[TableGen] Integrate TableGen-based macro fusion (#73115)

`Fusion` is inherited from `SubtargetFeature` now. Each definition
of `Fusion` will define a `SubtargetFeature` accordingly.

Method `getMacroFusions` is added to `TargetSubtargetInfo`, which
returns a list of `MacroFusionPredTy` that will be evaluated by
MacroFusionMution.

`getMacroFusions` will be auto-generated if the target has `Fusion`
definitions.

Author: wangpc-pp

llvm/include/llvm/CodeGen/TargetSubtargetInfo.h

@@ -16,6 +16,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/CodeGen/MacroFusion.h"
 #include "llvm/CodeGen/PBQPRAConstraint.h"
 #include "llvm/CodeGen/SchedulerRegistry.h"
 #include "llvm/IR/GlobalValue.h"
@@ -323,6 +324,9 @@ class TargetSubtargetInfo : public MCSubtargetInfo {
   /// helps removing redundant copies generated by register allocator when
   /// handling complex eviction chains.
   virtual bool enableSpillageCopyElimination() const { return false; }
+
+  /// Get the list of MacroFusion predicates.
+  virtual std::vector<MacroFusionPredTy> getMacroFusions() const { return {}; };
 };
 
 } // end namespace llvm

llvm/include/llvm/Target/Target.td

@@ -459,6 +459,52 @@ class DwarfRegAlias<Register reg> {
       Register DwarfAlias = reg;
 }
 
+//===----------------------------------------------------------------------===//
+// SubtargetFeature - A characteristic of the chip set.
+//
+class SubtargetFeature<string n, string f, string v, string d,
+                       list<SubtargetFeature> i = []> {
+  // Name - Feature name.  Used by command line (-mattr=) to determine the
+  // appropriate target chip.
+  //
+  string Name = n;
+
+  // FieldName - Field in XXXSubtarget to be set by feature.
+  //
+  string FieldName = f;
+
+  // Value - Value the XXXSubtarget field to be set to by feature.
+  //
+  // A value of "true" or "false" implies the field is a bool. Otherwise,
+  // it is assumed to be an integer. the integer value may be the name of an
+  // enum constant. If multiple features use the same integer field, the
+  // field will be set to the maximum value of all enabled features that
+  // share the field.
+  //
+  string Value = v;
+
+  // Desc - Feature description.  Used by command line (-mattr=) to display help
+  // information.
+  //
+  string Desc = d;
+
+  // Implies - Features that this feature implies are present. If one of those
+  // features isn't set, then this one shouldn't be set either.
+  //
+  list<SubtargetFeature> Implies = i;
+}
+
+/// Specifies a Subtarget feature that this instruction is deprecated on.
+class Deprecated<SubtargetFeature dep> {
+  SubtargetFeature DeprecatedFeatureMask = dep;
+}
+
+/// A custom predicate used to determine if an instruction is
+/// deprecated or not.
+class ComplexDeprecationPredicate<string dep> {
+  string ComplexDeprecationPredicate = dep;
+}
+
 //===----------------------------------------------------------------------===//
 // Pull in the common support for MCPredicate (portable scheduling predicates).
 //
@@ -1680,52 +1726,6 @@ class Target {
   int AllowRegisterRenaming = 0;
 }
 
-//===----------------------------------------------------------------------===//
-// SubtargetFeature - A characteristic of the chip set.
-//
-class SubtargetFeature<string n, string f, string v, string d,
-                       list<SubtargetFeature> i = []> {
-  // Name - Feature name.  Used by command line (-mattr=) to determine the
-  // appropriate target chip.
-  //
-  string Name = n;
-
-  // FieldName - Field in XXXSubtarget to be set by feature.
-  //
-  string FieldName = f;
-
-  // Value - Value the XXXSubtarget field to be set to by feature.
-  //
-  // A value of "true" or "false" implies the field is a bool. Otherwise,
-  // it is assumed to be an integer. the integer value may be the name of an
-  // enum constant. If multiple features use the same integer field, the
-  // field will be set to the maximum value of all enabled features that
-  // share the field.
-  //
-  string Value = v;
-
-  // Desc - Feature description.  Used by command line (-mattr=) to display help
-  // information.
-  //
-  string Desc = d;
-
-  // Implies - Features that this feature implies are present. If one of those
-  // features isn't set, then this one shouldn't be set either.
-  //
-  list<SubtargetFeature> Implies = i;
-}
-
-/// Specifies a Subtarget feature that this instruction is deprecated on.
-class Deprecated<SubtargetFeature dep> {
-  SubtargetFeature DeprecatedFeatureMask = dep;
-}
-
-/// A custom predicate used to determine if an instruction is
-/// deprecated or not.
-class ComplexDeprecationPredicate<string dep> {
-  string ComplexDeprecationPredicate = dep;
-}
-
 //===----------------------------------------------------------------------===//
 // Processor chip sets - These values represent each of the chip sets supported
 // by the scheduler.  Each Processor definition requires corresponding

llvm/include/llvm/Target/TargetSchedule.td

@@ -658,7 +658,8 @@ def OneUse : OneUsePred;
 //   return true;
 // }
 // ```
-class Fusion<list<FusionPredicate> predicates> {
+class Fusion<string name, string fieldName, string desc, list<FusionPredicate> predicates>
+  : SubtargetFeature<name, fieldName, "true", desc> {
   list<FusionPredicate> Predicates = predicates;
 }
 
@@ -679,21 +680,23 @@ class Fusion<list<FusionPredicate> predicates> {
 //   return true;
 // }
 // ```
-class SimpleFusion<MCInstPredicate firstPred, MCInstPredicate secondPred,
+class SimpleFusion<string name, string fieldName, string desc,
+                   MCInstPredicate firstPred, MCInstPredicate secondPred,
                    list<FusionPredicate> prolog = [],
                    list<FusionPredicate> epilog = []>
-  : Fusion<!listconcat(
-                  prolog,
-                  [
-                    SecondFusionPredicateWithMCInstPredicate<secondPred>,
-                    WildcardTrue,
-                    FirstFusionPredicateWithMCInstPredicate<firstPred>,
-                    SecondFusionPredicateWithMCInstPredicate<
-                      CheckAny<[
-                        CheckIsVRegOperand<0>,
-                        CheckSameRegOperand<0, 1>
-                      ]>>,
-                    OneUse,
-                    TieReg<0, 1>,
-                  ],
-                  epilog)>;
+  : Fusion<name, fieldName, desc,
+           !listconcat(
+              prolog,
+              [
+                SecondFusionPredicateWithMCInstPredicate<secondPred>,
+                WildcardTrue,
+                FirstFusionPredicateWithMCInstPredicate<firstPred>,
+                SecondFusionPredicateWithMCInstPredicate<
+                  CheckAny<[
+                    CheckIsVRegOperand<0>,
+                    CheckSameRegOperand<0, 1>
+                  ]>>,
+                OneUse,
+                TieReg<0, 1>,
+              ],
+              epilog)>;

llvm/test/TableGen/MacroFusion.td

@@ -1,4 +1,5 @@
 // RUN: llvm-tblgen -gen-macro-fusion-pred -I %p/../../include %s | FileCheck %s --check-prefix=CHECK-PREDICATOR
+// RUN: llvm-tblgen -gen-subtarget -I %p/../../include %s | FileCheck %s --check-prefix=CHECK-SUBTARGET
 
 include "llvm/Target/Target.td"
 
@@ -33,7 +34,8 @@ let Namespace = "Test" in {
 def Inst0 : TestInst<0>;
 def Inst1 : TestInst<1>;
 
-def TestFusion: SimpleFusion<CheckOpcode<[Inst0]>,
+def TestFusion: SimpleFusion<"test-fusion", "HasTestFusion", "Test Fusion",
+                             CheckOpcode<[Inst0]>,
                              CheckAll<[
                               CheckOpcode<[Inst1]>,
                               CheckRegOperand<0, X0>
@@ -95,3 +97,15 @@ def TestFusion: SimpleFusion<CheckOpcode<[Inst0]>,
 // CHECK-PREDICATOR-NEXT:  } // end namespace llvm
 // CHECK-PREDICATOR-EMPTY:
 // CHECK-PREDICATOR-NEXT:  #endif
+
+// Check that we have generated target subfeature.
+// CHECK-SUBTARGET: { "test-fusion", "Test Fusion", Test::TestFusion
+
+// Check that we have generated `getMacroFusions()` function.
+// CHECK-SUBTARGET:      std::vector<MacroFusionPredTy> getMacroFusions() const override;
+
+// CHECK-SUBTARGET:      std::vector<MacroFusionPredTy> TestGenSubtargetInfo::getMacroFusions() const {
+// CHECK-SUBTARGET-NEXT:   std::vector<MacroFusionPredTy> Fusions;
+// CHECK-SUBTARGET-NEXT:   if (hasFeature(Test::TestFusion)) Fusions.push_back(llvm::isTestFusion);
+// CHECK-SUBTARGET-NEXT:   return Fusions;
+// CHECK-SUBTARGET-NEXT: }

llvm/utils/TableGen/CodeGenTarget.cpp

@@ -291,6 +291,7 @@ CodeGenTarget::CodeGenTarget(RecordKeeper &records)
   if (Targets.size() != 1)
     PrintFatalError("Multiple subclasses of Target defined!");
   TargetRec = Targets[0];
+  MacroFusions = Records.getAllDerivedDefinitions("Fusion");
 }
 
 CodeGenTarget::~CodeGenTarget() {

llvm/utils/TableGen/CodeGenTarget.h

@@ -64,6 +64,8 @@ class CodeGenTarget {
   mutable std::vector<Record*> RegAltNameIndices;
   mutable SmallVector<ValueTypeByHwMode, 8> LegalValueTypes;
   CodeGenHwModes CGH;
+  std::vector<Record *> MacroFusions;
+
   void ReadRegAltNameIndices() const;
   void ReadInstructions() const;
   void ReadLegalValueTypes() const;
@@ -149,6 +151,10 @@ class CodeGenTarget {
 
   const CodeGenHwModes &getHwModes() const { return CGH; }
 
+  bool hasMacroFusion() const { return !MacroFusions.empty(); }
+
+  const std::vector<Record *> getMacroFusions() const { return MacroFusions; }
+
 private:
   DenseMap<const Record*, std::unique_ptr<CodeGenInstruction>> &
   getInstructions() const {

llvm/utils/TableGen/SubtargetEmitter.cpp

@@ -133,6 +133,7 @@ class SubtargetEmitter {
   void EmitMCInstrAnalysisPredicateFunctions(raw_ostream &OS);
 
   void EmitSchedModel(raw_ostream &OS);
+  void emitGetMacroFusions(const std::string &ClassName, raw_ostream &OS);
   void EmitHwModeCheck(const std::string &ClassName, raw_ostream &OS);
   void ParseFeaturesFunction(raw_ostream &OS);
 
@@ -1786,6 +1787,24 @@ void SubtargetEmitter::EmitHwModeCheck(const std::string &ClassName,
   OS << "  return 0;\n}\n";
 }
 
+void SubtargetEmitter::emitGetMacroFusions(const std::string &ClassName,
+                                           raw_ostream &OS) {
+  if (!TGT.hasMacroFusion())
+    return;
+
+  OS << "std::vector<MacroFusionPredTy> " << ClassName
+     << "::getMacroFusions() const {\n";
+  OS.indent(2) << "std::vector<MacroFusionPredTy> Fusions;\n";
+  for (auto *Fusion : TGT.getMacroFusions()) {
+    std::string Name = Fusion->getNameInitAsString();
+    OS.indent(2) << "if (hasFeature(" << Target << "::" << Name
+                 << ")) Fusions.push_back(llvm::is" << Name << ");\n";
+  }
+
+  OS.indent(2) << "return Fusions;\n";
+  OS << "}\n";
+}
+
 // Produces a subtarget specific function for parsing
 // the subtarget features string.
 void SubtargetEmitter::ParseFeaturesFunction(raw_ostream &OS) {
@@ -1987,6 +2006,9 @@ void SubtargetEmitter::run(raw_ostream &OS) {
      << " const;\n";
   if (TGT.getHwModes().getNumModeIds() > 1)
     OS << "  unsigned getHwMode() const override;\n";
+  if (TGT.hasMacroFusion())
+    OS << "  std::vector<MacroFusionPredTy> getMacroFusions() const "
+          "override;\n";
 
   STIPredicateExpander PE(Target);
   PE.setByRef(false);
@@ -2044,6 +2066,7 @@ void SubtargetEmitter::run(raw_ostream &OS) {
 
   EmitSchedModelHelpers(ClassName, OS);
   EmitHwModeCheck(ClassName, OS);
+  emitGetMacroFusions(ClassName, OS);
 
   OS << "} // end namespace llvm\n\n";