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