llvm/lib/Target/Mips/MipsPreLegalizerCombiner.cpp

   1 //=== lib/CodeGen/GlobalISel/MipsPreLegalizerCombiner.cpp --------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This pass does combining of machine instructions at the generic MI level,
  10 // before the legalizer.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "MipsLegalizerInfo.h"
  15 #include "MipsTargetMachine.h"
  16 #include "llvm/CodeGen/GlobalISel/Combiner.h"
  17 #include "llvm/CodeGen/GlobalISel/CombinerHelper.h"
  18 #include "llvm/CodeGen/GlobalISel/CombinerInfo.h"
  19 #include "llvm/CodeGen/GlobalISel/GISelKnownBits.h"
  20 #include "llvm/CodeGen/MachineFunctionPass.h"
  21 #include "llvm/CodeGen/TargetPassConfig.h"
  22 #include "llvm/InitializePasses.h"
  23
  24 #define DEBUG_TYPE "mips-prelegalizer-combiner"
  25
  26 using namespace llvm;
  27
  28 namespace {
  29 struct MipsPreLegalizerCombinerInfo : public CombinerInfo {
  30 public:
  31   MipsPreLegalizerCombinerInfo()
  32       : CombinerInfo(/*AllowIllegalOps*/ true, /*ShouldLegalizeIllegal*/ false,
  33                      /*LegalizerInfo*/ nullptr, /*EnableOpt*/ false,
  34                      /*EnableOptSize*/ false, /*EnableMinSize*/ false) {}
  35 };
  36
  37 class MipsPreLegalizerCombinerImpl : public Combiner {
  38 protected:
  39   const MipsSubtarget &STI;
  40   // TODO: Make CombinerHelper methods const.
  41   mutable CombinerHelper Helper;
  42
  43 public:
  44   MipsPreLegalizerCombinerImpl(MachineFunction &MF, CombinerInfo &CInfo,
  45                                const TargetPassConfig *TPC, GISelKnownBits &KB,
  46                                GISelCSEInfo *CSEInfo, const MipsSubtarget &STI,
  47                                MachineDominatorTree *MDT,
  48                                const LegalizerInfo *LI)
  49       : Combiner(MF, CInfo, TPC, &KB, CSEInfo), STI(STI),
  50         Helper(Observer, B, /*IsPreLegalize*/ true, &KB, MDT, LI) {}
  51
  52   static const char *getName() { return "MipsPreLegalizerCombiner"; }
  53
  54   void setupGeneratedPerFunctionState(MachineFunction &MF) override {
  55     // TODO: TableGen-erate this class' impl.
  56   }
  57
  58   bool tryCombineAll(MachineInstr &MI) const override {
  59
  60     switch (MI.getOpcode()) {
  61     default:
  62       return false;
  63     case TargetOpcode::G_MEMCPY_INLINE:
  64       return Helper.tryEmitMemcpyInline(MI);
  65     case TargetOpcode::G_LOAD:
  66     case TargetOpcode::G_SEXTLOAD:
  67     case TargetOpcode::G_ZEXTLOAD: {
  68       // Don't attempt to combine non power of 2 loads or unaligned loads when
  69       // subtarget doesn't support them.
  70       auto MMO = *MI.memoperands_begin();
  71       const MipsSubtarget &STI = MI.getMF()->getSubtarget<MipsSubtarget>();
  72       if (!MMO->getSize().hasValue() ||
  73           !isPowerOf2_64(MMO->getSize().getValue()))
  74         return false;
  75       bool isUnaligned = MMO->getAlign() < MMO->getSize().getValue();
  76       if (!STI.systemSupportsUnalignedAccess() && isUnaligned)
  77         return false;
  78
  79       return Helper.tryCombineExtendingLoads(MI);
  80     }
  81     }
  82
  83     return false;
  84   }
  85 };
  86
  87 // Pass boilerplate
  88 // ================
  89
  90 class MipsPreLegalizerCombiner : public MachineFunctionPass {
  91 public:
  92   static char ID;
  93
  94   MipsPreLegalizerCombiner();
  95
  96   StringRef getPassName() const override { return "MipsPreLegalizerCombiner"; }
  97
  98   bool runOnMachineFunction(MachineFunction &MF) override;
  99
 100   void getAnalysisUsage(AnalysisUsage &AU) const override;
 101 };
 102 } // end anonymous namespace
 103
 104 void MipsPreLegalizerCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
 105   AU.addRequired<TargetPassConfig>();
 106   AU.addRequired<GISelKnownBitsAnalysis>();
 107   AU.addPreserved<GISelKnownBitsAnalysis>();
 108   AU.setPreservesCFG();
 109   getSelectionDAGFallbackAnalysisUsage(AU);
 110   MachineFunctionPass::getAnalysisUsage(AU);
 111 }
 112
 113 MipsPreLegalizerCombiner::MipsPreLegalizerCombiner() : MachineFunctionPass(ID) {
 114   initializeMipsPreLegalizerCombinerPass(*PassRegistry::getPassRegistry());
 115 }
 116
 117 bool MipsPreLegalizerCombiner::runOnMachineFunction(MachineFunction &MF) {
 118   if (MF.getProperties().hasProperty(
 119           MachineFunctionProperties::Property::FailedISel))
 120     return false;
 121
 122   auto *TPC = &getAnalysis<TargetPassConfig>();
 123   const MipsSubtarget &ST = MF.getSubtarget<MipsSubtarget>();
 124   const MipsLegalizerInfo *LI =
 125       static_cast<const MipsLegalizerInfo *>(ST.getLegalizerInfo());
 126
 127   GISelKnownBits *KB = &getAnalysis<GISelKnownBitsAnalysis>().get(MF);
 128   MipsPreLegalizerCombinerInfo PCInfo;
 129   MipsPreLegalizerCombinerImpl Impl(MF, PCInfo, TPC, *KB, /*CSEInfo*/ nullptr,
 130                                     ST, /*MDT*/ nullptr, LI);
 131   return Impl.combineMachineInstrs();
 132 }
 133
 134 char MipsPreLegalizerCombiner::ID = 0;
 135 INITIALIZE_PASS_BEGIN(MipsPreLegalizerCombiner, DEBUG_TYPE,
 136                       "Combine Mips machine instrs before legalization", false,
 137                       false)
 138 INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
 139 INITIALIZE_PASS_DEPENDENCY(GISelKnownBitsAnalysis)
 140 INITIALIZE_PASS_END(MipsPreLegalizerCombiner, DEBUG_TYPE,
 141                     "Combine Mips machine instrs before legalization", false,
 142                     false)
 143
 144 namespace llvm {
 145 FunctionPass *createMipsPreLegalizeCombiner() {
 146   return new MipsPreLegalizerCombiner();
 147 }
 148 } // end namespace llvm