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[lld][WebAssembly] Fix static linking of -fPIC code with external undefined functions 

Differential Revision: https://reviews.llvm.org/D66784

llvm-svn: 372779
This commit is contained in:
Sam Clegg 2019-09-24 20:52:12 +00:00
parent e9e1c88ed9
commit 937b955837
7 changed files with 72 additions and 38 deletions
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23
lld/test/wasm/pic-static.ll
View File

@ -3,12 +3,13 @@
; fixed values.
; RUN: llc -relocation-model=pic -filetype=obj %p/Inputs/ret32.ll -o %t.ret32.o
; RUN: llc -relocation-model=pic -filetype=obj %s -o %t.o
; RUN: wasm-ld -o %t.wasm %t.o %t.ret32.o
; RUN: wasm-ld --allow-undefined --export-all -o %t.wasm %t.o %t.ret32.o
; RUN: obj2yaml %t.wasm | FileCheck %s
target triple = "wasm32-unknown-emscripten"
declare i32 @ret32(float)
declare i32 @missing_function(float)
@global_float = global float 1.0
@hidden_float = hidden global float 2.0
@ -18,6 +19,10 @@ define i32 (float)* @getaddr_external() {
ret i32 (float)* @ret32;
}
define i32 (float)* @getaddr_missing_function() {
ret i32 (float)* @missing_function;
}
define i32 ()* @getaddr_hidden() {
ret i32 ()* @hidden_func;
}
@ -60,10 +65,18 @@ entry:
; CHECK-NEXT: Mutable: false
; CHECK-NEXT: InitExpr:
; CHECK-NEXT: Opcode: I32_CONST
; CHECK-NEXT: Value: 1
; GOT.func.missing_function
; CHECK-NEXT: - Index: 2
; CHECK-NEXT: Type: I32
; CHECK-NEXT: Mutable: false
; CHECK-NEXT: InitExpr:
; CHECK-NEXT: Opcode: I32_CONST
; CHECK-NEXT: Value: 2
; __table_base
; CHECK-NEXT: - Index: 2
; CHECK-NEXT: - Index: 3
; CHECK-NEXT: Type: I32
; CHECK-NEXT: Mutable: false
; CHECK-NEXT: InitExpr:
@ -71,7 +84,7 @@ entry:
; CHECK-NEXT: Value: 1
; GOT.mem.global_float
; CHECK-NEXT: - Index: 3
; CHECK-NEXT: - Index: 4
; CHECK-NEXT: Type: I32
; CHECK-NEXT: Mutable: false
; CHECK-NEXT: InitExpr:
@ -79,7 +92,7 @@ entry:
; CHECK-NEXT: Value: 1024
; GOT.mem.ret32_ptr
; CHECK-NEXT: - Index: 4
; CHECK-NEXT: - Index: 5
; CHECK-NEXT: Type: I32
; CHECK-NEXT: Mutable: false
; CHECK-NEXT: InitExpr:
@ -87,7 +100,7 @@ entry:
; CHECK-NEXT: Value: 1032
; __memory_base
; CHECK-NEXT: - Index: 5
; CHECK-NEXT: - Index: 6
; CHECK-NEXT: Type: I32
; CHECK-NEXT: Mutable: false
; CHECK-NEXT: InitExpr:

9
lld/wasm/InputFiles.cpp
View File

@ -165,10 +165,15 @@ uint32_t ObjFile::calcNewValue(const WasmRelocation &reloc) const {
switch (reloc.Type) {
case R_WASM_TABLE_INDEX_I32:
case R_WASM_TABLE_INDEX_SLEB:
case R_WASM_TABLE_INDEX_REL_SLEB:
case R_WASM_TABLE_INDEX_REL_SLEB: {
if (!getFunctionSymbol(reloc.Index)->hasTableIndex())
return 0;
return getFunctionSymbol(reloc.Index)->getTableIndex();
uint32_t index = getFunctionSymbol(reloc.Index)->getTableIndex();
if (reloc.Type == R_WASM_TABLE_INDEX_REL_SLEB)
index -= config->tableBase;
return index;
}
case R_WASM_MEMORY_ADDR_SLEB:
case R_WASM_MEMORY_ADDR_I32:
case R_WASM_MEMORY_ADDR_LEB:

2
lld/wasm/Relocations.cpp
View File

@ -51,7 +51,7 @@ static void addGOTEntry(Symbol *sym) {
if (config->isPic)
out.importSec->addGOTEntry(sym);
else
out.globalSec->addDummyGOTEntry(sym);
out.globalSec->addStaticGOTEntry(sym);
}
void lld::wasm::scanRelocations(InputChunk *chunk) {

11
lld/wasm/Symbols.h
View File

@ -113,8 +113,6 @@ public:
const WasmSignature* getSignature() const;
bool isInGOT() const { return gotIndex != INVALID_INDEX; }
uint32_t getGOTIndex() const {
assert(gotIndex != INVALID_INDEX);
return gotIndex;
@ -126,8 +124,9 @@ public:
protected:
Symbol(StringRef name, Kind k, uint32_t flags, InputFile *f)
: name(name), file(f), flags(flags), symbolKind(k),
referenced(!config->gcSections), isUsedInRegularObj(false),
forceExport(false), canInline(false), traced(false) {}
referenced(!config->gcSections), requiresGOT(false),
isUsedInRegularObj(false), forceExport(false), canInline(false),
traced(false) {}
StringRef name;
InputFile *file;
@ -139,6 +138,10 @@ protected:
public:
bool referenced : 1;
// True for data symbols that needs a dummy GOT entry. Used for static
// linking of GOT accesses.
bool requiresGOT : 1;
// True if the symbol was used for linking and thus need to be added to the
// output file's symbol table. This is true for all symbols except for
// unreferenced DSO symbols, lazy (archive) symbols, and bitcode symbols that

41
lld/wasm/SyntheticSections.cpp
View File

@ -103,9 +103,9 @@ uint32_t ImportSection::getNumImports() const {
void ImportSection::addGOTEntry(Symbol *sym) {
assert(!isSealed);
LLVM_DEBUG(dbgs() << "addGOTEntry: " << toString(*sym) << "\n");
if (sym->hasGOTIndex())
return;
LLVM_DEBUG(dbgs() << "addGOTEntry: " << toString(*sym) << "\n");
sym->setGOTIndex(numImportedGlobals++);
gotSymbols.push_back(sym);
}
@ -244,15 +244,21 @@ void GlobalSection::assignIndexes() {
uint32_t globalIndex = out.importSec->getNumImportedGlobals();
for (InputGlobal *g : inputGlobals)
g->setGlobalIndex(globalIndex++);
for (Symbol *sym : gotSymbols)
for (Symbol *sym : staticGotSymbols)
sym->setGOTIndex(globalIndex++);
isSealed = true;
}
void GlobalSection::addDummyGOTEntry(Symbol *sym) {
LLVM_DEBUG(dbgs() << "addDummyGOTEntry: " << toString(*sym) << "\n");
if (sym->hasGOTIndex())
void GlobalSection::addStaticGOTEntry(Symbol *sym) {
assert(!isSealed);
if (sym->requiresGOT)
return;
gotSymbols.push_back(sym);
LLVM_DEBUG(dbgs() << "addStaticGOTEntry: " << sym->getName() << " "
<< toString(sym->kind()) << "\n");
sym->requiresGOT = true;
if (auto *F = dyn_cast<FunctionSymbol>(sym))
out.elemSec->addEntry(F);
staticGotSymbols.push_back(sym);
}
void GlobalSection::writeBody() {
@ -261,26 +267,27 @@ void GlobalSection::writeBody() {
writeUleb128(os, numGlobals(), "global count");
for (InputGlobal *g : inputGlobals)
writeGlobal(os, g->global);
for (const DefinedData *sym : definedFakeGlobals) {
for (const Symbol *sym : staticGotSymbols) {
WasmGlobal global;
global.Type = {WASM_TYPE_I32, false};
global.InitExpr.Opcode = WASM_OPCODE_I32_CONST;
if (auto *d = dyn_cast<DefinedData>(sym))
global.InitExpr.Value.Int32 = d->getVirtualAddress();
else if (auto *f = cast<FunctionSymbol>(sym))
global.InitExpr.Value.Int32 = f->getTableIndex();
writeGlobal(os, global);
}
for (const DefinedData *sym : dataAddressGlobals) {
WasmGlobal global;
global.Type = {WASM_TYPE_I32, false};
global.InitExpr.Opcode = WASM_OPCODE_I32_CONST;
global.InitExpr.Value.Int32 = sym->getVirtualAddress();
writeGlobal(os, global);
}
for (const Symbol *sym : gotSymbols) {
WasmGlobal global;
global.Type = {WASM_TYPE_I32, false};
global.InitExpr.Opcode = WASM_OPCODE_I32_CONST;
if (auto *d = dyn_cast<DefinedData>(sym))
global.InitExpr.Value.Int32 = d->getVirtualAddress();
else if (auto *f = cast<DefinedFunction>(sym))
global.InitExpr.Value.Int32 = f->getTableIndex();
writeGlobal(os, global);
}
}
void GlobalSection::addGlobal(InputGlobal *global) {
assert(!isSealed);
if (!global->live)
return;
inputGlobals.push_back(global);

14
lld/wasm/SyntheticSections.h
View File

@ -175,17 +175,23 @@ class GlobalSection : public SyntheticSection {
public:
GlobalSection() : SyntheticSection(llvm::wasm::WASM_SEC_GLOBAL) {}
uint32_t numGlobals() const {
return inputGlobals.size() + definedFakeGlobals.size() + gotSymbols.size();
assert(isSealed);
return inputGlobals.size() + dataAddressGlobals.size() +
staticGotSymbols.size();
}
bool isNeeded() const override { return numGlobals() > 0; }
void assignIndexes() override;
void writeBody() override;
void addGlobal(InputGlobal *global);
void addDummyGOTEntry(Symbol *sym);
void addDataAddressGlobal(DefinedData *global);
void addStaticGOTEntry(Symbol *sym);
std::vector<const DefinedData *> definedFakeGlobals;
std::vector<const DefinedData *> dataAddressGlobals;
protected:
bool isSealed = false;
std::vector<InputGlobal *> inputGlobals;
std::vector<Symbol *> gotSymbols;
std::vector<Symbol *> staticGotSymbols;
};
// The event section contains a list of declared wasm events associated with the

10
lld/wasm/Writer.cpp
View File

@ -509,8 +509,8 @@ void Writer::calculateExports() {
out.exportSec->exports.push_back(
WasmExport{functionTableName, WASM_EXTERNAL_TABLE, 0});
unsigned fakeGlobalIndex = out.importSec->getNumImportedGlobals() +
out.globalSec->inputGlobals.size();
unsigned globalIndex =
out.importSec->getNumImportedGlobals() + out.globalSec->numGlobals();
for (Symbol *sym : symtab->getSymbols()) {
if (!sym->isExported())
@ -536,8 +536,8 @@ void Writer::calculateExports() {
export_ = {name, WASM_EXTERNAL_EVENT, e->getEventIndex()};
} else {
auto *d = cast<DefinedData>(sym);
out.globalSec->definedFakeGlobals.emplace_back(d);
export_ = {name, WASM_EXTERNAL_GLOBAL, fakeGlobalIndex++};
out.globalSec->dataAddressGlobals.push_back(d);
export_ = {name, WASM_EXTERNAL_GLOBAL, globalIndex++};
}
LLVM_DEBUG(dbgs() << "Export: " << name << "\n");
@ -1035,7 +1035,7 @@ void Writer::run() {
if (errorHandler().verbose) {
log("Defined Functions: " + Twine(out.functionSec->inputFunctions.size()));
log("Defined Globals : " + Twine(out.globalSec->inputGlobals.size()));
log("Defined Globals : " + Twine(out.globalSec->numGlobals()));
log("Defined Events : " + Twine(out.eventSec->inputEvents.size()));
log("Function Imports : " +
Twine(out.importSec->getNumImportedFunctions()));