[llvm] [TableGen] Add a backend to generate MacroFusion predicators (PR #72222)

[Pierre van Houtryve via llvm-commits]

================
@@ -0,0 +1,199 @@
+//===--- MacroFusionPredicatorEmitter.cpp - Generator for Fusion ----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// MacroFusionPredicatorEmitter implements a TableGen-driven predicators
+// generator for macro-op fusions.
+//
+//===---------------------------------------------------------------------===//
+
+#include "CodeGenTarget.h"
+#include "PredicateExpander.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/TableGen/Error.h"
+#include "llvm/TableGen/Record.h"
+#include "llvm/TableGen/TableGenBackend.h"
+#include <set>
+#include <vector>
+
+using namespace llvm;
+
+#define DEBUG_TYPE "macro-fusion-predicator"
+
+namespace {
+class MacroFusionPredicatorEmitter {
+  RecordKeeper &Records;
+  CodeGenTarget Target;
+
+  void emitMacroFusionDecl(std::vector<Record *> Fusions, PredicateExpander &PE,
+                           raw_ostream &OS);
+  void emitMacroFusionImpl(std::vector<Record *> Fusions, PredicateExpander &PE,
+                           raw_ostream &OS);
+  void emitPredicates(std::vector<Record *> &FirstPredicate,
+                      PredicateExpander &PE, raw_ostream &OS);
+  void emitFirstPredicate(Record *SecondPredicate, PredicateExpander &PE,
+                          raw_ostream &OS);
+  void emitSecondPredicate(Record *SecondPredicate, PredicateExpander &PE,
+                           raw_ostream &OS);
+  void emitBothPredicate(Record *Predicates, PredicateExpander &PE,
+                         raw_ostream &OS);
+
+public:
+  MacroFusionPredicatorEmitter(RecordKeeper &R) : Records(R), Target(R) {}
+
+  void run(raw_ostream &OS);
+};
+} // End anonymous namespace.
+
+void MacroFusionPredicatorEmitter::emitMacroFusionDecl(
+    std::vector<Record *> Fusions, PredicateExpander &PE, raw_ostream &OS) {
+  OS << "#ifdef GET_" << Target.getName() << "_MACRO_FUSION_PRED_DECL\n\n";
+
+  for (Record *Fusion : Fusions) {
+    OS << "bool is" << Fusion->getName() << "(const TargetInstrInfo &, "
+       << "const TargetSubtargetInfo &, " << "const MachineInstr *, "
+       << "const MachineInstr &);\n";
+  }
+
+  OS << "\n#endif\n";
+  OS << "#undef GET_" << Target.getName() << "_MACRO_FUSION_PRED_DECL\n";
+}
+
+void MacroFusionPredicatorEmitter::emitMacroFusionImpl(
+    std::vector<Record *> Fusions, PredicateExpander &PE, raw_ostream &OS) {
+  OS << "#ifdef GET_" << Target.getName() << "_MACRO_FUSION_PRED_IMPL\n\n";
+
+  for (Record *Fusion : Fusions) {
+    std::vector<Record *> Predicates =
+        Fusion->getValueAsListOfDefs("Predicates");
+
+    OS << "bool is" << Fusion->getName() << "(\n";
+    OS.indent(5) << "const TargetInstrInfo &TII,\n";
+    OS.indent(5) << "const TargetSubtargetInfo &STI,\n";
+    OS.indent(5) << "const MachineInstr *FirstMI,\n";
+    OS.indent(5) << "const MachineInstr &SecondMI) {\n";
+    OS.indent(2) << "auto &MRI = SecondMI.getMF()->getRegInfo();\n";
+
+    emitPredicates(Predicates, PE, OS);
+
+    OS.indent(2) << "return true;\n";
+    OS << "}\n";
+  }
+
+  OS << "\n#endif\n";
+  OS << "#undef GET_" << Target.getName() << "_MACRO_FUSION_PRED_IMPL\n\n";
+}
+
+void MacroFusionPredicatorEmitter::emitPredicates(
+    std::vector<Record *> &Predicates, PredicateExpander &PE, raw_ostream &OS) {
+  for (Record *Predicate : Predicates) {
+    Record *Target = Predicate->getValueAsDef("Target");
+    if (Target->getName() == "first")
+      emitFirstPredicate(Predicate, PE, OS);
+    else if (Target->getName() == "second")
+      emitSecondPredicate(Predicate, PE, OS);
+    else if (Target->getName() == "both")
+      emitBothPredicate(Predicate, PE, OS);
+    else
+      PrintFatalError(Target->getLoc(),
+                      "Unsupported 'FusionTarget': " + Target->getName());
+  }
+}
+
+void MacroFusionPredicatorEmitter::emitFirstPredicate(Record *Predicate,
+                                                      PredicateExpander &PE,
+                                                      raw_ostream &OS) {
+  if (Predicate->isSubClassOf("WildcardPred")) {
+    OS.indent(2) << "if (!FirstMI)\n";
+    OS.indent(2) << "  return "
+                 << (Predicate->getValueAsBit("ReturnValue") ? "true" : "false")
+                 << ";\n";
+  } else if (Predicate->isSubClassOf("OneUsePred")) {
+    OS.indent(2) << "{\n";
+    OS.indent(4) << "Register FirstDest = FirstMI->getOperand(0).getReg();\n";
+    OS.indent(4)
+        << "if (FirstDest.isVirtual() && !MRI.hasOneNonDBGUse(FirstDest))\n";
+    OS.indent(4) << "  return false;\n";
+    OS.indent(2) << "}\n";
+  } else if (Predicate->isSubClassOf(
+                 "FirstFusionPredicateWithMCInstPredicate")) {
+    OS.indent(2) << "{\n";
+    OS.indent(4) << "const MachineInstr *MI = FirstMI;\n";
+    OS.indent(4) << "if (";
+    PE.setNegatePredicate(true);
+    PE.setIndentLevel(3);
+    PE.expandPredicate(OS, Predicate->getValueAsDef("Predicate"));
+    OS << ")\n";
+    OS.indent(4) << "  return false;\n";
+    OS.indent(2) << "}\n";
+  } else
+    PrintFatalError(Predicate->getLoc(),
+                    "Unsupported predicate for first instruction: " +
+                        Predicate->getType()->getAsString());
+}
+
+void MacroFusionPredicatorEmitter::emitSecondPredicate(Record *Predicate,
+                                                       PredicateExpander &PE,
+                                                       raw_ostream &OS) {
+  if (Predicate->isSubClassOf("SecondFusionPredicateWithMCInstPredicate")) {
+    OS.indent(2) << "{\n";
+    OS.indent(4) << "const MachineInstr *MI = &SecondMI;\n";
+    OS.indent(4) << "if (";
+    PE.setNegatePredicate(true);
+    PE.setIndentLevel(3);
+    PE.expandPredicate(OS, Predicate->getValueAsDef("Predicate"));
+    OS << ")\n";
+    OS.indent(4) << "  return false;\n";
+    OS.indent(2) << "}\n";
+  } else
+    PrintFatalError(Predicate->getLoc(),
+                    "Unsupported predicate for first instruction: " +
+                        Predicate->getType()->getAsString());
+}
+
+void MacroFusionPredicatorEmitter::emitBothPredicate(Record *Predicate,
+                                                     PredicateExpander &PE,
+                                                     raw_ostream &OS) {
+  if (Predicate->isSubClassOf("FusionPredicateWithCode"))
+    OS << Predicate->getValueAsString("Predicate");
+  else if (Predicate->isSubClassOf("BothFusionPredicateWithMCInstPredicate")) {
+    Record *MCPred = Predicate->getValueAsDef("Predicate");
+    emitFirstPredicate(MCPred, PE, OS);
+    emitSecondPredicate(MCPred, PE, OS);
+  } else if (Predicate->isSubClassOf("TieReg")) {
+    int FirstOpIdx = Predicate->getValueAsInt("FirstOpIdx");
+    int SecondOpIdx = Predicate->getValueAsInt("SecondOpIdx");
+    OS.indent(2) << "if (!(FirstMI->getOperand(" << FirstOpIdx
+                 << ").isReg() &&\n";
+    OS.indent(2) << "      SecondMI.getOperand(" << SecondOpIdx
+                 << ").isReg() &&\n";
+    OS.indent(2) << "      FirstMI->getOperand(" << FirstOpIdx
+                 << ").getReg() == SecondMI.getOperand(" << SecondOpIdx
+                 << ").getReg()))\n";
+    OS.indent(2) << "  return false;\n";
+  } else
+    PrintFatalError(Predicate->getLoc(),
+                    "Unsupported predicate for both instruction: " +
+                        Predicate->getType()->getAsString());
+}
+
+void MacroFusionPredicatorEmitter::run(raw_ostream &OS) {
+  // Emit file header.
+  emitSourceFileHeader("Macro Fusion Predicators", OS);
+
+  PredicateExpander PE(Target.getName());
+  PE.setByRef(false);
+  PE.setExpandForMC(false);
+
+  std::vector<Record *> Fusions = Records.getAllDerivedDefinitions("Fusion");
+  // Sort macro fusions by name.
+  llvm::sort(Fusions, LessRecord());
----------------
Pierre-vh wrote:

don't need `llvm::`

https://github.com/llvm/llvm-project/pull/72222