[WebAssembly] Remove custom handling for undefined entry

This code was needed back when we were not able to write
out the synthetic symbol for main.

Add tests to make sure we can handle this now.

Differential Revision: https://reviews.llvm.org/D42322

llvm-svn: 323020

lld/test/wasm/undefined-entry.test

@@ -2,3 +2,9 @@ RUN: llc -filetype=obj -mtriple=wasm32-unknown-unknown-wasm %p/Inputs/ret32.ll -
 RUN: not lld -flavor wasm -o %t.wasm %t.ret32.o 2>&1 | FileCheck %s
 
 CHECK: error: undefined symbol: _start
+
+RUN: not lld -flavor wasm -entry=foo -o %t.wasm %t.ret32.o 2>&1 | FileCheck %s -check-prefix=CHECK-CUSTOM
+
+CHECK-CUSTOM: error: undefined symbol: foo
+
+RUN: lld -flavor wasm -entry=foo --allow-undefined -o %t.wasm %t.ret32.o

lld/wasm/Driver.cpp

@@ -349,8 +349,6 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
       Sym->setHidden(false);
   }
 
-  if (!Config->Entry.empty() && !Symtab->find(Config->Entry)->isDefined())
-    error("entry point not found: " + Config->Entry);
   if (errorCount())
     return;