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[WebAssembly] Add --no-entry argument 

This adds a `--no-entry` argument to wasm LLD used to
suppress the default `_start` entry point.

Patch by Nicholas Wilson!

Differential Revision: https://reviews.llvm.org/D40725

llvm-svn: 320167
This commit is contained in:
Sam Clegg 2017-12-08 17:58:25 +00:00
parent de5209bdbd
commit 2c096bacc6
3 changed files with 23 additions and 14 deletions
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2
lld/test/wasm/data-layout.ll
View File

@ -1,6 +1,6 @@
; RUN: llc -filetype=obj %p/Inputs/hello.ll -o %t.hello.o
; RUN: llc -filetype=obj %s -o %t.o
; RUN: lld -flavor wasm --emit-relocs --allow-undefined -o %t.wasm %t.o %t.hello.o
; RUN: lld -flavor wasm --emit-relocs --allow-undefined --no-entry -o %t.wasm %t.o %t.hello.o
; RUN: obj2yaml %t.wasm | FileCheck %s
target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"

32
lld/wasm/Driver.cpp
View File

@ -202,6 +202,15 @@ void LinkerDriver::createFiles(opt::InputArgList &Args) {
error("no input files");
}
static const char *getEntry(opt::InputArgList &Args, const char *def) {
auto *Arg = Args.getLastArg(OPT_entry, OPT_no_entry);
if (!Arg)
return def;
if (Arg->getOption().getID() == OPT_no_entry)
return "";
return Arg->getValue();
}
void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
WasmOptTable Parser;
opt::InputArgList Args = Parser.parse(ArgsArr.slice(1));
@ -230,10 +239,10 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
Config->CheckSignatures =
Args.hasFlag(OPT_check_signatures, OPT_no_check_signatures, false);
Config->EmitRelocs = Args.hasArg(OPT_emit_relocs);
Config->Entry = Args.getLastArgValue(OPT_entry);
Config->Relocatable = Args.hasArg(OPT_relocatable);
Config->Entry = getEntry(Args, Config->Relocatable ? "" : "_start");
Config->ImportMemory = Args.hasArg(OPT_import_memory);
Config->OutputFile = Args.getLastArgValue(OPT_o);
Config->Relocatable = Args.hasArg(OPT_relocatable);
Config->SearchPaths = args::getStrings(Args, OPT_L);
Config->StripAll = Args.hasArg(OPT_strip_all);
Config->StripDebug = Args.hasArg(OPT_strip_debug);
@ -265,10 +274,10 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
error("undefined symbols specified for relocatable output file");
if (!Config->Relocatable) {
if (Config->Entry.empty())
Config->Entry = "_start";
static WasmSignature Signature = {{}, WASM_TYPE_NORESULT};
addSyntheticUndefinedFunction(Config->Entry, &Signature);
if (!Config->Entry.empty()) {
static WasmSignature Signature = {{}, WASM_TYPE_NORESULT};
addSyntheticUndefinedFunction(Config->Entry, &Signature);
}
// Handle the `--undefined <sym>` options.
for (StringRef S : args::getStrings(Args, OPT_undefined))
@ -301,15 +310,12 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
if (!Sym->isDefined())
error("function forced with --undefined not found: " + Sym->getName());
}
if (errorCount())
return;
}
if (!Config->Entry.empty()) {
Symbol *Sym = Symtab->find(Config->Entry);
if (!Sym->isFunction())
fatal("entry point is not a function: " + Sym->getName());
}
if (!Config->Entry.empty() && !Symtab->find(Config->Entry)->isDefined())
error("entry point not found: " + Config->Entry);
if (errorCount())
return;
// Write the result to the file.
writeResult();

3
lld/wasm/Options.td
View File

@ -66,6 +66,9 @@ def z: JoinedOrSeparate<["-"], "z">, MetaVarName<"<option>">,
def entry: S<"entry">, MetaVarName<"<entry>">,
HelpText<"Name of entry point symbol">;
def no_entry: F<"no-entry">,
HelpText<"Do not output any entry point">;
def error_limit: J<"error-limit=">,
HelpText<"Maximum number of errors to emit before stopping (0 = no limit)">;