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

diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 41f1613..6d9bbcb 100644 (file)
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -2725,3 +2725,11 @@ The ``#pragma clang section`` directive obeys the following rules:
 * The decision about which section-kind applies to each global is taken in the back-end.
   Once the section-kind is known, appropriate section name, as specified by the user using
   ``#pragma clang section`` directive, is applied to that global.
+
+Specifying Linker Options on ELF Targets
+========================================
+
+The ``#pragma comment(lib, ...)`` directive is supported on all ELF targets.
+The second parameter is the library name (without the traditional Unix prefix of
+``lib``).  This allows you to provide an implicit link of dependent libraries.
+

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 760327d..b39e0f4 100644 (file)
--- 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:

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 42e9e1b..61b97e6 100644 (file)
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1094,6 +1094,8 @@ public:
   /// value.
   void AddDependentLib(StringRef Lib);
 
+  void AddELFLibDirective(StringRef Lib);
+
   llvm::GlobalVariable::LinkageTypes getFunctionLinkage(GlobalDecl GD);
 
   void setFunctionLinkage(GlobalDecl GD, llvm::Function *F) {

diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 8152176..3517264 100644 (file)
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -295,7 +295,8 @@ void Parser::initializePragmaHandlers() {
     OpenMPHandler.reset(new PragmaNoOpenMPHandler());
   PP.AddPragmaHandler(OpenMPHandler.get());
 
-  if (getLangOpts().MicrosoftExt || getTargetInfo().getTriple().isPS4()) {
+  if (getLangOpts().MicrosoftExt ||
+      getTargetInfo().getTriple().isOSBinFormatELF()) {
     MSCommentHandler.reset(new PragmaCommentHandler(Actions));
     PP.AddPragmaHandler(MSCommentHandler.get());
   }
@@ -377,7 +378,8 @@ void Parser::resetPragmaHandlers() {
   PP.RemovePragmaHandler(OpenMPHandler.get());
   OpenMPHandler.reset();
 
-  if (getLangOpts().MicrosoftExt || getTargetInfo().getTriple().isPS4()) {
+  if (getLangOpts().MicrosoftExt ||
+      getTargetInfo().getTriple().isOSBinFormatELF()) {
     PP.RemovePragmaHandler(MSCommentHandler.get());
     MSCommentHandler.reset();
   }
@@ -2449,6 +2451,12 @@ void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
     return;
   }
 
+  if (PP.getTargetInfo().getTriple().isOSBinFormatELF() && Kind != PCK_Lib) {
+    PP.Diag(Tok.getLocation(), diag::warn_pragma_comment_ignored)
+        << II->getName();
+    return;
+  }
+
   // On PS4, issue a warning about any pragma comments other than
   // #pragma comment lib.
   if (PP.getTargetInfo().getTriple().isPS4() && Kind != PCK_Lib) {

diff --git a/clang/test/CodeGen/elf-linker-options.c b/clang/test/CodeGen/elf-linker-options.c
new file mode 100644 (file)
index 0000000..cf2d1b9
--- /dev/null
+++ b/clang/test/CodeGen/elf-linker-options.c
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -triple i686---elf -emit-llvm %s -o - | FileCheck %s
+
+#pragma comment(lib, "alpha")
+
+// CHECK: !llvm.linker.options = !{[[NODE:![0-9]+]]}
+// CHECK: [[NODE]] = !{!"lib", !"alpha"}
+

diff --git a/clang/test/CodeGen/pragma-comment.c b/clang/test/CodeGen/pragma-comment.c
index fae9b8f..1896e5c 100644 (file)
--- a/clang/test/CodeGen/pragma-comment.c
+++ b/clang/test/CodeGen/pragma-comment.c
@@ -23,10 +23,9 @@
 // CHECK: ![[bar]] = !{!" /bar=2"}
 // CHECK: ![[foo]] = !{!" /foo=\22foo bar\22"}
 
-// LINUX: !{!"-lmsvcrt.lib"}
-// LINUX: !{!"-lkernel32"}
-// LINUX: !{!"-lUSER32.LIB"}
-// LINUX: !{!" /bar=2"}
+// LINUX: !{!"lib", !"msvcrt.lib"}
+// LINUX: !{!"lib", !"kernel32"}
+// LINUX: !{!"lib", !"USER32.LIB"}
 
 // PS4: !{!"\01msvcrt.lib"}
 // PS4: !{!"\01kernel32"}

diff --git a/clang/test/Preprocessor/pragma-comment-linux.c b/clang/test/Preprocessor/pragma-comment-linux.c
new file mode 100644 (file)
index 0000000..fcac049
--- /dev/null
+++ b/clang/test/Preprocessor/pragma-comment-linux.c
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 -triple i686-unknown-linux-gnu -fsyntax-only -verify %s -Wunknown-pragmas
+
+#pragma comment(linker, "")
+// expected-warning@-1 {{'#pragma comment linker' ignored}}
+

diff --git a/clang/test/Preprocessor/pragma_microsoft.c b/clang/test/Preprocessor/pragma_microsoft.c
index b256b2b..5d08943 100644 (file)
--- a/clang/test/Preprocessor/pragma_microsoft.c
+++ b/clang/test/Preprocessor/pragma_microsoft.c
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 %s -fsyntax-only -verify -fms-extensions -Wunknown-pragmas
-// RUN: not %clang_cc1 %s -fms-extensions -E | FileCheck %s
+// RUN: %clang_cc1 -triple i686-unknown-windows-msvc %s -fsyntax-only -verify -fms-extensions -Wunknown-pragmas
+// RUN: not %clang_cc1 -triple i686-unknown-windows-msvc %s -fms-extensions -E | FileCheck %s
 // REQUIRES: non-ps4-sdk
 
 // rdar://6495941