[LLD] Fix findOrphanPos to consistently ignore "dead" OutputSection's

When findOrphanPos does the reverse search to find the OutputSection
preceding the orphan's insertion point, look for a live OutputSection
and ignore "dead" OutputSection's. This matches the behaviour of the
forward search performed earlier in this function.

Added test which without the above fix fails as a result of an orphan
executable section being incorrectly placed in a non-executable segment.

Differential Review: https://reviews.llvm.org/D38690

llvm-svn: 315292

1 files changed, 5 insertions, 3 deletions

diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 92888930247..396e9ae1552 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -1031,9 +1031,11 @@ findOrphanPos(std::vector<BaseCommand *>::iterator B,
         Sec->SortRank < CurSec->SortRank)
       break;
   }
-  auto J = std::find_if(
-      llvm::make_reverse_iterator(I), llvm::make_reverse_iterator(B),
-      [](BaseCommand *Cmd) { return isa<OutputSection>(Cmd); });
+  auto J = std::find_if(llvm::make_reverse_iterator(I),
+                        llvm::make_reverse_iterator(B), [](BaseCommand *Cmd) {
+                          auto *OS = dyn_cast<OutputSection>(Cmd);
+                          return OS && OS->Live;
+                        });
   I = J.base();
 
   // As a special case, if the orphan section is the last section, put