Be sure to always increment the Versym pointer.

It was getting out of sync if we had undefined symbols at the start of
the symbol table.

llvm-svn: 268077

3 files changed, 27 insertions, 3 deletions

diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index a4b5b718e38..2c7124e6a05 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -490,16 +490,19 @@ template <class ELFT> void SharedFile<ELFT>::parseRest() {
   uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
   SymbolBodies.reserve(NumSymbols);
   for (const Elf_Sym &Sym : Syms) {
+    unsigned VersymIndex = 0;
+    if (Versym) {
+      VersymIndex = Versym->vs_index;
+      ++Versym;
+    }
+
     StringRef Name = check(Sym.getName(this->StringTable));
     if (Sym.isUndefined()) {
       Undefs.push_back(Name);
       continue;
     }
 
-    unsigned VersymIndex = 0;
     if (Versym) {
-      VersymIndex = Versym->vs_index;
-      ++Versym;
       // Ignore local symbols and non-default versions.
       if (VersymIndex == 0 || (VersymIndex & VERSYM_HIDDEN))
         continue;
diff --git a/lld/test/ELF/Inputs/version-undef-sym.so b/lld/test/ELF/Inputs/version-undef-sym.so
new file mode 100755
index 00000000000..abb4399cd6c
--- /dev/null
+++ b/lld/test/ELF/Inputs/version-undef-sym.so
diff --git a/lld/test/ELF/version-undef-sym.s b/lld/test/ELF/version-undef-sym.s
new file mode 100644
index 00000000000..bdb4795fd1f
--- /dev/null
+++ b/lld/test/ELF/version-undef-sym.s
@@ -0,0 +1,21 @@
+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+// RUN: llvm-readobj --dyn-symbols %p/Inputs/version-undef-sym.so | FileCheck %s
+
+
+// Show that the input .so has undefined symbols before bar. That is what would
+// get our version parsing out of sync.
+
+// CHECK: Section: Undefined
+// CHECK: Section: Undefined
+// CHECK: Section: Undefined
+// CHECK: Section: Undefined
+// CHECK: Section: Undefined
+// CHECK: Name: bar
+
+// But now we can successfully find bar.
+// RUN: ld.lld %t %p/Inputs/version-undef-sym.so -o %t.exe
+
+        .global _start
+_start:
+        call bar@plt