Revert "Reland D61583 [ELF] Error on relocations to STT_SECTION symbols if the sections were discarded"

This reverts commit 5d3b3188f722456a6470c7effcacf17656406429.

Breaks the PowerPC multi-stage buildbot.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@362739 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/ELF/DWARF.cpp b/ELF/DWARF.cpp
index 6ebe724..6b90a03 100644
--- a/ELF/DWARF.cpp
+++ b/ELF/DWARF.cpp
@@ -93,11 +93,8 @@
   uint32_t SecIndex = File->getSectionIndex(Sym);
 
   // Broken debug info can point to a non-Defined symbol.
-  Symbol &S = File->getRelocTargetSym(Rel);
-  auto *DR = dyn_cast<Defined>(&S);
+  auto *DR = dyn_cast<Defined>(&File->getRelocTargetSym(Rel));
   if (!DR) {
-    if (S.isSection())
-      return None;
     RelType Type = Rel.getType(Config->IsMips64EL);
     if (Type != Target->NoneRel)
       error(toString(File) + ": relocation " + lld::toString(Type) + " at 0x" +
diff --git a/ELF/InputFiles.cpp b/ELF/InputFiles.cpp
index dd38478..815a4ad 100644
--- a/ELF/InputFiles.cpp
+++ b/ELF/InputFiles.cpp
@@ -1075,9 +1075,6 @@
 
       if (ESym.st_shndx == SHN_UNDEF)
         this->Symbols[I] = make<Undefined>(this, Name, Binding, StOther, Type);
-      else if (Sec == &InputSection::Discarded)
-        this->Symbols[I] = make<Undefined>(this, Name, Binding, StOther, Type,
-                                           /*DiscardedSecIdx=*/SecIdx);
       else
         this->Symbols[I] =
             make<Defined>(this, Name, Binding, StOther, Type, Value, Size, Sec);
diff --git a/ELF/InputSection.cpp b/ELF/InputSection.cpp
index 832e02c..de97517 100644
--- a/ELF/InputSection.cpp
+++ b/ELF/InputSection.cpp
@@ -438,8 +438,7 @@
       // hopefully creates a frame that is ignored at runtime.
       auto *D = dyn_cast<Defined>(&Sym);
       if (!D) {
-        warn("STT_SECTION symbol should be defined");
-        P->setSymbolAndType(0, 0, false);
+        error("STT_SECTION symbol should be defined");
         continue;
       }
       SectionBase *Section = D->Section->Repl;
diff --git a/ELF/Relocations.cpp b/ELF/Relocations.cpp
index d3cc608..9eb10f9 100644
--- a/ELF/Relocations.cpp
+++ b/ELF/Relocations.cpp
@@ -679,17 +679,9 @@
     return "";
   ArrayRef<Elf_Shdr_Impl<ELFT>> ObjSections =
       CHECK(File->getObj().sections(), File);
-
-  std::string Msg;
-  if (Sym.Type == ELF::STT_SECTION) {
-    Msg = "relocation refers to a discarded section: ";
-    Msg += CHECK(
-        File->getObj().getSectionName(&ObjSections[Sym.DiscardedSecIdx]), File);
-  } else {
-    Msg = "relocation refers to a symbol in a discarded section: " +
-          toString(Sym);
-  }
-  Msg += "\n>>> defined in " + toString(File);
+  std::string Msg =
+      "relocation refers to a symbol in a discarded section: " + toString(Sym) +
+      "\n>>> defined in " + toString(File);
 
   Elf_Shdr_Impl<ELFT> ELFSec = ObjSections[Sym.DiscardedSecIdx - 1];
   if (ELFSec.sh_type != SHT_GROUP)
diff --git a/test/ELF/comdat-discarded-error.s b/test/ELF/comdat-discarded-error.s
index 0f6b417..3584783 100644
--- a/test/ELF/comdat-discarded-error.s
+++ b/test/ELF/comdat-discarded-error.s
@@ -5,7 +5,7 @@
 # RUN: echo '.section .text.foo,"axG",@progbits,foo,comdat; .globl bar; bar:' | \
 # RUN:   llvm-mc -filetype=obj -triple=x86_64 - -o %t3.o
 
-# RUN: not ld.lld %t2.o %t3.o %t1.o -o /dev/null 2>&1 | FileCheck %s
+# RUN: not ld.lld %t1.o %t2.o %t3.o -o /dev/null 2>&1 | FileCheck %s
 
 # CHECK:      error: relocation refers to a symbol in a discarded section: bar
 # CHECK-NEXT: >>> defined in {{.*}}3.o
@@ -13,16 +13,6 @@
 # CHECK-NEXT: >>> prevailing definition is in {{.*}}2.o
 # CHECK-NEXT: >>> referenced by {{.*}}1.o:(.text+0x1)
 
-# CHECK:      error: relocation refers to a discarded section: .text.foo
-# CHECK-NEXT: >>> defined in {{.*}}1.o
-# CHECK-NEXT: >>> section group signature: foo
-# CHECK-NEXT: >>> prevailing definition is in {{.*}}2.o
-# CHECK-NEXT: >>> referenced by {{.*}}1.o:(.data+0x0)
-
 .globl _start
 _start:
   jmp bar
-
-.section .text.foo,"axG",@progbits,foo,comdat
-.data
-  .quad .text.foo
diff --git a/test/ELF/comdat-discarded-gdb-index.s b/test/ELF/comdat-discarded-gdb-index.s
deleted file mode 100644
index 4350596..0000000
--- a/test/ELF/comdat-discarded-gdb-index.s
+++ /dev/null
@@ -1,63 +0,0 @@
-# REQUIRES: x86
-# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
-# RUN: ld.lld --gdb-index %t.o %t.o -o %t
-
-## .debug_info has a relocation to .text.foo . The second %t.o is discarded.
-## Check we don't error on the relocation.
-# CHECK: .rela.debug_info {
-# CHECK-NEXT: 0xC R_X86_64_64 .text.foo 0x0
-
-.section .text.foo,"axG",@progbits,foo,comdat
-.globl foo
-.Lfunc_begin0:
-foo:
-  ret
-.Lfunc_end0:
-
-.section .debug_abbrev,"",@progbits
-  .byte   1       # Abbreviation Code
-  .byte   17      # DW_TAG_compile_unit
-  .byte   1       # DW_CHILDREN_yes
-  .byte   17      # DW_AT_low_pc
-  .byte   1       # DW_FORM_addr
-  .byte   18      # DW_AT_high_pc
-  .byte   6       # DW_FORM_data4
-  .ascii  "\264B" # DW_AT_GNU_pubnames
-  .byte   25      # DW_FORM_flag_present
-  .byte   0       # EOM(1)
-  .byte   0       # EOM(2)
-  .byte   2       # Abbreviation Code
-  .byte   46      # DW_TAG_subprogram
-  .byte   0       # DW_CHILDREN_no
-  .byte   3       # DW_AT_name
-  .byte   8       # DW_FORM_string
-  .byte   0       # EOM(1)
-  .byte   0       # EOM(2)
-  .byte   0
-
-.section .debug_info,"",@progbits
-.Lcu_begin0:
-  .long   .Lcu_end0 - .Lcu_begin0 - 4
-  .short  4              # DWARF version number
-  .long   0              # Offset Into Abbrev. Section
-  .byte   4              # Address Size
-.Ldie0:
-  .byte   1              # Abbrev [1] DW_TAG_compile_unit
-  .quad   .Lfunc_begin0  # DW_AT_low_pc
-  .long   .Lfunc_end0 - .Lfunc_begin0 # DW_AT_high_pc
-  .byte   2              # Abbrev [2] DW_TAG_subprogram
-  .asciz  "foo"          # DW_AT_name
-  .byte   0
-.Lcu_end0:
-
-.section .debug_gnu_pubnames,"",@progbits
-  .long   .LpubNames_end0 - .LpubNames_begin0
-.LpubNames_begin0:
-  .short  2              # Version
-  .long   .Lcu_begin0    # CU Offset
-  .long   .Lcu_end0 - .Lcu_begin0
-  .long   .Ldie0 - .Lcu_begin0
-  .byte   48             # Attributes: FUNCTION, EXTERNAL
-  .asciz  "foo"          # External Name
-  .long   0
-.LpubNames_end0:
diff --git a/test/ELF/comdat-discarded-reloc.s b/test/ELF/comdat-discarded-reloc.s
index d12732c..d23baf3 100644
--- a/test/ELF/comdat-discarded-reloc.s
+++ b/test/ELF/comdat-discarded-reloc.s
@@ -1,7 +1,7 @@
 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/comdat-discarded-reloc.s -o %t2.o
-# RUN: ld.lld -gc-sections --noinhibit-exec %t.o %t2.o -o /dev/null
+# RUN: ld.lld -gc-sections %t.o %t2.o -o %t
 
 ## ELF spec doesn't allow a relocation to point to a deduplicated
 ## COMDAT section. Unfortunately this happens in practice (e.g. .eh_frame)
diff --git a/test/ELF/comdat.s b/test/ELF/comdat.s
index 9e3f5a8..86103e5 100644
--- a/test/ELF/comdat.s
+++ b/test/ELF/comdat.s
@@ -1,7 +1,7 @@
 // REQUIRES: x86
 // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
 // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/comdat.s -o %t2.o
-// RUN: ld.lld -shared %t.o %t2.o -o %t
+// RUN: ld.lld -shared %t.o %t.o %t2.o -o %t
 // RUN: llvm-objdump -d %t | FileCheck %s
 // RUN: llvm-readobj -S --symbols %t | FileCheck --check-prefix=READ %s
 
@@ -31,7 +31,9 @@
 // CHECK-EMPTY:
 // CHECK-NEXT: bar:
 // 0x1000 - 0x1001 - 5 = -6
+// 0      - 0x1006 - 5 = -4107
 // CHECK-NEXT:   1001:	{{.*}}  callq  -6
+// CHECK-NEXT:   1006:	{{.*}}  callq  -4107
 
         .section .text3,"axG",@progbits,zed,comdat,unique,0
 
diff --git a/test/ELF/invalid-undef-section-symbol.test b/test/ELF/invalid-undef-section-symbol.test
index 80e5a14..1d66885 100644
--- a/test/ELF/invalid-undef-section-symbol.test
+++ b/test/ELF/invalid-undef-section-symbol.test
@@ -1,5 +1,5 @@
 # RUN: yaml2obj %s -o %t.o
-# RUN: not ld.lld -r --fatal-warnings %t.o -o /dev/null 2>&1 | FileCheck %s
+# RUN: not ld.lld -r %t.o -o /dev/null 2>&1 | FileCheck %s
 
 # We used to crash at this.
 # CHECK: STT_SECTION symbol should be defined
diff --git a/test/ELF/relocatable-eh-frame.s b/test/ELF/relocatable-eh-frame.s
index 6172dd3..dee906a 100644
--- a/test/ELF/relocatable-eh-frame.s
+++ b/test/ELF/relocatable-eh-frame.s
@@ -1,12 +1,10 @@
 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
-# RUN: ld.lld -r %t.o %t.o -o %t 2>&1 | FileCheck --check-prefix=WARN %s
+# RUN: ld.lld -r %t.o %t.o -o %t
 # RUN: llvm-readobj -r %t | FileCheck %s
 # RUN: ld.lld %t -o %t.so -shared
 # RUN: llvm-objdump -h %t.so | FileCheck --check-prefix=DSO %s
 
-# WARN: STT_SECTION symbol should be defined
-
 # DSO: .eh_frame     00000034
 
 # CHECK:      Relocations [