[PATCH] D35263: [ELF] - Fix handling of weak symbols from static library when using version script.

George Rimar via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Tue Jul 11 09:03:53 PDT 2017


grimar created this revision.
Herald added a subscriber: emaste.

This is PR33738.

In short issue is next. Imagine code and script.
**Version script:**

  { local: *; };

**Dso code:**

  .text
   callq foo at PLT
  .weak foo

`foo` here is a weak undefined symbol that can be found in archive.
Undefined weak will not fetch archive members

During scan of relocations we call `isPreemptible()` which calls `includeInDynsym()' inside,
the latter one calls `computeBinding()` which computed binding as STB_LOCAL for such symbols,
making it non-preemptible what broked output.


https://reviews.llvm.org/D35263

Files:
  ELF/SymbolTable.cpp
  ELF/Symbols.h
  test/ELF/Inputs/version-script-weak.s
  test/ELF/version-script-weak.s


Index: test/ELF/version-script-weak.s
===================================================================
--- test/ELF/version-script-weak.s
+++ test/ELF/version-script-weak.s
@@ -0,0 +1,27 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/version-script-weak.s -o %tmp.o
+# RUN: llvm-ar rcs %t.a %tmp.o
+# RUN: echo "{ local: *; };" > %t.script
+# RUN: ld.lld -shared --version-script %t.script %t.o %t.a -o %t.so
+# RUN: llvm-readobj -dyn-symbols -r %t.so | FileCheck %s
+
+# CHECK:      Relocations [
+# CHECK-NEXT:   Section ({{.*}}) .rela.plt {
+# CHECK-NEXT:     0x2018 R_X86_64_JUMP_SLOT foo
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]
+# CHECK:      Symbol {
+# CHECK:        Name: foo@
+# CHECK-NEXT:   Value: 0x0
+# CHECK-NEXT:   Size: 0
+# CHECK-NEXT:   Binding: Weak
+# CHECK-NEXT:   Type: None
+# CHECK-NEXT:   Other: 0
+# CHECK-NEXT:   Section: Undefined
+# CHECK-NEXT: }
+
+.text
+ callq foo at PLT
+.weak foo
Index: test/ELF/Inputs/version-script-weak.s
===================================================================
--- test/ELF/Inputs/version-script-weak.s
+++ test/ELF/Inputs/version-script-weak.s
@@ -0,0 +1,4 @@
+.text
+.globl foo
+.type foo, at function
+foo:
Index: ELF/Symbols.h
===================================================================
--- ELF/Symbols.h
+++ ELF/Symbols.h
@@ -65,7 +65,9 @@
     return SymbolKind == LazyArchiveKind || SymbolKind == LazyObjectKind;
   }
   bool isShared() const { return SymbolKind == SharedKind; }
-  bool isInCurrentDSO() const { return !isUndefined() && !isShared(); }
+  bool isInCurrentDSO() const {
+    return !isUndefined() && !isShared() && !isLazy();
+  }
   bool isLocal() const { return IsLocal; }
   bool isPreemptible() const;
   StringRef getName() const { return Name; }
Index: ELF/SymbolTable.cpp
===================================================================
--- ELF/SymbolTable.cpp
+++ ELF/SymbolTable.cpp
@@ -326,7 +326,7 @@
   if (WasInserted)
     return 1;
   SymbolBody *Body = S->body();
-  if (Body->isLazy() || !Body->isInCurrentDSO())
+  if (!Body->isInCurrentDSO())
     return 1;
   if (Binding == STB_WEAK)
     return -1;


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