From 8f88cb08999187b143c6772216dd2ef18d9b7824 Mon Sep 17 00:00:00 2001
From: Anton Korobeynikov <asl@math.spbu.ru>
Date: Sat, 22 Mar 2008 20:37:30 +0000
Subject: [PATCH] Initial support for Win64 calling conventions. Still in early
 state.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48690 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86CallingConv.td   | 47 +++++++++++++++++++++++++++++-
 lib/Target/X86/X86ISelLowering.cpp | 12 +++++---
 2 files changed, 54 insertions(+), 5 deletions(-)

diff --git a/lib/Target/X86/X86CallingConv.td b/lib/Target/X86/X86CallingConv.td
index 70f18c57897..3206e183eb7 100644
--- a/lib/Target/X86/X86CallingConv.td
+++ b/lib/Target/X86/X86CallingConv.td
@@ -78,6 +78,16 @@ def RetCC_X86_64_C : CallingConv<[
   CCDelegateTo<RetCC_X86Common>
 ]>;
 
+// X86-Win64 C return-value convention.
+def RetCC_X86_Win64_C : CallingConv<[
+  // The X86-Win64 calling convention always returns __m64 values in RAX
+  CCIfType<[v8i8, v4i16, v2i32, v1i64], CCAssignToReg<[RAX]>>,
+
+  // Otherwise, everything is the same as 'norma' X86-64 C CC
+  CCDelegateTo<RetCC_X86_64_C>
+]>;
+
+
 // This is the root return-value convention for the X86-32 backend.
 def RetCC_X86_32 : CallingConv<[
   // If FastCC, use RetCC_X86_32_Fast.
@@ -90,7 +100,11 @@ def RetCC_X86_32 : CallingConv<[
 
 // This is the root return-value convention for the X86-64 backend.
 def RetCC_X86_64 : CallingConv<[
-  // Always just the same as C calling conv for X86-64.
+  // Mingw64 and native Win64 use Win64 CC
+  CCIfSubtarget<"isTargetMingw()", CCDelegateTo<RetCC_X86_Win64_C>>,
+  CCIfSubtarget<"isTargetWindows()", CCDelegateTo<RetCC_X86_Win64_C>>,
+
+  // Otherwise, drop to normal X86-64 CC
   CCDelegateTo<RetCC_X86_64_C>
 ]>;
 
@@ -141,6 +155,37 @@ def CC_X86_64_C : CallingConv<[
   CCIfType<[v8i8, v4i16, v2i32, v1i64], CCAssignToStack<8, 8>>
 ]>;
 
+// Calling convention used on Win64
+def CC_X86_Win64_C : CallingConv<[
+  // FIXME: Handle byval stuff
+  // FIXME: Handle fp80
+  // FIXME: Handle shadowed arguments
+
+  // Promote i8/i16 arguments to i32.
+  CCIfType<[i8, i16], CCPromoteToType<i32>>,
+
+  // The first 4 integer arguments are passed in integer registers.
+  CCIfType<[i32], CCAssignToReg<[ECX, EDX, R8D, R9D]>>,
+  CCIfType<[i64], CCAssignToReg<[RCX, RDX, R8 , R9 ]>>,
+
+  // The first 4 FP/Vector arguments are passed in XMM registers.
+  CCIfType<[f32, f64, v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
+              CCAssignToReg<[XMM0, XMM1, XMM2, XMM3]>>,
+
+  // The first 4 MMX vector arguments are passed in GPRs.
+  CCIfType<[v8i8, v4i16, v2i32, v1i64], CCAssignToReg<[RCX, RDX, R8, R9]>>,
+
+  // Integer/FP values get stored in stack slots that are 8 bytes in size and
+  // 16-byte aligned if there are no more registers to hold them.
+  CCIfType<[i32, i64, f32, f64], CCAssignToStack<8, 16>>,
+
+  // Vectors get 16-byte stack slots that are 16-byte aligned.
+  CCIfType<[v16i8, v8i16, v4i32, v2i64, v4f32, v2f64], CCAssignToStack<16, 16>>,
+
+  // __m64 vectors get 8-byte stack slots that are 16-byte aligned.
+  CCIfType<[v8i8, v4i16, v2i32, v1i64], CCAssignToStack<8, 16>>
+]>;
+
 // Tail call convention (fast): One register is reserved for target address,
 // namely R9
 def CC_X86_64_TailCall : CallingConv<[
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 9d22fbeaaad..933c33e3d4d 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1009,10 +1009,14 @@ CCAssignFn *X86TargetLowering::CCAssignFnForNode(SDOperand Op) const {
   unsigned CC = cast<ConstantSDNode>(Op.getOperand(1))->getValue();
   
   if (Subtarget->is64Bit()) {
-    if (CC == CallingConv::Fast && PerformTailCallOpt)
-      return CC_X86_64_TailCall;
-    else
-      return CC_X86_64_C;
+    if (Subtarget->isTargetWindows() || Subtarget->isTargetMingw())
+      return CC_X86_Win64_C;
+    else {
+      if (CC == CallingConv::Fast && PerformTailCallOpt)
+        return CC_X86_64_TailCall;
+      else
+        return CC_X86_64_C;
+    }
   }
 
   if (CC == CallingConv::X86_FastCall)