[𝘀𝗽𝗿] initial version

Created using spr 1.3.5-bogner

Author: MaskRay

lld/ELF/Symbols.h

@@ -313,6 +313,8 @@ class Symbol {
   // represents the Verdef index within the input DSO, which will be converted
   // to a Verneed index in the output. Otherwise, this represents the Verdef
   // index (VER_NDX_LOCAL, VER_NDX_GLOBAL, or a named version).
+  // VER_NDX_LOCAL indicates a defined symbol that has been localized by a
+  // version script's local: directive or --exclude-libs.
   uint16_t versionId;
   LLVM_PREFERRED_TYPE(bool)
   uint8_t versionScriptAssigned : 1;

lld/ELF/SyntheticSections.cpp

@@ -3784,9 +3784,10 @@ void VersionTableSection::writeTo(uint8_t *buf) {
   buf += 2;
   for (const SymbolTableEntry &s : getPartition(ctx).dynSymTab->getSymbols()) {
     // For an unextracted lazy symbol (undefined weak), it must have been
-    // converted to Undefined and have VER_NDX_GLOBAL version here.
+    // converted to Undefined.
     assert(!s.sym->isLazy());
-    write16(ctx, buf, s.sym->versionId);
+    // Undefined symbols should use index 0 when unversioned.
+    write16(ctx, buf, s.sym->isUndefined() ? 0 : s.sym->versionId);
     buf += 2;
   }
 }

lld/test/ELF/linkerscript/version-script.s

@@ -17,7 +17,7 @@
 # CHECK-NEXT:     Name:
 # CHECK-NEXT:   }
 # CHECK-NEXT:   Symbol {
-# CHECK-NEXT:     Version: 1
+# CHECK-NEXT:     Version: 0
 # CHECK-NEXT:     Name: und
 # CHECK-NEXT:   }
 # CHECK-NEXT:   Symbol {

lld/test/ELF/version-script-extern-undefined.s

@@ -11,7 +11,7 @@
 # CHECK-NEXT:     Name:
 # CHECK-NEXT:   }
 # CHECK-NEXT:   Symbol {
-# CHECK-NEXT:     Version: 1
+# CHECK-NEXT:     Version: 0
 # CHECK-NEXT:     Name: _Z3abbi
 # CHECK-NEXT:   }
 # CHECK-NEXT: ]

llvm/include/llvm/BinaryFormat/ELF.h

@@ -1710,8 +1710,8 @@ enum { VER_FLG_BASE = 0x1, VER_FLG_WEAK = 0x2, VER_FLG_INFO = 0x4 };
 
 // Special constants for the version table. (SHT_GNU_versym/.gnu.version)
 enum {
-  VER_NDX_LOCAL = 0,       // Unversioned local symbol
-  VER_NDX_GLOBAL = 1,      // Unversioned global symbol
+  VER_NDX_LOCAL = 0,       // Unversioned undefined or localized defined symbol
+  VER_NDX_GLOBAL = 1,      // Unversioned non-local defined symbol
   VERSYM_VERSION = 0x7fff, // Version Index mask
   VERSYM_HIDDEN = 0x8000   // Hidden bit (non-default version)
 };