[PATCH] D35724: [ELF] - Fix missing relocation when linking executable with --unresolved-symbols=ignore-all

[George Rimar via Phabricator via llvm-commits]

grimar updated this revision to Diff 109075.
grimar added a comment.

- Rebased, addressed comments.


https://reviews.llvm.org/D35724

Files:
  ELF/Symbols.cpp
  test/ELF/executable-undefined-ignoreall.s
  test/ELF/executable-undefined-protected-ignoreall.s
  test/ELF/no-inhibit-exec.s


Index: test/ELF/no-inhibit-exec.s
===================================================================
--- test/ELF/no-inhibit-exec.s
+++ test/ELF/no-inhibit-exec.s
@@ -2,11 +2,15 @@
 # RUN: not ld.lld %t -o %t2
 # RUN: ld.lld %t --noinhibit-exec -o %t2
 # RUN: llvm-objdump -d %t2 | FileCheck %s
+# RUN: llvm-readobj -r %t2 | FileCheck %s --check-prefix=RELOC
 # REQUIRES: x86
 
 # CHECK: Disassembly of section .text:
 # CHECK-NEXT: _start
-# CHECK-NEXT: 201000: {{.*}} callq -2101253
+# CHECK-NEXT: 201000: {{.*}} callq 0
+
+# RELOC:      Relocations [
+# RELOC-NEXT: ]
 
 # next code will not link without noinhibit-exec flag
 # because of undefined symbol _bar
Index: ELF/Symbols.cpp
===================================================================
--- ELF/Symbols.cpp
+++ ELF/Symbols.cpp
@@ -141,18 +141,23 @@
   if (isShared())
     return !NeedsCopy && !NeedsPltAddr;
 
-  // That's all that can be preempted in a non-DSO.
-  if (!Config->Shared)
-    return false;
-
   // Only symbols that appear in dynsym can be preempted.
   if (!symbol()->includeInDynsym())
     return false;
 
   // Only default visibility symbols can be preempted.
   if (symbol()->Visibility != STV_DEFAULT)
     return false;
 
+  // Undefined symbols in non-DSOs are usually just an error, so it
+  // doesn't matter whether we return true or false here. However, if
+  // -unresolved-symbols=ignore-all is specified, undefined symbols in
+  // executables are automatically exported so that the runtime linker
+  // can try to resolve them. In that case, they is preemptible. So, we
+  // return true for an undefined symbol in case the option is specified.
+  if (!Config->Shared)
+    return isUndefined();
+
   // -Bsymbolic means that definitions are not preempted.
   if (Config->Bsymbolic || (Config->BsymbolicFunctions && isFunc()))
     return !isDefined();
@@ -358,7 +363,7 @@
   if (computeBinding() == STB_LOCAL)
     return false;
   if (body()->isUndefined())
-    return Config->Shared;
+    return Config->Shared || !body()->symbol()->isWeak();
   return ExportDynamic || body()->isShared();
 }
 


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