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

[Craig Topper via llvm-commits]

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@@ -0,0 +1,236 @@
+//===------ 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.
+//
+// This TableGen backend processes `Fusion` definitions and generates
+// predicators for checking if input instructions can be fused. These
+// predicators can used in `MacroFusion` DAG mutation.
+//
+// The generated header file contains two parts: one for predicator
+// declarations and one for predicator implementations. The user can get them
+// by defining macro `GET_<TargetName>_MACRO_FUSION_PRED_DECL` or
+// `GET_<TargetName>_MACRO_FUSION_PRED_IMPL` and then including the generated
+// header file.
+//
+// The generated predicator will be like:
+//
+// ```
+// bool isNAME(const TargetInstrInfo &TII,
+//             const TargetSubtargetInfo &STI,
+//             const MachineInstr *FirstMI,
+//             const MachineInstr &SecondMI) {
+//   auto &MRI = SecondMI.getMF()->getRegInfo();
+//   /* Predicates */
+//   return true;
+// }
+// ```
+//
+// The `Predicates` part is generated from a list of `FusionPredicate`, which
+// can be predefined predicates, a raw code string or `MCInstPredicate` defined
+// in TargetInstrPredicate.td.
+//
+//===---------------------------------------------------------------------===//
+
+#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";
+  OS << "#undef GET_" << Target.getName() << "_MACRO_FUSION_PRED_DECL\n\n";
+  OS << "namespace llvm {\n";
+
+  for (Record *Fusion : Fusions) {
+    OS << "bool is" << Fusion->getName() << "(const TargetInstrInfo &, "
+       << "const TargetSubtargetInfo &, "
+       << "const MachineInstr *, "
+       << "const MachineInstr &);\n";
+  }
+
+  OS << "} // end namespace llvm\n";
+  OS << "\n#endif\n";
+}
+
+void MacroFusionPredicatorEmitter::emitMacroFusionImpl(
+    std::vector<Record *> Fusions, PredicateExpander &PE, raw_ostream &OS) {
+  OS << "#ifdef GET_" << Target.getName() << "_MACRO_FUSION_PRED_IMPL\n";
+  OS << "#undef GET_" << Target.getName() << "_MACRO_FUSION_PRED_IMPL\n\n";
+  OS << "namespace llvm {\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";
----------------
topperc wrote:

I think 4 is the correct indent according to clang-format.

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