[PATCH] D93208: [TableGen] Slim down the data structures in xxxGenInstrInfo.inc, step 1

[Paul C. Anagnostopoulos via Phabricator via llvm-commits]

Paul-C-Anagnostopoulos created this revision.
Paul-C-Anagnostopoulos added reviewers: lattner, nhaehnle, madhur13490, dylanmckay.
Paul-C-Anagnostopoulos requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

This simple patch reduces the size of the Offsets and OpcodeOperandTypes tables in the xxxGenInstrInfo.inc files. It is the first step in trying to reduce the size of data structures in those files.

Not until I made these changes did I realize that these two data structures are used only by the AVR target. But perhaps it will come into play in future targets.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D93208

Files:
  llvm/utils/TableGen/InstrInfoEmitter.cpp


Index: llvm/utils/TableGen/InstrInfoEmitter.cpp
===================================================================
--- llvm/utils/TableGen/InstrInfoEmitter.cpp
+++ llvm/utils/TableGen/InstrInfoEmitter.cpp
@@ -371,7 +371,7 @@
   OS << "namespace " << Namespace << " {\n";
   OS << "LLVM_READONLY\n";
   OS << "static int getOperandType(uint16_t Opcode, uint16_t OpIdx) {\n";
-  // TODO: Factor out instructions with same operands to compress the tables.
+  // TODO: Factor out duplicate operand lists to compress the tables.
   if (!NumberedInstructions.empty()) {
     std::vector<int> OperandOffsets;
     std::vector<Record *> OperandRecords;
@@ -393,16 +393,26 @@
       }
     }
 
-    // Emit the table of offsets for the opcode lookup.
-    OS << "  const int Offsets[] = {\n";
+    // Emit the table of offsets (indexes) into the operand type table.
+    // Size the unsigned integer offset to save space.
+    assert(OperandRecords.size() <= UINT32_MAX &&
+               "Too many operands for offset table");
+    OS << ((OperandRecords.size() <= UINT16_MAX) ? "  const uint16_t"
+                                                 : "  const uint32_t");
+    OS << " Offsets[] = {\n";
     for (int I = 0, E = OperandOffsets.size(); I != E; ++I)
       OS << "    " << OperandOffsets[I] << ",\n";
     OS << "  };\n";
 
     // Add an entry for the end so that we don't need to special case it below.
     OperandOffsets.push_back(OperandRecords.size());
+
     // Emit the actual operand types in a flat table.
-    OS << "  const int OpcodeOperandTypes[] = {\n    ";
+    // Size the signed integer operand type to save space.
+    assert(EnumVal <= INT16_MAX &&
+               "Too many operand types for operand types table");
+    OS << ((EnumVal <= INT8_MAX) ? "  const int8_t" : "  const int16_t");
+    OS << " OpcodeOperandTypes[] = {\n    ";
     for (int I = 0, E = OperandRecords.size(), CurOffset = 1; I != E; ++I) {
       // We print each Opcode's operands in its own row.
       if (I == OperandOffsets[CurOffset]) {


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D93208.311561.patch
Type: text/x-patch
Size: 2044 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20201214/33100fb9/attachment.bin>