Add support for #pragma clang section

This patch provides a means to specify section-names for global variables, 
functions and static variables, using #pragma directives. 
This feature is only defined to work sensibly for ELF targets.
One can specify section names as:
#pragma clang section bss="myBSS" data="myData" rodata="myRodata" text="myText"
One can "unspecify" a section name with empty string e.g.
#pragma clang section bss="" data="" text="" rodata=""

Reviewers: Roger Ferrer, Jonathan Roelofs, Reid Kleckner
Differential Revision: https://reviews.llvm.org/D33412

llvm-svn: 304705

1 files changed, 60 insertions, 0 deletions

diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 18aebe65807..262743756a6 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -49,6 +49,15 @@ struct PragmaPackHandler : public PragmaHandler {
                     Token &FirstToken) override;
 };
 
+struct PragmaClangSectionHandler : public PragmaHandler {
+  explicit PragmaClangSectionHandler(Sema &S)
+             : PragmaHandler("section"), Actions(S) {}
+  void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
+                    Token &FirstToken) override;
+private:
+  Sema &Actions;
+};
+
 struct PragmaMSStructHandler : public PragmaHandler {
   explicit PragmaMSStructHandler() : PragmaHandler("ms_struct") {}
   void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
@@ -224,6 +233,9 @@ void Parser::initializePragmaHandlers() {
   FPContractHandler.reset(new PragmaFPContractHandler());
   PP.AddPragmaHandler("STDC", FPContractHandler.get());
 
+  PCSectionHandler.reset(new PragmaClangSectionHandler(Actions));
+  PP.AddPragmaHandler("clang", PCSectionHandler.get());
+
   if (getLangOpts().OpenCL) {
     OpenCLExtensionHandler.reset(new PragmaOpenCLExtensionHandler());
     PP.AddPragmaHandler("OPENCL", OpenCLExtensionHandler.get());
@@ -323,6 +335,9 @@ void Parser::resetPragmaHandlers() {
     MSCommentHandler.reset();
   }
 
+  PP.RemovePragmaHandler("clang", PCSectionHandler.get());
+  PCSectionHandler.reset();
+
   if (getLangOpts().MicrosoftExt) {
     PP.RemovePragmaHandler(MSDetectMismatchHandler.get());
     MSDetectMismatchHandler.reset();
@@ -1614,6 +1629,51 @@ void PragmaMSStructHandler::HandlePragma(Preprocessor &PP,
   PP.EnterTokenStream(Toks, /*DisableMacroExpansion=*/true);
 }
 
+// #pragma clang section bss="abc" data="" rodata="def" text=""
+void PragmaClangSectionHandler::HandlePragma(Preprocessor &PP,
+             PragmaIntroducerKind Introducer, Token &FirstToken) {
+
+  Token Tok;
+  auto SecKind = Sema::PragmaClangSectionKind::PCSK_Invalid;
+
+  PP.Lex(Tok); // eat 'section'
+  while (Tok.isNot(tok::eod)) {
+    if (Tok.isNot(tok::identifier)) {
+      PP.Diag(Tok.getLocation(), diag::err_pragma_expected_clang_section_name) << "clang section";
+      return;
+    }
+
+    const IdentifierInfo *SecType = Tok.getIdentifierInfo();
+    if (SecType->isStr("bss"))
+      SecKind = Sema::PragmaClangSectionKind::PCSK_BSS;
+    else if (SecType->isStr("data"))
+      SecKind = Sema::PragmaClangSectionKind::PCSK_Data;
+    else if (SecType->isStr("rodata"))
+      SecKind = Sema::PragmaClangSectionKind::PCSK_Rodata;
+    else if (SecType->isStr("text"))
+      SecKind = Sema::PragmaClangSectionKind::PCSK_Text;
+    else {
+      PP.Diag(Tok.getLocation(), diag::err_pragma_expected_clang_section_name) << "clang section";
+      return;
+    }
+
+    PP.Lex(Tok); // eat ['bss'|'data'|'rodata'|'text']
+    if (Tok.isNot(tok::equal)) {
+      PP.Diag(Tok.getLocation(), diag::err_pragma_clang_section_expected_equal) << SecKind;
+      return;
+    }
+
+    std::string SecName;
+    if (!PP.LexStringLiteral(Tok, SecName, "pragma clang section", false))
+      return;
+
+    Actions.ActOnPragmaClangSection(Tok.getLocation(),
+      (SecName.size()? Sema::PragmaClangSectionAction::PCSA_Set :
+                       Sema::PragmaClangSectionAction::PCSA_Clear),
+       SecKind, SecName);
+  }
+}
+
 // #pragma 'align' '=' {'native','natural','mac68k','power','reset'}
 // #pragma 'options 'align' '=' {'native','natural','mac68k','power','reset'}
 static void ParseAlignPragma(Preprocessor &PP, Token &FirstTok,