[VE][NFC] Refactor to support more than one calling conv

[simoll]

Summary

Prepare for supporting different calling conventions by factoring out things into CC-dependent selection functions (getParamCC, getReturnCC).

[kaz7]

Thank you for separating this!

llvm/lib/Target/VE/VEISelLowering.cpp

542

It's better to be getParamCC(CLI.CallConv, true). All calls using getParamCC should be written in the similar manner.

[simoll]

Made getParamCC calls all the same.

[kaz7]

Thanks. LGTM.

llvm/lib/Target/VE/VECallingConv.td

 def CC_VE_C_Stack: CallingConv<[
   // F128 are assigned to the stack in 16-byte aligned units
   CCIfType<[f128], CCAssignToStackWithShadow<16, 16, [SX7]>>,
 
   // All of the rest are assigned to the stack in 8-byte aligned units.
   CCAssignToStack<0, 8>
 ]>;
 
-def CC_VE : CallingConv<[
+///// C Calling Convention (VE ABI v2.1) /////
+//
+// Reference: https://www.nec.com/en/global/prod/hpc/aurora/document/VE-ABI_v2.1.pdf
+//
+def CC_VE_C : CallingConv<[
   // All arguments get passed in generic registers if there is space.
 
   // Promote i1/i8/i16/i32 arguments to i64.
   CCIfType<[i1, i8, i16, i32], CCPromoteToType<i64>>,
 
   // Convert float arguments to i64 with padding.
   //     63     31   0
   //    +------+------+
def CC_VE_C : CallingConv<[
   CCIfType<[f128],
            CCAssignToRegWithShadow<[Q0, Q1, Q2, Q3],
                                    [SX0, SX1, SX3, SX5]>>,
 
   // Alternatively, they are assigned to the stack in 8-byte aligned units.
   CCDelegateTo<CC_VE_C_Stack>
 ]>;
 
+///// Standard vararg C Calling Convention (VE ABI v2.1) /////
 // All arguments get passed in stack for varargs function or non-prototyped
 // function.
 def CC_VE2 : CallingConv<[
   // Promote i1/i8/i16/i32 arguments to i64.
   CCIfType<[i1, i8, i16, i32], CCPromoteToType<i64>>,
 
   // Convert float arguments to i64 with padding.
   //     63     31   0
   //    +------+------+
   //    | float|   0  |
   //    +------+------+
   CCIfType<[f32], CCBitConvertToType<i64>>,
 
   // F128 are assigned to the stack in 16-byte aligned units
   CCIfType<[f128], CCAssignToStack<16, 16>>,
 
   CCAssignToStack<0, 8>
 ]>;
 
-def RetCC_VE : CallingConv<[
+def RetCC_VE_C : CallingConv<[
   // Promote i1/i8/i16/i32 return values to i64.
   CCIfType<[i1, i8, i16, i32], CCPromoteToType<i64>>,
 
   // Convert float return values to i64 with padding.
   //     63     31   0
   //    +------+------+
   //    | float|   0  |
   //    +------+------+

llvm/lib/Target/VE/VEISelLowering.cpp

 #define DEBUG_TYPE "ve-lower"
 
 //===----------------------------------------------------------------------===//
 // Calling Convention Implementation
 //===----------------------------------------------------------------------===//
 
 #include "VEGenCallingConv.inc"
 
+CCAssignFn *getReturnCC(CallingConv::ID CallConv) {
+  switch (CallConv) {
+  default:
+    return RetCC_VE_C;
+  }
+}
+
+CCAssignFn *getParamCC(CallingConv::ID CallConv, bool IsVarArg) {
+  if (IsVarArg)
+    return CC_VE2;
+  switch (CallConv) {
+  default:
+    return CC_VE_C;
+  }
+}
+
 bool VETargetLowering::CanLowerReturn(
     CallingConv::ID CallConv, MachineFunction &MF, bool IsVarArg,
     const SmallVectorImpl<ISD::OutputArg> &Outs, LLVMContext &Context) const {
-  CCAssignFn *RetCC = RetCC_VE;
+  CCAssignFn *RetCC = getReturnCC(CallConv);
   SmallVector<CCValAssign, 16> RVLocs;
   CCState CCInfo(CallConv, IsVarArg, MF, RVLocs, Context);
   return CCInfo.CheckReturn(Outs, RetCC);
 }
 
 void VETargetLowering::initRegisterClasses() {
   // Set up the register classes.
   addRegisterClass(MVT::i32, &VE::I32RegClass);
VETargetLowering::LowerReturn(SDValue Chain, CallingConv::ID CallConv,
   // CCValAssign - represent the assignment of the return value to locations.
   SmallVector<CCValAssign, 16> RVLocs;
 
   // CCState - Info about the registers and stack slot.
   CCState CCInfo(CallConv, IsVarArg, DAG.getMachineFunction(), RVLocs,
                  *DAG.getContext());
 
   // Analyze return values.
-  CCInfo.AnalyzeReturn(Outs, RetCC_VE);
+  CCInfo.AnalyzeReturn(Outs, getReturnCC(CallConv));
 
   SDValue Flag;
   SmallVector<SDValue, 4> RetOps(1, Chain);
 
   // Copy the result values into the output registers.
   for (unsigned i = 0; i != RVLocs.size(); ++i) {
     CCValAssign &VA = RVLocs[i];
     assert(VA.isRegLoc() && "Can only return in registers!");
SDValue VETargetLowering::LowerFormalArguments(
   // Analyze arguments according to CC_VE.
   SmallVector<CCValAssign, 16> ArgLocs;
   CCState CCInfo(CallConv, IsVarArg, DAG.getMachineFunction(), ArgLocs,
                  *DAG.getContext());
   // Allocate the preserved area first.
   CCInfo.AllocateStack(ArgsPreserved, Align(8));
   // We already allocated the preserved area, so the stack offset computed
   // by CC_VE would be correct now.
-  CCInfo.AnalyzeFormalArguments(Ins, CC_VE);
+  CCInfo.AnalyzeFormalArguments(Ins, getParamCC(CallConv, false));
 
   for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
     CCValAssign &VA = ArgLocs[i];
     if (VA.isRegLoc()) {
       // This argument is passed in a register.
       // All integer register arguments are promoted by the caller to i64.
 
       // Create a virtual register for the promoted live-in value.
SDValue VETargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   // Analyze operands of the call, assigning locations to each operand.
   SmallVector<CCValAssign, 16> ArgLocs;
   CCState CCInfo(CLI.CallConv, CLI.IsVarArg, DAG.getMachineFunction(), ArgLocs,
                  *DAG.getContext());
   // Allocate the preserved area first.
   CCInfo.AllocateStack(ArgsPreserved, Align(8));
   // We already allocated the preserved area, so the stack offset computed
   // by CC_VE would be correct now.
-  CCInfo.AnalyzeCallOperands(CLI.Outs, CC_VE);
+  CCInfo.AnalyzeCallOperands(CLI.Outs, getParamCC(CLI.CallConv, false));
 
   // VE requires to use both register and stack for varargs or no-prototyped
   // functions.
   bool UseBoth = CLI.IsVarArg;
 
   // Analyze operands again if it is required to store BOTH.
   SmallVector<CCValAssign, 16> ArgLocs2;
   CCState CCInfo2(CLI.CallConv, CLI.IsVarArg, DAG.getMachineFunction(),
                   ArgLocs2, *DAG.getContext());
   if (UseBoth)
-    CCInfo2.AnalyzeCallOperands(CLI.Outs, CC_VE2);
+    CCInfo2.AnalyzeCallOperands(CLI.Outs, getParamCC(CLI.CallConv, true));
 
   // Get the size of the outgoing arguments stack space requirement.
   unsigned ArgsSize = CCInfo.getNextStackOffset();
 
   // Keep stack frames 16-byte aligned.
   ArgsSize = alignTo(ArgsSize, 16);
 
   // Adjust the stack pointer to make room for the arguments.
   // FIXME: Use hasReservedCallFrame to avoid %sp adjustments around all calls
SDValue VETargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   CCState RVInfo(CLI.CallConv, CLI.IsVarArg, DAG.getMachineFunction(), RVLocs,
                  *DAG.getContext());
 
   // Set inreg flag manually for codegen generated library calls that
   // return float.
   if (CLI.Ins.size() == 1 && CLI.Ins[0].VT == MVT::f32 && !CLI.CB)
     CLI.Ins[0].Flags.setInReg();
 
-  RVInfo.AnalyzeCallResult(CLI.Ins, RetCC_VE);
+  RVInfo.AnalyzeCallResult(CLI.Ins, getReturnCC(CLI.CallConv));
 
   // Copy all of the result registers out of their specified physreg.
   for (unsigned i = 0; i != RVLocs.size(); ++i) {
     CCValAssign &VA = RVLocs[i];
     unsigned Reg = VA.getLocReg();
 
     // When returning 'inreg {i32, i32 }', two consecutive i32 arguments can
     // reside in the same register in the high and low bits. Reuse the