Support `#pragma comment(lib, "name")` in the frontend for ELF

This adds the frontend support required to support the use of the
comment pragma to enable auto linking on ELFish targets. This is a
generic ELF extension supported by LLVM. We need to change the handling
for the "dependentlib" in order to accommodate the previously discussed
encoding for the dependent library descriptor. Without the custom
handling of the PCK_Lib directive, the -l prefixed option would be
encoded into the resulting object (which is treated as a frontend
error).

llvm-svn: 324438

1 files changed, 11 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 760327deb17..b39e0f445c7 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1411,6 +1411,12 @@ void CodeGenModule::AddDetectMismatch(StringRef Name, StringRef Value) {
   LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
 }
 
+void CodeGenModule::AddELFLibDirective(StringRef Lib) {
+  auto &C = getLLVMContext();
+  LinkerOptionsMetadata.push_back(llvm::MDNode::get(
+      C, {llvm::MDString::get(C, "lib"), llvm::MDString::get(C, Lib)}));
+}
+
 void CodeGenModule::AddDependentLib(StringRef Lib) {
   llvm::SmallString<24> Opt;
   getTargetCodeGenInfo().getDependentLibraryOption(Lib, Opt);
@@ -4329,7 +4335,11 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
       AppendLinkerOptions(PCD->getArg());
       break;
     case PCK_Lib:
-      AddDependentLib(PCD->getArg());
+      if (getTarget().getTriple().isOSBinFormatELF() &&
+          !getTarget().getTriple().isPS4())
+        AddELFLibDirective(PCD->getArg());
+      else
+        AddDependentLib(PCD->getArg());
       break;
     case PCK_Compiler:
     case PCK_ExeStr: