[RISCV] Separate the calling convention handlers into their own file. NFC (#107484)

These are used by both SelectionDAG and GlobalISel and are separate from
RISCVTargetLowering.

Having a separate file is how other targets are structured. Though other
targets generate most of their calling convention code through tablegen.

I moved the `CC_RISV` functions from the `llvm::RISCV` namespace to
`llvm::`. That's what the tablegen code on other targets does and the
functions already have RISCV in their name. `RISCVCCAssignFn` is moved
from `RISCVTargetLowering` to the `llvm` namespace.

Author: topperc

llvm/lib/Target/RISCV/CMakeLists.txt

@@ -29,6 +29,7 @@ add_public_tablegen_target(RISCVCommonTableGen)
 
 add_llvm_target(RISCVCodeGen
   RISCVAsmPrinter.cpp
+  RISCVCallingConv.cpp
   RISCVCodeGenPrepare.cpp
   RISCVDeadRegisterDefinitions.cpp
   RISCVMakeCompressible.cpp

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

@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "RISCVCallLowering.h"
+#include "RISCVCallingConv.h"
 #include "RISCVISelLowering.h"
 #include "RISCVMachineFunctionInfo.h"
 #include "RISCVSubtarget.h"
@@ -30,14 +31,13 @@ struct RISCVOutgoingValueAssigner : public CallLowering::OutgoingValueAssigner {
   // The function used internally to assign args - we ignore the AssignFn stored
   // by OutgoingValueAssigner since RISC-V implements its CC using a custom
   // function with a different signature.
-  RISCVTargetLowering::RISCVCCAssignFn *RISCVAssignFn;
+  RISCVCCAssignFn *RISCVAssignFn;
 
   // Whether this is assigning args for a return.
   bool IsRet;
 
 public:
-  RISCVOutgoingValueAssigner(
-      RISCVTargetLowering::RISCVCCAssignFn *RISCVAssignFn_, bool IsRet)
+  RISCVOutgoingValueAssigner(RISCVCCAssignFn *RISCVAssignFn_, bool IsRet)
       : CallLowering::OutgoingValueAssigner(nullptr),
         RISCVAssignFn(RISCVAssignFn_), IsRet(IsRet) {}
 
@@ -182,14 +182,13 @@ struct RISCVIncomingValueAssigner : public CallLowering::IncomingValueAssigner {
   // The function used internally to assign args - we ignore the AssignFn stored
   // by IncomingValueAssigner since RISC-V implements its CC using a custom
   // function with a different signature.
-  RISCVTargetLowering::RISCVCCAssignFn *RISCVAssignFn;
+  RISCVCCAssignFn *RISCVAssignFn;
 
   // Whether this is assigning args from a return.
   bool IsRet;
 
 public:
-  RISCVIncomingValueAssigner(
-      RISCVTargetLowering::RISCVCCAssignFn *RISCVAssignFn_, bool IsRet)
+  RISCVIncomingValueAssigner(RISCVCCAssignFn *RISCVAssignFn_, bool IsRet)
       : CallLowering::IncomingValueAssigner(nullptr),
         RISCVAssignFn(RISCVAssignFn_), IsRet(IsRet) {}
 
@@ -425,7 +424,7 @@ bool RISCVCallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
     splitToValueTypes(OrigRetInfo, SplitRetInfos, DL, CC);
 
     RISCVOutgoingValueAssigner Assigner(
-        CC == CallingConv::Fast ? RISCV::CC_RISCV_FastCC : RISCV::CC_RISCV,
+        CC == CallingConv::Fast ? CC_RISCV_FastCC : CC_RISCV,
         /*IsRet=*/true);
     RISCVOutgoingValueHandler Handler(MIRBuilder, MF.getRegInfo(), Ret);
     if (!determineAndHandleAssignments(Handler, Assigner, SplitRetInfos,
@@ -461,9 +460,9 @@ bool RISCVCallLowering::canLowerReturn(MachineFunction &MF,
 
   for (unsigned I = 0, E = Outs.size(); I < E; ++I) {
     MVT VT = MVT::getVT(Outs[I].Ty);
-    if (RISCV::CC_RISCV(MF.getDataLayout(), ABI, I, VT, VT, CCValAssign::Full,
-                        Outs[I].Flags[0], CCInfo, /*IsFixed=*/true,
-                        /*isRet=*/true, nullptr, TLI))
+    if (CC_RISCV(MF.getDataLayout(), ABI, I, VT, VT, CCValAssign::Full,
+                 Outs[I].Flags[0], CCInfo, /*IsFixed=*/true,
+                 /*isRet=*/true, nullptr, TLI))
       return false;
   }
   return true;
@@ -576,9 +575,9 @@ bool RISCVCallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
     ++Index;
   }
 
-  RISCVIncomingValueAssigner Assigner(
-      CC == CallingConv::Fast ? RISCV::CC_RISCV_FastCC : RISCV::CC_RISCV,
-      /*IsRet=*/false);
+  RISCVIncomingValueAssigner Assigner(CC == CallingConv::Fast ? CC_RISCV_FastCC
+                                                              : CC_RISCV,
+                                      /*IsRet=*/false);
   RISCVFormalArgHandler Handler(MIRBuilder, MF.getRegInfo());
 
   SmallVector<CCValAssign, 16> ArgLocs;
@@ -639,7 +638,7 @@ bool RISCVCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
   Call.addRegMask(TRI->getCallPreservedMask(MF, Info.CallConv));
 
   RISCVOutgoingValueAssigner ArgAssigner(
-      CC == CallingConv::Fast ? RISCV::CC_RISCV_FastCC : RISCV::CC_RISCV,
+      CC == CallingConv::Fast ? CC_RISCV_FastCC : CC_RISCV,
       /*IsRet=*/false);
   RISCVOutgoingValueHandler ArgHandler(MIRBuilder, MF.getRegInfo(), Call);
   if (!determineAndHandleAssignments(ArgHandler, ArgAssigner, SplitArgInfos,
@@ -667,7 +666,7 @@ bool RISCVCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
     splitToValueTypes(Info.OrigRet, SplitRetInfos, DL, CC);
 
     RISCVIncomingValueAssigner RetAssigner(
-        CC == CallingConv::Fast ? RISCV::CC_RISCV_FastCC : RISCV::CC_RISCV,
+        CC == CallingConv::Fast ? CC_RISCV_FastCC : CC_RISCV,
         /*IsRet=*/true);
     RISCVCallReturnHandler RetHandler(MIRBuilder, MF.getRegInfo(), Call);
     if (!determineAndHandleAssignments(RetHandler, RetAssigner, SplitRetInfos,