xref: /freebsd/contrib/llvm-project/llvm/lib/Object/OffloadBinary.cpp (revision b1879975794772ee51f0b4865753364c7d7626c3)
1 //===- Offloading.cpp - Utilities for handling offloading code  -*- C++ -*-===//
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 #include "llvm/Object/OffloadBinary.h"
10 
11 #include "llvm/ADT/StringSwitch.h"
12 #include "llvm/BinaryFormat/Magic.h"
13 #include "llvm/IR/Constants.h"
14 #include "llvm/IR/Module.h"
15 #include "llvm/IRReader/IRReader.h"
16 #include "llvm/MC/StringTableBuilder.h"
17 #include "llvm/Object/Archive.h"
18 #include "llvm/Object/ArchiveWriter.h"
19 #include "llvm/Object/Binary.h"
20 #include "llvm/Object/COFF.h"
21 #include "llvm/Object/ELFObjectFile.h"
22 #include "llvm/Object/Error.h"
23 #include "llvm/Object/IRObjectFile.h"
24 #include "llvm/Object/ObjectFile.h"
25 #include "llvm/Support/Alignment.h"
26 #include "llvm/Support/FileOutputBuffer.h"
27 #include "llvm/Support/SourceMgr.h"
28 
29 using namespace llvm;
30 using namespace llvm::object;
31 
32 namespace {
33 
34 /// Attempts to extract all the embedded device images contained inside the
35 /// buffer \p Contents. The buffer is expected to contain a valid offloading
36 /// binary format.
37 Error extractOffloadFiles(MemoryBufferRef Contents,
38                           SmallVectorImpl<OffloadFile> &Binaries) {
39   uint64_t Offset = 0;
40   // There could be multiple offloading binaries stored at this section.
41   while (Offset < Contents.getBuffer().size()) {
42     std::unique_ptr<MemoryBuffer> Buffer =
43         MemoryBuffer::getMemBuffer(Contents.getBuffer().drop_front(Offset), "",
44                                    /*RequiresNullTerminator*/ false);
45     if (!isAddrAligned(Align(OffloadBinary::getAlignment()),
46                        Buffer->getBufferStart()))
47       Buffer = MemoryBuffer::getMemBufferCopy(Buffer->getBuffer(),
48                                               Buffer->getBufferIdentifier());
49     auto BinaryOrErr = OffloadBinary::create(*Buffer);
50     if (!BinaryOrErr)
51       return BinaryOrErr.takeError();
52     OffloadBinary &Binary = **BinaryOrErr;
53 
54     // Create a new owned binary with a copy of the original memory.
55     std::unique_ptr<MemoryBuffer> BufferCopy = MemoryBuffer::getMemBufferCopy(
56         Binary.getData().take_front(Binary.getSize()),
57         Contents.getBufferIdentifier());
58     auto NewBinaryOrErr = OffloadBinary::create(*BufferCopy);
59     if (!NewBinaryOrErr)
60       return NewBinaryOrErr.takeError();
61     Binaries.emplace_back(std::move(*NewBinaryOrErr), std::move(BufferCopy));
62 
63     Offset += Binary.getSize();
64   }
65 
66   return Error::success();
67 }
68 
69 // Extract offloading binaries from an Object file \p Obj.
70 Error extractFromObject(const ObjectFile &Obj,
71                         SmallVectorImpl<OffloadFile> &Binaries) {
72   assert((Obj.isELF() || Obj.isCOFF()) && "Invalid file type");
73 
74   for (SectionRef Sec : Obj.sections()) {
75     // ELF files contain a section with the LLVM_OFFLOADING type.
76     if (Obj.isELF() &&
77         static_cast<ELFSectionRef>(Sec).getType() != ELF::SHT_LLVM_OFFLOADING)
78       continue;
79 
80     // COFF has no section types so we rely on the name of the section.
81     if (Obj.isCOFF()) {
82       Expected<StringRef> NameOrErr = Sec.getName();
83       if (!NameOrErr)
84         return NameOrErr.takeError();
85 
86       if (!NameOrErr->starts_with(".llvm.offloading"))
87         continue;
88     }
89 
90     Expected<StringRef> Buffer = Sec.getContents();
91     if (!Buffer)
92       return Buffer.takeError();
93 
94     MemoryBufferRef Contents(*Buffer, Obj.getFileName());
95     if (Error Err = extractOffloadFiles(Contents, Binaries))
96       return Err;
97   }
98 
99   return Error::success();
100 }
101 
102 Error extractFromBitcode(MemoryBufferRef Buffer,
103                          SmallVectorImpl<OffloadFile> &Binaries) {
104   LLVMContext Context;
105   SMDiagnostic Err;
106   std::unique_ptr<Module> M = getLazyIRModule(
107       MemoryBuffer::getMemBuffer(Buffer, /*RequiresNullTerminator=*/false), Err,
108       Context);
109   if (!M)
110     return createStringError(inconvertibleErrorCode(),
111                              "Failed to create module");
112 
113   // Extract offloading data from globals referenced by the
114   // `llvm.embedded.object` metadata with the `.llvm.offloading` section.
115   auto *MD = M->getNamedMetadata("llvm.embedded.objects");
116   if (!MD)
117     return Error::success();
118 
119   for (const MDNode *Op : MD->operands()) {
120     if (Op->getNumOperands() < 2)
121       continue;
122 
123     MDString *SectionID = dyn_cast<MDString>(Op->getOperand(1));
124     if (!SectionID || SectionID->getString() != ".llvm.offloading")
125       continue;
126 
127     GlobalVariable *GV =
128         mdconst::dyn_extract_or_null<GlobalVariable>(Op->getOperand(0));
129     if (!GV)
130       continue;
131 
132     auto *CDS = dyn_cast<ConstantDataSequential>(GV->getInitializer());
133     if (!CDS)
134       continue;
135 
136     MemoryBufferRef Contents(CDS->getAsString(), M->getName());
137     if (Error Err = extractOffloadFiles(Contents, Binaries))
138       return Err;
139   }
140 
141   return Error::success();
142 }
143 
144 Error extractFromArchive(const Archive &Library,
145                          SmallVectorImpl<OffloadFile> &Binaries) {
146   // Try to extract device code from each file stored in the static archive.
147   Error Err = Error::success();
148   for (auto Child : Library.children(Err)) {
149     auto ChildBufferOrErr = Child.getMemoryBufferRef();
150     if (!ChildBufferOrErr)
151       return ChildBufferOrErr.takeError();
152     std::unique_ptr<MemoryBuffer> ChildBuffer =
153         MemoryBuffer::getMemBuffer(*ChildBufferOrErr, false);
154 
155     // Check if the buffer has the required alignment.
156     if (!isAddrAligned(Align(OffloadBinary::getAlignment()),
157                        ChildBuffer->getBufferStart()))
158       ChildBuffer = MemoryBuffer::getMemBufferCopy(
159           ChildBufferOrErr->getBuffer(),
160           ChildBufferOrErr->getBufferIdentifier());
161 
162     if (Error Err = extractOffloadBinaries(*ChildBuffer, Binaries))
163       return Err;
164   }
165 
166   if (Err)
167     return Err;
168   return Error::success();
169 }
170 
171 } // namespace
172 
173 Expected<std::unique_ptr<OffloadBinary>>
174 OffloadBinary::create(MemoryBufferRef Buf) {
175   if (Buf.getBufferSize() < sizeof(Header) + sizeof(Entry))
176     return errorCodeToError(object_error::parse_failed);
177 
178   // Check for 0x10FF1OAD magic bytes.
179   if (identify_magic(Buf.getBuffer()) != file_magic::offload_binary)
180     return errorCodeToError(object_error::parse_failed);
181 
182   // Make sure that the data has sufficient alignment.
183   if (!isAddrAligned(Align(getAlignment()), Buf.getBufferStart()))
184     return errorCodeToError(object_error::parse_failed);
185 
186   const char *Start = Buf.getBufferStart();
187   const Header *TheHeader = reinterpret_cast<const Header *>(Start);
188   if (TheHeader->Version != OffloadBinary::Version)
189     return errorCodeToError(object_error::parse_failed);
190 
191   if (TheHeader->Size > Buf.getBufferSize() ||
192       TheHeader->Size < sizeof(Entry) || TheHeader->Size < sizeof(Header))
193     return errorCodeToError(object_error::unexpected_eof);
194 
195   if (TheHeader->EntryOffset > TheHeader->Size - sizeof(Entry) ||
196       TheHeader->EntrySize > TheHeader->Size - sizeof(Header))
197     return errorCodeToError(object_error::unexpected_eof);
198 
199   const Entry *TheEntry =
200       reinterpret_cast<const Entry *>(&Start[TheHeader->EntryOffset]);
201 
202   if (TheEntry->ImageOffset > Buf.getBufferSize() ||
203       TheEntry->StringOffset > Buf.getBufferSize())
204     return errorCodeToError(object_error::unexpected_eof);
205 
206   return std::unique_ptr<OffloadBinary>(
207       new OffloadBinary(Buf, TheHeader, TheEntry));
208 }
209 
210 SmallString<0> OffloadBinary::write(const OffloadingImage &OffloadingData) {
211   // Create a null-terminated string table with all the used strings.
212   StringTableBuilder StrTab(StringTableBuilder::ELF);
213   for (auto &KeyAndValue : OffloadingData.StringData) {
214     StrTab.add(KeyAndValue.first);
215     StrTab.add(KeyAndValue.second);
216   }
217   StrTab.finalize();
218 
219   uint64_t StringEntrySize =
220       sizeof(StringEntry) * OffloadingData.StringData.size();
221 
222   // Make sure the image we're wrapping around is aligned as well.
223   uint64_t BinaryDataSize = alignTo(sizeof(Header) + sizeof(Entry) +
224                                         StringEntrySize + StrTab.getSize(),
225                                     getAlignment());
226 
227   // Create the header and fill in the offsets. The entry will be directly
228   // placed after the header in memory. Align the size to the alignment of the
229   // header so this can be placed contiguously in a single section.
230   Header TheHeader;
231   TheHeader.Size = alignTo(
232       BinaryDataSize + OffloadingData.Image->getBufferSize(), getAlignment());
233   TheHeader.EntryOffset = sizeof(Header);
234   TheHeader.EntrySize = sizeof(Entry);
235 
236   // Create the entry using the string table offsets. The string table will be
237   // placed directly after the entry in memory, and the image after that.
238   Entry TheEntry;
239   TheEntry.TheImageKind = OffloadingData.TheImageKind;
240   TheEntry.TheOffloadKind = OffloadingData.TheOffloadKind;
241   TheEntry.Flags = OffloadingData.Flags;
242   TheEntry.StringOffset = sizeof(Header) + sizeof(Entry);
243   TheEntry.NumStrings = OffloadingData.StringData.size();
244 
245   TheEntry.ImageOffset = BinaryDataSize;
246   TheEntry.ImageSize = OffloadingData.Image->getBufferSize();
247 
248   SmallString<0> Data;
249   Data.reserve(TheHeader.Size);
250   raw_svector_ostream OS(Data);
251   OS << StringRef(reinterpret_cast<char *>(&TheHeader), sizeof(Header));
252   OS << StringRef(reinterpret_cast<char *>(&TheEntry), sizeof(Entry));
253   for (auto &KeyAndValue : OffloadingData.StringData) {
254     uint64_t Offset = sizeof(Header) + sizeof(Entry) + StringEntrySize;
255     StringEntry Map{Offset + StrTab.getOffset(KeyAndValue.first),
256                     Offset + StrTab.getOffset(KeyAndValue.second)};
257     OS << StringRef(reinterpret_cast<char *>(&Map), sizeof(StringEntry));
258   }
259   StrTab.write(OS);
260   // Add padding to required image alignment.
261   OS.write_zeros(TheEntry.ImageOffset - OS.tell());
262   OS << OffloadingData.Image->getBuffer();
263 
264   // Add final padding to required alignment.
265   assert(TheHeader.Size >= OS.tell() && "Too much data written?");
266   OS.write_zeros(TheHeader.Size - OS.tell());
267   assert(TheHeader.Size == OS.tell() && "Size mismatch");
268 
269   return Data;
270 }
271 
272 Error object::extractOffloadBinaries(MemoryBufferRef Buffer,
273                                      SmallVectorImpl<OffloadFile> &Binaries) {
274   file_magic Type = identify_magic(Buffer.getBuffer());
275   switch (Type) {
276   case file_magic::bitcode:
277     return extractFromBitcode(Buffer, Binaries);
278   case file_magic::elf_relocatable:
279   case file_magic::elf_executable:
280   case file_magic::elf_shared_object:
281   case file_magic::coff_object: {
282     Expected<std::unique_ptr<ObjectFile>> ObjFile =
283         ObjectFile::createObjectFile(Buffer, Type);
284     if (!ObjFile)
285       return ObjFile.takeError();
286     return extractFromObject(*ObjFile->get(), Binaries);
287   }
288   case file_magic::archive: {
289     Expected<std::unique_ptr<llvm::object::Archive>> LibFile =
290         object::Archive::create(Buffer);
291     if (!LibFile)
292       return LibFile.takeError();
293     return extractFromArchive(*LibFile->get(), Binaries);
294   }
295   case file_magic::offload_binary:
296     return extractOffloadFiles(Buffer, Binaries);
297   default:
298     return Error::success();
299   }
300 }
301 
302 OffloadKind object::getOffloadKind(StringRef Name) {
303   return llvm::StringSwitch<OffloadKind>(Name)
304       .Case("openmp", OFK_OpenMP)
305       .Case("cuda", OFK_Cuda)
306       .Case("hip", OFK_HIP)
307       .Default(OFK_None);
308 }
309 
310 StringRef object::getOffloadKindName(OffloadKind Kind) {
311   switch (Kind) {
312   case OFK_OpenMP:
313     return "openmp";
314   case OFK_Cuda:
315     return "cuda";
316   case OFK_HIP:
317     return "hip";
318   default:
319     return "none";
320   }
321 }
322 
323 ImageKind object::getImageKind(StringRef Name) {
324   return llvm::StringSwitch<ImageKind>(Name)
325       .Case("o", IMG_Object)
326       .Case("bc", IMG_Bitcode)
327       .Case("cubin", IMG_Cubin)
328       .Case("fatbin", IMG_Fatbinary)
329       .Case("s", IMG_PTX)
330       .Default(IMG_None);
331 }
332 
333 StringRef object::getImageKindName(ImageKind Kind) {
334   switch (Kind) {
335   case IMG_Object:
336     return "o";
337   case IMG_Bitcode:
338     return "bc";
339   case IMG_Cubin:
340     return "cubin";
341   case IMG_Fatbinary:
342     return "fatbin";
343   case IMG_PTX:
344     return "s";
345   default:
346     return "";
347   }
348 }
349 
350 bool object::areTargetsCompatible(const OffloadFile::TargetID &LHS,
351                                   const OffloadFile::TargetID &RHS) {
352   // Exact matches are not considered compatible because they are the same
353   // target. We are interested in different targets that are compatible.
354   if (LHS == RHS)
355     return false;
356 
357   // The triples must match at all times.
358   if (LHS.first != RHS.first)
359     return false;
360 
361   // If the architecture is "all" we assume it is always compatible.
362   if (LHS.second == "generic" || RHS.second == "generic")
363     return true;
364 
365   // Only The AMDGPU target requires additional checks.
366   llvm::Triple T(LHS.first);
367   if (!T.isAMDGPU())
368     return false;
369 
370   // The base processor must always match.
371   if (LHS.second.split(":").first != RHS.second.split(":").first)
372     return false;
373 
374   // Check combintions of on / off features that must match.
375   if (LHS.second.contains("xnack+") && RHS.second.contains("xnack-"))
376     return false;
377   if (LHS.second.contains("xnack-") && RHS.second.contains("xnack+"))
378     return false;
379   if (LHS.second.contains("sramecc-") && RHS.second.contains("sramecc+"))
380     return false;
381   if (LHS.second.contains("sramecc+") && RHS.second.contains("sramecc-"))
382     return false;
383   return true;
384 }
385