[SIL] Hollow out Builtin.copy, deprecate _copy.

nate-chandler · nate-chandler · commit 06921cfe84d3 · 2024-05-03T15:56:25.000-07:00
The copy operator has been implemented and doesn't use it.  Remove
`Builtin.copy` and `_copy` as much as currently possible.

Source compatibility requires that `_copy` remain in the stdlib.  It is
deprecated here and just uses the copy operator.

Handling old swiftinterfaces requires that `Builtin.copy` be defined.
Redefine it here as a passthrough--SILGen machinery will produce the
necessary copy_addr.

rdar://127502242
diff --git a/SwiftCompilerSources/Sources/Optimizer/Utilities/AddressUtils.swift b/SwiftCompilerSources/Sources/Optimizer/Utilities/AddressUtils.swift
@@ -165,12 +165,6 @@ extension AddressUseVisitor {
 
     case let builtin as BuiltinInst:
       switch builtin.id {
-      case .Copy where builtin.operands[1] == operand: // source
-        return loadedAddressUse(of: operand, into: builtin.operands[0])
-
-      case .Copy where builtin.operands[0] == operand: // dest
-        return leafAddressUse(of: operand)
-
       // Builtins that cannot load a nontrivial value.
       case .TSanInoutAccess, .ResumeThrowingContinuationReturning,
            .ResumeNonThrowingContinuationReturning, .GenericAdd,
diff --git a/SwiftCompilerSources/Sources/Optimizer/Utilities/LifetimeDependenceUtils.swift b/SwiftCompilerSources/Sources/Optimizer/Utilities/LifetimeDependenceUtils.swift
@@ -909,12 +909,6 @@ extension LifetimeDependenceDefUseWalker {
     case let tai as TupleAddrConstructorInst:
       return visitStoredUses(of: operand, into: tai.destinationOperand.value)
 
-    case let bi as BuiltinInst where bi.id == .Copy:  
-      // This must be a non-address-lowered form of Builtin.Copy that
-      // produces an owned value.
-      assert(bi.ownership == .owned)
-      return walkDownUses(of: bi, using: operand)
-
     default:
       return nonForwardingUse(of: operand)
     }
diff --git a/include/swift/AST/Builtins.def b/include/swift/AST/Builtins.def
@@ -537,6 +537,14 @@ BUILTIN_SIL_OPERATION(HopToActor, "hopToActor", None)
 /// Returns the number of items in a pack.
 BUILTIN_SIL_OPERATION(PackLength, "packLength", Special)
 
+/// TODO: Remove.  Only exists to avoid a reverse condfail.
+///       rdar://127516085 (Complete removal of Builtin.copy)
+///
+/// copy: <T>(T) -> T
+///
+/// Creates a copy of the source at the destination.
+BUILTIN_SIL_OPERATION(Copy, "copy", Special)
+
 // BUILTIN_RUNTIME_CALL - A call into a runtime function.
 // These functions accept a single argument of any type.
 #ifndef BUILTIN_RUNTIME_CALL
@@ -804,24 +812,6 @@ BUILTIN_MISC_OPERATION(CreateTaskGroupWithFlags,
 BUILTIN_MISC_OPERATION(DestroyTaskGroup,
                        "destroyTaskGroup", "", Special)
 
-/// A builtin that can only be called from a transparent generic function. Takes
-/// two operands, the first operand the result address, the second operand the
-/// input address. Transforms into
-///
-///   %input = load [take] %inputAddr
-///   %result = explicit_copy_value %input
-///   store %result to [init] %resultAddr
-///   store %input to [init] %inputAddr
-///
-/// transparently inlined into a caller that has the generic of the callee
-/// specialized into a loadable type. If the transparent inlining does not
-/// specialize the type (due to being inlined into a non-generic context, the
-/// SILVerifier will abort).
-///
-/// Illegal to call except for in Swift._copy in the stdlib. This is enforced by
-/// the SILVerifier.
-BUILTIN_MISC_OPERATION(Copy, "copy", "", Special)
-
 /// Unchecked pointer alignment assertion. Allows the compiler to assume
 /// alignment of the pointer to emit more efficient code.
 ///
diff --git a/include/swift/AST/SemanticAttrs.def b/include/swift/AST/SemanticAttrs.def
@@ -124,7 +124,6 @@ SEMANTICS_ATTR(FORCE_EMIT_OPT_REMARK_PREFIX, "optremark")
 SEMANTICS_ATTR(OBJC_FORBID_ASSOCIATED_OBJECTS, "objc.forbidAssociatedObjects")
 
 SEMANTICS_ATTR(LIFETIMEMANAGEMENT_MOVE, "lifetimemanagement.move")
-SEMANTICS_ATTR(LIFETIMEMANAGEMENT_COPY, "lifetimemanagement.copy")
 
 SEMANTICS_ATTR(NO_PERFORMANCE_ANALYSIS, "no_performance_analysis")
 
diff --git a/include/swift/SIL/AddressWalker.h b/include/swift/SIL/AddressWalker.h
@@ -251,7 +251,6 @@ TransitiveAddressWalker<Impl>::walk(SILValue projectedAddress) && {
         case BuiltinValueKind::TSanInoutAccess:
         case BuiltinValueKind::ResumeThrowingContinuationReturning:
         case BuiltinValueKind::ResumeNonThrowingContinuationReturning:
-        case BuiltinValueKind::Copy:
         case BuiltinValueKind::GenericAdd:
         case BuiltinValueKind::GenericFAdd:
         case BuiltinValueKind::GenericAnd:
diff --git a/lib/IRGen/GenBuiltin.cpp b/lib/IRGen/GenBuiltin.cpp
@@ -1437,16 +1437,6 @@ void irgen::emitBuiltinCall(IRGenFunction &IGF, const BuiltinInfo &Builtin,
     return;
   }
 
-  if (Builtin.ID == BuiltinValueKind::Copy) {
-    auto input = args.claimNext();
-    auto result = args.claimNext();
-    SILType addrTy = argTypes[0];
-    const TypeInfo &addrTI = IGF.getTypeInfo(addrTy);
-    Address inputAttr = addrTI.getAddressForPointer(input);
-    Address resultAttr = addrTI.getAddressForPointer(result);
-    addrTI.initializeWithCopy(IGF, resultAttr, inputAttr, addrTy, false);
-    return;
-  }
   if (Builtin.ID == BuiltinValueKind::AssumeAlignment) {
     // A no-op pointer cast that passes on its first value. Common occurrences of
     // this builtin should already be removed with the alignment guarantee moved
diff --git a/lib/SIL/IR/OperandOwnership.cpp b/lib/SIL/IR/OperandOwnership.cpp
@@ -899,14 +899,6 @@ BUILTIN_OPERAND_OWNERSHIP(InstantaneousUse, GetEnumTag)
 BUILTIN_OPERAND_OWNERSHIP(InstantaneousUse, InjectEnumTag)
 BUILTIN_OPERAND_OWNERSHIP(InstantaneousUse, DistributedActorAsAnyActor)
 BUILTIN_OPERAND_OWNERSHIP(InstantaneousUse, AddressOfRawLayout)
-OperandOwnership OperandOwnershipBuiltinClassifier::visitCopy(BuiltinInst *bi,
-                                                              StringRef) {
-  if (bi->getFunction()->getConventions().useLoweredAddresses()) {
-    return OperandOwnership::UnownedInstantaneousUse;
-  } else {
-    return OperandOwnership::DestroyingConsume;
-  }
-}
 BUILTIN_OPERAND_OWNERSHIP(DestroyingConsume, StartAsyncLet)
 BUILTIN_OPERAND_OWNERSHIP(InstantaneousUse, EndAsyncLet)
 BUILTIN_OPERAND_OWNERSHIP(InstantaneousUse, EndAsyncLetLifetime)
diff --git a/lib/SIL/IR/ValueOwnership.cpp b/lib/SIL/IR/ValueOwnership.cpp
@@ -629,7 +629,6 @@ CONSTANT_OWNERSHIP_BUILTIN(None, CreateTaskGroup)
 CONSTANT_OWNERSHIP_BUILTIN(None, CreateTaskGroupWithFlags)
 CONSTANT_OWNERSHIP_BUILTIN(None, DestroyTaskGroup)
 CONSTANT_OWNERSHIP_BUILTIN(None, TaskRunInline)
-CONSTANT_OWNERSHIP_BUILTIN(None, Copy)
 CONSTANT_OWNERSHIP_BUILTIN(None, GetEnumTag)
 CONSTANT_OWNERSHIP_BUILTIN(None, InjectEnumTag)
 CONSTANT_OWNERSHIP_BUILTIN(Owned, DistributedActorAsAnyActor)
diff --git a/lib/SIL/Utils/MemAccessUtils.cpp b/lib/SIL/Utils/MemAccessUtils.cpp
@@ -2592,11 +2592,6 @@ static void visitBuiltinAddress(BuiltinInst *builtin,
       visitor(&builtin->getAllOperands()[0]);
       return;
 
-    // These effect both operands.
-    case BuiltinValueKind::Copy:
-      visitor(&builtin->getAllOperands()[1]);
-      return;
-
     // These consume values out of their second operand.
     case BuiltinValueKind::ResumeNonThrowingContinuationReturning:
     case BuiltinValueKind::ResumeThrowingContinuationReturning:
diff --git a/lib/SIL/Verifier/SILVerifier.cpp b/lib/SIL/Verifier/SILVerifier.cpp
@@ -2343,22 +2343,6 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
       return;
     }
 
-    if (builtinKind == BuiltinValueKind::Copy) {
-      // We expect that this builtin will be specialized during transparent
-      // inlining into explicit_copy_value if we inline into a non-generic
-      // context. If the builtin still remains and is not in the specific copy
-      // semantic function (which is the only function marked with
-      // semantics::LIFETIMEMANAGEMENT_COPY), then we know that we did
-      // transparent inlining into a function that did not result in the Builtin
-      // being specialized out which is user error.
-      //
-      // NOTE: Once we have opaque values, this restriction will go away. This
-      // is just so we can call Builtin.copy outside of the stdlib.
-      auto semanticName = semantics::LIFETIMEMANAGEMENT_COPY;
-      require(BI->getFunction()->hasSemanticsAttr(semanticName),
-              "_copy used within a generic context");
-    }
-
     if (builtinKind == BuiltinValueKind::CreateAsyncTask) {
       requireType(BI->getType(), _object(_tuple(_nativeObject, _rawPointer)),
                   "result of createAsyncTask");
diff --git a/lib/SILGen/SILGenBuiltin.cpp b/lib/SILGen/SILGenBuiltin.cpp
@@ -2027,6 +2027,23 @@ static ManagedValue emitBuiltinAddressOfRawLayout(SILGenFunction &SGF,
   return ManagedValue::forObjectRValueWithoutOwnership(bi);
 }
 
+/// TODO: Remove.  Only exists to avoid a reverse condfail.
+///       rdar://127516085 (Complete removal of Builtin.copy)
+static ManagedValue emitBuiltinCopy(SILGenFunction &SGF, SILLocation loc,
+                                    SubstitutionMap subs,
+                                    ArrayRef<ManagedValue> args, SGFContext C) {
+  // Builtin.copy has no uses in current/future swiftinterfaces.  It has a
+  // single use in old swiftinterfaces:
+  // func _copy<T>(_ t: T) -> T {
+  //   Builtin.copy(t)
+  // }
+  // It is sufficient to have the builtin pass the value through.  When the
+  // return is emitted, a copy will be made.
+  assert(args.size() == 1 && "not two arguments!?");
+  return ManagedValue::forOwnedAddressRValue(args[0].getValue(),
+                                             CleanupHandle::invalid());
+}
+
 std::optional<SpecializedEmitter>
 SpecializedEmitter::forDecl(SILGenModule &SGM, SILDeclRef function) {
   // Only consider standalone declarations in the Builtin module.
diff --git a/lib/SILOptimizer/Mandatory/AddressLowering.cpp b/lib/SILOptimizer/Mandatory/AddressLowering.cpp
@@ -3389,11 +3389,6 @@ class UseRewriter : SILInstructionVisitor<UseRewriter> {
       bi->setOperand(use->getOperandNumber(), opAddr);
       break;
     }
-    case BuiltinValueKind::Copy: {
-      SILValue opAddr = addrMat.materializeAddress(use->get());
-      bi->setOperand(0, opAddr);
-      break;
-    }
     case BuiltinValueKind::AddressOfBorrowOpaque:
       visitAddressOfBorrowBuiltinInst(bi, /*stackProtected=*/true);
       break;
@@ -4084,14 +4079,6 @@ class DefRewriter : SILInstructionVisitor<DefRewriter> {
 
   void visitBuiltinInst(BuiltinInst *bi) {
     switch (bi->getBuiltinKind().value_or(BuiltinValueKind::None)) {
-    case BuiltinValueKind::Copy: {
-      SILValue addr = addrMat.materializeAddress(bi);
-      builder.createBuiltin(
-          bi->getLoc(), bi->getName(),
-          SILType::getEmptyTupleType(bi->getType().getASTContext()),
-          bi->getSubstitutions(), {addr, bi->getOperand(0)});
-      break;
-    }
     default:
       bi->dump();
       llvm::report_fatal_error("^^^ Unimplemented builtin opaque value def.");
diff --git a/lib/SILOptimizer/Transforms/AccessEnforcementReleaseSinking.cpp b/lib/SILOptimizer/Transforms/AccessEnforcementReleaseSinking.cpp
@@ -183,7 +183,6 @@ static bool isBarrier(SILInstruction *inst) {
     case BuiltinValueKind::AssignCopyArrayFrontToBack:
     case BuiltinValueKind::AssignCopyArrayBackToFront:
     case BuiltinValueKind::AssignTakeArray:
-    case BuiltinValueKind::Copy:
     case BuiltinValueKind::CancelAsyncTask:
     case BuiltinValueKind::StartAsyncLet:
     case BuiltinValueKind::CreateAsyncTask:
diff --git a/lib/SILOptimizer/Utils/SILInliner.cpp b/lib/SILOptimizer/Utils/SILInliner.cpp
@@ -320,7 +320,6 @@ class SILInlineCloner
   void visitHopToExecutorInst(HopToExecutorInst *Inst);
 
   void visitTerminator(SILBasicBlock *BB);
-  void visitBuiltinInst(BuiltinInst *BI);
 
   /// This hook is called after either of the top-level visitors:
   /// cloneReachableBlocks or cloneSILFunction.
@@ -820,51 +819,6 @@ static void diagnose(ASTContext &Context, SourceLoc loc, Diag<T...> diag,
   Context.Diags.diagnose(loc, diag, std::forward<U>(args)...);
 }
 
-void SILInlineCloner::visitBuiltinInst(BuiltinInst *Inst) {
-  if (IKind == InlineKind::MandatoryInline) {
-    if (auto kind = Inst->getBuiltinKind()) {
-      if (*kind == BuiltinValueKind::Copy) {
-        auto otherResultAddr = getOpValue(Inst->getOperand(0));
-        auto otherSrcAddr = getOpValue(Inst->getOperand(1));
-        auto otherType = otherSrcAddr->getType();
-
-        if (!otherType.isLoadable(*Inst->getFunction())) {
-          // If otherType is not loadable, emit a diagnostic since it was used
-          // on a generic or existential value.
-          diagnose(Inst->getModule().getASTContext(),
-                   getOpLocation(Inst->getLoc()).getSourceLoc(),
-                   diag::copy_operator_used_on_generic_or_existential_value);
-          return SILCloner<SILInlineCloner>::visitBuiltinInst(Inst);
-        }
-
-        getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
-        // We stash otherValue in originalOtherValue in case we need to
-        // perform a writeback.
-        auto opLoc = getOpLocation(Inst->getLoc());
-
-        assert(otherType.isAddress());
-
-        // Perform a load_borrow and then copy that.
-        SILValue otherValue =
-            getBuilder().emitLoadBorrowOperation(opLoc, otherSrcAddr);
-
-        auto *mvi = getBuilder().createExplicitCopyValue(opLoc, otherValue);
-
-        getBuilder().emitStoreValueOperation(opLoc, mvi, otherResultAddr,
-                                             StoreOwnershipQualifier::Init);
-        // End the borrowed value.
-        getBuilder().emitEndBorrowOperation(opLoc, otherValue);
-
-        // We know that Inst returns a tuple value that isn't used by anything
-        // else, so this /should/ be safe.
-        return recordClonedInstruction(Inst, mvi);
-      }
-    }
-  }
-
-  return SILCloner<SILInlineCloner>::visitBuiltinInst(Inst);
-}
-
 //===----------------------------------------------------------------------===//
 //                                 Cost Model
 //===----------------------------------------------------------------------===//
diff --git a/stdlib/public/core/LifetimeManager.swift b/stdlib/public/core/LifetimeManager.swift
@@ -266,31 +266,11 @@ extension String {
 }
 #endif
 
-/// Takes in a value at +0 and performs a Builtin.copy upon it.
-///
-/// IMPLEMENTATION NOTES: During transparent inlining, Builtin.copy becomes the
-/// explicit_copy_value instruction if we are inlining into a context where the
-/// specialized type is loadable. If the transparent function is called in a
-/// context where the inlined function specializes such that the specialized
-/// type is still not loadable, the compiler aborts (a). Once we have opaque
-/// values, this restriction will be lifted since after that address only types
-/// at SILGen time will be loadable objects.
-///
-/// (a). This is implemented by requiring that Builtin.copy only be called
-/// within a function marked with the semantic tag "lifetimemanagement.copy"
-/// which conveniently is only the function we are defining here: _copy.
-///
-/// NOTE: We mark this _alwaysEmitIntoClient to ensure that we are not creating
-/// new ABI that the stdlib must maintain if a user calls this ignoring the '_'
-/// implying it is stdlib SPI.
+@available(*, deprecated, message: "Use the copy operator")
 @_alwaysEmitIntoClient
 @inlinable
 @_transparent
 @_semantics("lifetimemanagement.copy")
 public func _copy<T>(_ value: T) -> T {
-  #if $BuiltinCopy
-    Builtin.copy(value)
-  #else
-    value
-  #endif
+  copy value
 }
diff --git a/test/SILGen/copy_operator.swift b/test/SILGen/copy_operator.swift
diff --git a/test/SILGen/copy_operator_generic_failure.swift b/test/SILGen/copy_operator_generic_failure.swift
diff --git a/test/SILOptimizer/moveonly_builtins.swift b/test/SILOptimizer/moveonly_builtins.swift
diff --git a/test/SILOptimizer/opaque_values_Onone_stdlib.swift b/test/SILOptimizer/opaque_values_Onone_stdlib.swift
diff --git a/test/stdlib/LifetimeManagement.swift b/test/stdlib/LifetimeManagement.swift
