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[WebAssembly] Convert to new "dylink.0" section format
This format is based on sub-sections (like the "linking" and "name" sections) and is therefore easier to extend going forward. spec change: WebAssembly/tool-conventions#170 binaryen change: WebAssembly/binaryen#4141 wabt change: WebAssembly/wabt#1707 emscripten change: emscripten-core/emscripten#15019 Differential Revision: https://reviews.llvm.org/D109595
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14 files changed

+105
-27
lines changed

14 files changed

+105
-27
lines changed

‎lld/test/wasm/pie.ll

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -34,7 +34,7 @@ declare void @external_func()
3434

3535
; CHECK: Sections:
3636
; CHECK-NEXT: - Type: CUSTOM
37-
; CHECK-NEXT: Name: dylink
37+
; CHECK-NEXT: Name: dylink.0
3838
; CHECK-NEXT: MemorySize: 16
3939
; CHECK-NEXT: MemoryAlignment: 2
4040
; CHECK-NEXT: TableSize: 1

‎lld/test/wasm/shared-needed.s

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -23,7 +23,7 @@ data:
2323

2424
# SO1: Sections:
2525
# SO1-NEXT: - Type: CUSTOM
26-
# SO1-NEXT: Name: dylink
26+
# SO1-NEXT: Name: dylink.0
2727
# SO1-NEXT: MemorySize: 4
2828
# SO1-NEXT: MemoryAlignment: 2
2929
# SO1-NEXT: TableSize: 0
@@ -33,7 +33,7 @@ data:
3333

3434
# SO2: Sections:
3535
# SO2-NEXT: - Type: CUSTOM
36-
# SO2-NEXT: Name: dylink
36+
# SO2-NEXT: Name: dylink.0
3737
# SO2-NEXT: MemorySize: 0
3838
# SO2-NEXT: MemoryAlignment: 0
3939
# SO2-NEXT: TableSize: 0

‎lld/test/wasm/shared.s

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -127,7 +127,7 @@ get_local_func_address:
127127

128128
# CHECK: Sections:
129129
# CHECK-NEXT: - Type: CUSTOM
130-
# CHECK-NEXT: Name: dylink
130+
# CHECK-NEXT: Name: dylink.0
131131
# CHECK-NEXT: MemorySize: 24
132132
# CHECK-NEXT: MemoryAlignment: 2
133133
# CHECK-NEXT: TableSize: 2

‎lld/test/wasm/shared64.s

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -128,7 +128,7 @@ get_local_func_address:
128128

129129
# CHECK: Sections:
130130
# CHECK-NEXT: - Type: CUSTOM
131-
# CHECK-NEXT: Name: dylink
131+
# CHECK-NEXT: Name: dylink.0
132132
# CHECK-NEXT: MemorySize: 36
133133
# CHECK-NEXT: MemoryAlignment: 2
134134
# CHECK-NEXT: TableSize: 2

‎lld/wasm/SyntheticSections.cpp

Lines changed: 16 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -57,13 +57,22 @@ class SubSection {
5757
void DylinkSection::writeBody() {
5858
raw_ostream &os = bodyOutputStream;
5959

60-
writeUleb128(os, memSize, "MemSize");
61-
writeUleb128(os, memAlign, "MemAlign");
62-
writeUleb128(os, out.elemSec->numEntries(), "TableSize");
63-
writeUleb128(os, 0, "TableAlign");
64-
writeUleb128(os, symtab->sharedFiles.size(), "Needed");
65-
for (auto *so : symtab->sharedFiles)
66-
writeStr(os, llvm::sys::path::filename(so->getName()), "so name");
60+
{
61+
SubSection sub(WASM_DYLINK_MEM_INFO);
62+
writeUleb128(sub.os, memSize, "MemSize");
63+
writeUleb128(sub.os, memAlign, "MemAlign");
64+
writeUleb128(sub.os, out.elemSec->numEntries(), "TableSize");
65+
writeUleb128(sub.os, 0, "TableAlign");
66+
sub.writeTo(os);
67+
}
68+
69+
if (symtab->sharedFiles.size()) {
70+
SubSection sub(WASM_DYLINK_NEEDED);
71+
writeUleb128(sub.os, symtab->sharedFiles.size(), "Needed");
72+
for (auto *so : symtab->sharedFiles)
73+
writeStr(sub.os, llvm::sys::path::filename(so->getName()), "so name");
74+
sub.writeTo(os);
75+
}
6776
}
6877

6978
uint32_t TypeSection::registerType(const WasmSignature &sig) {

‎lld/wasm/SyntheticSections.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -74,7 +74,7 @@ class SyntheticSection : public OutputSection {
7474
// https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
7575
class DylinkSection : public SyntheticSection {
7676
public:
77-
DylinkSection() : SyntheticSection(llvm::wasm::WASM_SEC_CUSTOM, "dylink") {}
77+
DylinkSection() : SyntheticSection(llvm::wasm::WASM_SEC_CUSTOM, "dylink.0") {}
7878
bool isNeeded() const override { return config->isPic; }
7979
void writeBody() override;
8080

‎llvm/include/llvm/BinaryFormat/Wasm.h

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -339,6 +339,12 @@ enum : unsigned {
339339
WASM_SYMBOL_TABLE = 0x8,
340340
};
341341

342+
// Kind codes used in the custom "dylink" section
343+
enum : unsigned {
344+
WASM_DYLINK_MEM_INFO = 0x1,
345+
WASM_DYLINK_NEEDED = 0x2,
346+
};
347+
342348
// Kind codes used in the custom "linking" section in the WASM_COMDAT_INFO
343349
enum : unsigned {
344350
WASM_COMDAT_DATA = 0x0,

‎llvm/include/llvm/Object/Wasm.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -260,6 +260,7 @@ class WasmObjectFile : public ObjectFile {
260260

261261
// Custom section types
262262
Error parseDylinkSection(ReadContext &Ctx);
263+
Error parseDylink0Section(ReadContext &Ctx);
263264
Error parseNameSection(ReadContext &Ctx);
264265
Error parseLinkingSection(ReadContext &Ctx);
265266
Error parseLinkingSectionSymtab(ReadContext &Ctx);

‎llvm/include/llvm/ObjectYAML/WasmYAML.h

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -200,11 +200,11 @@ struct CustomSection : Section {
200200
};
201201

202202
struct DylinkSection : CustomSection {
203-
DylinkSection() : CustomSection("dylink") {}
203+
DylinkSection() : CustomSection("dylink.0") {}
204204

205205
static bool classof(const Section *S) {
206206
auto C = dyn_cast<CustomSection>(S);
207-
return C && C->Name == "dylink";
207+
return C && C->Name == "dylink.0";
208208
}
209209

210210
uint32_t MemorySize;

‎llvm/lib/Object/WasmObjectFile.cpp

Lines changed: 52 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -339,7 +339,8 @@ Error WasmObjectFile::parseSection(WasmSection &Sec) {
339339
}
340340

341341
Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
342-
// See https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
342+
// Legacy "dylink" section support.
343+
// See parseDylink0Section for the current "dylink.0" section parsing.
343344
HasDylinkSection = true;
344345
DylinkInfo.MemorySize = readVaruint32(Ctx);
345346
DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
@@ -349,12 +350,58 @@ Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
349350
while (Count--) {
350351
DylinkInfo.Needed.push_back(readString(Ctx));
351352
}
353+
352354
if (Ctx.Ptr != Ctx.End)
353355
return make_error<GenericBinaryError>("dylink section ended prematurely",
354356
object_error::parse_failed);
355357
return Error::success();
356358
}
357359

360+
Error WasmObjectFile::parseDylink0Section(ReadContext &Ctx) {
361+
// See
362+
// https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
363+
HasDylinkSection = true;
364+
365+
const uint8_t *OrigEnd = Ctx.End;
366+
while (Ctx.Ptr < OrigEnd) {
367+
Ctx.End = OrigEnd;
368+
uint8_t Type = readUint8(Ctx);
369+
uint32_t Size = readVaruint32(Ctx);
370+
LLVM_DEBUG(dbgs() << "readSubsection type=" << int(Type) << " size=" << Size
371+
<< "\n");
372+
Ctx.End = Ctx.Ptr + Size;
373+
uint32_t Count;
374+
switch (Type) {
375+
case wasm::WASM_DYLINK_MEM_INFO:
376+
DylinkInfo.MemorySize = readVaruint32(Ctx);
377+
DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
378+
DylinkInfo.TableSize = readVaruint32(Ctx);
379+
DylinkInfo.TableAlignment = readVaruint32(Ctx);
380+
break;
381+
case wasm::WASM_DYLINK_NEEDED:
382+
Count = readVaruint32(Ctx);
383+
while (Count--) {
384+
DylinkInfo.Needed.push_back(readString(Ctx));
385+
}
386+
break;
387+
default:
388+
return make_error<GenericBinaryError>("unknown dylink.0 sub-section",
389+
object_error::parse_failed);
390+
Ctx.Ptr += Size;
391+
break;
392+
}
393+
if (Ctx.Ptr != Ctx.End) {
394+
return make_error<GenericBinaryError>(
395+
"dylink.0 sub-section ended prematurely", object_error::parse_failed);
396+
}
397+
}
398+
399+
if (Ctx.Ptr != Ctx.End)
400+
return make_error<GenericBinaryError>("dylink.0 section ended prematurely",
401+
object_error::parse_failed);
402+
return Error::success();
403+
}
404+
358405
Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
359406
llvm::DenseSet<uint64_t> SeenFunctions;
360407
llvm::DenseSet<uint64_t> SeenGlobals;
@@ -984,6 +1031,9 @@ Error WasmObjectFile::parseCustomSection(WasmSection &Sec, ReadContext &Ctx) {
9841031
if (Sec.Name == "dylink") {
9851032
if (Error Err = parseDylinkSection(Ctx))
9861033
return Err;
1034+
} else if (Sec.Name == "dylink.0") {
1035+
if (Error Err = parseDylink0Section(Ctx))
1036+
return Err;
9871037
} else if (Sec.Name == "name") {
9881038
if (Error Err = parseNameSection(Ctx))
9891039
return Err;
@@ -1793,6 +1843,7 @@ int WasmSectionOrderChecker::getSectionOrder(unsigned ID,
17931843
case wasm::WASM_SEC_CUSTOM:
17941844
return StringSwitch<unsigned>(CustomSectionName)
17951845
.Case("dylink", WASM_SEC_ORDER_DYLINK)
1846+
.Case("dylink.0", WASM_SEC_ORDER_DYLINK)
17961847
.Case("linking", WASM_SEC_ORDER_LINKING)
17971848
.StartsWith("reloc.", WASM_SEC_ORDER_RELOC)
17981849
.Case("name", WASM_SEC_ORDER_NAME)

‎llvm/lib/ObjectYAML/WasmEmitter.cpp

Lines changed: 18 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -157,13 +157,24 @@ void WasmWriter::writeInitExpr(raw_ostream &OS,
157157
void WasmWriter::writeSectionContent(raw_ostream &OS,
158158
WasmYAML::DylinkSection &Section) {
159159
writeStringRef(Section.Name, OS);
160-
encodeULEB128(Section.MemorySize, OS);
161-
encodeULEB128(Section.MemoryAlignment, OS);
162-
encodeULEB128(Section.TableSize, OS);
163-
encodeULEB128(Section.TableAlignment, OS);
164-
encodeULEB128(Section.Needed.size(), OS);
165-
for (StringRef Needed : Section.Needed)
166-
writeStringRef(Needed, OS);
160+
161+
writeUint8(OS, wasm::WASM_DYLINK_MEM_INFO);
162+
SubSectionWriter SubSection(OS);
163+
raw_ostream &SubOS = SubSection.getStream();
164+
encodeULEB128(Section.MemorySize, SubOS);
165+
encodeULEB128(Section.MemoryAlignment, SubOS);
166+
encodeULEB128(Section.TableSize, SubOS);
167+
encodeULEB128(Section.TableAlignment, SubOS);
168+
SubSection.done();
169+
170+
if (Section.Needed.size()) {
171+
writeUint8(OS, wasm::WASM_DYLINK_NEEDED);
172+
raw_ostream &SubOS = SubSection.getStream();
173+
encodeULEB128(Section.Needed.size(), SubOS);
174+
for (StringRef Needed : Section.Needed)
175+
writeStringRef(Needed, SubOS);
176+
SubSection.done();
177+
}
167178
}
168179

169180
void WasmWriter::writeSectionContent(raw_ostream &OS,

‎llvm/lib/ObjectYAML/WasmYAML.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -177,7 +177,7 @@ void MappingTraits<std::unique_ptr<WasmYAML::Section>>::mapping(
177177
} else {
178178
IO.mapRequired("Name", SectionName);
179179
}
180-
if (SectionName == "dylink") {
180+
if (SectionName == "dylink" || SectionName == "dylink.0") {
181181
if (!IO.outputting())
182182
Section.reset(new WasmYAML::DylinkSection());
183183
sectionMapping(IO, *cast<WasmYAML::DylinkSection>(Section.get()));

‎llvm/test/ObjectYAML/wasm/dylink_section.yaml

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,7 @@ FileHeader:
55

66
Sections:
77
- Type: CUSTOM
8-
Name: dylink
8+
Name: dylink.0
99
MemorySize: 4
1010
MemoryAlignment: 2
1111
TableSize: 1
@@ -17,7 +17,7 @@ Sections:
1717
# CHECK: Version: 0x1
1818
# CHECK: Sections:
1919
# CHECK: - Type: CUSTOM
20-
# CHECK: Name: dylink
20+
# CHECK: Name: dylink.0
2121
# CHECK: MemorySize: 4
2222
# CHECK: MemoryAlignment: 2
2323
# CHECK: TableSize: 1

‎llvm/tools/obj2yaml/wasm2yaml.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -51,7 +51,7 @@ static WasmYAML::Table makeTable(uint32_t Index,
5151
std::unique_ptr<WasmYAML::CustomSection>
5252
WasmDumper::dumpCustomSection(const WasmSection &WasmSec) {
5353
std::unique_ptr<WasmYAML::CustomSection> CustomSec;
54-
if (WasmSec.Name == "dylink") {
54+
if (WasmSec.Name == "dylink" || WasmSec.Name == "dylink.0") {
5555
std::unique_ptr<WasmYAML::DylinkSection> DylinkSec =
5656
std::make_unique<WasmYAML::DylinkSection>();
5757
const wasm::WasmDylinkInfo& Info = Obj.dylinkInfo();

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