[GCC] Attribute ifunc support in clang

This patch add support for GCC attribute((ifunc("resolver"))) for
targets that use ELF as object file format. In general ifunc is a
special kind of function alias with type @gnu_indirect_function. LLVM
patch http://reviews.llvm.org/D15525

Differential Revision: http://reviews.llvm.org/D15524

llvm-svn: 265917

2 files changed, 29 insertions, 4 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 35682943907..b0e79f6f0e7 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2299,7 +2299,7 @@ static void checkNewAttributesAfterDef(Sema &S, Decl *New, const Decl *Old) {
   for (unsigned I = 0, E = NewAttributes.size(); I != E;) {
     const Attr *NewAttribute = NewAttributes[I];
 
-    if (isa<AliasAttr>(NewAttribute)) {
+    if (isa<AliasAttr>(NewAttribute) || isa<IFuncAttr>(NewAttribute)) {
       if (FunctionDecl *FD = dyn_cast<FunctionDecl>(New)) {
         Sema::SkipBodyInfo SkipBody;
         S.CheckForFunctionRedefinition(FD, cast<FunctionDecl>(Def), &SkipBody);
@@ -5464,7 +5464,7 @@ static void checkAttributesAfterMerging(Sema &S, NamedDecl &ND) {
       if (const auto *Attr = VD->getAttr<AliasAttr>()) {
         assert(VD->isThisDeclarationADefinition() &&
                !VD->isExternallyVisible() && "Broken AliasAttr handled late!");
-        S.Diag(Attr->getLocation(), diag::err_alias_is_definition) << VD;
+        S.Diag(Attr->getLocation(), diag::err_alias_is_definition) << VD << 0;
         VD->dropAttr<AliasAttr>();
       }
     }
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 9066e761ad6..0ba9799d042 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -1548,6 +1548,28 @@ static void handleWeakRefAttr(Sema &S, Decl *D, const AttributeList &Attr) {
                          Attr.getAttributeSpellingListIndex()));
 }
 
+static void handleIFuncAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+  StringRef Str;
+  if (!S.checkStringLiteralArgumentAttr(Attr, 0, Str))
+    return;
+
+  // Aliases should be on declarations, not definitions.
+  const auto *FD = cast<FunctionDecl>(D);
+  if (FD->isThisDeclarationADefinition()) {
+    S.Diag(Attr.getLoc(), diag::err_alias_is_definition) << FD << 1;
+    return;
+  }
+  // FIXME: it should be handled as a target specific attribute.
+  if (S.Context.getTargetInfo().getTriple().getObjectFormat() !=
+          llvm::Triple::ELF) {
+    S.Diag(Attr.getLoc(), diag::warn_attribute_ignored) << Attr.getName();
+    return;
+  }
+
+  D->addAttr(::new (S.Context) IFuncAttr(Attr.getRange(), S.Context, Str,
+                                         Attr.getAttributeSpellingListIndex()));
+}
+
 static void handleAliasAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   StringRef Str;
   if (!S.checkStringLiteralArgumentAttr(Attr, 0, Str))
@@ -1564,13 +1586,13 @@ static void handleAliasAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   // Aliases should be on declarations, not definitions.
   if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
     if (FD->isThisDeclarationADefinition()) {
-      S.Diag(Attr.getLoc(), diag::err_alias_is_definition) << FD;
+      S.Diag(Attr.getLoc(), diag::err_alias_is_definition) << FD << 0;
       return;
     }
   } else {
     const auto *VD = cast<VarDecl>(D);
     if (VD->isThisDeclarationADefinition() && VD->isExternallyVisible()) {
-      S.Diag(Attr.getLoc(), diag::err_alias_is_definition) << VD;
+      S.Diag(Attr.getLoc(), diag::err_alias_is_definition) << VD << 0;
       return;
     }
   }
@@ -5373,6 +5395,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_IBOutletCollection:
     handleIBOutletCollection(S, D, Attr);
     break;
+  case AttributeList::AT_IFunc:
+    handleIFuncAttr(S, D, Attr);
+    break;
   case AttributeList::AT_Alias:
     handleAliasAttr(S, D, Attr);
     break;