[llvm] f2af060 - [llvm-objcopy] Initial support for wasm in llvm-objcopy
Derek Schuff via llvm-commits
llvm-commits at lists.llvm.org
Wed Jan 29 17:35:55 PST 2020
Author: Derek Schuff
Date: 2020-01-29T17:32:02-08:00
New Revision: f2af0607000cb18bf9292457ea247bb6602b4cdb
URL: https://github.com/llvm/llvm-project/commit/f2af0607000cb18bf9292457ea247bb6602b4cdb
DIFF: https://github.com/llvm/llvm-project/commit/f2af0607000cb18bf9292457ea247bb6602b4cdb.diff
LOG: [llvm-objcopy] Initial support for wasm in llvm-objcopy
Currently only supports simple copying, other operations to follow.
Reviewers: sbc100, alexshap, jhenderson
Differential Revision: https://reviews.llvm.org/D70930
This is a reland of a928d127a with a one-line fix to ensure that
the wasm version number is written as little-endian (it's the only
field in all of the binary format that's not a single byte or an
LEB, but we may have to watch out more when we start handling the
linking section).
Added:
llvm/test/tools/llvm-objcopy/wasm/basic-archive-copy.test
llvm/test/tools/llvm-objcopy/wasm/basic-copy.test
llvm/tools/llvm-objcopy/wasm/Object.h
llvm/tools/llvm-objcopy/wasm/Reader.cpp
llvm/tools/llvm-objcopy/wasm/Reader.h
llvm/tools/llvm-objcopy/wasm/WasmObjcopy.cpp
llvm/tools/llvm-objcopy/wasm/WasmObjcopy.h
llvm/tools/llvm-objcopy/wasm/Writer.cpp
llvm/tools/llvm-objcopy/wasm/Writer.h
Modified:
llvm/include/llvm/Object/Wasm.h
llvm/tools/llvm-objcopy/CMakeLists.txt
llvm/tools/llvm-objcopy/llvm-objcopy.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/Object/Wasm.h b/llvm/include/llvm/Object/Wasm.h
index 8d6b914ff9fe..b3cbb5703605 100644
--- a/llvm/include/llvm/Object/Wasm.h
+++ b/llvm/include/llvm/Object/Wasm.h
@@ -152,6 +152,7 @@ class WasmObjectFile : public ObjectFile {
uint32_t getNumImportedGlobals() const { return NumImportedGlobals; }
uint32_t getNumImportedFunctions() const { return NumImportedFunctions; }
uint32_t getNumImportedEvents() const { return NumImportedEvents; }
+ uint32_t getNumSections() const { return Sections.size(); }
void moveSymbolNext(DataRefImpl &Symb) const override;
uint32_t getSymbolFlags(DataRefImpl Symb) const override;
diff --git a/llvm/test/tools/llvm-objcopy/wasm/basic-archive-copy.test b/llvm/test/tools/llvm-objcopy/wasm/basic-archive-copy.test
new file mode 100644
index 000000000000..31ad14a0ed0c
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/wasm/basic-archive-copy.test
@@ -0,0 +1,90 @@
+## Test a basic copy of an archive containing a wasm object.
+
+# RUN: yaml2obj %s -o %t
+
+## Create an archive and copy it using llvm-objcopy.
+# RUN: rm -f %t.a
+# RUN: llvm-ar crs %t.a %t
+# RUN: cp %t.a %t.copy.a
+# RUN: llvm-objcopy %t.a %t2.a
+## Create another archive from an objcopy-copied object, verify that they match.
+# RUN: llvm-objcopy %t %t2
+# RUN: llvm-ar p %t2.a > %t3
+# RUN: cmp %t2 %t3
+
+## Check that the copied archive has the correct index contents.
+# RUN: llvm-nm --print-armap %t.a | FileCheck --check-prefix=INDEX-TABLE %s
+# RUN: llvm-nm --print-armap %t2.a | FileCheck --check-prefix=INDEX-TABLE %s
+## Verify that llvm-objcopy has not modifed the input.
+# RUN: cmp %t.copy.a %t.a
+
+# INDEX-TABLE: Archive map
+# INDEX-TABLE-NEXT: func1 in
+
+## Do the same with an archive that has no index.
+# RUN: rm -f %t.no.index.a
+# RUN: llvm-ar crS %t.no.index.a %t
+# RUN: llvm-objcopy %t.no.index.a %t2.no.index.a
+# RUN: llvm-ar p %t2.no.index.a > %t4
+
+# RUN: llvm-nm --print-armap %t.no.index.a | FileCheck --check-prefix=NO-INDEX-TABLE %s
+# RUN: llvm-nm --print-armap %t2.no.index.a | FileCheck --check-prefix=NO-INDEX-TABLE %s
+# RUN: cmp %t2 %t4
+
+# NO-INDEX-TABLE-NOT: Archive map
+# NO-INDEX-TABLE-NOT: func1 in
+
+--- !WASM
+FileHeader:
+ Version: 0x00000001
+Sections:
+ - Type: TYPE
+ Signatures:
+ - Index: 0
+ ParamTypes:
+ - I32
+ ReturnTypes:
+ - F32
+ - Index: 1
+ ParamTypes:
+ - I32
+ - I64
+ ReturnTypes: []
+ - Type: FUNCTION
+ FunctionTypes:
+ - 0
+ - 1
+ - Type: CODE
+ Relocations:
+ - Type: R_WASM_TABLE_INDEX_SLEB
+ Index: 0
+ Offset: 0x00000002
+ - Type: R_WASM_FUNCTION_INDEX_LEB
+ Index: 1
+ Offset: 0x0000002
+ Functions:
+ - Index: 0
+ Locals:
+ - Type: I32
+ Count: 3
+ Body: 010101010B
+ - Index: 1
+ Locals:
+ - Type: I32
+ Count: 1
+ Body: 010101010B
+ - Type: CUSTOM
+ Name: linking
+ Version: 2
+ SymbolTable:
+ - Index: 0
+ Kind: FUNCTION
+ Name: func1
+ Flags: [ ]
+ Function: 0
+ - Index: 1
+ Kind: FUNCTION
+ Name: func2
+ Flags: [ ]
+ Function: 1
+...
diff --git a/llvm/test/tools/llvm-objcopy/wasm/basic-copy.test b/llvm/test/tools/llvm-objcopy/wasm/basic-copy.test
new file mode 100644
index 000000000000..4eb463435f4c
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/wasm/basic-copy.test
@@ -0,0 +1,63 @@
+## Test that the copied object has the same yaml conversion as the original.
+## The copied object is not bit-identical to the yaml2obj-generated
+## one, as yaml2obj uses 5-byte LEBs for section sizes (unlike objcopy/clang).
+# RUN: yaml2obj %s -o %t.o
+# RUN: llvm-objcopy %t.o %t2.o
+# RUN: obj2yaml %t.o > %t.yaml
+# RUN: obj2yaml %t2.o > %t2.yaml
+# RUN:
diff %t.yaml %t2.yaml
+
+--- !WASM
+FileHeader:
+ Version: 0x00000001
+Sections:
+ - Type: TYPE
+ Signatures:
+ - Index: 0
+ ParamTypes:
+ - I32
+ ReturnTypes:
+ - F32
+ - Index: 1
+ ParamTypes:
+ - I32
+ - I64
+ ReturnTypes: []
+ - Type: FUNCTION
+ FunctionTypes:
+ - 0
+ - 1
+ - Type: CODE
+ Relocations:
+ - Type: R_WASM_TABLE_INDEX_SLEB
+ Index: 0
+ Offset: 0x00000002
+ - Type: R_WASM_FUNCTION_INDEX_LEB
+ Index: 1
+ Offset: 0x0000002
+ Functions:
+ - Index: 0
+ Locals:
+ - Type: I32
+ Count: 3
+ Body: 010101010B
+ - Index: 1
+ Locals:
+ - Type: I32
+ Count: 1
+ Body: 010101010B
+ - Type: CUSTOM
+ Name: linking
+ Version: 2
+ SymbolTable:
+ - Index: 0
+ Kind: FUNCTION
+ Name: func1
+ Flags: [ ]
+ Function: 0
+ - Index: 1
+ Kind: FUNCTION
+ Name: func2
+ Flags: [ ]
+ Function: 1
+...
diff --git a/llvm/tools/llvm-objcopy/CMakeLists.txt b/llvm/tools/llvm-objcopy/CMakeLists.txt
index 6d4048f040ba..b3706bc69177 100644
--- a/llvm/tools/llvm-objcopy/CMakeLists.txt
+++ b/llvm/tools/llvm-objcopy/CMakeLists.txt
@@ -33,6 +33,9 @@ add_llvm_tool(llvm-objcopy
MachO/MachOWriter.cpp
MachO/MachOLayoutBuilder.cpp
MachO/Object.cpp
+ wasm/Reader.cpp
+ wasm/Writer.cpp
+ wasm/WasmObjcopy.cpp
DEPENDS
ObjcopyOptsTableGen
InstallNameToolOptsTableGen
diff --git a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
index e662f35f4b08..61efc742767d 100644
--- a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
+++ b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
@@ -8,10 +8,11 @@
#include "llvm-objcopy.h"
#include "Buffer.h"
+#include "COFF/COFFObjcopy.h"
#include "CopyConfig.h"
#include "ELF/ELFObjcopy.h"
-#include "COFF/COFFObjcopy.h"
#include "MachO/MachOObjcopy.h"
+#include "wasm/WasmObjcopy.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
@@ -25,6 +26,7 @@
#include "llvm/Object/ELFTypes.h"
#include "llvm/Object/Error.h"
#include "llvm/Object/MachO.h"
+#include "llvm/Object/Wasm.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/ArgList.h"
#include "llvm/Option/Option.h"
@@ -172,6 +174,8 @@ static Error executeObjcopyOnBinary(CopyConfig &Config, object::Binary &In,
return coff::executeObjcopyOnBinary(Config, *COFFBinary, Out);
else if (auto *MachOBinary = dyn_cast<object::MachOObjectFile>(&In))
return macho::executeObjcopyOnBinary(Config, *MachOBinary, Out);
+ else if (auto *WasmBinary = dyn_cast<object::WasmObjectFile>(&In))
+ return objcopy::wasm::executeObjcopyOnBinary(Config, *WasmBinary, Out);
else
return createStringError(object_error::invalid_file_type,
"unsupported object file format");
diff --git a/llvm/tools/llvm-objcopy/wasm/Object.h b/llvm/tools/llvm-objcopy/wasm/Object.h
new file mode 100644
index 000000000000..78a43be21d47
--- /dev/null
+++ b/llvm/tools/llvm-objcopy/wasm/Object.h
@@ -0,0 +1,39 @@
+//===- Object.h -------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_OBJCOPY_WASM_OBJECT_H
+#define LLVM_TOOLS_LLVM_OBJCOPY_WASM_OBJECT_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Object/Wasm.h"
+#include <vector>
+
+namespace llvm {
+namespace objcopy {
+namespace wasm {
+
+struct Section {
+ // For now, each section is only an opaque binary blob with no distinction
+ // between custom and known sections.
+ uint8_t SectionType;
+ StringRef Name;
+ ArrayRef<uint8_t> Contents;
+};
+
+struct Object {
+ llvm::wasm::WasmObjectHeader Header;
+ // For now don't discriminate between kinds of sections.
+ std::vector<Section> Sections;
+};
+
+} // end namespace wasm
+} // end namespace objcopy
+} // end namespace llvm
+
+#endif // LLVM_TOOLS_LLVM_OBJCOPY_WASM_OBJECT_H
diff --git a/llvm/tools/llvm-objcopy/wasm/Reader.cpp b/llvm/tools/llvm-objcopy/wasm/Reader.cpp
new file mode 100644
index 000000000000..13fa84ad8020
--- /dev/null
+++ b/llvm/tools/llvm-objcopy/wasm/Reader.cpp
@@ -0,0 +1,33 @@
+//===- Reader.cpp ---------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Reader.h"
+
+namespace llvm {
+namespace objcopy {
+namespace wasm {
+
+using namespace object;
+using namespace llvm::wasm;
+
+Expected<std::unique_ptr<Object>> Reader::create() const {
+ auto Obj = std::make_unique<Object>();
+ Obj->Header = WasmObj.getHeader();
+ std::vector<Section> Sections;
+ Obj->Sections.reserve(WasmObj.getNumSections());
+ for (const SectionRef &Sec : WasmObj.sections()) {
+ const WasmSection &WS = WasmObj.getWasmSection(Sec);
+ Obj->Sections.push_back(
+ {static_cast<uint8_t>(WS.Type), WS.Name, WS.Content});
+ }
+ return std::move(Obj);
+}
+
+} // end namespace wasm
+} // end namespace objcopy
+} // end namespace llvm
diff --git a/llvm/tools/llvm-objcopy/wasm/Reader.h b/llvm/tools/llvm-objcopy/wasm/Reader.h
new file mode 100644
index 000000000000..2dcf7dde029a
--- /dev/null
+++ b/llvm/tools/llvm-objcopy/wasm/Reader.h
@@ -0,0 +1,31 @@
+//===- Reader.h -------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_OBJCOPY_WASM_READER_H
+#define LLVM_TOOLS_LLVM_OBJCOPY_WASM_READER_H
+
+#include "Object.h"
+
+namespace llvm {
+namespace objcopy {
+namespace wasm {
+
+class Reader {
+public:
+ explicit Reader(const object::WasmObjectFile &O) : WasmObj(O) {}
+ Expected<std::unique_ptr<Object>> create() const;
+
+private:
+ const object::WasmObjectFile &WasmObj;
+};
+
+} // end namespace wasm
+} // end namespace objcopy
+} // end namespace llvm
+
+#endif // LLVM_TOOLS_LLVM_OBJCOPY_WASM_READER_H
diff --git a/llvm/tools/llvm-objcopy/wasm/WasmObjcopy.cpp b/llvm/tools/llvm-objcopy/wasm/WasmObjcopy.cpp
new file mode 100644
index 000000000000..41816a0b08ad
--- /dev/null
+++ b/llvm/tools/llvm-objcopy/wasm/WasmObjcopy.cpp
@@ -0,0 +1,65 @@
+//===- WasmObjcopy.cpp ----------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "WasmObjcopy.h"
+#include "Buffer.h"
+#include "CopyConfig.h"
+#include "Object.h"
+#include "Reader.h"
+#include "Writer.h"
+#include "llvm-objcopy.h"
+#include "llvm/Support/Errc.h"
+
+namespace llvm {
+namespace objcopy {
+namespace wasm {
+
+using namespace object;
+
+static Error handleArgs(const CopyConfig &Config, Object &Obj) {
+ if (!Config.AddGnuDebugLink.empty() || !Config.BuildIdLinkDir.empty() ||
+ Config.BuildIdLinkInput || Config.BuildIdLinkOutput ||
+ Config.ExtractPartition || !Config.SplitDWO.empty() ||
+ !Config.SymbolsPrefix.empty() || !Config.AllocSectionsPrefix.empty() ||
+ Config.DiscardMode != DiscardType::None || Config.NewSymbolVisibility ||
+ !Config.SymbolsToAdd.empty() || !Config.RPathToAdd.empty() ||
+ !Config.OnlySection.empty() || !Config.SymbolsToGlobalize.empty() ||
+ !Config.SymbolsToKeep.empty() || !Config.SymbolsToLocalize.empty() ||
+ !Config.SymbolsToRemove.empty() ||
+ !Config.UnneededSymbolsToRemove.empty() ||
+ !Config.SymbolsToWeaken.empty() || !Config.SymbolsToKeepGlobal.empty() ||
+ !Config.SectionsToRename.empty() || !Config.SetSectionAlignment.empty() ||
+ !Config.SetSectionFlags.empty() || !Config.SymbolsToRename.empty() ||
+ !Config.ToRemove.empty() || !Config.DumpSection.empty() ||
+ !Config.AddSection.empty()) {
+ return createStringError(
+ llvm::errc::invalid_argument,
+ "no flags are supported yet, only basic copying is allowed");
+ }
+ return Error::success();
+}
+
+Error executeObjcopyOnBinary(const CopyConfig &Config,
+ object::WasmObjectFile &In, Buffer &Out) {
+ Reader TheReader(In);
+ Expected<std::unique_ptr<Object>> ObjOrErr = TheReader.create();
+ if (!ObjOrErr)
+ return createFileError(Config.InputFilename, ObjOrErr.takeError());
+ Object *Obj = ObjOrErr->get();
+ assert(Obj && "Unable to deserialize Wasm object");
+ if (Error E = handleArgs(Config, *Obj))
+ return createFileError(Config.InputFilename, std::move(E));
+ Writer TheWriter(*Obj, Out);
+ if (Error E = TheWriter.write())
+ return createFileError(Config.OutputFilename, std::move(E));
+ return Error::success();
+}
+
+} // end namespace wasm
+} // end namespace objcopy
+} // end namespace llvm
diff --git a/llvm/tools/llvm-objcopy/wasm/WasmObjcopy.h b/llvm/tools/llvm-objcopy/wasm/WasmObjcopy.h
new file mode 100644
index 000000000000..3557d5c0a50d
--- /dev/null
+++ b/llvm/tools/llvm-objcopy/wasm/WasmObjcopy.h
@@ -0,0 +1,31 @@
+//===- WasmObjcopy.h -------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_OBJCOPY_WASM_WASMOBJCOPY_H
+#define LLVM_TOOLS_LLVM_OBJCOPY_WASM_WASMOBJCOPY_H
+
+namespace llvm {
+class Error;
+
+namespace object {
+class WasmObjectFile;
+} // end namespace object
+
+namespace objcopy {
+struct CopyConfig;
+class Buffer;
+
+namespace wasm {
+Error executeObjcopyOnBinary(const CopyConfig &Config,
+ object::WasmObjectFile &In, Buffer &Out);
+
+} // end namespace wasm
+} // end namespace objcopy
+} // end namespace llvm
+
+#endif // LLVM_TOOLS_LLVM_OBJCOPY_WASM_WASMOBJCOPY_H
diff --git a/llvm/tools/llvm-objcopy/wasm/Writer.cpp b/llvm/tools/llvm-objcopy/wasm/Writer.cpp
new file mode 100644
index 000000000000..996cfa76ad3c
--- /dev/null
+++ b/llvm/tools/llvm-objcopy/wasm/Writer.cpp
@@ -0,0 +1,78 @@
+//===- Writer.cpp ---------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Writer.h"
+
+#include "llvm/BinaryFormat/Wasm.h"
+#include "llvm/Support/LEB128.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace llvm {
+namespace objcopy {
+namespace wasm {
+
+using namespace object;
+using namespace llvm::wasm;
+
+Writer::SectionHeader Writer::createSectionHeader(const Section &S,
+ size_t &SectionSize) {
+ SectionHeader Header;
+ raw_svector_ostream OS(Header);
+ OS << S.SectionType;
+ bool HasName = S.SectionType == WASM_SEC_CUSTOM;
+ SectionSize = S.Contents.size();
+ if (HasName)
+ SectionSize += getULEB128Size(S.Name.size()) + S.Name.size();
+ // Pad the LEB value out to 5 bytes to make it a predictable size, and
+ // match the behavior of clang.
+ encodeULEB128(SectionSize, OS, 5);
+ if (HasName) {
+ encodeULEB128(S.Name.size(), OS);
+ OS << S.Name;
+ }
+ // Total section size is the content size plus 1 for the section type and
+ // 5 for the LEB-encoded size.
+ SectionSize = SectionSize + 1 + 5;
+ return Header;
+}
+
+size_t Writer::finalize() {
+ size_t ObjectSize = sizeof(WasmMagic) + sizeof(WasmVersion);
+ SectionHeaders.reserve(Obj.Sections.size());
+ // Finalize the headers of each section so we know the total size.
+ for (const Section &S : Obj.Sections) {
+ size_t SectionSize;
+ SectionHeaders.push_back(createSectionHeader(S, SectionSize));
+ ObjectSize += SectionSize;
+ }
+ return ObjectSize;
+}
+
+Error Writer::write() {
+ size_t FileSize = finalize();
+ if (Error E = Buf.allocate(FileSize))
+ return E;
+
+ // Write the header.
+ uint8_t *Ptr = Buf.getBufferStart();
+ Ptr = std::copy(Obj.Header.Magic.begin(), Obj.Header.Magic.end(), Ptr);
+ support::endian::write32le(Ptr, Obj.Header.Version);
+ Ptr += sizeof(Obj.Header.Version);
+
+ // Write each section.
+ for (size_t I = 0, S = SectionHeaders.size(); I < S; ++I) {
+ Ptr = std::copy(SectionHeaders[I].begin(), SectionHeaders[I].end(), Ptr);
+ ArrayRef<uint8_t> Contents = Obj.Sections[I].Contents;
+ Ptr = std::copy(Contents.begin(), Contents.end(), Ptr);
+ }
+ return Buf.commit();
+}
+
+} // end namespace wasm
+} // end namespace objcopy
+} // end namespace llvm
diff --git a/llvm/tools/llvm-objcopy/wasm/Writer.h b/llvm/tools/llvm-objcopy/wasm/Writer.h
new file mode 100644
index 000000000000..da48ee730c3b
--- /dev/null
+++ b/llvm/tools/llvm-objcopy/wasm/Writer.h
@@ -0,0 +1,50 @@
+//===- Writer.h -------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_OBJCOPY_WASM_WRITER_H
+#define LLVM_TOOLS_LLVM_OBJCOPY_WASM_WRITER_H
+
+#include "Buffer.h"
+#include "Object.h"
+#include <cstdint>
+#include <vector>
+
+namespace llvm {
+namespace objcopy {
+namespace wasm {
+
+class Writer {
+public:
+ Writer(Object &Obj, Buffer &Buf) : Obj(Obj), Buf(Buf) {}
+ Error write();
+
+private:
+ using SectionHeader = SmallVector<char, 8>;
+ Object &Obj;
+ Buffer &Buf;
+ std::vector<SectionHeader> SectionHeaders;
+
+ /// Generate a wasm section section header for S.
+ /// The header consists of
+ /// * A one-byte section ID (aka the section type).
+ /// * The size of the section contents, encoded as ULEB128.
+ /// * If the section is a custom section (type 0) it also has a name, which is
+ /// encoded as a length-prefixed string. The encoded section size *includes*
+ /// this string.
+ /// See https://webassembly.github.io/spec/core/binary/modules.html#sections
+ /// Return the header and store the total size in SectionSize.
+ static SectionHeader createSectionHeader(const Section &S,
+ size_t &SectionSize);
+ size_t finalize();
+};
+
+} // end namespace wasm
+} // end namespace objcopy
+} // end namespace llvm
+
+#endif // LLVM_TOOLS_LLVM_OBJCOPY_WASM_WRITER_H
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