[lld][WebAssembly] Warn on unknown -z flags

[sbc100]

Summary

This code mirrors that in lld/ELF/Driver.cpp, as does the new test code.

[dschuff]

lld/wasm/Driver.cpp

825

[sbc100]

feedback

[MaskRay]

LG

lld/ELF/Driver.cpp

for (auto *arg : args.filtered(OPT_z))
     if (!isKnownZFlag(arg->getValue()))
       warn("unknown -z value: " + StringRef(arg->getValue()));
 }
 
 void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   ELFOptTable parser;
   opt::InputArgList args = parser.parse(argsArr.slice(1));
 
-  // Interpret the flags early because error()/warn() depend on them.
+  // Interpret these flags early because error()/warn() depend on them.
   errorHandler().errorLimit = args::getInteger(args, OPT_error_limit, 20);
   errorHandler().fatalWarnings =
       args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false);
   checkZOptions(args);
 
   // Handle -help
   if (args.hasArg(OPT_help)) {
     printHelp();

lld/test/wasm/driver.ll

 ; RUN: llc -filetype=obj %s -o %t.o
 
 target triple = "wasm32-unknown-unknown"
 
-define hidden void @entry() local_unnamed_addr #0 {
+define hidden void @_start() local_unnamed_addr #0 {
 entry:
   ret void
 }
 
 ; RUN: not wasm-ld -o %t.exe 2>&1 | FileCheck -check-prefix=IN %s
 ; IN: error: no input files
 
 ; RUN: not wasm-ld %t.o 2>&1 | FileCheck -check-prefix=OUT %s
 ; OUT: error: no output file specified
 
 ; RUN: not wasm-ld 2>&1 | FileCheck -check-prefix=BOTH %s
 ; BOTH:     error: no input files
 ; BOTH-NOT: error: no output file specified
 
 ; RUN: not wasm-ld --export-table --import-table %t.o 2>&1 \
 ; RUN:   | FileCheck -check-prefix=TABLE %s
 ; TABLE: error: --import-table and --export-table may not be used together
 
 ; RUN: not wasm-ld --relocatable --shared-memory %t.o 2>&1 \
 ; RUN:   | FileCheck -check-prefix=SHARED-MEM %s
 ; SHARED-MEM: error: -r and --shared-memory may not be used together
+
+; RUN: wasm-ld %t.o -z foo -o /dev/null 2>&1 | FileCheck -check-prefix=ERR10 %s
+; RUN: wasm-ld %t.o -z foo -o /dev/null --version 2>&1 | FileCheck -check-prefix=ERR10 %s
+; ERR10: warning: unknown -z value: foo
+
+;; Check we report "unknown -z value" error even with -v.
+; RUN: wasm-ld %t.o -z foo -o /dev/null -v 2>&1 | FileCheck -check-prefix=ERR10 %s
+
+;; Note: in GNU ld, --fatal-warning still leads to a warning.
+; RUN: not wasm-ld %t.o -z foo --fatal-warnings 2>&1 | FileCheck --check-prefix=ERR10-FATAL %s
+; ERR10-FATAL: error: unknown -z value: foo
+
+;; stack-size without an = is also an error
+; RUN: not wasm-ld %t.o -z stack-size 2>&1 | FileCheck -check-prefix=ERR11 %s
+; ERR11: unknown -z value: stack-size

lld/wasm/Driver.cpp

static void readConfigs(opt::InputArgList &args) {
   config->demangle = args.hasFlag(OPT_demangle, OPT_no_demangle, true);
   config->disableVerify = args.hasArg(OPT_disable_verify);
   config->emitRelocs = args.hasArg(OPT_emit_relocs);
   config->experimentalPic = args.hasArg(OPT_experimental_pic);
   config->entry = getEntry(args);
   config->exportAll = args.hasArg(OPT_export_all);
   config->exportTable = args.hasArg(OPT_export_table);
   config->growableTable = args.hasArg(OPT_growable_table);
-  errorHandler().fatalWarnings =
-      args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false);
   config->importMemory = args.hasArg(OPT_import_memory);
   config->sharedMemory = args.hasArg(OPT_shared_memory);
   config->importTable = args.hasArg(OPT_import_table);
   config->importUndefined = args.hasArg(OPT_import_undefined);
   config->ltoo = args::getInteger(args, OPT_lto_O, 2);
   config->ltoPartitions = args::getInteger(args, OPT_lto_partitions, 1);
   config->ltoNewPassManager =
       args.hasFlag(OPT_no_lto_legacy_pass_manager, OPT_lto_legacy_pass_manager,
parallelForEach(symtab->objectFiles, [](ObjFile *file) {
     }
     for (InputChunk *sec : file->customSections) {
       if (auto *s = dyn_cast<MergeInputChunk>(sec))
         s->splitIntoPieces();
     }
   });
 }
 
+static bool isKnownZFlag(StringRef s) {
+  // For now, we only support a very limited set of -z flags
+  return s.startswith("stack-size=");
+}
+
+// Report a warning for an unknown -z option.
+static void checkZOptions(opt::InputArgList &args) {
+  for (auto *arg : args.filtered(OPT_z))
+    if (!isKnownZFlag(arg->getValue()))
+      warn("unknown -z value: " + StringRef(arg->getValue()));
+}
+
 void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   WasmOptTable parser;
   opt::InputArgList args = parser.parse(argsArr.slice(1));
 
+  // Interpret these flags early because error()/warn() depend on them.
+  errorHandler().errorLimit = args::getInteger(args, OPT_error_limit, 20);
+  errorHandler().fatalWarnings =
+      args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false);
+  checkZOptions(args);
+
   // Handle --help
   if (args.hasArg(OPT_help)) {
     parser.printHelp(lld::outs(),
                      (std::string(argsArr[0]) + " [options] file...").c_str(),
                      "LLVM Linker", false);
     return;
   }
 
void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   // Parse and evaluate -mllvm options.
   std::vector<const char *> v;
   v.push_back("wasm-ld (LLVM option parsing)");
   for (auto *arg : args.filtered(OPT_mllvm))
     v.push_back(arg->getValue());
   cl::ResetAllOptionOccurrences();
   cl::ParseCommandLineOptions(v.size(), v.data());
 
-  errorHandler().errorLimit = args::getInteger(args, OPT_error_limit, 20);
-
   readConfigs(args);
 
   createFiles(args);
   if (errorCount())
     return;
 
   setConfigs();
   checkOptions(args);