From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Wed, 7 Feb 2018 01:46:46 +0000 (+0000)
Subject: Support `#pragma comment(lib, "name")` in the frontend for ELF
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=bcd5214fa1ef182a24511240981e52b3dcd93d75;p=clang

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).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@324438 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/docs/LanguageExtensions.rst b/docs/LanguageExtensions.rst
index 41f161302f..6d9bbcbd3a 100644
--- a/docs/LanguageExtensions.rst
+++ b/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/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 760327deb1..b39e0f445c 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/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/lib/CodeGen/CodeGenModule.h b/lib/CodeGen/CodeGenModule.h
index 42e9e1be31..61b97e6124 100644
--- a/lib/CodeGen/CodeGenModule.h
+++ b/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/lib/Parse/ParsePragma.cpp b/lib/Parse/ParsePragma.cpp
index 8152176484..3517264d4e 100644
--- a/lib/Parse/ParsePragma.cpp
+++ b/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/test/CodeGen/elf-linker-options.c b/test/CodeGen/elf-linker-options.c
new file mode 100644
index 0000000000..cf2d1b92b9
--- /dev/null
+++ b/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/test/CodeGen/pragma-comment.c b/test/CodeGen/pragma-comment.c
index fae9b8fb9e..1896e5c0fb 100644
--- a/test/CodeGen/pragma-comment.c
+++ b/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/test/Preprocessor/pragma-comment-linux.c b/test/Preprocessor/pragma-comment-linux.c
new file mode 100644
index 0000000000..fcac049f46
--- /dev/null
+++ b/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/test/Preprocessor/pragma_microsoft.c b/test/Preprocessor/pragma_microsoft.c
index b256b2bee6..5d08943273 100644
--- a/test/Preprocessor/pragma_microsoft.c
+++ b/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