IRGen: Omit frame pointers from metadata accessors.

Author: jckarter

include/swift/SIL/SILFunction.h

@@ -198,7 +198,7 @@ class SILFunction
   /// Whether cross-module references to this function should use weak linking.
   unsigned IsWeakLinked : 1;
 
-  // Whether the implementation can be dynamically replaced.
+  /// Whether the implementation can be dynamically replaced.
   unsigned IsDynamicReplaceable : 1;
 
   /// If != OptimizationMode::NotSet, the optimization mode specified with an

lib/IRGen/GenMeta.cpp

@@ -172,6 +172,8 @@ static void emitMetadataCompletionFunction(IRGenModule &IGM,
   llvm::Function *f =
     IGM.getAddrOfTypeMetadataCompletionFunction(typeDecl, ForDefinition);
   f->setAttributes(IGM.constructInitialAttributes());
+  f->setDoesNotThrow();
+  IGM.setHasFramePointer(f, false);
 
   IRGenFunction IGF(IGM, f);
 
@@ -2133,6 +2135,8 @@ namespace {
       llvm::Function *f =
         IGM.getAddrOfTypeMetadataInstantiationFunction(Target, ForDefinition);
       f->setAttributes(IGM.constructInitialAttributes());
+      f->setDoesNotThrow();
+      IGM.setHasFramePointer(f, false);
 
       IRGenFunction IGF(IGM, f);
 

lib/IRGen/IRGenModule.cpp

@@ -891,17 +891,30 @@ bool swift::irgen::shouldRemoveTargetFeature(StringRef feature) {
   return feature == "+thumb-mode";
 }
 
-/// Construct initial function attributes from options.
-void IRGenModule::constructInitialFnAttributes(llvm::AttrBuilder &Attrs,
-                                               OptimizationMode FuncOptMode) {
-  // Add DisableFPElim. 
-  if (!IRGen.Opts.DisableFPElim) {
-    Attrs.addAttribute("no-frame-pointer-elim", "false");
-  } else {
+void IRGenModule::setHasFramePointer(llvm::AttrBuilder &Attrs,
+                                     bool HasFramePointer) {
+  if (HasFramePointer) {
     Attrs.addAttribute("no-frame-pointer-elim", "true");
     Attrs.addAttribute("no-frame-pointer-elim-non-leaf");
+  } else {
+    Attrs.addAttribute("no-frame-pointer-elim", "false");
+    Attrs.removeAttribute("no-frame-pointer-elim-non-leaf");
   }
+}
 
+void IRGenModule::setHasFramePointer(llvm::Function *F,
+                                     bool HasFramePointer) {
+  llvm::AttrBuilder b;
+  setHasFramePointer(b, HasFramePointer);
+  F->addAttributes(llvm::AttributeList::FunctionIndex, b);
+}
+
+/// Construct initial function attributes from options.
+void IRGenModule::constructInitialFnAttributes(llvm::AttrBuilder &Attrs,
+                                               OptimizationMode FuncOptMode) {
+  // Add frame pointer attributes.
+  setHasFramePointer(Attrs, IRGen.Opts.DisableFPElim);
+  
   // Add target-cpu and target-features if they are non-null.
   auto *Clang = static_cast<ClangImporter *>(Context.getClangModuleLoader());
   clang::TargetOptions &ClangOpts = Clang->getTargetInfo().getTargetOpts();

lib/IRGen/IRGenModule.h

@@ -1202,6 +1202,8 @@ private:                            \
   void constructInitialFnAttributes(llvm::AttrBuilder &Attrs,
                                     OptimizationMode FuncOptMode =
                                       OptimizationMode::NotSet);
+  void setHasFramePointer(llvm::AttrBuilder &Attrs, bool HasFP);
+  void setHasFramePointer(llvm::Function *F, bool HasFP);
   llvm::AttributeList constructInitialAttributes();
 
   void emitProtocolDecl(ProtocolDecl *D);

lib/IRGen/MetadataRequest.cpp

@@ -1404,6 +1404,8 @@ void irgen::emitCacheAccessFunction(IRGenModule &IGM,
   // overall performance.
   accessor->addAttribute(llvm::AttributeList::FunctionIndex,
                          llvm::Attribute::NoInline);
+  // Accessor functions don't need frame pointers.
+  IGM.setHasFramePointer(accessor, false);
 
   // This function is logically 'readnone': the caller does not need
   // to reason about any side effects or stores it might perform.
@@ -1689,6 +1691,7 @@ emitGenericTypeMetadataAccessFunction(IRGenFunction &IGF,
       thunkFn->setCallingConv(IGM.SwiftCC);
       thunkFn->addAttribute(llvm::AttributeList::FunctionIndex,
                             llvm::Attribute::NoInline);
+      IGM.setHasFramePointer(thunkFn, false);
 
       [&IGM, thunkFn]{
         IRGenFunction subIGF(IGM, thunkFn);
@@ -2145,6 +2148,7 @@ emitMetadataAccessByMangledName(IRGenFunction &IGF, CanType type,
     instantiationFn->setDoesNotThrow();
     instantiationFn->addAttribute(llvm::AttributeList::FunctionIndex,
                                   llvm::Attribute::NoInline);
+    IGM.setHasFramePointer(instantiationFn, false);
 
     [&IGM, instantiationFn]{
       IRGenFunction subIGF(IGM, instantiationFn);