[TableGen][DecoderEmitter] Synthesize decoder table name in emitTable (#154255)

Previously, HW mode name was appended to decoder namespace name when
enumerating encodings, and then emitTable appended the bit width to it
to form the final table name. Let's do this all in one place.
A nice side effect is that this allows us to avoid having to deal with
std::string.

The changes in the tests are caused by the different order of tables.

1 files changed, 21 insertions, 23 deletions

diff --git a/llvm/utils/TableGen/DecoderEmitter.cpp b/llvm/utils/TableGen/DecoderEmitter.cpp
index c1afbbd..c16d5b5 100644
--- a/llvm/utils/TableGen/DecoderEmitter.cpp
+++ b/llvm/utils/TableGen/DecoderEmitter.cpp
@@ -230,7 +230,7 @@ public:
   // Emit the decoder state machine table. Returns a mask of MCD decoder ops
   // that were emitted.
   unsigned emitTable(formatted_raw_ostream &OS, DecoderTable &Table,
-                     unsigned BitWidth, StringRef Namespace,
+                     StringRef Namespace, unsigned HwModeID, unsigned BitWidth,
                      ArrayRef<unsigned> EncodingIDs) const;
   void emitInstrLenTable(formatted_raw_ostream &OS,
                          ArrayRef<unsigned> InstrLen) const;
@@ -805,8 +805,8 @@ unsigned Filter::usefulness() const {
 // Emit the decoder state machine table. Returns a mask of MCD decoder ops
 // that were emitted.
 unsigned DecoderEmitter::emitTable(formatted_raw_ostream &OS,
-                                   DecoderTable &Table, unsigned BitWidth,
-                                   StringRef Namespace,
+                                   DecoderTable &Table, StringRef Namespace,
+                                   unsigned HwModeID, unsigned BitWidth,
                                    ArrayRef<unsigned> EncodingIDs) const {
   // We'll need to be able to map from a decoded opcode into the corresponding
   // EncodingID for this specific combination of BitWidth and Namespace. This
@@ -818,8 +818,10 @@ unsigned DecoderEmitter::emitTable(formatted_raw_ostream &OS,
     OpcodeToEncodingID[Target.getInstrIntValue(InstDef)] = EncodingID;
   }
 
-  OS << "static const uint8_t DecoderTable" << Namespace << BitWidth
-     << "[] = {\n";
+  OS << "static const uint8_t DecoderTable" << Namespace;
+  if (HwModeID != DefaultMode)
+    OS << '_' << Target.getHwModes().getModeName(HwModeID);
+  OS << BitWidth << "[] = {\n";
 
   // Emit ULEB128 encoded value to OS, returning the number of bytes emitted.
   auto emitULEB128 = [](DecoderTable::const_iterator &I,
@@ -2501,8 +2503,9 @@ namespace {
         NumberedAlias,
         &Target.getInstruction(NumberedAlias->getValueAsDef("AliasOf")));
 
-  // Map of (namespace, size) tuple to encoding IDs.
-  std::map<std::pair<std::string, unsigned>, std::vector<unsigned>> EncMap;
+  // Map of (namespace, hwmode, size) tuple to encoding IDs.
+  std::map<std::tuple<StringRef, unsigned, unsigned>, std::vector<unsigned>>
+      EncMap;
   std::map<unsigned, std::vector<OperandInfo>> Operands;
   std::vector<unsigned> InstrLen;
   bool IsVarLenInst = Target.hasVariableLengthEncodings();
@@ -2537,14 +2540,10 @@ namespace {
         MaxInstLen = std::max(MaxInstLen, Len);
         InstrLen[NEI] = Len;
       }
-      std::string DecoderNamespace =
-          EncodingDef->getValueAsString("DecoderNamespace").str();
-      // DecoderTables with DefaultMode should not have any suffix.
-      if (NumberedEncoding.HwModeID != DefaultMode) {
-        StringRef HwModeName = HWM.getModeName(NumberedEncoding.HwModeID);
-        DecoderNamespace += ("_" + HwModeName).str();
-      }
-      EncMap[{DecoderNamespace, Size}].push_back(NEI);
+      StringRef DecoderNamespace =
+          EncodingDef->getValueAsString("DecoderNamespace");
+      EncMap[{DecoderNamespace, NumberedEncoding.HwModeID, Size}].push_back(
+          NEI);
     } else {
       NumEncodingsOmitted++;
     }
@@ -2552,12 +2551,11 @@ namespace {
 
   DecoderTableInfo TableInfo;
   unsigned OpcodeMask = 0;
-  for (const auto &[NSAndByteSize, EncodingIDs] : EncMap) {
-    const std::string &DecoderNamespace = NSAndByteSize.first;
-    const unsigned BitWidth = 8 * NSAndByteSize.second;
-    // Emit the decoder for this namespace+width combination.
-    FilterChooser FC(NumberedEncodings, EncodingIDs, Operands,
-                     IsVarLenInst ? MaxInstLen : BitWidth, this);
+  for (const auto &[Key, EncodingIDs] : EncMap) {
+    auto [DecoderNamespace, HwModeID, Size] = Key;
+    const unsigned BitWidth = IsVarLenInst ? MaxInstLen : 8 * Size;
+    // Emit the decoder for this (namespace, hwmode, width) combination.
+    FilterChooser FC(NumberedEncodings, EncodingIDs, Operands, BitWidth, this);
 
     // The decode table is cleared for each top level decoder function. The
     // predicates and decoders themselves, however, are shared across all
@@ -2573,8 +2571,8 @@ namespace {
     TableInfo.Table.push_back(MCD::OPC_Fail);
 
     // Print the table to the output stream.
-    OpcodeMask |= emitTable(OS, TableInfo.Table, FC.getBitWidth(),
-                            DecoderNamespace, EncodingIDs);
+    OpcodeMask |= emitTable(OS, TableInfo.Table, DecoderNamespace, HwModeID,
+                            BitWidth, EncodingIDs);
   }
 
   // For variable instruction, we emit a instruction length table