[ELF][MIPS] Do not create a hidden definition for __tls_get_addr on MIPS

On most architectures the linker is required to optimize away any
references to __tls_get_addr in case of static linking. As usual
a special case is MIPS - libc defines __tls_get_addr itself because
there are no TLS optimizations for this architecture.

llvm-svn: 280664

lld/ELF/Writer.cpp

@@ -604,8 +604,10 @@ template <class ELFT> void Writer<ELFT>::addReservedSymbols() {
   // __tls_get_addr is defined by the dynamic linker for dynamic ELFs. For
   // static linking the linker is required to optimize away any references to
   // __tls_get_addr, so it's not defined anywhere. Create a hidden definition
-  // to avoid the undefined symbol error.
-  if (!Out<ELFT>::DynSymTab)
+  // to avoid the undefined symbol error. As usual as special case is MIPS -
+  // MIPS libc defines __tls_get_addr itself because there are no TLS
+  // optimizations for this target.
+  if (!Out<ELFT>::DynSymTab && Config->EMachine != EM_MIPS)
     Symtab<ELFT>::X->addIgnored("__tls_get_addr");
 
   // If linker script do layout we do not need to create any standart symbols.

lld/test/ELF/mips-tls-static.s

@@ -0,0 +1,23 @@
+# Check handling TLS related relocations and symbols when linking
+# a static executable.
+
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t
+# RUN: ld.lld -static %t -o %t.exe
+# RUN: llvm-readobj -d %t.exe | FileCheck %s
+
+# REQUIRES: mips
+
+# CHECK: LoadName
+
+  .text
+  .global __start
+__start:
+  nop
+
+  .global __tls_get_addr
+__tls_get_addr:
+  nop
+
+  .data
+loc:
+  .word __tls_get_addr