[PATCH] D100624: [ELF] Don't set versionId on undefined weak lazy symbols

[Fangrui Song via Phabricator via llvm-commits]

MaskRay updated this revision to Diff 338937.
MaskRay added a comment.

Add an inline comment


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100624/new/

https://reviews.llvm.org/D100624

Files:
  lld/ELF/SyntheticSections.cpp
  lld/test/ELF/version-script-weak.s


Index: lld/test/ELF/version-script-weak.s
===================================================================
--- lld/test/ELF/version-script-weak.s
+++ lld/test/ELF/version-script-weak.s
@@ -24,6 +24,19 @@
 # CHECK-NEXT:   Section: Undefined
 # CHECK-NEXT: }
 
+## The version of an unfetched lazy symbol is VER_NDX_GLOBAL. It is not affected by version scripts.
+# RUN: echo "v1 { *; };" > %t2.script
+# RUN: ld.lld -shared --version-script %t2.script %t.o --start-lib %t1.o --end-lib -o %t2.so
+# RUN: llvm-readelf --dyn-syms %t2.so | FileCheck %s --check-prefix=CHECK2
+
+# CHECK2: NOTYPE WEAK DEFAULT UND foo{{$}}
+
+# RUN: ld.lld -shared --soname=tshared --version-script %t2.script %t1.o -o %tshared.so
+# RUN: ld.lld -shared --version-script %t2.script %t.o --start-lib %t1.o --end-lib %tshared.so -o %t3.so
+# RUN: llvm-readelf --dyn-syms %t3.so | FileCheck %s --check-prefix=CHECK3
+
+# CHECK3: NOTYPE WEAK DEFAULT UND foo at v1
+
 .text
  callq foo at PLT
 .weak foo
Index: lld/ELF/SyntheticSections.cpp
===================================================================
--- lld/ELF/SyntheticSections.cpp
+++ lld/ELF/SyntheticSections.cpp
@@ -3123,7 +3123,9 @@
 void VersionTableSection::writeTo(uint8_t *buf) {
   buf += 2;
   for (const SymbolTableEntry &s : getPartition().dynSymTab->getSymbols()) {
-    write16(buf, s.sym->versionId);
+    // Use the original versionId for an unfetched lazy symbol (undefined weak),
+    // which must be VER_NDX_GLOBAL (an undefined versioned symbol is an error).
+    write16(buf, s.sym->isLazy() ? VER_NDX_GLOBAL : s.sym->versionId);
     buf += 2;
   }
 }


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D100624.338937.patch
Type: text/x-patch
Size: 1605 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20210420/50cac16e/attachment.bin>