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 "MipsTargetMachine.h"
15 #include "llvm/CodeGen/GlobalISel/Combiner.h"
16 #include "llvm/CodeGen/GlobalISel/CombinerHelper.h"
17 #include "llvm/CodeGen/GlobalISel/CombinerInfo.h"
18 #include "llvm/CodeGen/GlobalISel/MIPatternMatch.h"
19 #include "llvm/CodeGen/MachineFunctionPass.h"
20 #include "llvm/CodeGen/TargetPassConfig.h"
21 #include "llvm/InitializePasses.h"
22 
23 #define DEBUG_TYPE "mips-prelegalizer-combiner"
24 
25 using namespace llvm;
26 
27 namespace {
28 class MipsPreLegalizerCombinerInfo : public CombinerInfo {
29 public:
30   MipsPreLegalizerCombinerInfo()
31       : CombinerInfo(/*AllowIllegalOps*/ true, /*ShouldLegalizeIllegal*/ false,
32                      /*LegalizerInfo*/ nullptr, /*EnableOpt*/ false,
33                      /*EnableOptSize*/ false, /*EnableMinSize*/ false) {}
34   virtual bool combine(GISelChangeObserver &Observer, MachineInstr &MI,
35                        MachineIRBuilder &B) const override;
36 };
37 
38 bool MipsPreLegalizerCombinerInfo::combine(GISelChangeObserver &Observer,
39                                            MachineInstr &MI,
40                                            MachineIRBuilder &B) const {
41   CombinerHelper Helper(Observer, B);
42 
43   switch (MI.getOpcode()) {
44   default:
45     return false;
46   case TargetOpcode::G_MEMCPY_INLINE:
47     return Helper.tryEmitMemcpyInline(MI);
48   case TargetOpcode::G_LOAD:
49   case TargetOpcode::G_SEXTLOAD:
50   case TargetOpcode::G_ZEXTLOAD: {
51     // Don't attempt to combine non power of 2 loads or unaligned loads when
52     // subtarget doesn't support them.
53     auto MMO = *MI.memoperands_begin();
54     const MipsSubtarget &STI =
55         static_cast<const MipsSubtarget &>(MI.getMF()->getSubtarget());
56     if (!isPowerOf2_64(MMO->getSize()))
57       return false;
58     bool isUnaligned = MMO->getAlign() < MMO->getSize();
59     if (!STI.systemSupportsUnalignedAccess() && isUnaligned)
60       return false;
61 
62     return Helper.tryCombineExtendingLoads(MI);
63   }
64   }
65 
66   return false;
67 }
68 
69 // Pass boilerplate
70 // ================
71 
72 class MipsPreLegalizerCombiner : public MachineFunctionPass {
73 public:
74   static char ID;
75 
76   MipsPreLegalizerCombiner();
77 
78   StringRef getPassName() const override { return "MipsPreLegalizerCombiner"; }
79 
80   bool runOnMachineFunction(MachineFunction &MF) override;
81 
82   void getAnalysisUsage(AnalysisUsage &AU) const override;
83 };
84 } // end anonymous namespace
85 
86 void MipsPreLegalizerCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
87   AU.addRequired<TargetPassConfig>();
88   AU.setPreservesCFG();
89   getSelectionDAGFallbackAnalysisUsage(AU);
90   MachineFunctionPass::getAnalysisUsage(AU);
91 }
92 
93 MipsPreLegalizerCombiner::MipsPreLegalizerCombiner() : MachineFunctionPass(ID) {
94   initializeMipsPreLegalizerCombinerPass(*PassRegistry::getPassRegistry());
95 }
96 
97 bool MipsPreLegalizerCombiner::runOnMachineFunction(MachineFunction &MF) {
98   if (MF.getProperties().hasProperty(
99           MachineFunctionProperties::Property::FailedISel))
100     return false;
101   auto *TPC = &getAnalysis<TargetPassConfig>();
102   MipsPreLegalizerCombinerInfo PCInfo;
103   Combiner C(PCInfo, TPC);
104   return C.combineMachineInstrs(MF, nullptr);
105 }
106 
107 char MipsPreLegalizerCombiner::ID = 0;
108 INITIALIZE_PASS_BEGIN(MipsPreLegalizerCombiner, DEBUG_TYPE,
109                       "Combine Mips machine instrs before legalization", false,
110                       false)
111 INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
112 INITIALIZE_PASS_END(MipsPreLegalizerCombiner, DEBUG_TYPE,
113                     "Combine Mips machine instrs before legalization", false,
114                     false)
115 
116 namespace llvm {
117 FunctionPass *createMipsPreLegalizeCombiner() {
118   return new MipsPreLegalizerCombiner();
119 }
120 } // end namespace llvm
121