IRGen: Co-locate metadata instatiation/completions/accessor functions in a special section

For spatial locality on startup.

rdar://101593202

Author: aschwaighofer

lib/IRGen/GenClass.cpp

@@ -2511,6 +2511,7 @@ static llvm::Function *emitObjCMetadataUpdateFunction(IRGenModule &IGM,
   llvm::Function *f =
     IGM.getAddrOfObjCMetadataUpdateFunction(D, ForDefinition);
   f->setAttributes(IGM.constructInitialAttributes());
+  IGM.setColocateMetadataSection(f);
 
   IRGenFunction IGF(IGM, f);
   if (IGM.DebugInfo)

lib/IRGen/GenDecl.cpp

@@ -1974,6 +1974,7 @@ void IRGenerator::emitEagerClassInitialization() {
     IGM->DebugInfo->emitArtificialFunction(RegisterIGF, RegisterIGF.CurFn);
   RegisterFn->setAttributes(IGM->constructInitialAttributes());
   RegisterFn->setCallingConv(IGM->DefaultCC);
+  IGM->setColocateMetadataSection(RegisterFn);
 
   for (ClassDecl *CD : ClassesForEagerInitialization) {
     auto Ty = CD->getDeclaredType()->getCanonicalType();
@@ -2017,6 +2018,7 @@ void IRGenerator::emitObjCActorsNeedingSuperclassSwizzle() {
     IGM->DebugInfo->emitArtificialFunction(RegisterIGF, RegisterIGF.CurFn);
   RegisterFn->setAttributes(IGM->constructInitialAttributes());
   RegisterFn->setCallingConv(IGM->DefaultCC);
+  IGM->setColocateMetadataSection(RegisterFn);
 
   // Look up the SwiftNativeNSObject class.
   auto swiftNativeNSObjectName =
@@ -5853,3 +5855,24 @@ IRGenModule::getOrCreateHelperFunction(StringRef fnName, llvm::Type *resultTy,
 
   return fn;
 }
+
+void IRGenModule::setColocateMetadataSection(llvm::Function *f) {
+  switch (TargetInfo.OutputObjectFormat) {
+  case llvm::Triple::MachO:
+    f->setSection("__TEXT, __swift_colocat, regular");
+    break;
+  case llvm::Triple::DXContainer:
+  case llvm::Triple::GOFF:
+  case llvm::Triple::SPIRV:
+  case llvm::Triple::UnknownObjectFormat:
+    break;
+  case llvm::Triple::Wasm:
+  case llvm::Triple::ELF:
+    f->setSection("swift_colocate_functions");
+    break;
+  case llvm::Triple::XCOFF:
+  case llvm::Triple::COFF:
+    f->setSection(".sw5colo$B");
+    break;
+  }
+}

lib/IRGen/GenMeta.cpp

@@ -206,6 +206,7 @@ static void emitMetadataCompletionFunction(IRGenModule &IGM,
   f->setAttributes(IGM.constructInitialAttributes());
   f->setDoesNotThrow();
   IGM.setHasNoFramePointer(f);
+  IGM.setColocateMetadataSection(f);
 
   IRGenFunction IGF(IGM, f);
 
@@ -2969,6 +2970,7 @@ namespace {
       f->setAttributes(IGM.constructInitialAttributes());
       f->setDoesNotThrow();
       IGM.setHasNoFramePointer(f);
+      IGM.setColocateMetadataSection(f);
 
       IRGenFunction IGF(IGM, f);
 

lib/IRGen/IRGenModule.h

@@ -1575,6 +1575,8 @@ private:                                                                       \
   void appendLLVMUsedConditionalEntry(llvm::GlobalVariable *var,
                                       const ProtocolConformance *conformance);
 
+  void setColocateMetadataSection(llvm::Function *f);
+
   llvm::Constant *
   getAddrOfTypeMetadata(CanType concreteType,
                         TypeMetadataCanonicality canonicality =

lib/IRGen/MetadataRequest.cpp

@@ -2052,6 +2052,7 @@ void irgen::emitCacheAccessFunction(IRGenModule &IGM, llvm::Function *accessor,
   accessor->addFnAttr(llvm::Attribute::NoInline);
   // Accessor functions don't need frame pointers.
   IGM.setHasNoFramePointer(accessor);
+  IGM.setColocateMetadataSection(accessor);
 
   // This function is logically 'readnone': the caller does not need
   // to reason about any side effects or stores it might perform.
@@ -2404,6 +2405,7 @@ MetadataResponse irgen::emitGenericTypeMetadataAccessFunction(
           generateThunkFn,
           /*noinline*/ true));
     }
+    IGM.setColocateMetadataSection(thunkFn);
 
     // Call out to the helper.
     auto arg0 = numArguments >= 1
@@ -2674,6 +2676,8 @@ irgen::getGenericTypeMetadataAccessFunction(IRGenModule &IGM,
   llvm::Function *accessor =
     IGM.getAddrOfGenericTypeMetadataAccessFunction(
         nominal, genericArgs.Types, shouldDefine);
+  if (shouldDefine)
+    IGM.setColocateMetadataSection(accessor);
 
   // If we're not supposed to define the accessor, or if we already
   // have defined it, just return the pointer.
@@ -2917,6 +2921,7 @@ emitMetadataAccessByMangledName(IRGenFunction &IGF, CanType type,
     IGM.setHasNoFramePointer(subIGF.CurFn);
     if (IGM.DebugInfo)
       IGM.DebugInfo->emitArtificialFunction(subIGF, subIGF.CurFn);
+    IGM.setColocateMetadataSection(subIGF.CurFn);
 
     auto params = subIGF.collectParameters();
     auto cache = params.claimNext();