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

This reverts r361792 (git commit cfca5095df), the
revision causes link errors internally, will share more details with the
author.

llvm-svn: 361806

lld/ELF/InputFiles.cpp

@@ -997,9 +997,6 @@ template <class ELFT> void ObjFile<ELFT>::initializeSymbols() {
 
       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);

lld/ELF/InputSection.cpp

@@ -438,8 +438,7 @@ void InputSection::copyRelocations(uint8_t *Buf, ArrayRef<RelTy> Rels) {
       // 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;

lld/ELF/Relocations.cpp

@@ -681,17 +681,9 @@ static std::string maybeReportDiscarded(Undefined &Sym, InputSectionBase &Sec,
     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)

lld/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

lld/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)

lld/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 @@ foo:
 // 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
 

lld/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

lld/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 [