1 //=== HexagonSplitConst32AndConst64.cpp - split CONST32/Const64 into HI/LO ===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // When the compiler is invoked with no small data, for instance, with the -G0
11 // command line option, then all CONST* opcodes should be broken down into
12 // appropriate LO and HI instructions. This splitting is done by this pass.
13 // The only reason this is not done in the DAG lowering itself is that there
14 // is no simple way of getting the register allocator to allot the same hard
15 // register to the result of LO and HI instructions. This pass is always
16 // scheduled after register allocation.
17 //
18 //===----------------------------------------------------------------------===//
19 
20 #include "HexagonSubtarget.h"
21 #include "HexagonTargetMachine.h"
22 #include "HexagonTargetObjectFile.h"
23 #include "llvm/CodeGen/MachineFunctionPass.h"
24 #include "llvm/CodeGen/MachineInstrBuilder.h"
25 #include "llvm/CodeGen/Passes.h"
26 #include "llvm/Target/TargetInstrInfo.h"
27 #include "llvm/Target/TargetRegisterInfo.h"
28 
29 using namespace llvm;
30 
31 #define DEBUG_TYPE "xfer"
32 
33 namespace llvm {
34   FunctionPass *createHexagonSplitConst32AndConst64();
35   void initializeHexagonSplitConst32AndConst64Pass(PassRegistry&);
36 }
37 
38 namespace {
39   class HexagonSplitConst32AndConst64 : public MachineFunctionPass {
40   public:
41     static char ID;
42     HexagonSplitConst32AndConst64() : MachineFunctionPass(ID) {
43       PassRegistry &R = *PassRegistry::getPassRegistry();
44       initializeHexagonSplitConst32AndConst64Pass(R);
45     }
46     StringRef getPassName() const override {
47       return "Hexagon Split Const32s and Const64s";
48     }
49     bool runOnMachineFunction(MachineFunction &Fn) override;
50     MachineFunctionProperties getRequiredProperties() const override {
51       return MachineFunctionProperties().set(
52           MachineFunctionProperties::Property::NoVRegs);
53     }
54   };
55 }
56 
57 char HexagonSplitConst32AndConst64::ID = 0;
58 
59 INITIALIZE_PASS(HexagonSplitConst32AndConst64, "split-const-for-sdata",
60       "Hexagon Split Const32s and Const64s", false, false)
61 
62 bool HexagonSplitConst32AndConst64::runOnMachineFunction(MachineFunction &Fn) {
63   const HexagonTargetObjectFile &TLOF =
64       *static_cast<const HexagonTargetObjectFile *>(
65           Fn.getTarget().getObjFileLowering());
66   if (TLOF.isSmallDataEnabled())
67     return true;
68 
69   const TargetInstrInfo *TII = Fn.getSubtarget().getInstrInfo();
70   const TargetRegisterInfo *TRI = Fn.getSubtarget().getRegisterInfo();
71 
72   // Loop over all of the basic blocks
73   for (MachineBasicBlock &B : Fn) {
74     for (auto I = B.begin(), E = B.end(); I != E; ) {
75       MachineInstr &MI = *I;
76       ++I;
77       unsigned Opc = MI.getOpcode();
78 
79       if (Opc == Hexagon::CONST32) {
80         unsigned DestReg = MI.getOperand(0).getReg();
81         uint64_t ImmValue = MI.getOperand(1).getImm();
82         const DebugLoc &DL = MI.getDebugLoc();
83         BuildMI(B, MI, DL, TII->get(Hexagon::A2_tfrsi), DestReg)
84             .addImm(ImmValue);
85         B.erase(&MI);
86       } else if (Opc == Hexagon::CONST64) {
87         unsigned DestReg = MI.getOperand(0).getReg();
88         int64_t ImmValue = MI.getOperand(1).getImm();
89         const DebugLoc &DL = MI.getDebugLoc();
90         unsigned DestLo = TRI->getSubReg(DestReg, Hexagon::isub_lo);
91         unsigned DestHi = TRI->getSubReg(DestReg, Hexagon::isub_hi);
92 
93         int32_t LowWord = (ImmValue & 0xFFFFFFFF);
94         int32_t HighWord = (ImmValue >> 32) & 0xFFFFFFFF;
95 
96         BuildMI(B, MI, DL, TII->get(Hexagon::A2_tfrsi), DestLo)
97             .addImm(LowWord);
98         BuildMI(B, MI, DL, TII->get(Hexagon::A2_tfrsi), DestHi)
99             .addImm(HighWord);
100         B.erase(&MI);
101       }
102     }
103   }
104 
105   return true;
106 }
107 
108 
109 //===----------------------------------------------------------------------===//
110 //                         Public Constructor Functions
111 //===----------------------------------------------------------------------===//
112 
113 FunctionPass *llvm::createHexagonSplitConst32AndConst64() {
114   return new HexagonSplitConst32AndConst64();
115 }
116