[PATCH] D19836: ELF: Fix regression in TLS attribute mismatch logic.

[Peter Collingbourne via llvm-commits]

pcc created this revision.
pcc added reviewers: rafael, ruiu.
pcc added a subscriber: llvm-commits.

Introduce a special symbol type to indicate that we have not yet seen a type
for the symbol, so we should not report TLS mismatches for that symbol.

http://reviews.llvm.org/D19836

Files:
  ELF/SymbolTable.cpp
  ELF/Symbols.h
  test/ELF/tls-archive.s

Index: test/ELF/tls-archive.s
===================================================================
--- /dev/null
+++ test/ELF/tls-archive.s
@@ -0,0 +1,10 @@
+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/tls-mismatch.s -o %t2
+// RUN: rm -f %t.a
+// RUN: llvm-ar cru %t.a %t2
+// RUN: ld.lld %t.a %t -o %t3
+
+.globl _start,tlsvar
+_start:
+  movl tlsvar at GOTTPOFF(%rip),%edx
Index: ELF/Symbols.h
===================================================================
--- ELF/Symbols.h
+++ ELF/Symbols.h
@@ -127,6 +127,13 @@
   uint8_t Type;    // symbol type
   uint8_t StOther; // st_other field value
 
+  // The Type field may also have this value. It means that we have not yet seen
+  // a non-Lazy symbol with this name, so we don't know what its type is. The
+  // Type field is normally set to this value for Lazy symbols unless we saw a
+  // weak undefined symbol first, in which case we need to remember the original
+  // symbol's type in order to check for TLS mismatches.
+  enum { UnknownType = 255 };
+
   bool isSection() const { return Type == llvm::ELF::STT_SECTION; }
   bool isTls() const { return Type == llvm::ELF::STT_TLS; }
   bool isFunc() const { return Type == llvm::ELF::STT_FUNC; }
Index: ELF/SymbolTable.cpp
===================================================================
--- ELF/SymbolTable.cpp
+++ ELF/SymbolTable.cpp
@@ -240,7 +240,8 @@
     S->ExportDynamic = true;
   if (IsUsedInRegularObj)
     S->IsUsedInRegularObj = true;
-  if (!WasInserted && ((Type == STT_TLS) != S->body()->isTls()))
+  if (!WasInserted && S->body()->Type != SymbolBody::UnknownType &&
+      ((Type == STT_TLS) != S->body()->isTls()))
     error("TLS attribute mismatch for symbol: " +
           conflictMsg(S->body(), File));
 
@@ -466,7 +467,7 @@
   bool WasInserted;
   std::tie(S, WasInserted) = insert(Sym.getName());
   if (WasInserted) {
-    replaceBody<LazyArchive>(S, F, Sym, STT_NOTYPE);
+    replaceBody<LazyArchive>(S, F, Sym, SymbolBody::UnknownType);
     return;
   }
   if (!S->body()->isUndefined())
@@ -494,7 +495,7 @@
   bool WasInserted;
   std::tie(S, WasInserted) = insert(Name);
   if (WasInserted) {
-    replaceBody<LazyObject>(S, Name, MBRef, STT_NOTYPE);
+    replaceBody<LazyObject>(S, Name, MBRef, SymbolBody::UnknownType);
     return;
   }
   if (!S->body()->isUndefined())


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