Fix pr19653.

Warn if an alias requests a section other than the aliasee section.

llvm-svn: 207997

1 files changed, 23 insertions, 11 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index caa4f24899f..9c60eb55f87 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -238,11 +238,6 @@ void CodeGenModule::checkAliases() {
       Diags.Report(AA->getLocation(), diag::err_alias_to_undefined);
     }
 
-    // We have to handle alias to weak aliases in here. LLVM itself disallows
-    // this since the object semantics would not match the IL one. For
-    // compatibility with gcc we implement it by just pointing the alias
-    // to its aliasee's aliasee. We also warn, since the user is probably
-    // expecting the link to be weak.
     llvm::Constant *Aliasee = Alias->getAliasee();
     llvm::GlobalValue *AliaseeGV;
     if (auto CE = dyn_cast<llvm::ConstantExpr>(Aliasee)) {
@@ -253,6 +248,19 @@ void CodeGenModule::checkAliases() {
     } else {
       AliaseeGV = cast<llvm::GlobalValue>(Aliasee);
     }
+
+    if (const SectionAttr *SA = D->getAttr<SectionAttr>()) {
+      StringRef AliasSection = SA->getName();
+      if (AliasSection != AliaseeGV->getSection())
+        Diags.Report(SA->getLocation(), diag::warn_alias_with_section)
+            << AliasSection;
+    }
+
+    // We have to handle alias to weak aliases in here. LLVM itself disallows
+    // this since the object semantics would not match the IL one. For
+    // compatibility with gcc we implement it by just pointing the alias
+    // to its aliasee's aliasee. We also warn, since the user is probably
+    // expecting the link to be weak.
     if (auto GA = dyn_cast<llvm::GlobalAlias>(AliaseeGV)) {
       if (GA->mayBeOverridden()) {
         Diags.Report(AA->getLocation(), diag::warn_alias_to_weak_alias)
@@ -585,7 +593,7 @@ CodeGenModule::getFunctionLinkage(GlobalDecl GD) {
 /// variables (these details are set in EmitGlobalVarDefinition for variables).
 void CodeGenModule::SetFunctionDefinitionAttributes(const FunctionDecl *D,
                                                     llvm::GlobalValue *GV) {
-  SetCommonAttributes(D, GV);
+  setNonAliasAttributes(D, GV);
 }
 
 void CodeGenModule::SetLLVMFunctionAttributes(const Decl *D,
@@ -711,13 +719,17 @@ void CodeGenModule::SetCommonAttributes(const Decl *D,
 
   if (D->hasAttr<UsedAttr>())
     addUsedGlobal(GV);
+}
+
+void CodeGenModule::setNonAliasAttributes(const Decl *D,
+                                          llvm::GlobalValue *GV) {
+  assert(!isa<llvm::GlobalAlias>(GV));
+  SetCommonAttributes(D, GV);
 
   if (const SectionAttr *SA = D->getAttr<SectionAttr>())
     GV->setSection(SA->getName());
 
-  // Alias cannot have attributes. Filter them here.
-  if (!isa<llvm::GlobalAlias>(GV))
-    getTargetCodeGenInfo().SetTargetAttributes(D, GV, *this);
+  getTargetCodeGenInfo().SetTargetAttributes(D, GV, *this);
 }
 
 void CodeGenModule::SetInternalFunctionAttributes(const Decl *D,
@@ -728,7 +740,7 @@ void CodeGenModule::SetInternalFunctionAttributes(const Decl *D,
 
   F->setLinkage(llvm::Function::InternalLinkage);
 
-  SetCommonAttributes(D, F);
+  setNonAliasAttributes(D, F);
 }
 
 static void setLinkageAndVisibilityForGV(llvm::GlobalValue *GV,
@@ -1879,7 +1891,7 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
     // common vars aren't constant even if declared const.
     GV->setConstant(false);
 
-  SetCommonAttributes(D, GV);
+  setNonAliasAttributes(D, GV);
 
   // Emit the initializer function if necessary.
   if (NeedsGlobalCtor || NeedsGlobalDtor)