[RISCV] RISCV vector calling convention (2/2) (#79096)

This commit handles vector arguments/return for function definition/call,
the new class RVVArgDispatcher is added for doing all vector register
assignment including mask types, data types as well as tuple types.
It precomputes the register number for each argument as per
https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-cc.adoc#standard-vector-calling-convention-variant
and it's passed to calling convention function to handle all vector arguments.

Depends on: #78550

Author: 4vtomat

llvm/lib/Target/RISCV/GISel/RISCVCallLowering.cpp

@@ -34,14 +34,15 @@ struct RISCVOutgoingValueAssigner : public CallLowering::OutgoingValueAssigner {
   // Whether this is assigning args for a return.
   bool IsRet;
 
-  // true if assignArg has been called for a mask argument, false otherwise.
-  bool AssignedFirstMaskArg = false;
+  RVVArgDispatcher &RVVDispatcher;
 
 public:
   RISCVOutgoingValueAssigner(
-      RISCVTargetLowering::RISCVCCAssignFn *RISCVAssignFn_, bool IsRet)
+      RISCVTargetLowering::RISCVCCAssignFn *RISCVAssignFn_, bool IsRet,
+      RVVArgDispatcher &RVVDispatcher)
       : CallLowering::OutgoingValueAssigner(nullptr),
-        RISCVAssignFn(RISCVAssignFn_), IsRet(IsRet) {}
+        RISCVAssignFn(RISCVAssignFn_), IsRet(IsRet),
+        RVVDispatcher(RVVDispatcher) {}
 
   bool assignArg(unsigned ValNo, EVT OrigVT, MVT ValVT, MVT LocVT,
                  CCValAssign::LocInfo LocInfo,
@@ -51,16 +52,9 @@ struct RISCVOutgoingValueAssigner : public CallLowering::OutgoingValueAssigner {
     const DataLayout &DL = MF.getDataLayout();
     const RISCVSubtarget &Subtarget = MF.getSubtarget<RISCVSubtarget>();
 
-    std::optional<unsigned> FirstMaskArgument;
-    if (Subtarget.hasVInstructions() && !AssignedFirstMaskArg &&
-        ValVT.isVector() && ValVT.getVectorElementType() == MVT::i1) {
-      FirstMaskArgument = ValNo;
-      AssignedFirstMaskArg = true;
-    }
-
     if (RISCVAssignFn(DL, Subtarget.getTargetABI(), ValNo, ValVT, LocVT,
                       LocInfo, Flags, State, Info.IsFixed, IsRet, Info.Ty,
-                      *Subtarget.getTargetLowering(), FirstMaskArgument))
+                      *Subtarget.getTargetLowering(), RVVDispatcher))
       return true;
 
     StackSize = State.getStackSize();
@@ -181,14 +175,15 @@ struct RISCVIncomingValueAssigner : public CallLowering::IncomingValueAssigner {
   // Whether this is assigning args from a return.
   bool IsRet;
 
-  // true if assignArg has been called for a mask argument, false otherwise.
-  bool AssignedFirstMaskArg = false;
+  RVVArgDispatcher &RVVDispatcher;
 
 public:
   RISCVIncomingValueAssigner(
-      RISCVTargetLowering::RISCVCCAssignFn *RISCVAssignFn_, bool IsRet)
+      RISCVTargetLowering::RISCVCCAssignFn *RISCVAssignFn_, bool IsRet,
+      RVVArgDispatcher &RVVDispatcher)
       : CallLowering::IncomingValueAssigner(nullptr),
-        RISCVAssignFn(RISCVAssignFn_), IsRet(IsRet) {}
+        RISCVAssignFn(RISCVAssignFn_), IsRet(IsRet),
+        RVVDispatcher(RVVDispatcher) {}
 
   bool assignArg(unsigned ValNo, EVT OrigVT, MVT ValVT, MVT LocVT,
                  CCValAssign::LocInfo LocInfo,
@@ -201,16 +196,9 @@ struct RISCVIncomingValueAssigner : public CallLowering::IncomingValueAssigner {
     if (LocVT.isScalableVector())
       MF.getInfo<RISCVMachineFunctionInfo>()->setIsVectorCall();
 
-    std::optional<unsigned> FirstMaskArgument;
-    if (Subtarget.hasVInstructions() && !AssignedFirstMaskArg &&
-        ValVT.isVector() && ValVT.getVectorElementType() == MVT::i1) {
-      FirstMaskArgument = ValNo;
-      AssignedFirstMaskArg = true;
-    }
-
     if (RISCVAssignFn(DL, Subtarget.getTargetABI(), ValNo, ValVT, LocVT,
                       LocInfo, Flags, State, /*IsFixed=*/true, IsRet, Info.Ty,
-                      *Subtarget.getTargetLowering(), FirstMaskArgument))
+                      *Subtarget.getTargetLowering(), RVVDispatcher))
       return true;
 
     StackSize = State.getStackSize();
@@ -420,9 +408,11 @@ bool RISCVCallLowering::lowerReturnVal(MachineIRBuilder &MIRBuilder,
   SmallVector<ArgInfo, 4> SplitRetInfos;
   splitToValueTypes(OrigRetInfo, SplitRetInfos, DL, CC);
 
+  RVVArgDispatcher Dispatcher{&MF, getTLI<RISCVTargetLowering>(),
+                              F.getReturnType()};
   RISCVOutgoingValueAssigner Assigner(
       CC == CallingConv::Fast ? RISCV::CC_RISCV_FastCC : RISCV::CC_RISCV,
-      /*IsRet=*/true);
+      /*IsRet=*/true, Dispatcher);
   RISCVOutgoingValueHandler Handler(MIRBuilder, MF.getRegInfo(), Ret);
   return determineAndHandleAssignments(Handler, Assigner, SplitRetInfos,
                                        MIRBuilder, CC, F.isVarArg());
@@ -531,6 +521,7 @@ bool RISCVCallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
   CallingConv::ID CC = F.getCallingConv();
 
   SmallVector<ArgInfo, 32> SplitArgInfos;
+  SmallVector<Type *, 4> TypeList;
   unsigned Index = 0;
   for (auto &Arg : F.args()) {
     // Construct the ArgInfo object from destination register and argument type.
@@ -542,12 +533,15 @@ bool RISCVCallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
     // correspondingly and appended to SplitArgInfos.
     splitToValueTypes(AInfo, SplitArgInfos, DL, CC);
 
+    TypeList.push_back(Arg.getType());
+
     ++Index;
   }
 
+  RVVArgDispatcher Dispatcher{&MF, getTLI<RISCVTargetLowering>(), TypeList};
   RISCVIncomingValueAssigner Assigner(
       CC == CallingConv::Fast ? RISCV::CC_RISCV_FastCC : RISCV::CC_RISCV,
-      /*IsRet=*/false);
+      /*IsRet=*/false, Dispatcher);
   RISCVFormalArgHandler Handler(MIRBuilder, MF.getRegInfo());
 
   SmallVector<CCValAssign, 16> ArgLocs;
@@ -585,11 +579,13 @@ bool RISCVCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
 
   SmallVector<ArgInfo, 32> SplitArgInfos;
   SmallVector<ISD::OutputArg, 8> Outs;
+  SmallVector<Type *, 4> TypeList;
   for (auto &AInfo : Info.OrigArgs) {
     // Handle any required unmerging of split value types from a given VReg into
     // physical registers. ArgInfo objects are constructed correspondingly and
     // appended to SplitArgInfos.
     splitToValueTypes(AInfo, SplitArgInfos, DL, CC);
+    TypeList.push_back(AInfo.Ty);
   }
 
   // TODO: Support tail calls.
@@ -607,9 +603,10 @@ bool RISCVCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
   const TargetRegisterInfo *TRI = Subtarget.getRegisterInfo();
   Call.addRegMask(TRI->getCallPreservedMask(MF, Info.CallConv));
 
+  RVVArgDispatcher ArgDispatcher{&MF, getTLI<RISCVTargetLowering>(), TypeList};
   RISCVOutgoingValueAssigner ArgAssigner(
       CC == CallingConv::Fast ? RISCV::CC_RISCV_FastCC : RISCV::CC_RISCV,
-      /*IsRet=*/false);
+      /*IsRet=*/false, ArgDispatcher);
   RISCVOutgoingValueHandler ArgHandler(MIRBuilder, MF.getRegInfo(), Call);
   if (!determineAndHandleAssignments(ArgHandler, ArgAssigner, SplitArgInfos,
                                      MIRBuilder, CC, Info.IsVarArg))
@@ -637,9 +634,11 @@ bool RISCVCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
   SmallVector<ArgInfo, 4> SplitRetInfos;
   splitToValueTypes(Info.OrigRet, SplitRetInfos, DL, CC);
 
+  RVVArgDispatcher RetDispatcher{&MF, getTLI<RISCVTargetLowering>(),
+                                 F.getReturnType()};
   RISCVIncomingValueAssigner RetAssigner(
       CC == CallingConv::Fast ? RISCV::CC_RISCV_FastCC : RISCV::CC_RISCV,
-      /*IsRet=*/true);
+      /*IsRet=*/true, RetDispatcher);
   RISCVCallReturnHandler RetHandler(MIRBuilder, MF.getRegInfo(), Call);
   if (!determineAndHandleAssignments(RetHandler, RetAssigner, SplitRetInfos,
                                      MIRBuilder, CC, Info.IsVarArg))