[llvm] [Tablegen] Bugfix and refactor VarLenCodeEmitter HwModes. (PR #68795)

[Min-Yih Hsu via llvm-commits]

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@@ -253,36 +264,26 @@ void VarLenCodeEmitterGen::run(raw_ostream &OS) {
      << "    const MCSubtargetInfo &STI) const {\n";
 
   // Emit instruction base values
-  if (HwModes.empty()) {
-    emitInstructionBaseValues(OS, NumberedInstructions, Target);
-  } else {
-    for (unsigned HwMode : HwModes)
-      emitInstructionBaseValues(OS, NumberedInstructions, Target, (int)HwMode);
-  }
+  for (const auto &Mode : Modes)
+    emitInstructionBaseValues(OS, NumberedInstructions, Target, Mode.first);
 
-  if (!HwModes.empty()) {
-    OS << "  const unsigned **Index;\n";
-    OS << "  const uint64_t *InstBits;\n";
-    OS << "  unsigned HwMode = STI.getHwMode();\n";
-    OS << "  switch (HwMode) {\n";
-    OS << "  default: llvm_unreachable(\"Unknown hardware mode!\"); break;\n";
-    for (unsigned I : HwModes) {
-      OS << "  case " << I << ": InstBits = InstBits_" << HWM.getMode(I).Name
-         << "; Index = Index_" << HWM.getMode(I).Name << "; break;\n";
-    }
-    OS << "  };\n";
+  if (Modes.size() > 1) {
+    OS << "  unsigned Mode = STI.getHwMode();\n";
   }
 
-  // Emit helper function to retrieve base values.
-  OS << "  auto getInstBits = [&](unsigned Opcode) -> APInt {\n"
-     << "    unsigned NumBits = Index[Opcode][0];\n"
-     << "    if (!NumBits)\n"
-     << "      return APInt::getZeroWidth();\n"
-     << "    unsigned Idx = Index[Opcode][1];\n"
-     << "    ArrayRef<uint64_t> Data(&InstBits[Idx], "
-     << "APInt::getNumWords(NumBits));\n"
-     << "    return APInt(NumBits, Data);\n"
-     << "  };\n";
+  for (const auto &Mode : Modes) {
+    // Emit helper function to retrieve base values.
+    OS << "  auto getInstBits" << Mode.second
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mshockwave wrote:

Perfect! Thank you. 
Just a FYI: You can use `ninja check-llvm-codegen-<target name>` to run only the codegen test for a specific target. Similarly, using `ninja check-llvm-mc-<target name>` for a target's MC tests.

https://github.com/llvm/llvm-project/pull/68795