[llvm] [TableGen] Use bitwise operations to access HwMode ID. (PR #88377)

[Jason Eckhardt via llvm-commits]

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@@ -1781,13 +1781,68 @@ void SubtargetEmitter::EmitHwModeCheck(const std::string &ClassName,
   if (CGH.getNumModeIds() == 1)
     return;
 
-  OS << "unsigned " << ClassName << "::getHwMode() const {\n";
+  // Collect all HwModes and related features defined in the TD files,
+  // and store them in bit format.
+  unsigned ValueTypeModes = 0;
+  unsigned RegInfoModes = 0;
+  unsigned EncodingInfoModes = 0;
+  for (const auto &MS : CGH.getHwModeSelects()) {
+    for (const HwModeSelect::PairType &P : MS.second.Items) {
+      if (P.first == DefaultMode)
+        continue;
+      if (P.second->isSubClassOf("ValueType")) {
+        ValueTypeModes |= (1 << (P.first - 1));
+      } else if (P.second->isSubClassOf("RegInfo") ||
+                 P.second->isSubClassOf("SubRegRange")) {
+        RegInfoModes |= (1 << (P.first - 1));
+      } else if (P.second->isSubClassOf("InstructionEncoding")) {
+        EncodingInfoModes |= (1 << (P.first - 1));
+      }
+    }
+  }
+
+  // Start emitting for getHwModeSet().
+  OS << "unsigned " << ClassName << "::getHwModeSet() const {\n";
+  OS << "  // Collect HwModes and store them in bits\n";
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nvjle wrote:

Even though this is auto-generated code, we should try to adhere to the Coding Standards (i.e., comments are proper prose with punctuation, full stop, etc.).

https://github.com/llvm/llvm-project/pull/88377