1//===------ LeonPasses.cpp - Define passes specific to LEON ---------------===//
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//
10//===----------------------------------------------------------------------===//
11
12#include "LeonPasses.h"
13#include "llvm/CodeGen/ISDOpcodes.h"
14#include "llvm/CodeGen/MachineFunction.h"
15#include "llvm/CodeGen/MachineInstr.h"
16#include "llvm/CodeGen/MachineInstrBuilder.h"
17#include "llvm/CodeGen/MachineRegisterInfo.h"
18#include "llvm/IR/DiagnosticInfo.h"
19#include "llvm/IR/LLVMContext.h"
20#include "llvm/Support/raw_ostream.h"
21using namespace llvm;
22
23LEONMachineFunctionPass::LEONMachineFunctionPass(char &ID)
24    : MachineFunctionPass(ID) {}
25
26//*****************************************************************************
27//**** InsertNOPLoad pass
28//*****************************************************************************
29// This pass fixes the incorrectly working Load instructions that exists for
30// some earlier versions of the LEON processor line. NOP instructions must
31// be inserted after the load instruction to ensure that the Load instruction
32// behaves as expected for these processors.
33//
34// This pass inserts a NOP after any LD or LDF instruction.
35//
36char InsertNOPLoad::ID = 0;
37
38InsertNOPLoad::InsertNOPLoad() : LEONMachineFunctionPass(ID) {}
39
40bool InsertNOPLoad::runOnMachineFunction(MachineFunction &MF) {
41  Subtarget = &MF.getSubtarget<SparcSubtarget>();
42  const TargetInstrInfo &TII = *Subtarget->getInstrInfo();
43  DebugLoc DL = DebugLoc();
44
45  bool Modified = false;
46  for (auto MFI = MF.begin(), E = MF.end(); MFI != E; ++MFI) {
47    MachineBasicBlock &MBB = *MFI;
48    for (auto MBBI = MBB.begin(), E = MBB.end(); MBBI != E; ++MBBI) {
49      MachineInstr &MI = *MBBI;
50      unsigned Opcode = MI.getOpcode();
51      if (Opcode >= SP::LDDArr && Opcode <= SP::LDrr) {
52        MachineBasicBlock::iterator NMBBI = std::next(MBBI);
53        BuildMI(MBB, NMBBI, DL, TII.get(SP::NOP));
54        Modified = true;
55      }
56    }
57  }
58
59  return Modified;
60}
61
62
63
64//*****************************************************************************
65//**** DetectRoundChange pass
66//*****************************************************************************
67// To prevent any explicit change of the default rounding mode, this pass
68// detects any call of the fesetround function.
69// A warning is generated to ensure the user knows this has happened.
70//
71// Detects an erratum in UT699 LEON 3 processor
72
73char DetectRoundChange::ID = 0;
74
75DetectRoundChange::DetectRoundChange() : LEONMachineFunctionPass(ID) {}
76
77bool DetectRoundChange::runOnMachineFunction(MachineFunction &MF) {
78  Subtarget = &MF.getSubtarget<SparcSubtarget>();
79
80  bool Modified = false;
81  for (auto MFI = MF.begin(), E = MF.end(); MFI != E; ++MFI) {
82    MachineBasicBlock &MBB = *MFI;
83    for (auto MBBI = MBB.begin(), E = MBB.end(); MBBI != E; ++MBBI) {
84      MachineInstr &MI = *MBBI;
85      unsigned Opcode = MI.getOpcode();
86      if (Opcode == SP::CALL && MI.getNumOperands() > 0) {
87        MachineOperand &MO = MI.getOperand(0);
88
89        if (MO.isGlobal()) {
90          StringRef FuncName = MO.getGlobal()->getName();
91          if (FuncName.compare_lower("fesetround") == 0) {
92            errs() << "Error: You are using the detectroundchange "
93                      "option to detect rounding changes that will "
94                      "cause LEON errata. The only way to fix this "
95                      "is to remove the call to fesetround from "
96                      "the source code.\n";
97          }
98        }
99      }
100    }
101  }
102
103  return Modified;
104}
105
106//*****************************************************************************
107//**** FixAllFDIVSQRT pass
108//*****************************************************************************
109// This pass fixes the incorrectly working FDIVx and FSQRTx instructions that
110// exist for some earlier versions of the LEON processor line. Five NOP
111// instructions need to be inserted after these instructions to ensure the
112// correct result is placed in the destination registers before they are used.
113//
114// This pass implements two fixes:
115//  1) fixing the FSQRTS and FSQRTD instructions.
116//  2) fixing the FDIVS and FDIVD instructions.
117//
118// FSQRTS and FDIVS are converted to FDIVD and FSQRTD respectively earlier in
119// the pipeline when this option is enabled, so this pass needs only to deal
120// with the changes that still need implementing for the "double" versions
121// of these instructions.
122//
123char FixAllFDIVSQRT::ID = 0;
124
125FixAllFDIVSQRT::FixAllFDIVSQRT() : LEONMachineFunctionPass(ID) {}
126
127bool FixAllFDIVSQRT::runOnMachineFunction(MachineFunction &MF) {
128  Subtarget = &MF.getSubtarget<SparcSubtarget>();
129  const TargetInstrInfo &TII = *Subtarget->getInstrInfo();
130  DebugLoc DL = DebugLoc();
131
132  bool Modified = false;
133  for (auto MFI = MF.begin(), E = MF.end(); MFI != E; ++MFI) {
134    MachineBasicBlock &MBB = *MFI;
135    for (auto MBBI = MBB.begin(), E = MBB.end(); MBBI != E; ++MBBI) {
136      MachineInstr &MI = *MBBI;
137      unsigned Opcode = MI.getOpcode();
138
139      // Note: FDIVS and FSQRTS cannot be generated when this erratum fix is
140      // switched on so we don't need to check for them here. They will
141      // already have been converted to FSQRTD or FDIVD earlier in the
142      // pipeline.
143      if (Opcode == SP::FSQRTD || Opcode == SP::FDIVD) {
144        for (int InsertedCount = 0; InsertedCount < 5; InsertedCount++)
145          BuildMI(MBB, MBBI, DL, TII.get(SP::NOP));
146
147        MachineBasicBlock::iterator NMBBI = std::next(MBBI);
148        for (int InsertedCount = 0; InsertedCount < 28; InsertedCount++)
149          BuildMI(MBB, NMBBI, DL, TII.get(SP::NOP));
150
151        Modified = true;
152      }
153    }
154  }
155
156  return Modified;
157}
158