[WebAssembly] LTO: Don't include bitcode-only symbols in the symtab

[sbc100]

Summary

Fixes https://bugs.llvm.org/show_bug.cgi?id=40654

[sbc100]

Hey @ruiu, do you know how we can stop herrald from adding @espindola as reviewer on all these CLs? My understanding is that he in no longer involved with the project.

[pcc]

lld/wasm/Writer.cpp

953

Can this just be if (Sym->IsUsedInRegularObj)? AFAICT this flag is not set on lazy symbols (nor should it be).

[sbc100]

• feedback

lld/wasm/Writer.cpp

953

Thanks! Done.

[pcc]

LGTM

lld/test/ELF/lto/relocatable.ll

 define void @foo() {
   call void @bar()
   ret void
 }
 
 define internal void @bar() {
   ret void
 }
+
+declare i32 @baz(...)

lld/test/wasm/lto/relocatable.ll

+; RUN: llvm-as %s -o %t1.o
+; RUN: wasm-ld %t1.o -r -o %t
+; RUN: llvm-readobj -symbols %t | FileCheck %s
+
+; CHECK:      Symbols [
+; CHECK-NEXT:   Symbol {
+; CHECK-NEXT:     Name: foo
+; CHECK-NEXT:     Type: FUNCTION (0x0)
+; CHECK-NEXT:     Flags [ (0x0)
+; CHECK-NEXT:     ]
+; CHECK-NEXT:     ElementIndex: 0x0
+; CHECK-NEXT:   }
+; CHECK-NEXT: ]
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+define void @foo() {
+  call void @bar()
+  ret void
+}
+
+define internal void @bar() {
+  ret void
+}
+
+declare i32 @baz(...)

lld/wasm/Writer.cpp

auto AddSymbol = [&](Symbol *Sym) {
     // (Since this is relocatable output, GC is not performed so symbols must
     // be live.)
     assert(Sym->isLive());
     Sym->setOutputSymbolIndex(SymbolIndex++);
     SymtabEntries.emplace_back(Sym);
   };
 
   for (Symbol *Sym : Symtab->getSymbols())
-    if (!Sym->isLazy())
+    if (!Sym->isLazy() && Sym->IsUsedInRegularObj)
       AddSymbol(Sym);
 
   for (ObjFile *File : Symtab->ObjectFiles) {
     LLVM_DEBUG(dbgs() << "Local symtab entries: " << File->getName() << "\n");
     for (Symbol *Sym : File->getSymbols())
       if (Sym->isLocal())
         AddSymbol(Sym);
   }