1 //===----- HexagonMCShuffler.cpp - MC bundle shuffling --------------------===//
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 // This implements the shuffling of insns inside a bundle according to the
10 // packet formation rules of the Hexagon ISA.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "MCTargetDesc/HexagonMCShuffler.h"
15 #include "MCTargetDesc/HexagonMCInstrInfo.h"
16 #include "MCTargetDesc/HexagonShuffler.h"
17 #include "llvm/MC/MCInst.h"
18 #include "llvm/MC/MCInstrDesc.h"
19 #include "llvm/MC/MCInstrInfo.h"
20 #include "llvm/Support/CommandLine.h"
21 #include "llvm/Support/Debug.h"
22 #include "llvm/Support/raw_ostream.h"
23 #include <cassert>
24
25 #define DEBUG_TYPE "hexagon-shuffle"
26
27 using namespace llvm;
28
29 static cl::opt<bool>
30 DisableShuffle("disable-hexagon-shuffle", cl::Hidden, cl::init(false),
31 cl::desc("Disable Hexagon instruction shuffling"));
32
init(MCInst & MCB)33 void HexagonMCShuffler::init(MCInst &MCB) {
34 if (HexagonMCInstrInfo::isBundle(MCB)) {
35 MCInst const *Extender = nullptr;
36 // Copy the bundle for the shuffling.
37 for (const auto &I : HexagonMCInstrInfo::bundleInstructions(MCB)) {
38 MCInst &MI = *const_cast<MCInst *>(I.getInst());
39 LLVM_DEBUG(dbgs() << "Shuffling: " << MCII.getName(MI.getOpcode())
40 << '\n');
41 assert(!HexagonMCInstrInfo::getDesc(MCII, MI).isPseudo());
42
43 if (!HexagonMCInstrInfo::isImmext(MI)) {
44 append(MI, Extender, HexagonMCInstrInfo::getUnits(MCII, STI, MI));
45 Extender = nullptr;
46 } else
47 Extender = &MI;
48 }
49 }
50
51 Loc = MCB.getLoc();
52 BundleFlags = MCB.getOperand(0).getImm();
53 }
54
init(MCInst & MCB,MCInst const & AddMI,bool bInsertAtFront)55 void HexagonMCShuffler::init(MCInst &MCB, MCInst const &AddMI,
56 bool bInsertAtFront) {
57 if (HexagonMCInstrInfo::isBundle(MCB)) {
58 if (bInsertAtFront)
59 append(AddMI, nullptr, HexagonMCInstrInfo::getUnits(MCII, STI, AddMI));
60 MCInst const *Extender = nullptr;
61 // Copy the bundle for the shuffling.
62 for (auto const &I : HexagonMCInstrInfo::bundleInstructions(MCB)) {
63 assert(!HexagonMCInstrInfo::getDesc(MCII, *I.getInst()).isPseudo());
64 MCInst &MI = *const_cast<MCInst *>(I.getInst());
65 if (!HexagonMCInstrInfo::isImmext(MI)) {
66 append(MI, Extender, HexagonMCInstrInfo::getUnits(MCII, STI, MI));
67 Extender = nullptr;
68 } else
69 Extender = &MI;
70 }
71 if (!bInsertAtFront)
72 append(AddMI, nullptr, HexagonMCInstrInfo::getUnits(MCII, STI, AddMI));
73 }
74
75 Loc = MCB.getLoc();
76 BundleFlags = MCB.getOperand(0).getImm();
77 }
78
copyTo(MCInst & MCB)79 void HexagonMCShuffler::copyTo(MCInst &MCB) {
80 MCB.clear();
81 MCB.addOperand(MCOperand::createImm(BundleFlags));
82 MCB.setLoc(Loc);
83 // Copy the results into the bundle.
84 for (auto &I : *this) {
85 MCInst const &MI = I.getDesc();
86 MCInst const *Extender = I.getExtender();
87 if (Extender)
88 MCB.addOperand(MCOperand::createInst(Extender));
89 MCB.addOperand(MCOperand::createInst(&MI));
90 }
91 }
92
reshuffleTo(MCInst & MCB)93 bool HexagonMCShuffler::reshuffleTo(MCInst &MCB) {
94 if (shuffle()) {
95 // Copy the results into the bundle.
96 copyTo(MCB);
97 return true;
98 }
99 LLVM_DEBUG(MCB.dump());
100 return false;
101 }
102
HexagonMCShuffle(MCContext & Context,bool ReportErrors,MCInstrInfo const & MCII,MCSubtargetInfo const & STI,MCInst & MCB)103 bool llvm::HexagonMCShuffle(MCContext &Context, bool ReportErrors,
104 MCInstrInfo const &MCII, MCSubtargetInfo const &STI,
105 MCInst &MCB) {
106 HexagonMCShuffler MCS(Context, ReportErrors, MCII, STI, MCB);
107
108 if (DisableShuffle)
109 // Ignore if user chose so.
110 return false;
111
112 if (!HexagonMCInstrInfo::bundleSize(MCB)) {
113 // There once was a bundle:
114 // BUNDLE implicit-def %d2, implicit-def %r4, implicit-def %r5,
115 // implicit-def %d7, ...
116 // * %d2 = IMPLICIT_DEF; flags:
117 // * %d7 = IMPLICIT_DEF; flags:
118 // After the IMPLICIT_DEFs were removed by the asm printer, the bundle
119 // became empty.
120 LLVM_DEBUG(dbgs() << "Skipping empty bundle");
121 return false;
122 } else if (!HexagonMCInstrInfo::isBundle(MCB)) {
123 LLVM_DEBUG(dbgs() << "Skipping stand-alone insn");
124 return false;
125 }
126
127 return MCS.reshuffleTo(MCB);
128 }
129
HexagonMCShuffle(MCContext & Context,MCInstrInfo const & MCII,MCSubtargetInfo const & STI,MCInst & MCB,SmallVector<DuplexCandidate,8> possibleDuplexes)130 bool llvm::HexagonMCShuffle(MCContext &Context, MCInstrInfo const &MCII,
131 MCSubtargetInfo const &STI, MCInst &MCB,
132 SmallVector<DuplexCandidate, 8> possibleDuplexes) {
133
134 if (DisableShuffle || possibleDuplexes.size() == 0)
135 return false;
136
137 if (!HexagonMCInstrInfo::bundleSize(MCB)) {
138 // There once was a bundle:
139 // BUNDLE implicit-def %d2, implicit-def %r4, implicit-def %r5,
140 // implicit-def %d7, ...
141 // * %d2 = IMPLICIT_DEF; flags:
142 // * %d7 = IMPLICIT_DEF; flags:
143 // After the IMPLICIT_DEFs were removed by the asm printer, the bundle
144 // became empty.
145 LLVM_DEBUG(dbgs() << "Skipping empty bundle");
146 return false;
147 } else if (!HexagonMCInstrInfo::isBundle(MCB)) {
148 LLVM_DEBUG(dbgs() << "Skipping stand-alone insn");
149 return false;
150 }
151
152 bool doneShuffling = false;
153 while (possibleDuplexes.size() > 0 && (!doneShuffling)) {
154 // case of Duplex Found
155 DuplexCandidate duplexToTry = possibleDuplexes.pop_back_val();
156 MCInst Attempt(MCB);
157 HexagonMCInstrInfo::replaceDuplex(Context, Attempt, duplexToTry);
158 HexagonMCShuffler MCS(Context, false, MCII, STI, Attempt); // copy packet to the shuffler
159 if (MCS.size() == 1) { // case of one duplex
160 // copy the created duplex in the shuffler to the bundle
161 MCS.copyTo(MCB);
162 return false;
163 }
164 // try shuffle with this duplex
165 doneShuffling = MCS.reshuffleTo(MCB);
166
167 if (doneShuffling)
168 break;
169 }
170
171 if (!doneShuffling) {
172 HexagonMCShuffler MCS(Context, false, MCII, STI, MCB);
173 doneShuffling = MCS.reshuffleTo(MCB); // shuffle
174 }
175
176 return doneShuffling;
177 }
178
HexagonMCShuffle(MCContext & Context,MCInstrInfo const & MCII,MCSubtargetInfo const & STI,MCInst & MCB,MCInst const & AddMI,int fixupCount)179 bool llvm::HexagonMCShuffle(MCContext &Context, MCInstrInfo const &MCII,
180 MCSubtargetInfo const &STI, MCInst &MCB,
181 MCInst const &AddMI, int fixupCount) {
182 if (!HexagonMCInstrInfo::isBundle(MCB))
183 return false;
184
185 // if fixups present, make sure we don't insert too many nops that would
186 // later prevent an extender from being inserted.
187 unsigned int bundleSize = HexagonMCInstrInfo::bundleSize(MCB);
188 if (bundleSize >= HEXAGON_PACKET_SIZE)
189 return false;
190 bool bhasDuplex = HexagonMCInstrInfo::hasDuplex(MCII, MCB);
191 if (fixupCount >= 2) {
192 if (bhasDuplex) {
193 if (bundleSize >= HEXAGON_PACKET_SIZE - 1) {
194 return false;
195 }
196 } else {
197 return false;
198 }
199 } else {
200 if (bundleSize == HEXAGON_PACKET_SIZE - 1 && fixupCount)
201 return false;
202 }
203
204 if (DisableShuffle)
205 return false;
206
207 // mgl: temporary code (shuffler doesn't take into account the fact that
208 // a duplex takes up two slots. for example, 3 nops can be put into a packet
209 // containing a duplex oversubscribing slots by 1).
210 unsigned maxBundleSize = (HexagonMCInstrInfo::hasImmExt(MCB))
211 ? HEXAGON_PACKET_SIZE
212 : HEXAGON_PACKET_SIZE - 1;
213 if (bhasDuplex && bundleSize >= maxBundleSize)
214 return false;
215
216 HexagonMCShuffler MCS(Context, false, MCII, STI, MCB, AddMI, false);
217 return MCS.reshuffleTo(MCB);
218 }
219