Target/X86: Add explicit Win64 and System V/x86-64 calling conventions.

Summary:
This patch adds explicit calling convention types for the Win64 and
System V/x86-64 ABIs. This allows code to override the default, and use
the Win64 convention on a target that wants to use SysV (and
vice-versa). This is needed to implement the `ms_abi` and `sysv_abi` GNU
attributes.

Reviewers:

CC:

llvm-svn: 186144

4 files changed, 45 insertions, 25 deletions

diff --git a/llvm/lib/Target/X86/X86CallingConv.td b/llvm/lib/Target/X86/X86CallingConv.td
index 9eafbd55a5a..40c5d91b605 100644
--- a/llvm/lib/Target/X86/X86CallingConv.td
+++ b/llvm/lib/Target/X86/X86CallingConv.td
@@ -156,6 +156,11 @@ def RetCC_X86_32 : CallingConv<[
 def RetCC_X86_64 : CallingConv<[
   // HiPE uses RetCC_X86_64_HiPE
   CCIfCC<"CallingConv::HiPE", CCDelegateTo<RetCC_X86_64_HiPE>>,
+
+  // Handle explicit CC selection
+  CCIfCC<"CallingConv::X86_64_Win64", CCDelegateTo<RetCC_X86_Win64_C>>,
+  CCIfCC<"CallingConv::X86_64_SysV", CCDelegateTo<RetCC_X86_64_C>>,
+
   // Mingw64 and native Win64 use Win64 CC
   CCIfSubtarget<"isTargetWin64()", CCDelegateTo<RetCC_X86_Win64_C>>,
 
@@ -489,6 +494,8 @@ def CC_X86_32 : CallingConv<[
 def CC_X86_64 : CallingConv<[
   CCIfCC<"CallingConv::GHC", CCDelegateTo<CC_X86_64_GHC>>,
   CCIfCC<"CallingConv::HiPE", CCDelegateTo<CC_X86_64_HiPE>>,
+  CCIfCC<"CallingConv::X86_64_Win64", CCDelegateTo<CC_X86_Win64_C>>,
+  CCIfCC<"CallingConv::X86_64_SysV", CCDelegateTo<CC_X86_64_C>>,
 
   // Mingw64 and native Win64 use Win64 CC
   CCIfSubtarget<"isTargetWin64()", CCDelegateTo<CC_X86_Win64_C>>,
diff --git a/llvm/lib/Target/X86/X86FastISel.cpp b/llvm/lib/Target/X86/X86FastISel.cpp
index f8f06f60164..9c91e935f0b 100644
--- a/llvm/lib/Target/X86/X86FastISel.cpp
+++ b/llvm/lib/Target/X86/X86FastISel.cpp
@@ -712,10 +712,11 @@ bool X86FastISel::X86SelectRet(const Instruction *I) {
   CallingConv::ID CC = F.getCallingConv();
   if (CC != CallingConv::C &&
       CC != CallingConv::Fast &&
-      CC != CallingConv::X86_FastCall)
+      CC != CallingConv::X86_FastCall &&
+      CC != CallingConv::X86_64_SysV)
     return false;
 
-  if (Subtarget->isTargetWin64())
+  if (Subtarget->isCallingConvWin64(CC))
     return false;
 
   // Don't handle popping bytes on return for now.
@@ -1705,9 +1706,6 @@ bool X86FastISel::FastLowerArguments() {
   if (!FuncInfo.CanLowerReturn)
     return false;
 
-  if (Subtarget->isTargetWin64())
-    return false;
-
   const Function *F = FuncInfo.Fn;
   if (F->isVarArg())
     return false;
@@ -1715,7 +1713,10 @@ bool X86FastISel::FastLowerArguments() {
   CallingConv::ID CC = F->getCallingConv();
   if (CC != CallingConv::C)
     return false;
-  
+
+  if (Subtarget->isCallingConvWin64(CC))
+    return false;
+
   if (!Subtarget->is64Bit())
     return false;
   
@@ -1817,8 +1818,10 @@ bool X86FastISel::DoSelectCall(const Instruction *I, const char *MemIntName) {
   // Handle only C and fastcc calling conventions for now.
   ImmutableCallSite CS(CI);
   CallingConv::ID CC = CS.getCallingConv();
+  bool isWin64 = Subtarget->isCallingConvWin64(CC);
   if (CC != CallingConv::C && CC != CallingConv::Fast &&
-      CC != CallingConv::X86_FastCall)
+      CC != CallingConv::X86_FastCall && CC != CallingConv::X86_64_Win64 &&
+      CC != CallingConv::X86_64_SysV)
     return false;
 
   // fastcc with -tailcallopt is intended to provide a guaranteed
@@ -1832,7 +1835,7 @@ bool X86FastISel::DoSelectCall(const Instruction *I, const char *MemIntName) {
 
   // Don't know how to handle Win64 varargs yet.  Nothing special needed for
   // x86-32.  Special handling for x86-64 is implemented.
-  if (isVarArg && Subtarget->isTargetWin64())
+  if (isVarArg && isWin64)
     return false;
 
   // Fast-isel doesn't know about callee-pop yet.
@@ -1962,7 +1965,7 @@ bool X86FastISel::DoSelectCall(const Instruction *I, const char *MemIntName) {
                  I->getParent()->getContext());
 
   // Allocate shadow area for Win64
-  if (Subtarget->isTargetWin64())
+  if (isWin64)
     CCInfo.AllocateStack(32, 8);
 
   CCInfo.AnalyzeCallOperands(ArgVTs, ArgFlags, CC_X86);
@@ -2078,7 +2081,7 @@ bool X86FastISel::DoSelectCall(const Instruction *I, const char *MemIntName) {
             X86::EBX).addReg(Base);
   }
 
-  if (Subtarget->is64Bit() && isVarArg && !Subtarget->isTargetWin64()) {
+  if (Subtarget->is64Bit() && isVarArg && !isWin64) {
     // Count the number of XMM registers allocated.
     static const uint16_t XMMArgRegs[] = {
       X86::XMM0, X86::XMM1, X86::XMM2, X86::XMM3,
@@ -2147,7 +2150,7 @@ bool X86FastISel::DoSelectCall(const Instruction *I, const char *MemIntName) {
   if (Subtarget->isPICStyleGOT())
     MIB.addReg(X86::EBX, RegState::Implicit);
 
-  if (Subtarget->is64Bit() && isVarArg && !Subtarget->isTargetWin64())
+  if (Subtarget->is64Bit() && isVarArg && !isWin64)
     MIB.addReg(X86::AL, RegState::Implicit);
 
   // Add implicit physical register uses to the call.
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index f00df3543a8..6284dd7e58e 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -1880,13 +1880,19 @@ static bool IsTailCallConvention(CallingConv::ID CC) {
           CC == CallingConv::HiPE);
 }
 
+/// \brief Return true if the calling convention is a C calling convention.
+static bool IsCCallConvention(CallingConv::ID CC) {
+  return (CC == CallingConv::C || CC == CallingConv::X86_64_Win64 ||
+          CC == CallingConv::X86_64_SysV);
+}
+
 bool X86TargetLowering::mayBeEmittedAsTailCall(CallInst *CI) const {
   if (!CI->isTailCall() || getTargetMachine().Options.DisableTailCalls)
     return false;
 
   CallSite CS(CI);
   CallingConv::ID CalleeCC = CS.getCallingConv();
-  if (!IsTailCallConvention(CalleeCC) && CalleeCC != CallingConv::C)
+  if (!IsTailCallConvention(CalleeCC) && !IsCCallConvention(CalleeCC))
     return false;
 
   return true;
@@ -1961,7 +1967,7 @@ X86TargetLowering::LowerFormalArguments(SDValue Chain,
   MachineFrameInfo *MFI = MF.getFrameInfo();
   bool Is64Bit = Subtarget->is64Bit();
   bool IsWindows = Subtarget->isTargetWindows();
-  bool IsWin64 = Subtarget->isTargetWin64();
+  bool IsWin64 = Subtarget->isCallingConvWin64(CallConv);
 
   assert(!(isVarArg && IsTailCallConvention(CallConv)) &&
          "Var args not supported with calling convention fastcc, ghc or hipe");
@@ -1972,9 +1978,8 @@ X86TargetLowering::LowerFormalArguments(SDValue Chain,
                  ArgLocs, *DAG.getContext());
 
   // Allocate shadow area for Win64
-  if (IsWin64) {
+  if (IsWin64)
     CCInfo.AllocateStack(32, 8);
-  }
 
   CCInfo.AnalyzeFormalArguments(Ins, CC_X86);
 
@@ -2287,7 +2292,7 @@ X86TargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
 
   MachineFunction &MF = DAG.getMachineFunction();
   bool Is64Bit        = Subtarget->is64Bit();
-  bool IsWin64        = Subtarget->isTargetWin64();
+  bool IsWin64        = Subtarget->isCallingConvWin64(CallConv);
   bool IsWindows      = Subtarget->isTargetWindows();
   StructReturnType SR = callIsStructReturn(Outs);
   bool IsSibcall      = false;
@@ -2320,9 +2325,8 @@ X86TargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
                  ArgLocs, *DAG.getContext());
 
   // Allocate shadow area for Win64
-  if (IsWin64) {
+  if (IsWin64)
     CCInfo.AllocateStack(32, 8);
-  }
 
   CCInfo.AnalyzeCallOperands(Outs, CC_X86);
 
@@ -2833,13 +2837,12 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
                                     const SmallVectorImpl<SDValue> &OutVals,
                                     const SmallVectorImpl<ISD::InputArg> &Ins,
                                                      SelectionDAG &DAG) const {
-  if (!IsTailCallConvention(CalleeCC) &&
-      CalleeCC != CallingConv::C)
+  if (!IsTailCallConvention(CalleeCC) && !IsCCallConvention(CalleeCC))
     return false;
 
   // If -tailcallopt is specified, make fastcc functions tail-callable.
   const MachineFunction &MF = DAG.getMachineFunction();
-  const Function *CallerF = DAG.getMachineFunction().getFunction();
+  const Function *CallerF = MF.getFunction();
 
   // If the function return type is x86_fp80 and the callee return type is not,
   // then the FP_EXTEND of the call result is not a nop. It's not safe to
@@ -2849,6 +2852,8 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
 
   CallingConv::ID CallerCC = CallerF->getCallingConv();
   bool CCMatch = CallerCC == CalleeCC;
+  bool IsCalleeWin64 = Subtarget->isCallingConvWin64(CalleeCC);
+  bool IsCallerWin64 = Subtarget->isCallingConvWin64(CallerCC);
 
   if (getTargetMachine().Options.GuaranteedTailCallOpt) {
     if (IsTailCallConvention(CalleeCC) && CCMatch)
@@ -2882,7 +2887,7 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
 
     // Optimizing for varargs on Win64 is unlikely to be safe without
     // additional testing.
-    if (Subtarget->isTargetWin64())
+    if (IsCalleeWin64 || IsCallerWin64)
       return false;
 
     SmallVector<CCValAssign, 16> ArgLocs;
@@ -2957,9 +2962,8 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
                    getTargetMachine(), ArgLocs, *DAG.getContext());
 
     // Allocate shadow area for Win64
-    if (Subtarget->isTargetWin64()) {
+    if (IsCalleeWin64)
       CCInfo.AllocateStack(32, 8);
-    }
 
     CCInfo.AnalyzeCallOperands(Outs, CC_X86);
     if (CCInfo.getNextStackOffset()) {
diff --git a/llvm/lib/Target/X86/X86Subtarget.h b/llvm/lib/Target/X86/X86Subtarget.h
index 66832b989be..01a28d0fd1d 100644
--- a/llvm/lib/Target/X86/X86Subtarget.h
+++ b/llvm/lib/Target/X86/X86Subtarget.h
@@ -338,7 +338,13 @@ public:
   }
   bool isPICStyleStubAny() const {
     return PICStyle == PICStyles::StubDynamicNoPIC ||
-           PICStyle == PICStyles::StubPIC; }
+           PICStyle == PICStyles::StubPIC;
+  }
+
+  bool isCallingConvWin64(CallingConv::ID CC) const {
+    return (isTargetWin64() && CC != CallingConv::X86_64_SysV) ||
+           CC == CallingConv::X86_64_Win64;
+  }
 
   /// ClassifyGlobalReference - Classify a global variable reference for the
   /// current subtarget according to how we should reference it in a non-pcrel