[lld] r280630 - [ELF][MIPS] Do not emit DT_REL[A]COUNT for MIPS targets

[Simon Atanasyan via llvm-commits]

Author: atanasyan
Date: Sun Sep  4 12:40:12 2016
New Revision: 280630

URL: http://llvm.org/viewvc/llvm-project?rev=280630&view=rev
Log:
[ELF][MIPS] Do not emit DT_REL[A]COUNT for MIPS targets

It looks like MIPS dynamic loader does not support RELCOUNT tag.
Both gold/bfd linkers does not emit this tag on MIPS. I will investigate
the problem further but for now it is better to behave like GNU linkers.

Modified:
    lld/trunk/ELF/OutputSections.cpp
    lld/trunk/test/ELF/mips-32.s

Modified: lld/trunk/ELF/OutputSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.cpp?rev=280630&r1=280629&r2=280630&view=diff
==============================================================================
--- lld/trunk/ELF/OutputSections.cpp (original)
+++ lld/trunk/ELF/OutputSections.cpp Sun Sep  4 12:40:12 2016
@@ -671,9 +671,14 @@ template <class ELFT> void DynamicSectio
     Add({IsRela ? DT_RELAENT : DT_RELENT,
          uintX_t(IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel))});
 
-    size_t NumRelativeRels = Out<ELFT>::RelaDyn->getRelativeRelocCount();
-    if (Config->ZCombreloc && NumRelativeRels)
-      Add({IsRela ? DT_RELACOUNT : DT_RELCOUNT, NumRelativeRels});
+    // MIPS dynamic loader does not support RELCOUNT tag.
+    // The problem is in the tight relation between dynamic
+    // relocations and GOT. So do not emit this tag on MIPS.
+    if (Config->EMachine != EM_MIPS) {
+      size_t NumRelativeRels = Out<ELFT>::RelaDyn->getRelativeRelocCount();
+      if (Config->ZCombreloc && NumRelativeRels)
+        Add({IsRela ? DT_RELACOUNT : DT_RELCOUNT, NumRelativeRels});
+    }
   }
   if (Out<ELFT>::RelaPlt && Out<ELFT>::RelaPlt->hasRelocs()) {
     Add({DT_JMPREL, Out<ELFT>::RelaPlt});

Modified: lld/trunk/test/ELF/mips-32.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/mips-32.s?rev=280630&r1=280629&r2=280630&view=diff
==============================================================================
--- lld/trunk/test/ELF/mips-32.s (original)
+++ lld/trunk/test/ELF/mips-32.s Sun Sep  4 12:40:12 2016
@@ -52,10 +52,11 @@ v2:
 # REL-NEXT:   }
 # REL-NEXT: ]
 
-# REL: DynamicSection [
-# REL:   Tag        Type                 Name/Value
-# REL:   0x00000012 RELSZ                16 (bytes)
-# REL:   0x00000013 RELENT               8 (bytes)
+# REL:   DynamicSection [
+# REL:     Tag        Type                 Name/Value
+# REL:     0x00000012 RELSZ                16 (bytes)
+# REL:     0x00000013 RELENT               8 (bytes)
+# REL-NOT: 0x6FFFFFFA RELCOUNT
 
 # REL:      Primary GOT {
 # REL-NEXT:   Canonical gp value: