[PATCH] D126924: [lld][WebAssembly] Add support for --require-defined linker flag

[Sam Clegg via Phabricator via llvm-commits]

sbc100 created this revision.
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This option is the same as option --undefined except that if symbol is
not defined in the output file then the linker will issue an error and
exit.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D126924

Files:
  lld/wasm/Config.h
  lld/wasm/Options.td
  lld/wasm/Writer.cpp


Index: lld/wasm/Writer.cpp
===================================================================
--- lld/wasm/Writer.cpp
+++ lld/wasm/Writer.cpp
@@ -1585,6 +1585,13 @@
 
   // Delay reporting error about explicit exports until after
   // addStartStopSymbols which can create optional symbols.
+  for (auto &name : config->requireDefined) {
+    Symbol *sym = symtab->find(name);
+    if (!sym || !sym->isDefined()) {
+      error(Twine("required symbol `") + name + "` not defined");
+    }
+  }
+
   for (auto &name : config->requiredExports) {
     Symbol *sym = symtab->find(name);
     if (!sym || !sym->isDefined()) {
Index: lld/wasm/Options.td
===================================================================
--- lld/wasm/Options.td
+++ lld/wasm/Options.td
@@ -35,6 +35,9 @@
   def no_ # NAME: Flag<["--", "-"], "no-" # name>, HelpText<help2>;
 }
 
+defm require_defined: Eq<"require-defined",
+     "Force symbol to be added to symbol table as an undefined one">;
+
 // The following flags are shared with the ELF linker
 def Bsymbolic: F<"Bsymbolic">, HelpText<"Bind defined symbols locally">;
 
Index: lld/wasm/Config.h
===================================================================
--- lld/wasm/Config.h
+++ lld/wasm/Config.h
@@ -72,6 +72,7 @@
   llvm::StringSet<> allowUndefinedSymbols;
   llvm::StringSet<> exportedSymbols;
   std::vector<llvm::StringRef> requiredExports;
+  std::vector<llvm::StringRef> requireDefined;
   std::vector<llvm::StringRef> searchPaths;
   llvm::CachePruningPolicy thinLTOCachePolicy;
   llvm::Optional<std::vector<std::string>> features;


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