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 "SparcSubtarget.h"
14 #include "llvm/CodeGen/MachineBasicBlock.h"
15 #include "llvm/CodeGen/MachineFunction.h"
16 #include "llvm/CodeGen/MachineInstr.h"
17 #include "llvm/CodeGen/MachineInstrBuilder.h"
18 #include "llvm/Support/raw_ostream.h"
19
20 using namespace llvm;
21
LEONMachineFunctionPass(char & ID)22 LEONMachineFunctionPass::LEONMachineFunctionPass(char &ID)
23 : MachineFunctionPass(ID) {}
24
25 //*****************************************************************************
26 //**** InsertNOPLoad pass
27 //*****************************************************************************
28 // This pass fixes the incorrectly working Load instructions that exists for
29 // some earlier versions of the LEON processor line. NOP instructions must
30 // be inserted after the load instruction to ensure that the Load instruction
31 // behaves as expected for these processors.
32 //
33 // This pass inserts a NOP after any LD or LDF instruction.
34 //
35 char InsertNOPLoad::ID = 0;
36
InsertNOPLoad()37 InsertNOPLoad::InsertNOPLoad() : LEONMachineFunctionPass(ID) {}
38
runOnMachineFunction(MachineFunction & MF)39 bool InsertNOPLoad::runOnMachineFunction(MachineFunction &MF) {
40 Subtarget = &MF.getSubtarget<SparcSubtarget>();
41 if (!Subtarget->insertNOPLoad())
42 return false;
43
44 const TargetInstrInfo &TII = *Subtarget->getInstrInfo();
45 DebugLoc DL = DebugLoc();
46
47 bool Modified = false;
48 for (MachineBasicBlock &MBB : MF) {
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
DetectRoundChange()76 DetectRoundChange::DetectRoundChange() : LEONMachineFunctionPass(ID) {}
77
runOnMachineFunction(MachineFunction & MF)78 bool DetectRoundChange::runOnMachineFunction(MachineFunction &MF) {
79 Subtarget = &MF.getSubtarget<SparcSubtarget>();
80 if (!Subtarget->detectRoundChange())
81 return false;
82
83 bool Modified = false;
84 for (MachineBasicBlock &MBB : MF) {
85 for (MachineInstr &MI : MBB) {
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_insensitive("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
FixAllFDIVSQRT()126 FixAllFDIVSQRT::FixAllFDIVSQRT() : LEONMachineFunctionPass(ID) {}
127
runOnMachineFunction(MachineFunction & MF)128 bool FixAllFDIVSQRT::runOnMachineFunction(MachineFunction &MF) {
129 Subtarget = &MF.getSubtarget<SparcSubtarget>();
130 if (!Subtarget->fixAllFDIVSQRT())
131 return false;
132
133 const TargetInstrInfo &TII = *Subtarget->getInstrInfo();
134 DebugLoc DL = DebugLoc();
135
136 bool Modified = false;
137 for (MachineBasicBlock &MBB : MF) {
138 for (auto MBBI = MBB.begin(), E = MBB.end(); MBBI != E; ++MBBI) {
139 MachineInstr &MI = *MBBI;
140 unsigned Opcode = MI.getOpcode();
141
142 // Note: FDIVS and FSQRTS cannot be generated when this erratum fix is
143 // switched on so we don't need to check for them here. They will
144 // already have been converted to FSQRTD or FDIVD earlier in the
145 // pipeline.
146 if (Opcode == SP::FSQRTD || Opcode == SP::FDIVD) {
147 for (int InsertedCount = 0; InsertedCount < 5; InsertedCount++)
148 BuildMI(MBB, MBBI, DL, TII.get(SP::NOP));
149
150 MachineBasicBlock::iterator NMBBI = std::next(MBBI);
151 for (int InsertedCount = 0; InsertedCount < 28; InsertedCount++)
152 BuildMI(MBB, NMBBI, DL, TII.get(SP::NOP));
153
154 Modified = true;
155 }
156 }
157 }
158
159 return Modified;
160 }
161