[RISCV] Use a macro to simplify getTargetNodeName

[frasercrmck]

Summary

Similar to the X86 and AMDGPU targets, this uses a macro to cut down on
repetitive and error-prone code when converting RISCVISD node names to
strings in getTargetNodeName.

[frasercrmck]

The formatting was done by clang-format and it does look a little "off". We can go against it if people like.

If anyone's concerned about merge conflicts with ongoing work, just shout. This isn't the most important thing to get in ASAP, after all.

[asb]

I think moving NODE_NAME_CASE(foo) to the left so it's aligned where the case statement would be (same as the equivalent in X86ISelLowering and AMDGPUISelLowering) would be slightly better. I wouldn't be opposed to using // clang-format off to stop clang-format from reformatting (though it seems more common in LLVM right now to just ignore clang-format's preference).

But basically this looks good to me, and I leave it to your judgement if you want to further mess with the whitespace as suggested above. Thanks Fraser!

[frasercrmck]

In D91414#2393793, @asb wrote:

I think moving NODE_NAME_CASE(foo) to the left so it's aligned where the case statement would be (same as the equivalent in X86ISelLowering and AMDGPUISelLowering) would be slightly better. I wouldn't be opposed to using // clang-format off to stop clang-format from reformatting (though it seems more common in LLVM right now to just ignore clang-format's preference).

But basically this looks good to me, and I leave it to your judgement if you want to further mess with the whitespace as suggested above. Thanks Fraser!

Yep okay I'll align the cases left and go with clang-format off/on even though it's rarely used in the codebase. That should help to avoid having people use clang-format and wonder what's going on or manually having to undo bits. It's meant to make developers' lives easier, after all :)

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

F.getContext().diagnose(DiagnosticInfoUnsupported{
         F, "Argument register required, but has been reserved."});
 }
 
 bool RISCVTargetLowering::mayBeEmittedAsTailCall(const CallInst *CI) const {
   return CI->isTailCall();
 }
 
 const char *RISCVTargetLowering::getTargetNodeName(unsigned Opcode) const {
+#define NODE_NAME_CASE(NODE)                                                   \
+  case RISCVISD::NODE:                                                         \
+    return "RISCVISD::" #NODE;
   switch ((RISCVISD::NodeType)Opcode) {
   case RISCVISD::FIRST_NUMBER:
     break;
-  case RISCVISD::RET_FLAG:
-    return "RISCVISD::RET_FLAG";
-  case RISCVISD::URET_FLAG:
-    return "RISCVISD::URET_FLAG";
-  case RISCVISD::SRET_FLAG:
-    return "RISCVISD::SRET_FLAG";
-  case RISCVISD::MRET_FLAG:
-    return "RISCVISD::MRET_FLAG";
-  case RISCVISD::CALL:
-    return "RISCVISD::CALL";
-  case RISCVISD::SELECT_CC:
-    return "RISCVISD::SELECT_CC";
-  case RISCVISD::BuildPairF64:
-    return "RISCVISD::BuildPairF64";
-  case RISCVISD::SplitF64:
-    return "RISCVISD::SplitF64";
-  case RISCVISD::TAIL:
-    return "RISCVISD::TAIL";
-  case RISCVISD::SLLW:
-    return "RISCVISD::SLLW";
-  case RISCVISD::SRAW:
-    return "RISCVISD::SRAW";
-  case RISCVISD::SRLW:
-    return "RISCVISD::SRLW";
-  case RISCVISD::DIVW:
-    return "RISCVISD::DIVW";
-  case RISCVISD::DIVUW:
-    return "RISCVISD::DIVUW";
-  case RISCVISD::REMUW:
-    return "RISCVISD::REMUW";
-  case RISCVISD::FMV_W_X_RV64:
-    return "RISCVISD::FMV_W_X_RV64";
-  case RISCVISD::FMV_X_ANYEXTW_RV64:
-    return "RISCVISD::FMV_X_ANYEXTW_RV64";
-  case RISCVISD::READ_CYCLE_WIDE:
-    return "RISCVISD::READ_CYCLE_WIDE";
+    NODE_NAME_CASE(RET_FLAG)
+    NODE_NAME_CASE(URET_FLAG)
+    NODE_NAME_CASE(SRET_FLAG)
+    NODE_NAME_CASE(MRET_FLAG)
+    NODE_NAME_CASE(CALL)
+    NODE_NAME_CASE(SELECT_CC)
+    NODE_NAME_CASE(BuildPairF64)
+    NODE_NAME_CASE(SplitF64)
+    NODE_NAME_CASE(TAIL)
+    NODE_NAME_CASE(SLLW)
+    NODE_NAME_CASE(SRAW)
+    NODE_NAME_CASE(SRLW)
+    NODE_NAME_CASE(DIVW)
+    NODE_NAME_CASE(DIVUW)
+    NODE_NAME_CASE(REMUW)
+    NODE_NAME_CASE(FMV_W_X_RV64)
+    NODE_NAME_CASE(FMV_X_ANYEXTW_RV64)
+    NODE_NAME_CASE(READ_CYCLE_WIDE)
   }
   return nullptr;
+#undef NODE_NAME_CASE
 }
 
 /// getConstraintType - Given a constraint letter, return the type of
 /// constraint it is for this target.
 RISCVTargetLowering::ConstraintType
 RISCVTargetLowering::getConstraintType(StringRef Constraint) const {
   if (Constraint.size() == 1) {
     switch (Constraint[0]) {