Port r292594.

[ELF] - Do not crash when assign common symbol's values in script

Found that during attempts of linking linux kernel,
previously we partially duplicated code from getOutputSection(),
and it missed commons symbol case.

Differential revision: https://reviews.llvm.org/D28903

llvm-svn: 293284

lld/ELF/LinkerScript.cpp

@@ -918,12 +918,7 @@ const OutputSectionBase *LinkerScript<ELFT>::getSymbolSection(StringRef S) {
     return CurOutSec ? CurOutSec : (*OutputSections)[0];
   }
 
-  if (auto *DR = dyn_cast_or_null<DefinedRegular<ELFT>>(Sym))
-    return DR->Section ? DR->Section->OutSec : nullptr;
-  if (auto *DS = dyn_cast_or_null<DefinedSynthetic>(Sym))
-    return DS->Section;
-
-  return nullptr;
+  return SymbolTableSection<ELFT>::getOutputSection(Sym);
 }
 
 // Returns indices of ELF headers containing specific section, identified

lld/ELF/SyntheticSections.h

@@ -372,15 +372,15 @@ class SymbolTableSection final : public SyntheticSection<ELFT> {
 
   ArrayRef<SymbolTableEntry> getSymbols() const { return Symbols; }
 
+  static const OutputSectionBase *getOutputSection(SymbolBody *Sym);
+
   unsigned NumLocals = 0;
   StringTableSection<ELFT> &StrTabSec;
 
 private:
   void writeLocalSymbols(uint8_t *&Buf);
   void writeGlobalSymbols(uint8_t *Buf);
 
-  const OutputSectionBase *getOutputSection(SymbolBody *Sym);
-
   // A vector of symbols and their string table offsets.
   std::vector<SymbolTableEntry> Symbols;
 };

lld/test/ELF/linkerscript/common-assign.s

@@ -0,0 +1,48 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: echo "SECTIONS { . = SIZEOF_HEADERS; pfoo = foo; pbar = bar; }" > %t.script
+# RUN: ld.lld -o %t1 --script %t.script %t
+# RUN: llvm-readobj -symbols %t1 | FileCheck %s
+
+# CHECK:       Symbol {
+# CHECK:         Name: bar
+# CHECK-NEXT:     Value: 0x134
+# CHECK-NEXT:     Size: 4
+# CHECK-NEXT:     Binding: Global
+# CHECK-NEXT:     Type: Object
+# CHECK-NEXT:     Other: 0
+# CHECK-NEXT:     Section: .bss
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: foo
+# CHECK-NEXT:     Value: 0x138
+# CHECK-NEXT:     Size: 4
+# CHECK-NEXT:     Binding: Global
+# CHECK-NEXT:     Type: Object
+# CHECK-NEXT:     Other: 0
+# CHECK-NEXT:     Section: .bss
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: pfoo
+# CHECK-NEXT:     Value: 0x138
+# CHECK-NEXT:     Size: 0
+# CHECK-NEXT:     Binding: Global
+# CHECK-NEXT:     Type: None
+# CHECK-NEXT:     Other: 0
+# CHECK-NEXT:     Section: .bss
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: pbar
+# CHECK-NEXT:     Value: 0x134
+# CHECK-NEXT:     Size: 0
+# CHECK-NEXT:     Binding: Global
+# CHECK-NEXT:     Type: None
+# CHECK-NEXT:     Other: 0
+# CHECK-NEXT:     Section: .bss
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]
+
+.comm	foo,4,4
+.comm	bar,4,4
+movl	$1, foo(%rip)
+movl	$2, bar(%rip)