SILOptimizer: Add 'mandatory SIL linker' pass

As a first step to getting mandatory inlining out of the business
of 'linking' (walking the function graph and deserializing all
referenced functions), add a new optimizer pass which links
everything in the mandatory pipeline.

For now this is mostly NFC, except it regresses an optimization
I made recently by linking in bodies of methods of deserialized
vtables eagerly. This will be addressed in upcoming patches.

Author: slavapestov

include/swift/SILOptimizer/PassManager/Passes.def

@@ -226,6 +226,10 @@ PASS(LateReleaseHoisting, "late-release-hoisting",
      "Late SIL release Hoisting Preserving Epilogues")
 IRGEN_PASS(LoadableByAddress, "loadable-address",
      "SIL Large Loadable type by-address lowering.")
+PASS(MandatorySILLinker, "mandatory-linker",
+     "Deserialize all referenced SIL functions that are shared or transparent")
+PASS(PerformanceSILLinker, "performance-linker",
+     "Deserialize all referenced SIL functions")
 PASS(RemovePins, "remove-pins",
      "Remove SIL pin/unpin pairs")
 PASS(TempRValueOpt, "temp-rvalue-opt",
@@ -238,8 +242,6 @@ PASS(SILCombine, "sil-combine",
      "Combine SIL Instructions via Peephole Optimization")
 PASS(SILDebugInfoGenerator, "sil-debuginfo-gen",
      "Generate Debug Information with Source Locations into Textual SIL")
-PASS(SILLinker, "linker",
-     "Link all SIL Referenced within the Module via Deserialization")
 PASS(SROA, "sroa",
      "Scalar Replacement of Aggregate Stack Objects")
 PASS(SROABBArgs, "sroa-bb-args",

lib/SILOptimizer/PassManager/PassPipeline.cpp

@@ -90,6 +90,7 @@ static void addMandatoryOptPipeline(SILPassPipelinePlan &P,
   P.addDefiniteInitialization();
   P.addOwnershipModelEliminator();
   P.addMandatoryInlining();
+  P.addMandatorySILLinker();
   P.addPredictableMemoryOptimizations();
 
   // Diagnostic ConstantPropagation must be rerun on deserialized functions
@@ -314,7 +315,7 @@ void addSSAPasses(SILPassPipelinePlan &P, OptimizationLevelKind OpLevel) {
 
 static void addPerfDebugSerializationPipeline(SILPassPipelinePlan &P) {
   P.startPipeline("Performance Debug Serialization");
-  P.addSILLinker();
+  P.addPerformanceSILLinker();
 }
 
 static void addPerfEarlyModulePassPipeline(SILPassPipelinePlan &P) {
@@ -324,7 +325,7 @@ static void addPerfEarlyModulePassPipeline(SILPassPipelinePlan &P) {
   // we do not spend time optimizing them.
   P.addDeadFunctionElimination();
   // Start by cloning functions from stdlib.
-  P.addSILLinker();
+  P.addPerformanceSILLinker();
 
   // Cleanup after SILGen: remove trivial copies to temporaries.
   P.addTempRValueOpt();
@@ -344,7 +345,7 @@ static void addHighLevelEarlyLoopOptPipeline(SILPassPipelinePlan &P) {
 static void addMidModulePassesStackPromotePassPipeline(SILPassPipelinePlan &P) {
   P.startPipeline("MidModulePasses+StackPromote");
   P.addDeadFunctionElimination();
-  P.addSILLinker();
+  P.addPerformanceSILLinker();
   P.addDeadObjectElimination();
   P.addGlobalPropertyOpt();
 

lib/SILOptimizer/UtilityPasses/Link.cpp

@@ -25,18 +25,26 @@ namespace {
 /// Copies code from the standard library into the user program to enable
 /// optimizations.
 class SILLinker : public SILModuleTransform {
+  SILModule::LinkingMode LinkMode;
+
+public:
+  explicit SILLinker(SILModule::LinkingMode LinkMode) : LinkMode(LinkMode) {}
 
   void run() override {
     SILModule &M = *getModule();
     for (auto &Fn : M)
-      if (M.linkFunction(&Fn, SILModule::LinkingMode::LinkAll))
+      if (M.linkFunction(&Fn, LinkMode))
         invalidateAnalysis(&Fn, SILAnalysis::InvalidationKind::Everything);
   }
 
 };
 } // end anonymous namespace
 
 
-SILTransform *swift::createSILLinker() {
-  return new SILLinker();
+SILTransform *swift::createMandatorySILLinker() {
+  return new SILLinker(SILModule::LinkingMode::LinkNormal);
+}
+
+SILTransform *swift::createPerformanceSILLinker() {
+  return new SILLinker(SILModule::LinkingMode::LinkAll);
 }

test/SIL/Serialization/deserialize_generic.sil

@@ -1,7 +1,7 @@
 
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend -emit-module -o %t %S/Inputs/def_generic.swift
-// RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -linker -I %t %s | %FileCheck %s
+// RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -performance-linker -I %t %s | %FileCheck %s
 
 // Make sure that SILFunctionType with GenericSignature can match up with
 // SILFunctionType deserialized from module.

test/SIL/Serialization/deserialize_generic_marker.sil

@@ -1,7 +1,7 @@
 
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend -emit-module -o %t %S/Inputs/def_generic_marker.swift
-// RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -linker -I %t %s | %FileCheck %s
+// RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -performance-linker -I %t %s | %FileCheck %s
 
 // Make sure that SILFunctionType with GenericSignature can match up with
 // SILFunctionType deserialized from module.

test/SIL/Serialization/function_param_convention.sil

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend -parse-sil -sil-inline-threshold 0 %S/Inputs/function_param_convention_input.sil -o %t/FunctionInput.swiftmodule -emit-module -parse-as-library -parse-stdlib -module-name FunctionInput -O
-// RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -I %t -linker %s -o - | %FileCheck %s
+// RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -I %t -performance-linker %s -o - | %FileCheck %s
 
 import Swift
 import FunctionInput

test/SIL/Serialization/public_non_abi.sil

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend -emit-module -o %t %S/Inputs/def_public_non_abi.sil
-// RUN: %target-sil-opt -linker -I %t %s | %FileCheck %s
+// RUN: %target-sil-opt -performance-linker -I %t %s | %FileCheck %s
 
 sil_stage raw
 

test/SIL/Serialization/shared_function_serialization.sil

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend %S/Inputs/shared_function_serialization_input.swift -o %t/Swift.swiftmodule -emit-module -parse-as-library -parse-stdlib -module-link-name swiftCore -module-name Swift -O
-// RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -enable-sil-verify-all -I %t -linker -inline %s -o - | %FileCheck %s
+// RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -enable-sil-verify-all -I %t -performance-linker -inline %s -o - | %FileCheck %s
 
 // CHECK: sil private @top_level_code
 // CHECK: sil public_external [serialized] @$Ss1XVABycfC{{.*}}

test/SIL/Serialization/vtable_deserialization.swift

@@ -19,10 +19,11 @@ Class.firstMethod()
 // The other two methods should not be deserialized in the mandatory
 // pipeline.
 
-// CHECK-LABEL: sil [serialized] @$S28vtable_deserialization_input5ClassC12secondMethodyyFZ : $@convention(method) (@thick Class.Type) -> (){{$}}
+// FIXME: Temporary regression
+// CHECK-LABEL: sil public_external [serialized] @$S28vtable_deserialization_input5ClassC12secondMethodyyFZ : $@convention(method) (@thick Class.Type) -> () {
 // OPT-LABEL: sil public_external @$S28vtable_deserialization_input5ClassC12secondMethodyyFZ : $@convention(method) (@thick Class.Type) -> () {
 
-// CHECK-LABEL: sil [serialized] @$S28vtable_deserialization_input5ClassC11thirdMethodyyFZ : $@convention(method) (@thick Class.Type) -> (){{$}}
+// CHECK-LABEL: sil public_external [serialized] @$S28vtable_deserialization_input5ClassC11thirdMethodyyFZ : $@convention(method) (@thick Class.Type) -> () {
 // OPT-LABEL: sil public_external @$S28vtable_deserialization_input5ClassC11thirdMethodyyFZ : $@convention(method) (@thick Class.Type) -> () {
 
 // Make sure we deserialized the vtable.