[ELF2/Linkerscript] Skip semicolon in linker directives parsing

[davide]

Summary

According to docs, semicolons are mandatory at the end of assignment but they're allowed/optional in directives. I found an example of that in a FreeBSD linker script. I'll change the linker script in FreeBSD to remove the semicolon but I think it's good we support this for GNU ld compatibility.

[ruiu]

LGTM with a nit.

https://sourceware.org/binutils/docs/ld/Script-Format.html says that "You may separate commands using semicolons", so it seems optional. Probably single ';' at beginning of file is valid because of the same reason that empty statement is accepted in C.

ELF/LinkerScript.cpp

62–65 ↗

(On Diff #37277)

if (Tok == ";")
  continue;
if (Tok == "ENTRY") {

lld/trunk/ELF/LinkerScript.cpp

private:
   std::vector<StringRef> Tokens;
   size_t Pos = 0;
 };
 }
 
 void LinkerScript::run() {
   while (!atEOF()) {
     StringRef Tok = next();
+    if (Tok == ";")
+      continue;
     if (Tok == "ENTRY") {
       readEntry();
     } else if (Tok == "GROUP" || Tok == "INPUT") {
       readGroup();
     } else if (Tok == "INCLUDE") {
       readInclude();
     } else if (Tok == "OUTPUT") {
       readOutput();

lld/trunk/test/elf2/linkerscript.s

 # RUN: echo "OUTPUT(" %t.out ")" > %t.script
 # RUN: ld.lld2 %t.script %t
 # RUN: llvm-readobj %t.out > /dev/null
 
 # RUN: echo "SEARCH_DIR(/lib/foo/blah)" > %t.script
 # RUN: ld.lld2 %t.script %t
 # RUN: llvm-readobj %t.out > /dev/null
 
+# RUN: echo ";SEARCH_DIR(x);SEARCH_DIR(y);" > %t.script
+# RUN: ld.lld2 %t.script %t
+# RUN: llvm-readobj %t.out > /dev/null
+
+# RUN: echo ";" > %t.script
+# RUN: ld.lld2 %t.script %t
+# RUN: llvm-readobj %t.out > /dev/null
+
 # RUN: echo "INCLUDE " %t.script2 "OUTPUT(" %t.out ")" > %t.script1
 # RUN: echo "GROUP(" %t ")" > %t.script2
 # RUN: ld.lld2 %t.script1
 # RUN: llvm-readobj %t2 > /dev/null
 
 # RUN: echo "FOO(BAR)" > %t.script
 # RUN: not ld.lld2 -o foo %t.script > %t.log 2>&1
 # RUN: FileCheck -check-prefix=ERR1 %s < %t.log