CodeGen: support an extension to pass linker options on ELF

Introduce an extension to support passing linker options to the linker.
These would be ignored by older linkers, but newer linkers which support
this feature would be able to process the linker.

Emit a special discarded section `.linker-option`.  The content of this
section is a pair of strings (key, value).  The key is a type identifier for
the parameter.  This allows for an argument free parameter that will be
processed by the linker with the value being the parameter.  As an example,
`lib` identifies a library to be linked against, traditionally the `-l`
argument for Unix-based linkers with the parameter being the library name.

Thanks to James Henderson, Cary Coutant, Rafael Espinolda, Sean Silva
for the valuable discussion on the design of this feature.

llvm-svn: 323783

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCSectionELF.cpp b/llvm/lib/MC/MCSectionELF.cpp
index bf1fcb03273..36cdb421655 100644
--- a/llvm/lib/MC/MCSectionELF.cpp
+++ b/llvm/lib/MC/MCSectionELF.cpp
@@ -148,6 +148,8 @@ void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
     OS << "0x7000001e";
   else if (Type == ELF::SHT_LLVM_ODRTAB)
     OS << "llvm_odrtab";
+  else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS)
+    OS << "llvm_linker_options";
   else
     report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) +
                        " for section " + getSectionName());