[lld] support quoted and unquoted entry symbol

[MaskRay]

Summary

Match gnu linker behavior by supporting quoted and unquoted entry symbol

[MaskRay]

This needs a test in lld/test/ELF

[kmistryic]

Added test

[MaskRay]

Just add a "_label" test to linkerscript/entry.s.

[MaskRay]

Apologies. I know that you sent the patch first. I ended up cleaning up the existing linkerscript/entry.s a bit (c5578fca16d5e2b274a9bd44e59f5160e908e294) and added quoted symbol support.

Next time please mention this fixes/closes https://github.com/llvm/llvm-project/issues/56208

[lld] support quoted and unquoted entry symbol

[ELF] Support quoted entry symbol

Unquoted entry symbols are supported before this patch.

lld/ELF/ScriptParser.cpp

void ScriptParser::readAsNeeded() {
   config->asNeeded = orig;
 }
 
 void ScriptParser::readEntry() {
   // -e <symbol> takes predecence over ENTRY(<symbol>).
   expect("(");
   StringRef tok = next();
   if (config->entry.empty())
-    config->entry = tok;
+    config->entry = unquote(tok);
   expect(")");
 }
 
 void ScriptParser::readExtern() {
   expect("(");
   while (!errorCount() && !consume(")"))
     config->undefined.push_back(unquote(next()));
 }

lld/test/ELF/linkerscript/entry1.s

+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+// RUN: echo "ENTRY(\"__start\")" > %t.script
+// RUN: ld.lld -T %t.script %t -o %tout2 2>&1 | Filecheck %s
+// CHECK: ld.lld: warning: cannot find entry symbol __start; not setting start address
+// CHECK-NOT: ld.lld: warning: cannot find entry symbol {{\"__start\"}}; not setting start address
+.global _foo_
+_foo_:
+        retq