Revert "[ELF] -z combreloc: sort dynamic relocations by (symbol_index,r_offset)"

This reverts commit r361125.  This linker change breaks shared libraries
in some subtle way on x86_64.  (Specifically, gold segfaults when
loading the LLVMgold.so plugin linked with lldb with this patch.)

llvm-svn: 361150

lld/ELF/SyntheticSections.cpp

@@ -1488,15 +1488,17 @@ RelocationSection<ELFT>::RelocationSection(StringRef Name, bool Sort)
   this->Entsize = Config->IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
 }
 
+static bool compRelocations(const DynamicReloc &A, const DynamicReloc &B) {
+  bool AIsRel = A.Type == Target->RelativeRel;
+  bool BIsRel = B.Type == Target->RelativeRel;
+  if (AIsRel != BIsRel)
+    return AIsRel;
+  return A.getSymIndex() < B.getSymIndex();
+}
+
 template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
-  // Sort symbol index then by r_offset. Because we only emit R_*_RELATIVE as
-  // dynamic relocations with symbol index 0, this essentially places
-  // R_*_RELATIVE first (required by DT_REL[A]COUNT).
   if (Sort)
-    llvm::stable_sort(Relocs, [](const DynamicReloc &A, const DynamicReloc &B) {
+    llvm::stable_sort(Relocs, compRelocations);
-      return std::make_tuple(A.getSymIndex(), A.getOffset()) <
-             std::make_tuple(B.getSymIndex(), B.getOffset());
-    });
 
   for (const DynamicReloc &Rel : Relocs) {
     encodeDynamicReloc<ELFT>(reinterpret_cast<Elf_Rela *>(Buf), Rel);

lld/test/ELF/combreloc.s

@@ -1,48 +0,0 @@
-# REQUIRES: x86
-
-# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
-# RUN: echo 'mov aaa@gotpcrel(%rip), %rax' | llvm-mc -filetype=obj -triple=x86_64 - -o %t1.o
-
-# RUN: ld.lld -shared %t.o %t1.o -o %t.so
-# RUN: llvm-readobj -r --dynamic-table %t.so | FileCheck %s
-# RUN: ld.lld -shared %t.o %t1.o -o %t.so -z combreloc
-# RUN: llvm-readobj -r --dynamic-table %t.so | FileCheck %s
-
-# -z combreloc is the default: sort relocations by (SymIndex, r_offset), and
-# emit DT_RELACOUNT (except on MIPS) to indicate the number of relative
-# relocations.
-
-# CHECK:      Relocations [
-# CHECK-NEXT:   Section ({{.*}}) .rela.dyn {
-# CHECK-NEXT:     0x3020 R_X86_64_RELATIVE - 0x3028
-# CHECK-NEXT:     0x20B0 R_X86_64_GLOB_DAT aaa 0x0
-# CHECK-NEXT:     0x3000 R_X86_64_64 aaa 0x0
-# CHECK-NEXT:     0x3018 R_X86_64_64 aaa 0x0
-# CHECK-NEXT:     0x3010 R_X86_64_64 bbb 0x0
-# CHECK-NEXT:     0x3008 R_X86_64_64 ccc 0x0
-# CHECK-NEXT:   }
-# CHECK:      DynamicSection [
-# CHECK:        RELACOUNT 1
-
-# RUN: ld.lld -z nocombreloc -shared %t.o %t1.o -o %t.so
-# RUN: llvm-readobj -r --dynamic-table %t.so | FileCheck --check-prefix=NOCOMB %s
-
-# NOCOMB:      Relocations [
-# NOCOMB-NEXT:   Section ({{.*}}) .rela.dyn {
-# NOCOMB-NEXT:     0x3000 R_X86_64_64 aaa 0x0
-# NOCOMB-NEXT:     0x3008 R_X86_64_64 ccc 0x0
-# NOCOMB-NEXT:     0x3010 R_X86_64_64 bbb 0x0
-# NOCOMB-NEXT:     0x3018 R_X86_64_64 aaa 0x0
-# NOCOMB-NEXT:     0x3020 R_X86_64_RELATIVE - 0x3028
-# NOCOMB-NEXT:     0x20A0 R_X86_64_GLOB_DAT aaa 0x0
-# NOCOMB-NEXT:   }
-# NOCOMB:      DynamicSection [
-# NOCOMB-NOT:    RELACOUNT
-
-.data
- .quad aaa
- .quad ccc
- .quad bbb
- .quad aaa
- .quad relative
-relative:

lld/test/ELF/combrelocs.s

@@ -0,0 +1,95 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: ld.lld -shared %t.o -o %t.out
+# RUN: llvm-readobj -r --expand-relocs --dynamic-table %t.out | FileCheck %s
+
+# RUN: ld.lld -shared %t.o -o %t.out -z combreloc
+# RUN: llvm-readobj -r --expand-relocs --dynamic-table %t.out | FileCheck %s
+
+# CHECK:      Relocations [
+# CHECK-NEXT:   Section ({{.*}}) .rela.dyn {
+# CHECK-NEXT:     Relocation {
+# CHECK-NEXT:       Offset: 0x2000
+# CHECK-NEXT:       Type: R_X86_64_64
+# CHECK-NEXT:       Symbol: aaa (1)
+# CHECK-NEXT:       Addend: 0x0
+# CHECK-NEXT:     }
+# CHECK-NEXT:     Relocation {
+# CHECK-NEXT:       Offset: 0x2018
+# CHECK-NEXT:       Type: R_X86_64_64
+# CHECK-NEXT:       Symbol: aaa (1)
+# CHECK-NEXT:       Addend: 0x0
+# CHECK-NEXT:     }
+# CHECK-NEXT:     Relocation {
+# CHECK-NEXT:       Offset: 0x2010
+# CHECK-NEXT:       Type: R_X86_64_64
+# CHECK-NEXT:       Symbol: bbb (2)
+# CHECK-NEXT:       Addend: 0x0
+# CHECK-NEXT:     }
+# CHECK-NEXT:     Relocation {
+# CHECK-NEXT:       Offset: 0x2008
+# CHECK-NEXT:       Type: R_X86_64_64
+# CHECK-NEXT:       Symbol: ccc (3)
+# CHECK-NEXT:       Addend: 0x0
+# CHECK-NEXT:     }
+# CHECK-NEXT:     Relocation {
+# CHECK-NEXT:       Offset: 0x2020
+# CHECK-NEXT:       Type: R_X86_64_64
+# CHECK-NEXT:       Symbol: ddd (4)
+# CHECK-NEXT:       Addend: 0x0
+# CHECK-NEXT:     }
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]
+# CHECK:      DynamicSection [
+# CHECK-NEXT:   Tag
+# CHECK-NOT:    RELACOUNT
+
+# RUN: ld.lld -z nocombreloc -shared %t.o -o %t.out
+# RUN: llvm-readobj -r --expand-relocs --dynamic-table %t.out | \
+# RUN:    FileCheck --check-prefix=NOCOMB %s
+
+# NOCOMB:      Relocations [
+# NOCOMB-NEXT:    Section ({{.*}}) .rela.dyn {
+# NOCOMB-NEXT:     Relocation {
+# NOCOMB-NEXT:       Offset: 0x2000
+# NOCOMB-NEXT:       Type: R_X86_64_64
+# NOCOMB-NEXT:       Symbol: aaa (1)
+# NOCOMB-NEXT:       Addend: 0x0
+# NOCOMB-NEXT:     }
+# NOCOMB-NEXT:     Relocation {
+# NOCOMB-NEXT:       Offset: 0x2008
+# NOCOMB-NEXT:       Type: R_X86_64_64
+# NOCOMB-NEXT:       Symbol: ccc (3)
+# NOCOMB-NEXT:       Addend: 0x0
+# NOCOMB-NEXT:     }
+# NOCOMB-NEXT:     Relocation {
+# NOCOMB-NEXT:       Offset: 0x2010
+# NOCOMB-NEXT:       Type: R_X86_64_64
+# NOCOMB-NEXT:       Symbol: bbb (2)
+# NOCOMB-NEXT:       Addend: 0x0
+# NOCOMB-NEXT:     }
+# NOCOMB-NEXT:     Relocation {
+# NOCOMB-NEXT:       Offset: 0x2018
+# NOCOMB-NEXT:       Type: R_X86_64_64
+# NOCOMB-NEXT:       Symbol: aaa (1)
+# NOCOMB-NEXT:       Addend: 0x0
+# NOCOMB-NEXT:     }
+# NOCOMB-NEXT:     Relocation {
+# NOCOMB-NEXT:       Offset: 0x2020
+# NOCOMB-NEXT:       Type: R_X86_64_64
+# NOCOMB-NEXT:       Symbol: ddd (4)
+# NOCOMB-NEXT:       Addend: 0x0
+# NOCOMB-NEXT:     }
+# NOCOMB-NEXT:   }
+# NOCOMB-NEXT:  ]
+# NOCOMB:      DynamicSection [
+# NOCOMB-NEXT:   Tag
+# NOCOMB-NOT:    RELACOUNT
+
+.data
+ .quad aaa
+ .quad ccc
+ .quad bbb
+ .quad aaa
+ .quad ddd

lld/test/ELF/i386-got-and-copy.s

@@ -14,8 +14,8 @@
 
 # CHECK:      Relocations [
 # CHECK-NEXT:   Section (4) .rel.dyn {
-# CHECK-NEXT:     0x{{[0-9A-F]+}} R_386_GLOB_DAT foo
 # CHECK-NEXT:     0x{{[0-9A-F]+}} R_386_COPY foo
+# CHECK-NEXT:     0x{{[0-9A-F]+}} R_386_GLOB_DAT foo
 # CHECK-NEXT:   }
 # CHECK-NEXT: ]
 

lld/test/ELF/mips-mgot.s

@@ -34,14 +34,14 @@
 # GOT-NEXT:     0x70024 R_MIPS_REL32 - 0x0
 # GOT-NEXT:     0x70028 R_MIPS_REL32 - 0x0
 # GOT-NEXT:     0x7002C R_MIPS_REL32 - 0x0
+# GOT-NEXT:     0x70030 R_MIPS_REL32 foo0 0x0
+# GOT-NEXT:     0x70034 R_MIPS_REL32 foo2 0x0
 # GOT-NEXT:     0x70044 R_MIPS_TLS_DTPMOD32 - 0x0
 # GOT-NEXT:     0x70010 R_MIPS_TLS_TPREL32 tls0 0x0
 # GOT-NEXT:     0x70038 R_MIPS_TLS_TPREL32 tls0 0x0
 # GOT-NEXT:     0x7003C R_MIPS_TLS_DTPMOD32 tls0 0x0
 # GOT-NEXT:     0x70040 R_MIPS_TLS_DTPREL32 tls0 0x0
 # GOT-NEXT:     0x70014 R_MIPS_TLS_TPREL32 tls1 0x0
-# GOT-NEXT:     0x70030 R_MIPS_REL32 foo0 0x0
-# GOT-NEXT:     0x70034 R_MIPS_REL32 foo2 0x0
 # GOT-NEXT:   }
 # GOT-NEXT: ]