[yaml2obj] - Allow setting the symbol st_other field to any integer.

st_other field of a symbol usually contains its visibility.
Other bits are usually 0, though some targets, like
MIPS can set them using the named bit field values.

Problem is that there is no way to set an arbitrary value now,
though that might be useful for our test cases.

In this patch I introduced a way to set st_other to any numeric
value using the new StOther field.
I added a test and simplified the existent one to show the effect/benefit

Differential revision: https://reviews.llvm.org/D66583

llvm-svn: 369742

1 files changed, 19 insertions, 3 deletions

diff --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
index be191118c59..e7db190eb0a 100644
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -888,9 +888,25 @@ void MappingTraits<ELFYAML::Symbol>::mapping(IO &IO, ELFYAML::Symbol &Symbol) {
   IO.mapOptional("Binding", Symbol.Binding, ELFYAML::ELF_STB(0));
   IO.mapOptional("Value", Symbol.Value, Hex64(0));
   IO.mapOptional("Size", Symbol.Size, Hex64(0));
-  MappingNormalization<NormalizedOther, uint8_t> Keys(IO, Symbol.Other);
-  IO.mapOptional("Visibility", Keys->Visibility, ELFYAML::ELF_STV(0));
-  IO.mapOptional("Other", Keys->Other, ELFYAML::ELF_STO(0));
+
+  // Symbol's Other field is a bit special. It is a bit field that represents
+  // st_other and usually holds symbol visibility. When we write a YAML document
+  // we split it into two fields named "Visibility" and "Other". The latter one
+  // usually holds no value, and so is almost never printed, although some
+  // targets (e.g. MIPS) may use it to specify the named bits to set (e.g.
+  // STO_MIPS_OPTIONAL). For producing broken objects we want to allow writing
+  // any value to st_other. To do this we allow one more field called "StOther".
+  // If it is present in a YAML document, we set st_other to that integer,
+  // ignoring the other fields.
+  Optional<llvm::yaml::Hex64> Other;
+  IO.mapOptional("StOther", Other);
+  if (Other) {
+    Symbol.Other = *Other;
+  } else {
+    MappingNormalization<NormalizedOther, uint8_t> Keys(IO, Symbol.Other);
+    IO.mapOptional("Visibility", Keys->Visibility, ELFYAML::ELF_STV(0));
+    IO.mapOptional("Other", Keys->Other, ELFYAML::ELF_STO(0));
+  }
 }
 
 StringRef MappingTraits<ELFYAML::Symbol>::validate(IO &IO,