[llvm][NFC] Refactor AutoUpgrade case 'n'

[urnathan]

Summary

The NVPTX intrinsics are under 'n'. While that does first check for 'nvvm.', it didn't use the consume_front API, so fix that. Refactor the helper function to group matchers on the first component and check that first, rather than as a single monolithic list. Do similarly with the final set of intrinsics, which have a lot of commonality in the matching.
Finally reorder the argument/return type checking wrt name checking -- the former is going to be cheaper, so do that first before checking the name.

[tra]

Nice.

llvm/lib/IR/AutoUpgrade.cpp

if (Name == "seh.recoverfp") {
     NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_recoverfp);
     return true;
   }
 
   return false;
 }
 
 static Intrinsic::ID ShouldUpgradeNVPTXBF16Intrinsic(StringRef Name) {
+  if (Name.consume_front("abs."))
     return StringSwitch<Intrinsic::ID>(Name)
-      .Case("abs.bf16", Intrinsic::nvvm_abs_bf16)
-      .Case("abs.bf16x2", Intrinsic::nvvm_abs_bf16x2)
-      .Case("fma.rn.bf16", Intrinsic::nvvm_fma_rn_bf16)
-      .Case("fma.rn.bf16x2", Intrinsic::nvvm_fma_rn_bf16x2)
-      .Case("fma.rn.ftz_bf16", Intrinsic::nvvm_fma_rn_ftz_bf16)
-      .Case("fma.rn.ftz.bf16x2", Intrinsic::nvvm_fma_rn_ftz_bf16x2)
-      .Case("fma.rn.ftz.relu.bf16", Intrinsic::nvvm_fma_rn_ftz_relu_bf16)
-      .Case("fma.rn.ftz.relu.bf16x2", Intrinsic::nvvm_fma_rn_ftz_relu_bf16x2)
-      .Case("fma.rn.ftz_sat.bf16", Intrinsic::nvvm_fma_rn_ftz_sat_bf16)
-      .Case("fma.rn.ftz_sat.bf16x2", Intrinsic::nvvm_fma_rn_ftz_sat_bf16x2)
-      .Case("fma.rn.relu.bf16", Intrinsic::nvvm_fma_rn_relu_bf16)
-      .Case("fma.rn.relu.bf16x2", Intrinsic::nvvm_fma_rn_relu_bf16x2)
-      .Case("fma.rn.sat.bf16", Intrinsic::nvvm_fma_rn_sat_bf16)
-      .Case("fma.rn.sat.bf16x2", Intrinsic::nvvm_fma_rn_sat_bf16x2)
-      .Case("fmax.bf16", Intrinsic::nvvm_fmax_bf16)
-      .Case("fmax.bf16x2", Intrinsic::nvvm_fmax_bf16x2)
-      .Case("fmax.ftz.bf16", Intrinsic::nvvm_fmax_ftz_bf16)
-      .Case("fmax.ftz.bf16x2", Intrinsic::nvvm_fmax_ftz_bf16x2)
-      .Case("fmax.ftz.nan.bf16", Intrinsic::nvvm_fmax_ftz_nan_bf16)
-      .Case("fmax.ftz.nan.bf16x2", Intrinsic::nvvm_fmax_ftz_nan_bf16x2)
-      .Case("fmax.ftz.nan.xorsign.abs.bf16",
+        .Case("bf16", Intrinsic::nvvm_abs_bf16)
+        .Case("bf16x2", Intrinsic::nvvm_abs_bf16x2)
+        .Default(Intrinsic::not_intrinsic);
+
+  if (Name.consume_front("fma.rn."))
+    return StringSwitch<Intrinsic::ID>(Name)
+        .Case("bf16", Intrinsic::nvvm_fma_rn_bf16)
+        .Case("bf16x2", Intrinsic::nvvm_fma_rn_bf16x2)
+        .Case("ftz_bf16", Intrinsic::nvvm_fma_rn_ftz_bf16)
+        .Case("ftz.bf16x2", Intrinsic::nvvm_fma_rn_ftz_bf16x2)
+        .Case("ftz.relu.bf16", Intrinsic::nvvm_fma_rn_ftz_relu_bf16)
+        .Case("ftz.relu.bf16x2", Intrinsic::nvvm_fma_rn_ftz_relu_bf16x2)
+        .Case("ftz_sat.bf16", Intrinsic::nvvm_fma_rn_ftz_sat_bf16)
+        .Case("ftz_sat.bf16x2", Intrinsic::nvvm_fma_rn_ftz_sat_bf16x2)
+        .Case("relu.bf16", Intrinsic::nvvm_fma_rn_relu_bf16)
+        .Case("relu.bf16x2", Intrinsic::nvvm_fma_rn_relu_bf16x2)
+        .Case("sat.bf16", Intrinsic::nvvm_fma_rn_sat_bf16)
+        .Case("sat.bf16x2", Intrinsic::nvvm_fma_rn_sat_bf16x2)
+        .Default(Intrinsic::not_intrinsic);
+
+  if (Name.consume_front("fmax."))
+    return StringSwitch<Intrinsic::ID>(Name)
+        .Case("bf16", Intrinsic::nvvm_fmax_bf16)
+        .Case("bf16x2", Intrinsic::nvvm_fmax_bf16x2)
+        .Case("ftz.bf16", Intrinsic::nvvm_fmax_ftz_bf16)
+        .Case("ftz.bf16x2", Intrinsic::nvvm_fmax_ftz_bf16x2)
+        .Case("ftz.nan.bf16", Intrinsic::nvvm_fmax_ftz_nan_bf16)
+        .Case("ftz.nan.bf16x2", Intrinsic::nvvm_fmax_ftz_nan_bf16x2)
+        .Case("ftz.nan.xorsign.abs.bf16",
               Intrinsic::nvvm_fmax_ftz_nan_xorsign_abs_bf16)
-      .Case("fmax.ftz.nan.xorsign.abs.bf16x2",
+        .Case("ftz.nan.xorsign.abs.bf16x2",
               Intrinsic::nvvm_fmax_ftz_nan_xorsign_abs_bf16x2)
-      .Case("fmax.ftz.xorsign.abs.bf16",
-            Intrinsic::nvvm_fmax_ftz_xorsign_abs_bf16)
-      .Case("fmax.ftz.xorsign.abs.bf16x2",
+        .Case("ftz.xorsign.abs.bf16", Intrinsic::nvvm_fmax_ftz_xorsign_abs_bf16)
+        .Case("ftz.xorsign.abs.bf16x2",
               Intrinsic::nvvm_fmax_ftz_xorsign_abs_bf16x2)
-      .Case("fmax.nan.bf16", Intrinsic::nvvm_fmax_nan_bf16)
-      .Case("fmax.nan.bf16x2", Intrinsic::nvvm_fmax_nan_bf16x2)
-      .Case("fmax.nan.xorsign.abs.bf16",
-            Intrinsic::nvvm_fmax_nan_xorsign_abs_bf16)
-      .Case("fmax.nan.xorsign.abs.bf16x2",
+        .Case("nan.bf16", Intrinsic::nvvm_fmax_nan_bf16)
+        .Case("nan.bf16x2", Intrinsic::nvvm_fmax_nan_bf16x2)
+        .Case("nan.xorsign.abs.bf16", Intrinsic::nvvm_fmax_nan_xorsign_abs_bf16)
+        .Case("nan.xorsign.abs.bf16x2",
               Intrinsic::nvvm_fmax_nan_xorsign_abs_bf16x2)
-      .Case("fmax.xorsign.abs.bf16", Intrinsic::nvvm_fmax_xorsign_abs_bf16)
-      .Case("fmax.xorsign.abs.bf16x2", Intrinsic::nvvm_fmax_xorsign_abs_bf16x2)
-      .Case("fmin.bf16", Intrinsic::nvvm_fmin_bf16)
-      .Case("fmin.bf16x2", Intrinsic::nvvm_fmin_bf16x2)
-      .Case("fmin.ftz.bf16", Intrinsic::nvvm_fmin_ftz_bf16)
-      .Case("fmin.ftz.bf16x2", Intrinsic::nvvm_fmin_ftz_bf16x2)
-      .Case("fmin.ftz.nan_bf16", Intrinsic::nvvm_fmin_ftz_nan_bf16)
-      .Case("fmin.ftz.nan_bf16x2", Intrinsic::nvvm_fmin_ftz_nan_bf16x2)
-      .Case("fmin.ftz.nan.xorsign.abs.bf16",
+        .Case("xorsign.abs.bf16", Intrinsic::nvvm_fmax_xorsign_abs_bf16)
+        .Case("xorsign.abs.bf16x2", Intrinsic::nvvm_fmax_xorsign_abs_bf16x2)
+        .Default(Intrinsic::not_intrinsic);
+
+  if (Name.consume_front("fmin."))
+    return StringSwitch<Intrinsic::ID>(Name)
+        .Case("bf16", Intrinsic::nvvm_fmin_bf16)
+        .Case("bf16x2", Intrinsic::nvvm_fmin_bf16x2)
+        .Case("ftz.bf16", Intrinsic::nvvm_fmin_ftz_bf16)
+        .Case("ftz.bf16x2", Intrinsic::nvvm_fmin_ftz_bf16x2)
+        .Case("ftz.nan_bf16", Intrinsic::nvvm_fmin_ftz_nan_bf16)
+        .Case("ftz.nan_bf16x2", Intrinsic::nvvm_fmin_ftz_nan_bf16x2)
+        .Case("ftz.nan.xorsign.abs.bf16",
               Intrinsic::nvvm_fmin_ftz_nan_xorsign_abs_bf16)
-      .Case("fmin.ftz.nan.xorsign.abs.bf16x2",
+        .Case("ftz.nan.xorsign.abs.bf16x2",
               Intrinsic::nvvm_fmin_ftz_nan_xorsign_abs_bf16x2)
-      .Case("fmin.ftz.xorsign.abs.bf16",
-            Intrinsic::nvvm_fmin_ftz_xorsign_abs_bf16)
-      .Case("fmin.ftz.xorsign.abs.bf16x2",
+        .Case("ftz.xorsign.abs.bf16", Intrinsic::nvvm_fmin_ftz_xorsign_abs_bf16)
+        .Case("ftz.xorsign.abs.bf16x2",
               Intrinsic::nvvm_fmin_ftz_xorsign_abs_bf16x2)
-      .Case("fmin.nan.bf16", Intrinsic::nvvm_fmin_nan_bf16)
-      .Case("fmin.nan.bf16x2", Intrinsic::nvvm_fmin_nan_bf16x2)
-      .Case("fmin.nan.xorsign.abs.bf16",
-            Intrinsic::nvvm_fmin_nan_xorsign_abs_bf16)
-      .Case("fmin.nan.xorsign.abs.bf16x2",
+        .Case("nan.bf16", Intrinsic::nvvm_fmin_nan_bf16)
+        .Case("nan.bf16x2", Intrinsic::nvvm_fmin_nan_bf16x2)
+        .Case("nan.xorsign.abs.bf16", Intrinsic::nvvm_fmin_nan_xorsign_abs_bf16)
+        .Case("nan.xorsign.abs.bf16x2",
               Intrinsic::nvvm_fmin_nan_xorsign_abs_bf16x2)
-      .Case("fmin.xorsign.abs.bf16", Intrinsic::nvvm_fmin_xorsign_abs_bf16)
-      .Case("fmin.xorsign.abs.bf16x2", Intrinsic::nvvm_fmin_xorsign_abs_bf16x2)
-      .Case("neg.bf16", Intrinsic::nvvm_neg_bf16)
-      .Case("neg.bf16x2", Intrinsic::nvvm_neg_bf16x2)
+        .Case("xorsign.abs.bf16", Intrinsic::nvvm_fmin_xorsign_abs_bf16)
+        .Case("xorsign.abs.bf16x2", Intrinsic::nvvm_fmin_xorsign_abs_bf16x2)
+        .Default(Intrinsic::not_intrinsic);
+
+  if (Name.consume_front("neg."))
+    return StringSwitch<Intrinsic::ID>(Name)
+        .Case("bf16", Intrinsic::nvvm_neg_bf16)
+        .Case("bf16x2", Intrinsic::nvvm_neg_bf16x2)
         .Default(Intrinsic::not_intrinsic);
+
+  return Intrinsic::not_intrinsic;
 }
 
 static bool UpgradeIntrinsicFunction1(Function *F, Function *&NewFn) {
   assert(F && "Illegal to upgrade a non-existent Function.");
 
   // Quickly eliminate it, if it's not a candidate.
   StringRef Name = F->getName();
   if (Name.size() <= 7 || !Name.startswith("llvm."))
if (Name.startswith("memset.") && F->arg_size() == 5) {
       };
       NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::memset,
                                         ParamTypes);
       return true;
     }
     break;
   }
   case 'n': {
-    if (Name.startswith("nvvm.")) {
-      Name = Name.substr(5);
-
-      // The following nvvm intrinsics correspond exactly to an LLVM intrinsic.
-      Intrinsic::ID IID = StringSwitch<Intrinsic::ID>(Name)
-                              .Cases("brev32", "brev64", Intrinsic::bitreverse)
-                              .Case("clz.i", Intrinsic::ctlz)
-                              .Case("popc.i", Intrinsic::ctpop)
-                              .Default(Intrinsic::not_intrinsic);
-      if (IID != Intrinsic::not_intrinsic && F->arg_size() == 1) {
+    if (Name.consume_front("nvvm.")) {
+      // Check for nvvm intrinsics corresponding exactly to an LLVM intrinsic.
+      if (F->arg_size() == 1) {
+        Intrinsic::ID IID =
+            StringSwitch<Intrinsic::ID>(Name)
+        if (IID != Intrinsic::not_intrinsic) {
           NewFn = Intrinsic::getDeclaration(F->getParent(), IID,
                                             {F->getReturnType()});
           return true;
         }
-      IID = ShouldUpgradeNVPTXBF16Intrinsic(Name);
-      if (IID != Intrinsic::not_intrinsic &&
-          !F->getReturnType()->getScalarType()->isBFloatTy()) {
+      }
+
+      // Check for nvvm intrinsics that need a return type adjustment.
+      if (!F->getReturnType()->getScalarType()->isBFloatTy()) {
+        Intrinsic::ID IID = ShouldUpgradeNVPTXBF16Intrinsic(Name);
+        if (IID != Intrinsic::not_intrinsic) {
           NewFn = nullptr;
           return true;
         }
+      }
+
       // The following nvvm intrinsics correspond exactly to an LLVM idiom, but
       // not to an intrinsic alone.  We expand them in UpgradeIntrinsicCall.
       //
       // TODO: We could add lohi.i2d.
-      bool Expand = StringSwitch<bool>(Name)
-                        .Cases("abs.i", "abs.ll", true)
-                        .Cases("clz.ll", "popc.ll", "h2f", true)
-                        .Cases("max.i", "max.ll", "max.ui", "max.ull", true)
-                        .Cases("min.i", "min.ll", "min.ui", "min.ull", true)
-                        .StartsWith("atomic.load.add.f32.p", true)
-                        .StartsWith("atomic.load.add.f64.p", true)
-                        .Default(false);
+      bool Expand = false;
+      if (Name.consume_front("abs."))
+        // nvvm.abs.{i,ii}
+        Expand = Name == "i" || Name == "ll";
+      else if (Name == "clz.ll" || Name == "popc.ll" || Name == "h2f")
+        Expand = true;
+      else if (Name.consume_front("max.") || Name.consume_front("min."))
+        // nvvm.{min,max}.{i,ii,ui,ull}
+        Expand = Name == "i" || Name == "ll" || Name == "ui" || Name == "ull";
+      else if (Name.consume_front("atomic.load.add."))
+        // nvvm.atomic.load.add.{f32.p,f64.p}
+        Expand = Name.startswith("f32.p") || Name.startswith("f64.p");
+      else
+        Expand = false;
+
       if (Expand) {
         NewFn = nullptr;
         return true;
       }
+      break; // No other 'nvvm.*'.
     }
     break;
   }
   case 'o':
     // We only need to change the name to match the mangling including the
     // address space.
     if (Name.startswith("objectsize.")) {
       Type *Tys[2] = { F->getReturnType(), F->arg_begin()->getType() };