[llvm] r184513 - [yaml2obj][ELF] Allow expressing undefined symbols.

[Sean Silva]

Author: silvas
Date: Thu Jun 20 20:11:48 2013
New Revision: 184513

URL: http://llvm.org/viewvc/llvm-project?rev=184513&view=rev
Log:
[yaml2obj][ELF] Allow expressing undefined symbols.

Previously we unconditionally enforced that section references in
symbols in the YAML had a name that was a section name present in the
object, and linked the references to that section. Now, permit empty
section names (already the default, if the `Section` key is not
provided) to indicate SHN_UNDEF.

Modified:
    llvm/trunk/test/Object/yaml2obj-elf-symbol-basic.yaml
    llvm/trunk/tools/yaml2obj/yaml2elf.cpp

Modified: llvm/trunk/test/Object/yaml2obj-elf-symbol-basic.yaml
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Object/yaml2obj-elf-symbol-basic.yaml?rev=184513&r1=184512&r2=184513&view=diff
==============================================================================
--- llvm/trunk/test/Object/yaml2obj-elf-symbol-basic.yaml (original)
+++ llvm/trunk/test/Object/yaml2obj-elf-symbol-basic.yaml Thu Jun 20 20:11:48 2013
@@ -26,6 +26,7 @@ Sections:
           Section: .text
           Value: 0x1
           Size: 2
+        - Name: undefined_symbol
 
 # CHECK:      Symbols [
 # CHECK-NEXT:   Symbol {
@@ -37,6 +38,9 @@ Sections:
 # CHECK:          Binding: Global
 # CHECK-NEXT:     Type: Function
 # CHECK:          Section: .text
+# CHECK:        Symbol {
+# CHECK:          Name: undefined_symbol
+# CHECK:          Section:  (0x0)
 
 # DISASSEMBLY:      Disassembly of section .text:
 # DISASSEMBLY-NEXT: main:

Modified: llvm/trunk/tools/yaml2obj/yaml2elf.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/yaml2obj/yaml2elf.cpp?rev=184513&r1=184512&r2=184513&view=diff
==============================================================================
--- llvm/trunk/tools/yaml2obj/yaml2elf.cpp (original)
+++ llvm/trunk/tools/yaml2obj/yaml2elf.cpp Thu Jun 20 20:11:48 2013
@@ -184,13 +184,15 @@ addSymbols(const std::vector<ELFYAML::Sy
     if (!Sym.Name.empty())
       Symbol.st_name = State.getStringTable().addString(Sym.Name);
     Symbol.setBindingAndType(SymbolBinding, Sym.Type);
-    unsigned Index;
-    if (State.getSN2I().lookupSection(Sym.Section, Index)) {
-      errs() << "error: Unknown section referenced: '" << Sym.Section
-             << "' by YAML symbol " << Sym.Name << ".\n";
-      exit(1);
-    }
-    Symbol.st_shndx = Index;
+    if (!Sym.Section.empty()) {
+      unsigned Index;
+      if (State.getSN2I().lookupSection(Sym.Section, Index)) {
+        errs() << "error: Unknown section referenced: '" << Sym.Section
+               << "' by YAML symbol " << Sym.Name << ".\n";
+        exit(1);
+      }
+      Symbol.st_shndx = Index;
+    } // else Symbol.st_shndex == SHN_UNDEF (== 0), since it was zero'd earlier.
     Symbol.st_value = Sym.Value;
     Symbol.st_size = Sym.Size;
     Syms.push_back(Symbol);