[llvm] [Hexagon] Use MCRegisterClass::hasSubClassEq in HexagonBitTracker. NFCI. (PR #226110)

[Jay Foad via llvm-commits]

https://github.com/jayfoad created https://github.com/llvm/llvm-project/pull/226110

This avoids depending on the exact names of synthesized register classes
(motivated by #225809 which will change some of these) and generally
feels more future-proof.

Co-authored-by: Claude Opus 5 (1M context) <noreply at anthropic.com>


>From 53b583aad0938f92e83c9aee8eda4680dca1c7a5 Mon Sep 17 00:00:00 2001
From: Jay Foad <jay.foad at amd.com>
Date: Thu, 24 Sep 2026 11:41:28 +0100
Subject: [PATCH] [Hexagon] Use MCRegisterClass::hasSubClassEq in
 HexagonBitTracker. NFCI.

This avoids depending on the exact names of synthesized register classes
(motivated by #225809 which will change some of these) and generally
feels more future-proof.

Co-authored-by: Claude Opus 5 (1M context) <noreply at anthropic.com>
---
 llvm/lib/Target/Hexagon/HexagonBitTracker.cpp | 32 ++++++-------------
 1 file changed, 10 insertions(+), 22 deletions(-)

diff --git a/llvm/lib/Target/Hexagon/HexagonBitTracker.cpp b/llvm/lib/Target/Hexagon/HexagonBitTracker.cpp
index 360880a7afb19c..a5d706a7413227 100644
--- a/llvm/lib/Target/Hexagon/HexagonBitTracker.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonBitTracker.cpp
@@ -80,20 +80,13 @@ BT::BitMask HexagonEvaluator::mask(Register Reg, unsigned Sub) const {
   if (Sub == 0)
     return MachineEvaluator::mask(Reg, 0);
   const TargetRegisterClass &RC = *MRI.getRegClass(Reg);
-  unsigned ID = RC.getID();
   uint16_t RW = getRegBitWidth(RegisterRef(Reg, Sub));
   const auto &HRI = static_cast<const HexagonRegisterInfo&>(TRI);
   bool IsSubLo = (Sub == HRI.getHexagonSubRegIndex(RC, Hexagon::ps_sub_lo));
-  switch (ID) {
-    case Hexagon::DoubleRegsRegClassID:
-    case Hexagon::DoubleRegs_with_isub_hi_in_IntRegsLow8RegClassID:
-    case Hexagon::HvxWRRegClassID:
-    case Hexagon::HvxVQRRegClassID:
-      return IsSubLo ? BT::BitMask(0, RW-1)
-                     : BT::BitMask(RW, 2*RW-1);
-    default:
-      break;
-  }
+  if (Hexagon::DoubleRegsRegClass.hasSubClassEq(&RC) ||
+      Hexagon::HvxWRRegClass.hasSubClassEq(&RC) ||
+      Hexagon::HvxVQRRegClass.hasSubClassEq(&RC))
+    return IsSubLo ? BT::BitMask(0, RW - 1) : BT::BitMask(RW, 2 * RW - 1);
 #ifndef NDEBUG
   dbgs() << printReg(Reg, &TRI, Sub) << " in reg class "
          << TRI.getRegClassName(&RC) << '\n';
@@ -130,17 +123,12 @@ const TargetRegisterClass &HexagonEvaluator::composeWithSubRegIndex(
   assert(IsSubLo != IsSubHi && "Must refer to either low or high subreg");
 #endif
 
-  switch (RC.getID()) {
-    case Hexagon::DoubleRegsRegClassID:
-    case Hexagon::DoubleRegs_with_isub_hi_in_IntRegsLow8RegClassID:
-      return Hexagon::IntRegsRegClass;
-    case Hexagon::HvxWRRegClassID:
-      return Hexagon::HvxVRRegClass;
-    case Hexagon::HvxVQRRegClassID:
-      return Hexagon::HvxWRRegClass;
-    default:
-      break;
-  }
+  if (Hexagon::DoubleRegsRegClass.hasSubClassEq(&RC))
+    return Hexagon::IntRegsRegClass;
+  if (Hexagon::HvxWRRegClass.hasSubClassEq(&RC))
+    return Hexagon::HvxVRRegClass;
+  if (Hexagon::HvxVQRRegClass.hasSubClassEq(&RC))
+    return Hexagon::HvxWRRegClass;
 #ifndef NDEBUG
   dbgs() << "Reg class id: " << RC.getID() << " idx: " << Idx << '\n';
 #endif