Do conservative cross-module-optimization by default

lib/SILOptimizer/IPO/CrossModuleOptimization.cpp

@@ -55,11 +55,16 @@ class CrossModuleOptimization {
 
   SILModule &M;
 
+  /// True, if CMO runs by default.
+  /// In this case, serialization decisions are made very conservatively to
+  /// avoid code size increase.
+  bool conservative;
+
   typedef llvm::DenseMap<SILFunction *, bool> FunctionFlags;
 
 public:
-  CrossModuleOptimization(SILModule &M)
-    : M(M) { }
+  CrossModuleOptimization(SILModule &M, bool conservative)
+    : M(M), conservative(conservative) { }
 
   void serializeFunctionsInModule();
 
@@ -255,6 +260,12 @@ bool CrossModuleOptimization::canSerializeInstruction(SILInstruction *inst,
     if (!canUseFromInline(callee))
       return false;
 
+    // In conservative mode we don't want to turn non-public functions into
+    // public functions, because that can increase code size. E.g. if the
+    // function is completely inlined afterwards.
+    if (conservative && callee->getLinkage() != SILLinkage::Public)
+      return false;
+
     return true;
   }
   if (auto *KPI = dyn_cast<KeyPathInst>(inst)) {
@@ -273,6 +284,13 @@ bool CrossModuleOptimization::canSerializeInstruction(SILInstruction *inst,
   if (auto *MI = dyn_cast<MethodInst>(inst)) {
     return !MI->getMember().isForeign;
   }
+  if (auto *REAI = dyn_cast<RefElementAddrInst>(inst)) {
+    // In conservative mode, we don't support class field accesse of non-public
+    // properties, because that would require to make the field decl public -
+    // which keeps more metadata alive.
+    return !conservative ||
+           REAI->getField()->getEffectiveAccess() >= AccessLevel::Public;
+  }
   return true;
 }
 
@@ -298,6 +316,10 @@ bool CrossModuleOptimization::canSerializeType(SILType type) {
       CanType subType = rawSubType->getCanonicalType();
       if (NominalTypeDecl *subNT = subType->getNominalOrBoundGenericNominal()) {
 
+        if (conservative && subNT->getEffectiveAccess() < AccessLevel::Public) {
+          return true;
+        }
+
         // Exclude types which are defined in an @_implementationOnly imported
         // module. Such modules are not transitively available.
         if (!M.getSwiftModule()->canBeUsedForCrossModuleOptimization(subNT)) {
@@ -348,13 +370,15 @@ bool CrossModuleOptimization::shouldSerialize(SILFunction *function) {
   if (SerializeEverything)
     return true;
 
-  // The basic heursitic: serialize all generic functions, because it makes a
-  // huge difference if generic functions can be specialized or not.
-  if (function->getLoweredFunctionType()->isPolymorphic())
-    return true;
+  if (!conservative) {
+    // The basic heursitic: serialize all generic functions, because it makes a
+    // huge difference if generic functions can be specialized or not.
+    if (function->getLoweredFunctionType()->isPolymorphic())
+      return true;
 
-  if (function->getLinkage() == SILLinkage::Shared)
-    return true;
+    if (function->getLinkage() == SILLinkage::Shared)
+      return true;
+  }
 
   // Also serialize "small" non-generic functions.
   int size = 0;
@@ -401,8 +425,27 @@ void CrossModuleOptimization::serializeInstruction(SILInstruction *inst,
     if (!callee->isDefinition() || callee->isAvailableExternally())
       return;
     if (canUseFromInline(callee)) {
-      // Make the function 'public'.
-      makeFunctionUsableFromInline(callee);
+      if (conservative) {
+        // In conservative mode, avoid making non-public functions public,
+        // because that can increase code size.
+        if (callee->getLinkage() == SILLinkage::Private ||
+            callee->getLinkage() == SILLinkage::Hidden) {
+          if (callee->getEffectiveSymbolLinkage() == SILLinkage::Public) {
+            // It's a internal/private class method. There is no harm in making
+            // it public, because it gets public symbol linkage anyway.
+            makeFunctionUsableFromInline(callee);
+          } else {
+            // Treat the function like a 'shared' function, e.g. like a
+            // specialization. This is better for code size than to make it
+            // public, because in conservative mode we are only do this for very
+            // small functions.
+            callee->setLinkage(SILLinkage::Shared);
+          }
+        }
+      } else {
+        // Make the function 'public'.
+        makeFunctionUsableFromInline(callee);
+      }
     }
     serializeFunction(callee, canSerializeFlags);
     assert(callee->isSerialized() == IsSerialized ||
@@ -531,10 +574,9 @@ class CrossModuleOptimizationPass: public SILModuleTransform {
       return;
     if (!M.isWholeModule())
       return;
-    if (!M.getOptions().CrossModuleOptimization)
-      return;
 
-    CrossModuleOptimization CMO(M);
+    CrossModuleOptimization CMO(M,
+      /*conservative*/ !M.getOptions().CrossModuleOptimization);
     CMO.serializeFunctionsInModule();
   }
 };

test/AutoDiff/TBD/derivative_symbols.swift

@@ -1,5 +1,5 @@
-// RUN: %target-swift-frontend -emit-ir -o/dev/null -parse-as-library -module-name test -validate-tbd-against-ir=all %s
-// RUN: %target-swift-frontend -emit-ir -o/dev/null -parse-as-library -module-name test -validate-tbd-against-ir=all %s -O
+// RUN: %target-swift-frontend -emit-ir -o/dev/null -Xllvm -sil-disable-pass=cmo -parse-as-library -module-name test -validate-tbd-against-ir=all %s
+// RUN: %target-swift-frontend -emit-ir -o/dev/null -Xllvm -sil-disable-pass=cmo -parse-as-library -module-name test -validate-tbd-against-ir=all %s -O
 // RUN: %target-swift-frontend -emit-ir -o/dev/null -parse-as-library -module-name test -validate-tbd-against-ir=missing %s -enable-testing
 // RUN: %target-swift-frontend -emit-ir -o/dev/null -parse-as-library -module-name test -validate-tbd-against-ir=missing %s -enable-testing -O
 

test/Interpreter/SDK/mixed_mode_class_with_missing_properties.swift

@@ -1,6 +1,8 @@
 // RUN: %empty-directory(%t)
 // RUN: cp %s %t/main.swift
-// RUN: %target-build-swift -whole-module-optimization -emit-module-path %t/UsingObjCStuff.swiftmodule -c -o %t/UsingObjCStuff.o -module-name UsingObjCStuff -I %t -I %S/Inputs/mixed_mode -swift-version 5 -parse-as-library %S/Inputs/mixed_mode/UsingObjCStuff.swift
+
+// CMO does not work because of a deserialization failure: rdar://86575886
+// RUN: %target-build-swift -Xllvm -sil-disable-pass=cmo -whole-module-optimization -emit-module-path %t/UsingObjCStuff.swiftmodule -c -o %t/UsingObjCStuff.o -module-name UsingObjCStuff -I %t -I %S/Inputs/mixed_mode -swift-version 5 -parse-as-library %S/Inputs/mixed_mode/UsingObjCStuff.swift
 // RUN: %target-build-swift -o %t/a.out.v4 -I %t -I %S/Inputs/mixed_mode -module-name main -swift-version 4 %t/main.swift %t/UsingObjCStuff.o
 // RUN: %target-build-swift -o %t/a.out.v5 -I %t -I %S/Inputs/mixed_mode -module-name main -swift-version 5 %t/main.swift %t/UsingObjCStuff.o
 // RUN: %target-codesign %t/a.out.v4

test/SIL/Parser/array_roundtrip.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend %s -emit-sil -Ounchecked | %target-sil-opt
+// RUN: %target-swift-frontend %s -emit-sil -Ounchecked -Xllvm -sil-disable-pass=cmo | %target-sil-opt
 
 // Fails if the positions of the two Collection subscript requirements are
 // reversed. rdar://problem/46650834

test/SILGen/fragile_globals.swift

@@ -11,7 +11,7 @@ var mygg = 29
 // Check if we have one token: from mygg.
 // Initializers from other modules are never fragile.
 
-// CHECK: sil_global private{{.*}} @[[T3:.*]]Wz
+// CHECK: sil_global {{.*}} @[[T3:.*]]Wz
 
 //@inlinable
 public func sum() -> Int {

test/SILOptimizer/access_enforcement_options.swift

@@ -28,7 +28,7 @@ public func accessIntTwice() {
 // CHECK-LABEL: } // end sil function '$s26access_enforcement_options0A8IntTwiceyyF'
 
 // closure #1 in accessIntTwice()
-// CHECK-LABEL: sil private @$s26access_enforcement_options0A8IntTwiceyyFyycfU_ : $@convention(thin) (@guaranteed { var Int }) -> () {
+// CHECK-LABEL: sil {{.*}}@$s26access_enforcement_options0A8IntTwiceyyFyycfU_ : $@convention(thin) (@guaranteed { var Int }) -> () {
 // CHECK: bb0(%0 : ${ var Int }):
 // CHECK: [[PROJ:%.*]] = project_box %0 : ${ var Int }, 0
 // NONE: [[ACCESS:%.*]] = begin_access [modify] [dynamic] [[PROJ]] : $*Int

test/SILOptimizer/dead_function_elimination.swift

@@ -198,7 +198,7 @@ public func keepPtrAlive() {
 // CHECK-TESTING: sil {{.*}}publicClassMethod
 // CHECK-TESTING: sil {{.*}}DeadWitness
 
-// CHECK-LABEL: sil_global hidden @$s25dead_function_elimination5GFStrV12aliveFuncPtryycvpZ
+// CHECK-LABEL: sil_global {{.*}}@$s25dead_function_elimination5GFStrV12aliveFuncPtryycvpZ
 // CHECK-LABEL: @$s25dead_function_elimination14donotEliminateyyF
 // CHECK-LABEL: sil @$s25dead_function_elimination12keepPtrAliveyyF
 

test/SILOptimizer/dont_remove_dynamic_self_arg.swift

@@ -9,7 +9,7 @@ func transform<T>(_ a: Any, c: (Any) -> T?) -> T? {
   return c(a)
 }
 
-// CHECK-LABEL: sil private @$s4test1XC6testityACSgypFACXDSgypXEfU_ :
+// CHECK-LABEL: sil {{.*}}@$s4test1XC6testityACSgypFACXDSgypXEfU_ :
 // CHECK: bb0({{.*}}, {{%[0-9]+}} : $@thick @dynamic_self X.Type):
 
 // The checked_cast_addr_br must have %1 as implicit type dependend operand.

test/Serialization/xref-private-type.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
-// RUN: %target-build-swift -swift-version 4 -O  -whole-module-optimization -emit-module-path %t/LibCore.swiftmodule %S/Inputs/xref-private-type/LibCore.swift
-// RUN: %target-build-swift -swift-version 4 -O -I %t  -whole-module-optimization -emit-module-path %t/Lib.swiftmodule %S/Inputs/xref-private-type/Lib.swift 
+// RUN: %target-build-swift -swift-version 4 -O  -Xllvm -sil-disable-pass=cmo -whole-module-optimization -emit-module-path %t/LibCore.swiftmodule %S/Inputs/xref-private-type/LibCore.swift
+// RUN: %target-build-swift -swift-version 4 -O -Xllvm -sil-disable-pass=cmo -I %t  -whole-module-optimization -emit-module-path %t/Lib.swiftmodule %S/Inputs/xref-private-type/Lib.swift 
 // RUN: %target-build-swift -swift-version 4 -O -I %t -emit-sil %s | %FileCheck %s
 
 import Lib

test/TBD/all-in-one.swift

@@ -12,7 +12,7 @@
 // RUN: %target-build-swift -module-name all_in_one -emit-module-path %t/all_in_one.swiftmodule -emit-tbd-path %t/wmo_Onone.tbd %S/class.swift %t/class_objc.swift %S/enum.swift %t/extension.swift %S/function.swift %S/global.swift %S/main.swift %S/protocol.swift %S/struct.swift %t/subclass.swift -I %t -import-objc-header %S/Inputs/objc_class_header.h -Xfrontend -disable-objc-attr-requires-foundation-module -wmo
 
 // RUN: %target-build-swift -module-name all_in_one -emit-module-path %t/all_in_one.swiftmodule -emit-tbd-path %t/incremental_O.tbd %S/class.swift %t/class_objc.swift %S/enum.swift %t/extension.swift %S/function.swift %S/global.swift %S/main.swift %S/protocol.swift %S/struct.swift %t/subclass.swift -I %t -import-objc-header %S/Inputs/objc_class_header.h -Xfrontend -disable-objc-attr-requires-foundation-module -O
-// RUN: %target-build-swift -module-name all_in_one -emit-module-path %t/all_in_one.swiftmodule -emit-tbd-path %t/wmo_O.tbd %S/class.swift %t/class_objc.swift %S/enum.swift %t/extension.swift %S/function.swift %S/global.swift %S/main.swift %S/protocol.swift %S/struct.swift %t/subclass.swift -I %t -import-objc-header %S/Inputs/objc_class_header.h -Xfrontend -disable-objc-attr-requires-foundation-module -wmo -O
+// RUN: %target-build-swift -module-name all_in_one -emit-module-path %t/all_in_one.swiftmodule -emit-tbd-path %t/wmo_O.tbd %S/class.swift %t/class_objc.swift %S/enum.swift %t/extension.swift %S/function.swift %S/global.swift %S/main.swift %S/protocol.swift %S/struct.swift %t/subclass.swift -I %t -import-objc-header %S/Inputs/objc_class_header.h -Xfrontend -disable-objc-attr-requires-foundation-module -wmo -O -Xllvm -sil-disable-pass=cmo
 
 // RUN: diff %t/incremental_Onone.tbd %t/wmo_Onone.tbd
 // RUN: diff %t/incremental_O.tbd %t/wmo_O.tbd

test/TBD/specialization.swift

@@ -1,7 +1,7 @@
 // REQUIRES: VENDOR=apple 
 // Validate the the specializations actually exist (if they don't then we're not
 // validating that they end up with the correct linkages):
-// RUN: %target-swift-frontend -emit-sil -o- -O -validate-tbd-against-ir=none %s | %FileCheck %s
+// RUN: %target-swift-frontend -emit-sil -o- -O -Xllvm -sil-disable-pass=cmo -validate-tbd-against-ir=none %s | %FileCheck %s
 
 // RUN: %target-swift-frontend -emit-ir -o/dev/null -O -validate-tbd-against-ir=all %s
 // RUN: %target-swift-frontend -emit-ir -o/dev/null -O -validate-tbd-against-ir=all -enable-library-evolution %s