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

Wang Pengcheng via llvm-commits llvm-commits at lists.llvm.org
Fri Dec 8 02:19:55 PST 2023


https://github.com/wangpc-pp updated https://github.com/llvm/llvm-project/pull/73115

>From f137309d3772b18b83e0a587c7d4065ec4f610b8 Mon Sep 17 00:00:00 2001
From: wangpc <wangpengcheng.pp at bytedance.com>
Date: Fri, 10 Nov 2023 17:58:00 +0800
Subject: [PATCH 1/3] [MacroFusion] Support multiple predicators

The user can provide multiple predicators to MacroFusion and the
DAG mutation will be applied if one of them is evalated to true.

`ShouldSchedulePredTy` is renamed to `MacroFusionPredTy`.
---
 llvm/include/llvm/CodeGen/MacroFusion.h | 20 +++++++------
 llvm/lib/CodeGen/MacroFusion.cpp        | 37 +++++++++++++++++--------
 llvm/lib/Target/AMDGPU/GCNVOPDUtils.cpp |  4 +--
 3 files changed, 38 insertions(+), 23 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/MacroFusion.h b/llvm/include/llvm/CodeGen/MacroFusion.h
index ea2c7a5faae385..a359fca6042600 100644
--- a/llvm/include/llvm/CodeGen/MacroFusion.h
+++ b/llvm/include/llvm/CodeGen/MacroFusion.h
@@ -14,7 +14,7 @@
 #ifndef LLVM_CODEGEN_MACROFUSION_H
 #define LLVM_CODEGEN_MACROFUSION_H
 
-#include <functional>
+#include "llvm/ADT/ArrayRef.h"
 #include <memory>
 
 namespace llvm {
@@ -29,10 +29,10 @@ class SUnit;
 /// Check if the instr pair, FirstMI and SecondMI, should be fused
 /// together. Given SecondMI, when FirstMI is unspecified, then check if
 /// SecondMI may be part of a fused pair at all.
-using ShouldSchedulePredTy = std::function<bool(const TargetInstrInfo &TII,
-                                                const TargetSubtargetInfo &TSI,
-                                                const MachineInstr *FirstMI,
-                                                const MachineInstr &SecondMI)>;
+using MacroFusionPredTy = bool (*)(const TargetInstrInfo &TII,
+                                   const TargetSubtargetInfo &STI,
+                                   const MachineInstr *FirstMI,
+                                   const MachineInstr &SecondMI);
 
 /// Checks if the number of cluster edges between SU and its predecessors is
 /// less than FuseLimit
@@ -48,15 +48,17 @@ bool fuseInstructionPair(ScheduleDAGInstrs &DAG, SUnit &FirstSU,
 
 /// Create a DAG scheduling mutation to pair instructions back to back
 /// for instructions that benefit according to the target-specific
-/// shouldScheduleAdjacent predicate function.
+/// predicate functions. shouldScheduleAdjacent will be true if any of the
+/// provided predicates are true.
 std::unique_ptr<ScheduleDAGMutation>
-createMacroFusionDAGMutation(ShouldSchedulePredTy shouldScheduleAdjacent);
+createMacroFusionDAGMutation(ArrayRef<MacroFusionPredTy> Predicates);
 
 /// Create a DAG scheduling mutation to pair branch instructions with one
 /// of their predecessors back to back for instructions that benefit according
-/// to the target-specific shouldScheduleAdjacent predicate function.
+/// to the target-specific predicate functions. shouldScheduleAdjacent will be
+/// true if any of the provided predicates are true.
 std::unique_ptr<ScheduleDAGMutation>
-createBranchMacroFusionDAGMutation(ShouldSchedulePredTy shouldScheduleAdjacent);
+createBranchMacroFusionDAGMutation(ArrayRef<MacroFusionPredTy> Predicates);
 
 } // end namespace llvm
 
diff --git a/llvm/lib/CodeGen/MacroFusion.cpp b/llvm/lib/CodeGen/MacroFusion.cpp
index fa5df68b8abcc0..30affc93d4adc0 100644
--- a/llvm/lib/CodeGen/MacroFusion.cpp
+++ b/llvm/lib/CodeGen/MacroFusion.cpp
@@ -137,19 +137,34 @@ namespace {
 /// Post-process the DAG to create cluster edges between instrs that may
 /// be fused by the processor into a single operation.
 class MacroFusion : public ScheduleDAGMutation {
-  ShouldSchedulePredTy shouldScheduleAdjacent;
+  std::vector<MacroFusionPredTy> Predicates;
   bool FuseBlock;
   bool scheduleAdjacentImpl(ScheduleDAGInstrs &DAG, SUnit &AnchorSU);
 
 public:
-  MacroFusion(ShouldSchedulePredTy shouldScheduleAdjacent, bool FuseBlock)
-    : shouldScheduleAdjacent(shouldScheduleAdjacent), FuseBlock(FuseBlock) {}
+  MacroFusion(ArrayRef<MacroFusionPredTy> Predicates, bool FuseBlock)
+      : Predicates(Predicates.begin(), Predicates.end()), FuseBlock(FuseBlock) {
+  }
 
   void apply(ScheduleDAGInstrs *DAGInstrs) override;
+
+  bool shouldScheduleAdjacent(const TargetInstrInfo &TII,
+                              const TargetSubtargetInfo &STI,
+                              const MachineInstr *FirstMI,
+                              const MachineInstr &SecondMI);
 };
 
 } // end anonymous namespace
 
+bool MacroFusion::shouldScheduleAdjacent(const TargetInstrInfo &TII,
+                                         const TargetSubtargetInfo &STI,
+                                         const MachineInstr *FirstMI,
+                                         const MachineInstr &SecondMI) {
+  return llvm::any_of(Predicates, [&](MacroFusionPredTy Predicate) {
+    return Predicate(TII, STI, FirstMI, SecondMI);
+  });
+}
+
 void MacroFusion::apply(ScheduleDAGInstrs *DAG) {
   if (FuseBlock)
     // For each of the SUnits in the scheduling block, try to fuse the instr in
@@ -197,17 +212,15 @@ bool MacroFusion::scheduleAdjacentImpl(ScheduleDAGInstrs &DAG, SUnit &AnchorSU)
 }
 
 std::unique_ptr<ScheduleDAGMutation>
-llvm::createMacroFusionDAGMutation(
-     ShouldSchedulePredTy shouldScheduleAdjacent) {
-  if(EnableMacroFusion)
-    return std::make_unique<MacroFusion>(shouldScheduleAdjacent, true);
+llvm::createMacroFusionDAGMutation(ArrayRef<MacroFusionPredTy> Predicates) {
+  if (EnableMacroFusion)
+    return std::make_unique<MacroFusion>(std::move(Predicates), true);
   return nullptr;
 }
 
-std::unique_ptr<ScheduleDAGMutation>
-llvm::createBranchMacroFusionDAGMutation(
-     ShouldSchedulePredTy shouldScheduleAdjacent) {
-  if(EnableMacroFusion)
-    return std::make_unique<MacroFusion>(shouldScheduleAdjacent, false);
+std::unique_ptr<ScheduleDAGMutation> llvm::createBranchMacroFusionDAGMutation(
+    ArrayRef<MacroFusionPredTy> Predicates) {
+  if (EnableMacroFusion)
+    return std::make_unique<MacroFusion>(std::move(Predicates), false);
   return nullptr;
 }
diff --git a/llvm/lib/Target/AMDGPU/GCNVOPDUtils.cpp b/llvm/lib/Target/AMDGPU/GCNVOPDUtils.cpp
index 29c9b9ccf27614..0bddeeef9e9b1a 100644
--- a/llvm/lib/Target/AMDGPU/GCNVOPDUtils.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNVOPDUtils.cpp
@@ -142,10 +142,10 @@ namespace {
 /// be turned into VOPD instructions
 /// Greedily pairs instruction candidates. O(n^2) algorithm.
 struct VOPDPairingMutation : ScheduleDAGMutation {
-  ShouldSchedulePredTy shouldScheduleAdjacent; // NOLINT: function pointer
+  MacroFusionPredTy shouldScheduleAdjacent; // NOLINT: function pointer
 
   VOPDPairingMutation(
-      ShouldSchedulePredTy shouldScheduleAdjacent) // NOLINT: function pointer
+      MacroFusionPredTy shouldScheduleAdjacent) // NOLINT: function pointer
       : shouldScheduleAdjacent(shouldScheduleAdjacent) {}
 
   void apply(ScheduleDAGInstrs *DAG) override {

>From b1d75ceb3d7e85edb4b31b626a3f9a2929cfbe59 Mon Sep 17 00:00:00 2001
From: wangpc <wangpengcheng.pp at bytedance.com>
Date: Fri, 10 Nov 2023 18:18:18 +0800
Subject: [PATCH 2/3] [TableGen] Add a backend to generate MacroFusion
 predicators

`FusionPredicate` is used to predicate if target instruction matches
the requirement. The targets can be firstMI, secondMI or both.

The `Fusion` contains a list of `FusionPredicate`. The generated code
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;
}
```

A boilerplate class called `SimpleFusion` is added. `SimpleFusion` has
a predefined structure of predicates and accepts predicate for
`firstMI`, predicate for `secondMI` and epilog/prolog as arguments.
The generated code for `SimpleFusion` will be like:
```
bool isNAME(const TargetInstrInfo &TII,
            const TargetSubtargetInfo &STI,
            const MachineInstr *FirstMI,
            const MachineInstr &SecondMI) {
  auto &MRI = SecondMI.getMF()->getRegInfo();
  /* Prolog */
  /* Predicate for `SecondMI` */
  /* Wildcard */
  /* Predicate for `FirstMI` */
  /* Check One Use */
  /* Tie registers */
  /* Epilog */
  return true;
}
```
---
 .../llvm/Target/TargetInstrPredicate.td       |   6 +
 llvm/include/llvm/Target/TargetSchedule.td    | 113 +++++++++
 llvm/test/TableGen/MacroFusion.td             |  97 +++++++
 llvm/utils/TableGen/CMakeLists.txt            |   1 +
 .../TableGen/MacroFusionPredicatorEmitter.cpp | 236 ++++++++++++++++++
 llvm/utils/TableGen/PredicateExpander.cpp     |   8 +
 llvm/utils/TableGen/PredicateExpander.h       |   1 +
 7 files changed, 462 insertions(+)
 create mode 100644 llvm/test/TableGen/MacroFusion.td
 create mode 100644 llvm/utils/TableGen/MacroFusionPredicatorEmitter.cpp

diff --git a/llvm/include/llvm/Target/TargetInstrPredicate.td b/llvm/include/llvm/Target/TargetInstrPredicate.td
index 9f2cde9d923050..82c4c7b23a49b6 100644
--- a/llvm/include/llvm/Target/TargetInstrPredicate.td
+++ b/llvm/include/llvm/Target/TargetInstrPredicate.td
@@ -95,6 +95,12 @@ class MCOperandPredicate<int Index> : MCInstPredicate {
 // Return true if machine operand at position `Index` is a register operand.
 class CheckIsRegOperand<int Index> : MCOperandPredicate<Index>;
 
+// Return true if machine operand at position `Index` is a virtual register operand.
+class CheckIsVRegOperand<int Index> : MCOperandPredicate<Index>;
+
+// Return true if machine operand at position `Index` is not a virtual register operand.
+class CheckIsNotVRegOperand<int Index> : CheckNot<CheckIsVRegOperand<Index>>;
+
 // Return true if machine operand at position `Index` is an immediate operand.
 class CheckIsImmOperand<int Index> : MCOperandPredicate<Index>;
 
diff --git a/llvm/include/llvm/Target/TargetSchedule.td b/llvm/include/llvm/Target/TargetSchedule.td
index 949baa5d2105c4..74c9cd085b4ee2 100644
--- a/llvm/include/llvm/Target/TargetSchedule.td
+++ b/llvm/include/llvm/Target/TargetSchedule.td
@@ -584,3 +584,116 @@ class MemoryQueue<ProcResourceKind PR> {
 
 class LoadQueue<ProcResourceKind LDQueue> : MemoryQueue<LDQueue>;
 class StoreQueue<ProcResourceKind STQueue> : MemoryQueue<STQueue>;
+
+// The target instruction that FusionPredicate will be evaluated on.
+class FusionTarget;
+def first : FusionTarget;
+def second : FusionTarget;
+def both : FusionTarget;
+
+// Base class of FusionPredicate, etc. The avaliable variables are:
+// * const TargetInstrInfo &TII
+// * const TargetSubtargetInfo &STI
+// * const MachineRegisterInfo &MRI
+// * const MachineInstr *FirstMI
+// * const MachineInstr &SecondMI
+class FusionPredicate<FusionTarget target> {
+  FusionTarget Target = target;
+}
+class FirstFusionPredicate: FusionPredicate<first>;
+class SecondFusionPredicate: FusionPredicate<second>;
+class BothFusionPredicate: FusionPredicate<both>;
+
+// FusionPredicate with raw code predicate.
+class FusionPredicateWithCode<code pred> : FusionPredicate<both> {
+  code Predicate = pred;
+}
+
+// FusionPredicate with MCInstPredicate.
+class FusionPredicateWithMCInstPredicate<FusionTarget target, MCInstPredicate pred>
+  : FusionPredicate<target> {
+  MCInstPredicate Predicate = pred;
+}
+class FirstFusionPredicateWithMCInstPredicate<MCInstPredicate pred>
+  : FusionPredicateWithMCInstPredicate<first, pred>;
+class SecondFusionPredicateWithMCInstPredicate<MCInstPredicate pred>
+  : FusionPredicateWithMCInstPredicate<second, pred>;
+// The pred will be applied on both firstMI and secondMI.
+class BothFusionPredicateWithMCInstPredicate<MCInstPredicate pred>
+  : FusionPredicateWithMCInstPredicate<second, pred>;
+
+// Tie firstOpIdx and secondOpIdx. The operand of `FirstMI` at position
+// `firstOpIdx` should be the same as the operand of `SecondMI` at position
+// `secondOpIdx`.
+class TieReg<int firstOpIdx, int secondOpIdx> : BothFusionPredicate {
+  int FirstOpIdx = firstOpIdx;
+  int SecondOpIdx = secondOpIdx;
+}
+
+// A predicate for wildcard. The generated code will be like:
+// ```
+// if (!FirstMI)
+//   return ReturnValue;
+// ```
+class WildcardPred<bit ret> : FirstFusionPredicate {
+  bit ReturnValue = ret;
+}
+def WildcardFalse : WildcardPred<0>;
+def WildcardTrue : WildcardPred<1>;
+
+// Indicates that the destination register of `FirstMI` should have one use if
+// it is a virtual register.
+class OneUsePred : FirstFusionPredicate;
+def OneUse : OneUsePred;
+
+// Handled by MacroFusionPredicatorEmitter backend.
+// 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;
+// }
+// ```
+class Fusion<list<FusionPredicate> predicates> {
+  list<FusionPredicate> Predicates = predicates;
+}
+
+// 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();
+//   /* Prolog */
+//   /* Predicate for `SecondMI` */
+//   /* Wildcard */
+//   /* Predicate for `FirstMI` */
+//   /* Check One Use */
+//   /* Tie registers */
+//   /* Epilog */
+//   return true;
+// }
+// ```
+class SimpleFusion<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)>;
diff --git a/llvm/test/TableGen/MacroFusion.td b/llvm/test/TableGen/MacroFusion.td
new file mode 100644
index 00000000000000..72b0d1e19144f7
--- /dev/null
+++ b/llvm/test/TableGen/MacroFusion.td
@@ -0,0 +1,97 @@
+// RUN: llvm-tblgen -gen-macro-fusion-pred -I %p/../../include %s | FileCheck %s --check-prefix=CHECK-PREDICATOR
+
+include "llvm/Target/Target.td"
+
+def TestInstrInfo : InstrInfo { }
+def TestAsmWriter : AsmWriter {
+  int PassSubtarget = 1;
+}
+
+def Test : Target {
+  let InstructionSet = TestInstrInfo;
+  let AssemblyWriters = [TestAsmWriter];
+}
+
+let Namespace = "Test" in {
+  foreach i = 0-32 in {
+    def X#i : Register<"x"#i>;
+  }
+
+  def GPR : RegisterClass<"GPR", [i32], 32, (sequence  "X%u", 0, 32)>;
+
+  class TestInst<int Opc> : Instruction {
+    field bits<32> Inst;
+    field bits<32> SoftFail = 0;
+    let Size = 4;
+    let Inst = Opc;
+    let OutOperandList = (outs);
+    let InOperandList = (ins);
+    let AsmString = NAME;
+  }
+}
+
+def Inst0 : TestInst<0>;
+def Inst1 : TestInst<1>;
+
+def TestFusion: SimpleFusion<CheckOpcode<[Inst0]>,
+                             CheckAll<[
+                              CheckOpcode<[Inst1]>,
+                              CheckRegOperand<0, X0>
+                             ]>>;
+
+// CHECK-PREDICATOR:       #ifdef GET_Test_MACRO_FUSION_PRED_DECL
+// CHECK-PREDICATOR-NEXT:  #undef GET_Test_MACRO_FUSION_PRED_DECL
+// CHECK-PREDICATOR-EMPTY:
+// CHECK-PREDICATOR-NEXT:  namespace llvm {
+// CHECK-PREDICATOR-NEXT:  bool isTestFusion(const TargetInstrInfo &, const TargetSubtargetInfo &, const MachineInstr *, const MachineInstr &);
+// CHECK-PREDICATOR-NEXT:  } // end namespace llvm
+// CHECK-PREDICATOR-EMPTY:
+// CHECK-PREDICATOR-NEXT:  #endif
+
+// CHECK-PREDICATOR:       #ifdef GET_Test_MACRO_FUSION_PRED_IMPL
+// CHECK-PREDICATOR-NEXT:  #undef GET_Test_MACRO_FUSION_PRED_IMPL
+// CHECK-PREDICATOR-EMPTY:
+// CHECK-PREDICATOR-NEXT:  namespace llvm {
+// CHECK-PREDICATOR-NEXT:  bool isTestFusion(
+// CHECK-PREDICATOR-NEXT:       const TargetInstrInfo &TII,
+// CHECK-PREDICATOR-NEXT:       const TargetSubtargetInfo &STI,
+// CHECK-PREDICATOR-NEXT:       const MachineInstr *FirstMI,
+// CHECK-PREDICATOR-NEXT:       const MachineInstr &SecondMI) {
+// CHECK-PREDICATOR-NEXT:    auto &MRI = SecondMI.getMF()->getRegInfo();
+// CHECK-PREDICATOR-NEXT:    {
+// CHECK-PREDICATOR-NEXT:      const MachineInstr *MI = &SecondMI;
+// CHECK-PREDICATOR-NEXT:      if (!(
+// CHECK-PREDICATOR-NEXT:          ( MI->getOpcode() == Test::Inst1 )
+// CHECK-PREDICATOR-NEXT:          && MI->getOperand(0).getReg() == Test::X0
+// CHECK-PREDICATOR-NEXT:        ))
+// CHECK-PREDICATOR-NEXT:        return false;
+// CHECK-PREDICATOR-NEXT:    }
+// CHECK-PREDICATOR-NEXT:    if (!FirstMI)
+// CHECK-PREDICATOR-NEXT:      return true;
+// CHECK-PREDICATOR-NEXT:    {
+// CHECK-PREDICATOR-NEXT:      const MachineInstr *MI = FirstMI;
+// CHECK-PREDICATOR-NEXT:      if (( MI->getOpcode() != Test::Inst0 ))
+// CHECK-PREDICATOR-NEXT:        return false;
+// CHECK-PREDICATOR-NEXT:    }
+// CHECK-PREDICATOR-NEXT:    {
+// CHECK-PREDICATOR-NEXT:      const MachineInstr *MI = &SecondMI;
+// CHECK-PREDICATOR-NEXT:      if (!(
+// CHECK-PREDICATOR-NEXT:          MI->getOperand(0).getReg().isVirtual()
+// CHECK-PREDICATOR-NEXT:          || MI->getOperand(0).getReg() == MI->getOperand(1).getReg()
+// CHECK-PREDICATOR-NEXT:        ))
+// CHECK-PREDICATOR-NEXT:        return false;
+// CHECK-PREDICATOR-NEXT:    }
+// CHECK-PREDICATOR-NEXT:    {
+// CHECK-PREDICATOR-NEXT:      Register FirstDest = FirstMI->getOperand(0).getReg();
+// CHECK-PREDICATOR-NEXT:      if (FirstDest.isVirtual() && !MRI.hasOneNonDBGUse(FirstDest))
+// CHECK-PREDICATOR-NEXT:        return false;
+// CHECK-PREDICATOR-NEXT:    }
+// CHECK-PREDICATOR-NEXT:    if (!(FirstMI->getOperand(0).isReg() &&
+// CHECK-PREDICATOR-NEXT:          SecondMI.getOperand(1).isReg() &&
+// CHECK-PREDICATOR-NEXT:          FirstMI->getOperand(0).getReg() == SecondMI.getOperand(1).getReg()))
+// CHECK-PREDICATOR-NEXT:      return false;
+// CHECK-PREDICATOR-NEXT:    return true;
+// CHECK-PREDICATOR-NEXT:  }
+// CHECK-PREDICATOR-NEXT:  } // end namespace llvm
+// CHECK-PREDICATOR-EMPTY:
+// CHECK-PREDICATOR-NEXT:  #endif
diff --git a/llvm/utils/TableGen/CMakeLists.txt b/llvm/utils/TableGen/CMakeLists.txt
index 071ea3bc07054b..f765cc36d3bebe 100644
--- a/llvm/utils/TableGen/CMakeLists.txt
+++ b/llvm/utils/TableGen/CMakeLists.txt
@@ -72,6 +72,7 @@ add_tablegen(llvm-tblgen LLVM
   PredicateExpander.cpp
   PseudoLoweringEmitter.cpp
   CompressInstEmitter.cpp
+  MacroFusionPredicatorEmitter.cpp
   RegisterBankEmitter.cpp
   RegisterInfoEmitter.cpp
   SearchableTableEmitter.cpp
diff --git a/llvm/utils/TableGen/MacroFusionPredicatorEmitter.cpp b/llvm/utils/TableGen/MacroFusionPredicatorEmitter.cpp
new file mode 100644
index 00000000000000..422f9fb4297147
--- /dev/null
+++ b/llvm/utils/TableGen/MacroFusionPredicatorEmitter.cpp
@@ -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";
+    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 << "} // end namespace llvm\n";
+  OS << "\n#endif\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.
+  sort(Fusions, LessRecord());
+  emitMacroFusionDecl(Fusions, PE, OS);
+  OS << "\n";
+  emitMacroFusionImpl(Fusions, PE, OS);
+}
+
+static TableGen::Emitter::OptClass<MacroFusionPredicatorEmitter>
+    X("gen-macro-fusion-pred", "Generate macro fusion predicators.");
diff --git a/llvm/utils/TableGen/PredicateExpander.cpp b/llvm/utils/TableGen/PredicateExpander.cpp
index 8f96d3307ded8b..d3a73e02cd916f 100644
--- a/llvm/utils/TableGen/PredicateExpander.cpp
+++ b/llvm/utils/TableGen/PredicateExpander.cpp
@@ -194,6 +194,11 @@ void PredicateExpander::expandCheckIsRegOperand(raw_ostream &OS, int OpIndex) {
      << "getOperand(" << OpIndex << ").isReg() ";
 }
 
+void PredicateExpander::expandCheckIsVRegOperand(raw_ostream &OS, int OpIndex) {
+  OS << (shouldNegate() ? "!" : "") << "MI" << (isByRef() ? "." : "->")
+     << "getOperand(" << OpIndex << ").getReg().isVirtual()";
+}
+
 void PredicateExpander::expandCheckIsImmOperand(raw_ostream &OS, int OpIndex) {
   OS << (shouldNegate() ? "!" : "") << "MI" << (isByRef() ? "." : "->")
      << "getOperand(" << OpIndex << ").isImm() ";
@@ -319,6 +324,9 @@ void PredicateExpander::expandPredicate(raw_ostream &OS, const Record *Rec) {
   if (Rec->isSubClassOf("CheckIsRegOperand"))
     return expandCheckIsRegOperand(OS, Rec->getValueAsInt("OpIndex"));
 
+  if (Rec->isSubClassOf("CheckIsVRegOperand"))
+    return expandCheckIsVRegOperand(OS, Rec->getValueAsInt("OpIndex"));
+
   if (Rec->isSubClassOf("CheckIsImmOperand"))
     return expandCheckIsImmOperand(OS, Rec->getValueAsInt("OpIndex"));
 
diff --git a/llvm/utils/TableGen/PredicateExpander.h b/llvm/utils/TableGen/PredicateExpander.h
index 27f049a715aad5..cfb0a3d51e6776 100644
--- a/llvm/utils/TableGen/PredicateExpander.h
+++ b/llvm/utils/TableGen/PredicateExpander.h
@@ -75,6 +75,7 @@ class PredicateExpander {
                                bool IsCheckAll);
   void expandTIIFunctionCall(raw_ostream &OS, StringRef MethodName);
   void expandCheckIsRegOperand(raw_ostream &OS, int OpIndex);
+  void expandCheckIsVRegOperand(raw_ostream &OS, int OpIndex);
   void expandCheckIsImmOperand(raw_ostream &OS, int OpIndex);
   void expandCheckInvalidRegOperand(raw_ostream &OS, int OpIndex);
   void expandCheckFunctionPredicate(raw_ostream &OS, StringRef MCInstFn,

>From fba9b6ac94de372e8297647e5644b8f079c2b673 Mon Sep 17 00:00:00 2001
From: wangpc <wangpengcheng.pp at bytedance.com>
Date: Tue, 14 Nov 2023 10:48:27 +0800
Subject: [PATCH 3/3] [TableGen] Integrate TableGen-based macro fusion

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

Two methods `enableMacroFusion` and `getMacroFusions` are added to
`TargetSubtargetInfo`. `enableMacroFusion` indicates whether macro
fusion shoule be enabled and `getMacroFusions` returns a list of
`MacroFusionPredTy` that will be evaluated by MacroFusionMution.

`enableMacroFusion` and `getMacroFusions` will be auto-generated
if the target has `Fusion` definitions.
---
 .../llvm/CodeGen/TargetSubtargetInfo.h        |  7 ++
 llvm/include/llvm/Target/Target.td            | 92 +++++++++----------
 llvm/include/llvm/Target/TargetSchedule.td    | 39 ++++----
 llvm/test/TableGen/MacroFusion.td             | 22 ++++-
 llvm/utils/TableGen/CodeGenTarget.cpp         |  1 +
 llvm/utils/TableGen/CodeGenTarget.h           |  6 ++
 llvm/utils/TableGen/SubtargetEmitter.cpp      | 42 +++++++++
 7 files changed, 145 insertions(+), 64 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/TargetSubtargetInfo.h b/llvm/include/llvm/CodeGen/TargetSubtargetInfo.h
index 55ef95c2854319..84b89336db58a5 100644
--- a/llvm/include/llvm/CodeGen/TargetSubtargetInfo.h
+++ b/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 +324,12 @@ class TargetSubtargetInfo : public MCSubtargetInfo {
   /// helps removing redundant copies generated by register allocator when
   /// handling complex eviction chains.
   virtual bool enableSpillageCopyElimination() const { return false; }
+
+  /// Enable macro fusion for this subtarget.
+  virtual bool enableMacroFusion() const { return false; }
+
+  /// Get the list of MacroFusion predicates.
+  virtual std::vector<MacroFusionPredTy> getMacroFusions() const { return {}; };
 };
 
 } // end namespace llvm
diff --git a/llvm/include/llvm/Target/Target.td b/llvm/include/llvm/Target/Target.td
index 3b1d2f45267e9e..0d97a47190b196 100644
--- a/llvm/include/llvm/Target/Target.td
+++ b/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
diff --git a/llvm/include/llvm/Target/TargetSchedule.td b/llvm/include/llvm/Target/TargetSchedule.td
index 74c9cd085b4ee2..003cf2d5844d45 100644
--- a/llvm/include/llvm/Target/TargetSchedule.td
+++ b/llvm/include/llvm/Target/TargetSchedule.td
@@ -658,7 +658,10 @@ 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> {
+  string Name = name;
+  string Desc = desc;
   list<FusionPredicate> Predicates = predicates;
 }
 
@@ -679,21 +682,23 @@ 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)>;
diff --git a/llvm/test/TableGen/MacroFusion.td b/llvm/test/TableGen/MacroFusion.td
index 72b0d1e19144f7..64ded75d1f0865 100644
--- a/llvm/test/TableGen/MacroFusion.td
+++ b/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 +97,21 @@ 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 `enableMacroFusion()` and `getMacroFusions()` function.
+// CHECK-SUBTARGET:      bool enableMacroFusion() const override;
+// CHECK-SUBTARGET:      std::vector<MacroFusionPredTy> getMacroFusions() const override;
+
+// CHECK-SUBTARGET:      bool TestGenSubtargetInfo::enableMacroFusion() const {
+// CHECK-SUBTARGET-NEXT:   if (hasFeature(Test::TestFusion)) return true;
+// CHECK-SUBTARGET-NEXT:   return false;
+// CHECK-SUBTARGET-NEXT: }
+
+// 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: }
diff --git a/llvm/utils/TableGen/CodeGenTarget.cpp b/llvm/utils/TableGen/CodeGenTarget.cpp
index 53efa66f9dfc1b..37fa30349eea9f 100644
--- a/llvm/utils/TableGen/CodeGenTarget.cpp
+++ b/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() {
diff --git a/llvm/utils/TableGen/CodeGenTarget.h b/llvm/utils/TableGen/CodeGenTarget.h
index a2b559d53b19c2..d7388dceca37fe 100644
--- a/llvm/utils/TableGen/CodeGenTarget.h
+++ b/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 {
diff --git a/llvm/utils/TableGen/SubtargetEmitter.cpp b/llvm/utils/TableGen/SubtargetEmitter.cpp
index f7a7172d61fc61..2da35a735aceb5 100644
--- a/llvm/utils/TableGen/SubtargetEmitter.cpp
+++ b/llvm/utils/TableGen/SubtargetEmitter.cpp
@@ -133,6 +133,8 @@ class SubtargetEmitter {
   void EmitMCInstrAnalysisPredicateFunctions(raw_ostream &OS);
 
   void EmitSchedModel(raw_ostream &OS);
+  void emitGetMacroFusions(const std::string &ClassName, raw_ostream &OS);
+  void emitEnableMacroFusion(const std::string &ClassName, raw_ostream &OS);
   void EmitHwModeCheck(const std::string &ClassName, raw_ostream &OS);
   void ParseFeaturesFunction(raw_ostream &OS);
 
@@ -1786,6 +1788,39 @@ void SubtargetEmitter::EmitHwModeCheck(const std::string &ClassName,
   OS << "  return 0;\n}\n";
 }
 
+void SubtargetEmitter::emitEnableMacroFusion(const std::string &ClassName,
+                                             raw_ostream &OS) {
+  if (!TGT.hasMacroFusion())
+    return;
+
+  OS << "bool " << ClassName << "::enableMacroFusion() const {\n";
+  for (auto *Fusion : TGT.getMacroFusions())
+    OS.indent(2) << "if (hasFeature(" << Target
+                 << "::" << Fusion->getNameInitAsString()
+                 << ")) return true;\n";
+
+  OS.indent(2) << "return false;\n";
+  OS << "}\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 +2022,11 @@ void SubtargetEmitter::run(raw_ostream &OS) {
      << " const;\n";
   if (TGT.getHwModes().getNumModeIds() > 1)
     OS << "  unsigned getHwMode() const override;\n";
+  if (TGT.hasMacroFusion()) {
+    OS << "  bool enableMacroFusion() const override;\n";
+    OS << "  std::vector<MacroFusionPredTy> getMacroFusions() const "
+          "override;\n";
+  }
 
   STIPredicateExpander PE(Target);
   PE.setByRef(false);
@@ -2044,6 +2084,8 @@ void SubtargetEmitter::run(raw_ostream &OS) {
 
   EmitSchedModelHelpers(ClassName, OS);
   EmitHwModeCheck(ClassName, OS);
+  emitEnableMacroFusion(ClassName, OS);
+  emitGetMacroFusions(ClassName, OS);
 
   OS << "} // end namespace llvm\n\n";
 



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