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[WebAssembly] Don't allow functions to be named more than once 

Even though a function can have multiple names in the
linking standards (i.e. due to aliases), there can only
be one name for a given function in the NAME section.

Differential Revision: https://reviews.llvm.org/D41975

llvm-svn: 322383
This commit is contained in:
Sam Clegg 2018-01-12 17:56:15 +00:00
parent ffbfc0f827
commit 408064ef1e
5 changed files with 82 additions and 5 deletions
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66
lld/test/wasm/alias.ll Normal file
View File

@ -0,0 +1,66 @@
; RUN: llc -mtriple=wasm32-unknown-unknown-wasm -filetype=obj -o %t.o %s
; RUN: lld -flavor wasm %t.o -o %t.wasm
; RUN: obj2yaml %t.wasm | FileCheck %s
@start_alias = alias i32 (), i32 ()* @_start
; Function Attrs: nounwind uwtable
define i32 @_start() local_unnamed_addr #1 {
entry:
ret i32 0
}
; CHECK: --- !WASM
; CHECK-NEXT: FileHeader:
; CHECK-NEXT: Version: 0x00000001
; CHECK-NEXT: Sections:
; CHECK-NEXT: - Type: TYPE
; CHECK-NEXT: Signatures:
; CHECK-NEXT: - Index: 0
; CHECK-NEXT: ReturnType: I32
; CHECK-NEXT: ParamTypes:
; CHECK-NEXT: - Type: FUNCTION
; CHECK-NEXT: FunctionTypes: [ 0 ]
; CHECK-NEXT: - Type: TABLE
; CHECK-NEXT: Tables:
; CHECK-NEXT: - ElemType: ANYFUNC
; CHECK-NEXT: Limits:
; CHECK-NEXT: Flags: [ HAS_MAX ]
; CHECK-NEXT: Initial: 0x00000001
; CHECK-NEXT: Maximum: 0x00000001
; CHECK-NEXT: - Type: MEMORY
; CHECK-NEXT: Memories:
; CHECK-NEXT: - Initial: 0x00000002
; CHECK-NEXT: - Type: GLOBAL
; CHECK-NEXT: Globals:
; CHECK-NEXT: - Index: 0
; CHECK-NEXT: Type: I32
; CHECK-NEXT: Mutable: true
; CHECK-NEXT: InitExpr:
; CHECK-NEXT: Opcode: I32_CONST
; CHECK-NEXT: Value: 66560
; CHECK-NEXT: - Type: EXPORT
; CHECK-NEXT: Exports:
; CHECK-NEXT: - Name: memory
; CHECK-NEXT: Kind: MEMORY
; CHECK-NEXT: Index: 0
; CHECK-NEXT: - Name: _start
; CHECK-NEXT: Kind: FUNCTION
; CHECK-NEXT: Index: 0
; CHECK-NEXT: - Name: start_alias
; CHECK-NEXT: Kind: FUNCTION
; CHECK-NEXT: Index: 0
; CHECK-NEXT: - Type: CODE
; CHECK-NEXT: Functions:
; CHECK-NEXT: - Index: 0
; CHECK-NEXT: Locals:
; CHECK-NEXT: Body: 41000B
; CHECK-NEXT: - Type: CUSTOM
; CHECK-NEXT: Name: linking
; CHECK-NEXT: DataSize: 0
; CHECK-NEXT: - Type: CUSTOM
; CHECK-NEXT: Name: name
; CHECK-NEXT: FunctionNames:
; CHECK-NEXT: - Index: 0
; CHECK-NEXT: Name: start_alias
; CHECK-NEXT: ...

4
lld/wasm/InputChunks.h
View File

@ -110,7 +110,7 @@ class InputFunction : public InputChunk {
public:
InputFunction(const WasmSignature &S, const WasmFunction &Func,
const ObjFile &F)
: InputChunk(F), Signature(S), Function(Func) {}
: InputChunk(F), Signature(S), WrittenToNameSec(false), Function(Func) {}
uint32_t getSize() const override { return Function.Size; }
const uint8_t *getData() const override {
@ -126,6 +126,8 @@ public:
const WasmSignature &Signature;
unsigned WrittenToNameSec : 1;
protected:
uint32_t getInputSectionOffset() const override {
return Function.CodeSectionOffset;

2
lld/wasm/Symbols.cpp
View File

@ -74,7 +74,7 @@ void Symbol::setTableIndex(uint32_t Index) {
}
void Symbol::update(Kind K, InputFile *F, uint32_t Flags_,
const InputSegment *Seg, const InputFunction *Func,
const InputSegment *Seg, InputFunction *Func,
uint32_t Address) {
SymbolKind = K;
File = F;

6
lld/wasm/Symbols.h
View File

@ -93,11 +93,11 @@ public:
void update(Kind K, InputFile *F = nullptr, uint32_t Flags = 0,
const InputSegment *Segment = nullptr,
const InputFunction *Function = nullptr,
uint32_t Address = UINT32_MAX);
InputFunction *Function = nullptr, uint32_t Address = UINT32_MAX);
void setArchiveSymbol(const Archive::Symbol &Sym) { ArchiveSymbol = Sym; }
const Archive::Symbol &getArchiveSymbol() { return ArchiveSymbol; }
InputFunction *getFunction() { return Function; }
// This bit is used by Writer::writeNameSection() to prevent
// symbols from being written to the symbol table more than once.
@ -113,7 +113,7 @@ protected:
Kind SymbolKind = InvalidKind;
InputFile *File = nullptr;
const InputSegment *Segment = nullptr;
const InputFunction *Function = nullptr;
InputFunction *Function = nullptr;
llvm::Optional<uint32_t> OutputIndex;
llvm::Optional<uint32_t> TableIndex;
const WasmSignature *FunctionType = nullptr;

9
lld/wasm/Writer.cpp
View File

@ -442,6 +442,15 @@ void Writer::createNameSection() {
for (Symbol *S : File->getSymbols()) {
if (!S->isFunction() || S->isWeak() || S->WrittenToNameSec)
continue;
// We also need to guard against two different symbols (two different
// names) for the same wasm function. While this is possible (aliases)
// it is not legal in the "name" section.
InputFunction *Function = S->getFunction();
if (Function) {
if (Function->WrittenToNameSec)
continue;
Function->WrittenToNameSec = true;
}
S->WrittenToNameSec = true;
Names.emplace_back(S);
}