Merge pull request #7779 from slavapestov/devirt-gardening

slavapestov · web-flow · commit 47b43097edc8 · 2017-02-27T10:48:35.000-08:00
Simplify devirtualization and fix a bug
diff --git a/include/swift/SILOptimizer/Utils/Devirtualize.h b/include/swift/SILOptimizer/Utils/Devirtualize.h
@@ -54,9 +54,7 @@ DevirtualizationResult devirtualizeClassMethod(FullApplySite AI,
                                                SILValue ClassInstance);
 DevirtualizationResult tryDevirtualizeClassMethod(FullApplySite AI,
                                                   SILValue ClassInstance);
-DevirtualizationResult tryDevirtualizeWitnessMethod(ApplySite AI); 
-/// Check if an upcast is legal.
-bool isLegalUpcast(SILType FromTy, SILType ToTy);
+DevirtualizationResult tryDevirtualizeWitnessMethod(ApplySite AI);
 }
 
 #endif
diff --git a/include/swift/SILOptimizer/Utils/Local.h b/include/swift/SILOptimizer/Utils/Local.h
@@ -110,22 +110,10 @@ SILValue isPartialApplyOfReabstractionThunk(PartialApplyInst *PAI);
 /// - a type of the return value is a subclass of the expected return type.
 /// - actual return type and expected return type differ in optionality.
 /// - both types are tuple-types and some of the elements need to be casted.
-///
-/// If CheckOnly flag is set, then this function only checks if the
-/// required casting is possible. If it is not possible, then None
-/// is returned.
-/// If CheckOnly is not set, then a casting code is generated and the final
-/// casted value is returned.
-Optional<SILValue> castValueToABICompatibleType(SILBuilder *B, SILLocation Loc,
-                                                SILValue Value,
-                                                SILType SrcTy,
-                                                SILType DestTy,
-                                                bool CheckOnly = false);
-
-/// Check if the optimizer can cast a value into the expected,
-/// ABI compatible type if necessary.
-bool canCastValueToABICompatibleType(SILModule &M,
-                                     SILType SrcTy, SILType DestTy);
+SILValue castValueToABICompatibleType(SILBuilder *B, SILLocation Loc,
+                                      SILValue Value,
+                                      SILType SrcTy,
+                                      SILType DestTy);
 
 /// Returns a project_box if it is the next instruction after \p ABI and
 /// and has \p ABI as operand. Otherwise it creates a new project_box right
diff --git a/lib/SILOptimizer/Transforms/SimplifyCFG.cpp b/lib/SILOptimizer/Transforms/SimplifyCFG.cpp
@@ -1875,23 +1875,6 @@ static bool isTryApplyOfConvertFunction(TryApplyInst *TAI,
   if (!TargetFnTy || !TargetFnTy->hasErrorResult())
     return false;
 
-  // Check if the converted function type has the same number of arguments.
-  // Currently this is always the case, but who knows what convert_function can
-  // do in the future?
-  unsigned numParams = OrigFnTy->getParameters().size();
-  if (TargetFnTy->getParameters().size() != numParams)
-    return false;
-
-  // Check that the argument types are matching.
-  SILModuleConventions silConv(TAI->getModule());
-  for (unsigned Idx = 0; Idx < numParams; Idx++) {
-    if (!canCastValueToABICompatibleType(
-            TAI->getModule(),
-            silConv.getSILType(OrigFnTy->getParameters()[Idx]),
-            silConv.getSILType(TargetFnTy->getParameters()[Idx])))
-      return false;
-  }
-
   // Look through the conversions and find the real callee.
   Callee = getActualCallee(CFI->getConverted());
   CalleeType = Callee->getType();
@@ -1936,12 +1919,6 @@ bool SimplifyCFG::simplifyTryApplyBlock(TryApplyInst *TAI) {
     auto ResultTy = calleeConv.getSILResultType();
     auto OrigResultTy = TAI->getNormalBB()->getArgument(0)->getType();
 
-    // Bail if the cast between the actual and expected return types cannot
-    // be handled.
-    if (!canCastValueToABICompatibleType(TAI->getModule(),
-                                         ResultTy, OrigResultTy))
-      return false;
-
     SILBuilderWithScope Builder(TAI);
 
     auto TargetFnTy = CalleeFnTy;
@@ -1959,28 +1936,14 @@ bool SimplifyCFG::simplifyTryApplyBlock(TryApplyInst *TAI) {
     }
     SILFunctionConventions origConv(OrigFnTy, TAI->getModule());
 
-    unsigned numArgs = TAI->getNumArguments();
-
-    // First check if it is possible to convert all arguments.
-    // Currently we believe that castValueToABICompatibleType can handle all
-    // cases, so this check should never fail. We just do it to be absolutely
-    // sure that we don't crash.
-    for (unsigned i = 0; i < numArgs; ++i) {
-      if (!canCastValueToABICompatibleType(TAI->getModule(),
-                                           origConv.getSILArgumentType(i),
-                                           targetConv.getSILArgumentType(i))) {
-        return false;
-      }
-    }
-
     SmallVector<SILValue, 8> Args;
+    unsigned numArgs = TAI->getNumArguments();
     for (unsigned i = 0; i < numArgs; ++i) {
       auto Arg = TAI->getArgument(i);
       // Cast argument if required.
       Arg = castValueToABICompatibleType(&Builder, TAI->getLoc(), Arg,
                                          origConv.getSILArgumentType(i),
-                                         targetConv.getSILArgumentType(i))
-                .getValue();
+                                         targetConv.getSILArgumentType(i));
       Args.push_back(Arg);
     }
 
@@ -1998,8 +1961,7 @@ bool SimplifyCFG::simplifyTryApplyBlock(TryApplyInst *TAI) {
     auto *NormalBB = TAI->getNormalBB();
 
     auto CastedResult = castValueToABICompatibleType(&Builder, Loc, NewAI,
-                                                     ResultTy, OrigResultTy)
-                                                    .getValue();
+                                                     ResultTy, OrigResultTy);
 
     Builder.createBranch(Loc, NormalBB, { CastedResult });
     TAI->eraseFromParent();
diff --git a/lib/SILOptimizer/Utils/Devirtualize.cpp b/lib/SILOptimizer/Utils/Devirtualize.cpp
@@ -546,31 +546,6 @@ bool swift::canDevirtualizeClassMethod(FullApplySite AI,
     return false;
   }
 
-  // Type of the actual function to be called.
-  CanSILFunctionType GenCalleeType = F->getLoweredFunctionType();
-
-  // Type of the actual function to be called with substitutions applied.
-  CanSILFunctionType SubstCalleeType = GenCalleeType;
-
-  // For polymorphic functions, bail if the number of substitutions is
-  // not the same as the number of expected generic parameters.
-  if (GenCalleeType->isPolymorphic()) {
-    // First, find proper list of substitutions for the concrete
-    // method to be called.
-    SmallVector<Substitution, 4> Subs;
-    getSubstitutionsForCallee(Mod, GenCalleeType,
-                              ClassOrMetatypeType.getSwiftRValueType(),
-                              AI, Subs);
-    SubstCalleeType = GenCalleeType->substGenericArgs(Mod, Subs);
-  }
-
-  // Check if the optimizer knows how to cast the return type.
-  SILType ReturnType =
-      SILFunctionConventions(SubstCalleeType, Mod).getSILResultType();
-
-  if (!canCastValueToABICompatibleType(Mod, ReturnType, AI.getType()))
-      return false;
-
   return true;
 }
 
@@ -612,8 +587,7 @@ DevirtualizationResult swift::devirtualizeClassMethod(FullApplySite AI,
   for (auto ResultTy : substConv.getIndirectSILResultTypes()) {
     NewArgs.push_back(
         castValueToABICompatibleType(&B, AI.getLoc(), *IndirectResultArgIter,
-                                     IndirectResultArgIter->getType(), ResultTy)
-            .getValue());
+                                     IndirectResultArgIter->getType(), ResultTy));
     ++IndirectResultArgIter;
   }
 
@@ -623,8 +597,7 @@ DevirtualizationResult swift::devirtualizeClassMethod(FullApplySite AI,
     auto paramType = substConv.getSILType(param);
     NewArgs.push_back(
         castValueToABICompatibleType(&B, AI.getLoc(), *ParamArgIter,
-                                     ParamArgIter->getType(), paramType)
-            .getValue());
+                                     ParamArgIter->getType(), paramType));
     ++ParamArgIter;
   }
 
@@ -634,7 +607,7 @@ DevirtualizationResult swift::devirtualizeClassMethod(FullApplySite AI,
   NewArgs.push_back(castValueToABICompatibleType(&B, AI.getLoc(),
                                                  ClassOrMetatype,
                                                  ClassOrMetatypeType,
-                                                 SelfParamTy).getValue());
+                                                 SelfParamTy));
 
   SILType ResultTy = substConv.getSILResultType();
 
@@ -707,7 +680,7 @@ DevirtualizationResult swift::devirtualizeClassMethod(FullApplySite AI,
 
   // Check if any casting is required for the return value.
   ResultValue = castValueToABICompatibleType(&B, NewAI.getLoc(), ResultValue,
-                                             ResultTy, AI.getType()).getValue();
+                                             ResultTy, AI.getType());
 
   DEBUG(llvm::dbgs() << "        SUCCESS: " << F->getName() << "\n");
   NumClassDevirt++;
@@ -871,75 +844,6 @@ static void getWitnessMethodSubstitutions(ApplySite AI, SILFunction *F,
                                 origSubs, isDefaultWitness, NewSubs);
 }
 
-/// Check if an upcast is legal.
-/// The logic in this function is heavily based on the checks in
-/// the SILVerifier.
-bool swift::isLegalUpcast(SILType FromTy, SILType ToTy) {
-  if (ToTy.is<MetatypeType>()) {
-    CanType InstTy(ToTy.castTo<MetatypeType>()->getInstanceType());
-    if (!FromTy.is<MetatypeType>())
-      return false;
-    CanType OpInstTy(FromTy.castTo<MetatypeType>()->getInstanceType());
-    auto InstClass = InstTy->getClassOrBoundGenericClass();
-    if (!InstClass)
-      return false;
-
-    bool CanBeUpcasted =
-        InstClass->usesObjCGenericsModel()
-            ? InstClass->getDeclaredTypeInContext()->isBindableToSuperclassOf(
-                  OpInstTy, nullptr)
-            : InstTy->isExactSuperclassOf(OpInstTy, nullptr);
-
-    return CanBeUpcasted;
-  }
-
-  // Upcast from Optional<B> to Optional<A> is legal as long as B is a
-  // subclass of A.
-  if (ToTy.getSwiftRValueType().getAnyOptionalObjectType() &&
-      FromTy.getSwiftRValueType().getAnyOptionalObjectType()) {
-    ToTy = SILType::getPrimitiveObjectType(
-        ToTy.getSwiftRValueType().getAnyOptionalObjectType());
-    FromTy = SILType::getPrimitiveObjectType(
-        FromTy.getSwiftRValueType().getAnyOptionalObjectType());
-  }
-
-  auto ToClass = ToTy.getClassOrBoundGenericClass();
-  if (!ToClass)
-    return false;
-  bool CanBeUpcasted =
-      ToClass->usesObjCGenericsModel()
-          ? ToClass->getDeclaredTypeInContext()->isBindableToSuperclassOf(
-                FromTy.getSwiftRValueType(), nullptr)
-          : ToTy.isExactSuperclassOf(FromTy);
-
-  return CanBeUpcasted;
-}
-
-/// Check if we can pass/convert all arguments of the original apply
-/// as required by the found devirtualized method.
-/// FIXME: This method was introduced as a workaround. We need to
-/// revisit it and check if it is still needed.
-static bool
-canPassOrConvertAllArguments(ApplySite AI,
-                             CanSILFunctionType SubstCalleeCanType) {
-  SILFunctionConventions substConv(SubstCalleeCanType, AI.getModule());
-  unsigned substArgIdx = AI.getCalleeArgIndexOfFirstAppliedArg();
-  for (auto arg : AI.getArguments()) {
-    // Check if we can cast the provided argument into the required
-    // parameter type.
-    auto FromTy = arg->getType();
-    auto ToTy = substConv.getSILArgumentType(substArgIdx++);
-    // If types are the same, no conversion will be required.
-    if (FromTy == ToTy)
-      continue;
-    // Otherwise, it should be possible to upcast the arguments.
-    if (!isLegalUpcast(FromTy, ToTy))
-      return false;
-  }
-  assert(substArgIdx == substConv.getNumSILArguments());
-  return true;
-}
-
 /// Generate a new apply of a function_ref to replace an apply of a
 /// witness_method when we've determined the actual function we'll end
 /// up calling.
@@ -963,11 +867,6 @@ static ApplySite devirtualizeWitnessMethod(ApplySite AI, SILFunction *F,
   auto CalleeCanType = F->getLoweredFunctionType();
   auto SubstCalleeCanType = CalleeCanType->substGenericArgs(Module, NewSubs);
 
-  // Bail if some of the arguments cannot be converted into
-  // types required by the found devirtualized method.
-  if (!canPassOrConvertAllArguments(AI, SubstCalleeCanType))
-    return ApplySite();
-
   // Collect arguments from the apply instruction.
   auto Arguments = SmallVector<SILValue, 4>();
 
@@ -979,7 +878,8 @@ static ApplySite devirtualizeWitnessMethod(ApplySite AI, SILFunction *F,
   for (auto arg : AI.getArguments()) {
     auto paramType = substConv.getSILArgumentType(substArgIdx++);
     if (arg->getType() != paramType)
-      arg = B.createUpcast(AI.getLoc(), arg, paramType);
+      arg = castValueToABICompatibleType(&B, AI.getLoc(), arg,
+                                         arg->getType(), paramType);
     Arguments.push_back(arg);
   }
   assert(substArgIdx == substConv.getNumSILArguments());
@@ -1030,26 +930,6 @@ static bool canDevirtualizeWitnessMethod(ApplySite AI) {
       return false;
   }
 
-  // Collect all the required substitutions.
-  //
-  // The complete set of substitutions may be different, e.g. because the found
-  // witness thunk F may have been created by a specialization pass and have
-  // additional generic parameters.
-  SmallVector<Substitution, 4> NewSubs;
-
-  getWitnessMethodSubstitutions(AI, F, WMI->getConformance(), NewSubs);
-
-  // Figure out the exact bound type of the function to be called by
-  // applying all substitutions.
-  auto &Module = AI.getModule();
-  auto CalleeCanType = F->getLoweredFunctionType();
-  auto SubstCalleeCanType = CalleeCanType->substGenericArgs(Module, NewSubs);
-
-  // Bail if some of the arguments cannot be converted into
-  // types required by the found devirtualized method.
-  if (!canPassOrConvertAllArguments(AI, SubstCalleeCanType))
-    return false;
-
   return true;
 }
 
diff --git a/lib/SILOptimizer/Utils/Local.cpp b/lib/SILOptimizer/Utils/Local.cpp
diff --git a/test/SILOptimizer/existential_type_propagation.sil b/test/SILOptimizer/existential_type_propagation.sil
