Don't add null and discarded sections to the global list.

Avoids having to skip them multiple times.

llvm-svn: 286261
diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index 53d2cc5..ddd2f9f 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -117,10 +117,6 @@
   return C->Kind == BytesDataKind;
 }
 
-template <class ELFT> static bool isDiscarded(InputSectionBase<ELFT> *S) {
-  return !S || !S->Live;
-}
-
 template <class ELFT> LinkerScript<ELFT>::LinkerScript() = default;
 template <class ELFT> LinkerScript<ELFT>::~LinkerScript() = default;
 
@@ -195,7 +191,7 @@
     size_t SizeBefore = I->Sections.size();
 
     for (InputSectionBase<ELFT> *S : Symtab<ELFT>::X->Sections) {
-      if (isDiscarded(S) || S->OutSec)
+      if (!S->Live || S->OutSec)
         continue;
 
       StringRef Filename;
@@ -368,7 +364,7 @@
 
   // Add orphan sections.
   for (InputSectionBase<ELFT> *S : Symtab<ELFT>::X->Sections)
-    if (!isDiscarded(S) && !S->OutSec)
+    if (S->Live && !S->OutSec)
       addSection(Factory, S, getOutputSectionName(S->Name));
 }