[PATCH] D126554: [lld][WebAssembly] Fix crash on undefined/weak function symbols in LTO objects

[Sam Clegg via Phabricator via llvm-commits]

sbc100 created this revision.
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Symbols from LTO objects don't contain Wasm signatures, but we need a
signature when we create undefined/stub functions for missing weakly
undefined symbols.

Luckily, after LTO, we know that symbols that are not referenced by a
regular object file must not be needed in the final output so there
is no need to generate undefined/stub function for them.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D126554

Files:
  lld/wasm/SymbolTable.cpp


Index: lld/wasm/SymbolTable.cpp
===================================================================
--- lld/wasm/SymbolTable.cpp
+++ lld/wasm/SymbolTable.cpp
@@ -842,7 +842,7 @@
 void SymbolTable::replaceWithUndefined(Symbol *sym) {
   // Add a synthetic dummy for weak undefined functions.  These dummies will
   // be GC'd if not used as the target of any "call" instructions.
-  StringRef debugName = saver().save("undefined_weak:" + toString(*sym));
+  StringRef debugName = saver().save("undefined_weak:" + sym->getName());
   replaceWithUnreachable(sym, *sym->getSignature(), debugName);
   // Hide our dummy to prevent export.
   sym->setHidden(true);
@@ -854,7 +854,7 @@
 // the call instruction that passes Wasm validation.
 void SymbolTable::handleWeakUndefines() {
   for (Symbol *sym : getSymbols()) {
-    if (sym->isUndefWeak()) {
+    if (sym->isUndefWeak() && sym->isUsedInRegularObj) {
       if (sym->getSignature()) {
         replaceWithUndefined(sym);
       } else {


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