Tue, 1 Sep 2009 10:40:00 +0000
Subject: [PATCH] X64: Obey WIN64 ABI more exactly, in WIN64 build. Review URL:
 http://codereview.chromium.org/182027

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2791 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/x64/codegen-x64.cc         |  8 ++++----
 src/x64/macro-assembler-x64.cc | 17 +++++++++++------
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index 3f33122d83..ea6b90a3f2 100644
--- a/src/x64/codegen-x64.cc
+++ b/src/x64/codegen-x64.cc
@@ -6953,11 +6953,11 @@ void CEntryStub::GenerateCore(MacroAssembler* masm,
   // Call C function.
 #ifdef _WIN64
   // Windows 64-bit ABI passes arguments in rcx, rdx, r8, r9
-  // Store Arguments object on stack
-  __ movq(Operand(rsp, 1 * kPointerSize), r14);  // argc.
-  __ movq(Operand(rsp, 2 * kPointerSize), r15);  // argv.
+  // Store Arguments object on stack, below the 4 WIN64 ABI parameter slots.
+  __ movq(Operand(rsp, 4 * kPointerSize), r14);  // argc.
+  __ movq(Operand(rsp, 5 * kPointerSize), r15);  // argv.
   // Pass a pointer to the Arguments object as the first argument.
-  __ lea(rcx, Operand(rsp, 1 * kPointerSize));
+  __ lea(rcx, Operand(rsp, 4 * kPointerSize));
 #else  // ! defined(_WIN64)
   // GCC passes arguments in rdi, rsi, rdx, rcx, r8, r9.
   __ movq(rdi, r14);  // argc.
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index b29fd033cc..5fd48da75c 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -1010,12 +1010,6 @@ void MacroAssembler::EnterExitFrame(StackFrame::Type type) {
   }
 #endif
 
-  // Reserve space for the Arguments object.  The Windows 64-bit ABI
-  // requires us to pass this structure as a pointer to its location on
-  // the stack.  We also need backing space for the pointer, even though
-  // it is passed in a register.
-  subq(rsp, Immediate(3 * kPointerSize));
-
   // Get the required frame alignment for the OS.
   static const int kFrameAlignment = OS::ActivationFrameAlignment();
   if (kFrameAlignment > 0) {
@@ -1024,6 +1018,17 @@ void MacroAssembler::EnterExitFrame(StackFrame::Type type) {
     and_(rsp, kScratchRegister);
   }
 
+#ifdef _WIN64
+  // Reserve space for the Arguments object.  The Windows 64-bit ABI
+  // requires us to pass this structure as a pointer to its location on
+  // the stack.  The structure contains 2 pointers.
+  // The structure on the stack must be 16-byte aligned.
+  // We also need backing space for 4 parameters, even though
+  // we only pass one parameter, and it is in a register.
+  subq(rsp, Immediate(6 * kPointerSize));
+  ASSERT(kFrameAlignment == 2 * kPointerSize);  // Change the padding if needed.
+#endif
+
   // Patch the saved entry sp.
   movq(Operand(rbp, ExitFrameConstants::kSPOffset), rsp);
 }