[TableGen] Move getSuperRegForSubReg into CodeGenRegBank. NFC. (#142979)

This method doesn't use anything from CodeGenTarget, so it seems to
belong in CodeGenRegBank.

Author: jayfoad

llvm/utils/TableGen/Common/CodeGenRegisters.cpp

@@ -2623,6 +2623,55 @@ CodeGenRegBank::getMinimalPhysRegClass(const Record *RegRecord,
   return BestRC;
 }
 
+const CodeGenRegisterClass *
+CodeGenRegBank::getSuperRegForSubReg(const ValueTypeByHwMode &ValueTy,
+                                     const CodeGenSubRegIndex *SubIdx,
+                                     bool MustBeAllocatable) const {
+  std::vector<const CodeGenRegisterClass *> Candidates;
+  auto &RegClasses = getRegClasses();
+
+  // Try to find a register class which supports ValueTy, and also contains
+  // SubIdx.
+  for (const CodeGenRegisterClass &RC : RegClasses) {
+    // Is there a subclass of this class which contains this subregister index?
+    const CodeGenRegisterClass *SubClassWithSubReg =
+        RC.getSubClassWithSubReg(SubIdx);
+    if (!SubClassWithSubReg)
+      continue;
+
+    // We have a class. Check if it supports this value type.
+    if (!llvm::is_contained(SubClassWithSubReg->VTs, ValueTy))
+      continue;
+
+    // If necessary, check that it is allocatable.
+    if (MustBeAllocatable && !SubClassWithSubReg->Allocatable)
+      continue;
+
+    // We have a register class which supports both the value type and
+    // subregister index. Remember it.
+    Candidates.push_back(SubClassWithSubReg);
+  }
+
+  // If we didn't find anything, we're done.
+  if (Candidates.empty())
+    return nullptr;
+
+  // Find and return the largest of our candidate classes.
+  llvm::stable_sort(Candidates, [&](const CodeGenRegisterClass *A,
+                                    const CodeGenRegisterClass *B) {
+    if (A->getMembers().size() > B->getMembers().size())
+      return true;
+
+    if (A->getMembers().size() < B->getMembers().size())
+      return false;
+
+    // Order by name as a tie-breaker.
+    return StringRef(A->getName()) < B->getName();
+  });
+
+  return Candidates[0];
+}
+
 BitVector
 CodeGenRegBank::computeCoveredRegisters(ArrayRef<const Record *> Regs) {
   SetVector<const CodeGenRegister *> Set;

llvm/utils/TableGen/Common/CodeGenRegisters.h

@@ -831,6 +831,13 @@ class CodeGenRegBank {
   getMinimalPhysRegClass(const Record *RegRecord,
                          ValueTypeByHwMode *VT = nullptr);
 
+  /// Return the largest register class which supports \p Ty and covers \p
+  /// SubIdx if it exists.
+  const CodeGenRegisterClass *
+  getSuperRegForSubReg(const ValueTypeByHwMode &Ty,
+                       const CodeGenSubRegIndex *SubIdx,
+                       bool MustBeAllocatable = false) const;
+
   // Get the sum of unit weights.
   unsigned getRegUnitSetWeight(const std::vector<unsigned> &Units) const {
     unsigned Weight = 0;

llvm/utils/TableGen/Common/CodeGenTarget.cpp

@@ -160,54 +160,6 @@ CodeGenRegBank &CodeGenTarget::getRegBank() const {
   return *RegBank;
 }
 
-const CodeGenRegisterClass *CodeGenTarget::getSuperRegForSubReg(
-    const ValueTypeByHwMode &ValueTy, CodeGenRegBank &RegBank,
-    const CodeGenSubRegIndex *SubIdx, bool MustBeAllocatable) const {
-  std::vector<const CodeGenRegisterClass *> Candidates;
-  auto &RegClasses = RegBank.getRegClasses();
-
-  // Try to find a register class which supports ValueTy, and also contains
-  // SubIdx.
-  for (const CodeGenRegisterClass &RC : RegClasses) {
-    // Is there a subclass of this class which contains this subregister index?
-    const CodeGenRegisterClass *SubClassWithSubReg =
-        RC.getSubClassWithSubReg(SubIdx);
-    if (!SubClassWithSubReg)
-      continue;
-
-    // We have a class. Check if it supports this value type.
-    if (!llvm::is_contained(SubClassWithSubReg->VTs, ValueTy))
-      continue;
-
-    // If necessary, check that it is allocatable.
-    if (MustBeAllocatable && !SubClassWithSubReg->Allocatable)
-      continue;
-
-    // We have a register class which supports both the value type and
-    // subregister index. Remember it.
-    Candidates.push_back(SubClassWithSubReg);
-  }
-
-  // If we didn't find anything, we're done.
-  if (Candidates.empty())
-    return nullptr;
-
-  // Find and return the largest of our candidate classes.
-  llvm::stable_sort(Candidates, [&](const CodeGenRegisterClass *A,
-                                    const CodeGenRegisterClass *B) {
-    if (A->getMembers().size() > B->getMembers().size())
-      return true;
-
-    if (A->getMembers().size() < B->getMembers().size())
-      return false;
-
-    // Order by name as a tie-breaker.
-    return StringRef(A->getName()) < B->getName();
-  });
-
-  return Candidates[0];
-}
-
 /// getRegisterByName - If there is a register with the specific AsmName,
 /// return it.
 const CodeGenRegister *CodeGenTarget::getRegisterByName(StringRef Name) const {

llvm/utils/TableGen/Common/CodeGenTarget.h

@@ -122,13 +122,6 @@ class CodeGenTarget {
   /// getRegBank - Return the register bank description.
   CodeGenRegBank &getRegBank() const;
 
-  /// Return the largest register class on \p RegBank which supports \p Ty and
-  /// covers \p SubIdx if it exists.
-  const CodeGenRegisterClass *
-  getSuperRegForSubReg(const ValueTypeByHwMode &Ty, CodeGenRegBank &RegBank,
-                       const CodeGenSubRegIndex *SubIdx,
-                       bool MustBeAllocatable = false) const;
-
   /// getRegisterByName - If there is a register with the specific AsmName,
   /// return it.
   const CodeGenRegister *getRegisterByName(StringRef Name) const;

llvm/utils/TableGen/GlobalISelEmitter.cpp

@@ -2019,7 +2019,7 @@ const CodeGenRegisterClass *GlobalISelEmitter::inferSuperRegisterClass(
 
   // Use the information we found above to find a minimal register class which
   // supports the subregister and type we want.
-  return Target.getSuperRegForSubReg(Ty.getValueTypeByHwMode(), CGRegs, SubIdx,
+  return CGRegs.getSuperRegForSubReg(Ty.getValueTypeByHwMode(), SubIdx,
                                      /*MustBeAllocatable=*/true);
 }