1 //===------ LeonPasses.cpp - Define passes specific to LEON ---------------===//
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 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "LeonPasses.h"
14 #include "llvm/CodeGen/ISDOpcodes.h"
15 #include "llvm/CodeGen/MachineFunction.h"
16 #include "llvm/CodeGen/MachineInstr.h"
17 #include "llvm/CodeGen/MachineInstrBuilder.h"
18 #include "llvm/CodeGen/MachineRegisterInfo.h"
19 #include "llvm/IR/DiagnosticInfo.h"
20 #include "llvm/IR/LLVMContext.h"
21 #include "llvm/Support/raw_ostream.h"
22 using namespace llvm;
23 
24 LEONMachineFunctionPass::LEONMachineFunctionPass(char &ID)
25     : MachineFunctionPass(ID) {}
26 
27 //*****************************************************************************
28 //**** InsertNOPLoad pass
29 //*****************************************************************************
30 // This pass fixes the incorrectly working Load instructions that exists for
31 // some earlier versions of the LEON processor line. NOP instructions must
32 // be inserted after the load instruction to ensure that the Load instruction
33 // behaves as expected for these processors.
34 //
35 // This pass inserts a NOP after any LD or LDF instruction.
36 //
37 char InsertNOPLoad::ID = 0;
38 
39 InsertNOPLoad::InsertNOPLoad() : LEONMachineFunctionPass(ID) {}
40 
41 bool InsertNOPLoad::runOnMachineFunction(MachineFunction &MF) {
42   Subtarget = &MF.getSubtarget<SparcSubtarget>();
43   const TargetInstrInfo &TII = *Subtarget->getInstrInfo();
44   DebugLoc DL = DebugLoc();
45 
46   bool Modified = false;
47   for (auto MFI = MF.begin(), E = MF.end(); MFI != E; ++MFI) {
48     MachineBasicBlock &MBB = *MFI;
49     for (auto MBBI = MBB.begin(), E = MBB.end(); MBBI != E; ++MBBI) {
50       MachineInstr &MI = *MBBI;
51       unsigned Opcode = MI.getOpcode();
52       if (Opcode >= SP::LDDArr && Opcode <= SP::LDrr) {
53         MachineBasicBlock::iterator NMBBI = std::next(MBBI);
54         BuildMI(MBB, NMBBI, DL, TII.get(SP::NOP));
55         Modified = true;
56       }
57     }
58   }
59 
60   return Modified;
61 }
62 
63 
64 
65 //*****************************************************************************
66 //**** DetectRoundChange pass
67 //*****************************************************************************
68 // To prevent any explicit change of the default rounding mode, this pass
69 // detects any call of the fesetround function.
70 // A warning is generated to ensure the user knows this has happened.
71 //
72 // Detects an erratum in UT699 LEON 3 processor
73 
74 char DetectRoundChange::ID = 0;
75 
76 DetectRoundChange::DetectRoundChange() : LEONMachineFunctionPass(ID) {}
77 
78 bool DetectRoundChange::runOnMachineFunction(MachineFunction &MF) {
79   Subtarget = &MF.getSubtarget<SparcSubtarget>();
80 
81   bool Modified = false;
82   for (auto MFI = MF.begin(), E = MF.end(); MFI != E; ++MFI) {
83     MachineBasicBlock &MBB = *MFI;
84     for (auto MBBI = MBB.begin(), E = MBB.end(); MBBI != E; ++MBBI) {
85       MachineInstr &MI = *MBBI;
86       unsigned Opcode = MI.getOpcode();
87       if (Opcode == SP::CALL && MI.getNumOperands() > 0) {
88         MachineOperand &MO = MI.getOperand(0);
89 
90         if (MO.isGlobal()) {
91           StringRef FuncName = MO.getGlobal()->getName();
92           if (FuncName.compare_lower("fesetround") == 0) {
93             errs() << "Error: You are using the detectroundchange "
94                       "option to detect rounding changes that will "
95                       "cause LEON errata. The only way to fix this "
96                       "is to remove the call to fesetround from "
97                       "the source code.\n";
98           }
99         }
100       }
101     }
102   }
103 
104   return Modified;
105 }
106 
107 //*****************************************************************************
108 //**** FixAllFDIVSQRT pass
109 //*****************************************************************************
110 // This pass fixes the incorrectly working FDIVx and FSQRTx instructions that
111 // exist for some earlier versions of the LEON processor line. Five NOP
112 // instructions need to be inserted after these instructions to ensure the
113 // correct result is placed in the destination registers before they are used.
114 //
115 // This pass implements two fixes:
116 //  1) fixing the FSQRTS and FSQRTD instructions.
117 //  2) fixing the FDIVS and FDIVD instructions.
118 //
119 // FSQRTS and FDIVS are converted to FDIVD and FSQRTD respectively earlier in
120 // the pipeline when this option is enabled, so this pass needs only to deal
121 // with the changes that still need implementing for the "double" versions
122 // of these instructions.
123 //
124 char FixAllFDIVSQRT::ID = 0;
125 
126 FixAllFDIVSQRT::FixAllFDIVSQRT() : LEONMachineFunctionPass(ID) {}
127 
128 bool FixAllFDIVSQRT::runOnMachineFunction(MachineFunction &MF) {
129   Subtarget = &MF.getSubtarget<SparcSubtarget>();
130   const TargetInstrInfo &TII = *Subtarget->getInstrInfo();
131   DebugLoc DL = DebugLoc();
132 
133   bool Modified = false;
134   for (auto MFI = MF.begin(), E = MF.end(); MFI != E; ++MFI) {
135     MachineBasicBlock &MBB = *MFI;
136     for (auto MBBI = MBB.begin(), E = MBB.end(); MBBI != E; ++MBBI) {
137       MachineInstr &MI = *MBBI;
138       unsigned Opcode = MI.getOpcode();
139 
140       // Note: FDIVS and FSQRTS cannot be generated when this erratum fix is
141       // switched on so we don't need to check for them here. They will
142       // already have been converted to FSQRTD or FDIVD earlier in the
143       // pipeline.
144       if (Opcode == SP::FSQRTD || Opcode == SP::FDIVD) {
145         for (int InsertedCount = 0; InsertedCount < 5; InsertedCount++)
146           BuildMI(MBB, MBBI, DL, TII.get(SP::NOP));
147 
148         MachineBasicBlock::iterator NMBBI = std::next(MBBI);
149         for (int InsertedCount = 0; InsertedCount < 28; InsertedCount++)
150           BuildMI(MBB, NMBBI, DL, TII.get(SP::NOP));
151 
152         Modified = true;
153       }
154     }
155   }
156 
157   return Modified;
158 }
159