[ELF][MIPS] Treat R_MIPS_TLS_{D}TPREL_HI16/LO16 as relative relocations

These relocations are calculated as S + A - DTPREL or S + A - TPREL,
where DTPREL = TlsVA - 0x8000, TPREL = TlsVA - 0x7000. So the result
is relative to the TLS output section and is not an absolut value
The fix allows to escape creation of unnecessary dynamic relocations
in case of DSO linking.

llvm-svn: 266923

lld/ELF/Target.cpp

@@ -1752,10 +1752,6 @@ bool MipsTargetInfo<ELFT>::isRelRelative(uint32_t Type) const {
   case R_MIPS_32:
   case R_MIPS_64:
   case R_MIPS_HI16:
-  case R_MIPS_TLS_DTPREL_HI16:
-  case R_MIPS_TLS_DTPREL_LO16:
-  case R_MIPS_TLS_TPREL_HI16:
-  case R_MIPS_TLS_TPREL_LO16:
     return false;
   }
 }

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

@@ -6,6 +6,9 @@
 # RUN: llvm-objdump -d -t %t.exe | FileCheck -check-prefix=DIS %s
 # RUN: llvm-readobj -r -mips-plt-got %t.exe | FileCheck %s
 
+# RUN: ld.lld %t.o -shared -o %t.so
+# RUN: llvm-readobj -r -mips-plt-got %t.so | FileCheck -check-prefix=SO %s
+
 # REQUIRES: mips
 
 # DIS:      __start:
@@ -25,6 +28,16 @@
 # CHECK-NEXT: ]
 # CHECK-NOT:  Primary GOT
 
+# SO:      Relocations [
+# SO-NEXT: ]
+# SO:      Primary GOT {
+# SO:        Local entries [
+# SO-NEXT:   ]
+# SO-NEXT:   Global entries [
+# SO-NEXT:   ]
+# SO-NEXT:   Number of TLS and multi-GOT entries: 0
+# SO-NEXT: }
+
   .text
   .globl  __start
   .type __start,@function