[WebAssembly] Don't include lazy symbols in import table

[sbc100]

Summary

This bug was introduced in: https://reviews.llvm.org/D41304.
Add a test for this case.

[ruiu]

LGTM

test/wasm/archive.ll

-; Verify that multually dependant object files in an archive is handled
-; correctly.
-;
 ; RUN: llc -filetype=obj -mtriple=wasm32-unknown-uknown-wasm %s -o %t.o
-; RUN: llc -filetype=obj -mtriple=wasm32-unknown-uknown-wasm %S/Inputs/archive1.ll -o %t2.o
-; RUN: llc -filetype=obj -mtriple=wasm32-unknown-uknown-wasm %S/Inputs/archive2.ll -o %t3.o
-; RUN: llvm-ar rcs %t.a %t2.o %t3.o
+; RUN: llc -filetype=obj -mtriple=wasm32-unknown-uknown-wasm %S/Inputs/archive1.ll -o %t.a1.o
+; RUN: llc -filetype=obj -mtriple=wasm32-unknown-uknown-wasm %S/Inputs/archive2.ll -o %t.a2.o
+; RUN: llc -filetype=obj -mtriple=wasm32-unknown-uknown-wasm %S/Inputs/hello.ll -o %t.a3.o
+; RUN: llvm-ar rcs %t.a %t.a1.o %t.a2.o %t.a3.o
 ; RUN: lld -flavor wasm %t.a %t.o -o %t.wasm
 ; RUN: llvm-nm -a %t.wasm | FileCheck %s
 
-; Specifying the same archive twice is allowed.
-; RUN: lld -flavor wasm %t.a %t.a %t.o -o %t.wasm
-
 declare i32 @foo() local_unnamed_addr #1
 
 define i32 @_start() local_unnamed_addr #0 {
 entry:
   %call = tail call i32 @foo() #2
   ret i32 %call
 }
 
-; CHECK: T _start
-; CHECK: T bar
-; CHECK: T foo
+; Verify that multually dependant object files in an archive is handled
+; correctly.
+
+; CHECK:      00000002 T _start
+; CHECK-NEXT: 00000002 T _start
+; CHECK-NEXT: 00000000 T bar
+; CHECK-NEXT: 00000000 T bar
+; CHECK-NEXT: 00000001 T foo
+; CHECK-NEXT: 00000001 T foo
+
+; Verify that symbols from unused objects don't appear in the symbol table
+; CHECK-NOT: hello
+
+; Specifying the same archive twice is allowed.
+; RUN: lld -flavor wasm %t.a %t.a %t.o -o %t.wasm

wasm/Writer.cpp

for (ObjFile *File : Symtab->ObjectFiles) {
     // Memory
     if (WasmFile->memories().size() > 1)
       fatal(File->getName() + ": contains more than one memory");
   }
 }
 
 void Writer::calculateImports() {
   for (Symbol *Sym : Symtab->getSymbols()) {
-    if (Sym->isDefined() || Sym->isWeak())
+    if (!Sym->isUndefined() || Sym->isWeak())
       continue;
 
     if (Sym->isFunction()) {
       Sym->setOutputIndex(FunctionImports.size());
       FunctionImports.push_back(Sym);
     } else {
       Sym->setOutputIndex(GlobalImports.size());
       GlobalImports.push_back(Sym);