Merge pull request #39984 from gottesmm/pr-135d6a4f34ad56ff7b7f978fdb5599412fd608c0

[moveOnly] Add a semi-generic _copy function similar to the semi-generic _move

Author: gottesmm

docs/SIL.rst

@@ -5205,6 +5205,36 @@ independent of the operand. In terms of specific types:
 In ownership qualified functions, a ``copy_value`` produces a +1 value that must
 be consumed at most once along any path through the program.
 
+explicit_copy_value
+```````````````````
+
+::
+
+   sil-instruction ::= 'explicit_copy_value' sil-operand
+
+   %1 = explicit_copy_value %0 : $A
+
+Performs a copy of a loadable value as if by the value's type lowering and
+returns the copy. The returned copy semantically is a value that is completely
+independent of the operand. In terms of specific types:
+
+1. For trivial types, this is equivalent to just propagating through the trivial
+   value.
+2. For reference types, this is equivalent to performing a ``strong_retain``
+   operation and returning the reference.
+3. For ``@unowned`` types, this is equivalent to performing an
+   ``unowned_retain`` and returning the operand.
+4. For aggregate types, this is equivalent to recursively performing a
+   ``copy_value`` on its components, forming a new aggregate from the copied
+   components, and then returning the new aggregate.
+
+In ownership qualified functions, a ``explicit_copy_value`` produces a +1 value
+that must be consumed at most once along any path through the program.
+
+When move only variable checking is performed, ``explicit_copy_value`` is
+treated as an explicit copy asked for by the user that should not be rewritten
+and should be treated as a non-consuming use.
+
 move_value
 ``````````
 

include/swift/AST/Builtins.def

@@ -790,6 +790,24 @@ BUILTIN_MISC_OPERATION(DestroyTaskGroup,
 /// the SILVerifier.
 BUILTIN_MISC_OPERATION(Move, "move", "", 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)
+
 // BUILTIN_MISC_OPERATION_WITH_SILGEN - Miscellaneous operations that are
 // specially emitted during SIL generation.
 //

include/swift/AST/DiagnosticsSIL.def

@@ -718,6 +718,10 @@ NOTE(capturepromotion_variable_defined_here,none,
 ERROR(move_operator_used_on_generic_or_existential_value, none,
       "move() used on a generic or existential value", ())
 
+// copy operator used on generic or evalue
+ERROR(copy_operator_used_on_generic_or_existential_value, none,
+      "copy() used on a generic or existential value", ())
+
 // noimplicitcopy on generic or existential binding
 ERROR(noimplicitcopy_used_on_generic_or_existential, none,
       "@_noImplicitCopy can not be used on a generic or existential typed "

include/swift/AST/SemanticAttrs.def

@@ -114,6 +114,7 @@ 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")
 

include/swift/Basic/Features.def

@@ -55,5 +55,6 @@ LANGUAGE_FEATURE(BuiltinBuildExecutor, 0, "Executor-building builtins", true)
 LANGUAGE_FEATURE(BuiltinBuildMainExecutor, 0, "MainActor executor building builtin", true)
 LANGUAGE_FEATURE(BuiltinCreateAsyncTaskInGroup, 0, "MainActor executor building builtin", true)
 LANGUAGE_FEATURE(BuiltinMove, 0, "Builtin.move()", true)
+LANGUAGE_FEATURE(BuiltinCopy, 0, "Builtin.copy()", true)
 
 #undef LANGUAGE_FEATURE

include/swift/SIL/SILBuilder.h

@@ -1237,6 +1237,15 @@ class SILBuilder {
                       CopyValueInst(getSILDebugLocation(Loc), operand));
   }
 
+  ExplicitCopyValueInst *createExplicitCopyValue(SILLocation Loc,
+                                                 SILValue operand) {
+    assert(!operand->getType().isTrivial(getFunction()) &&
+           "Should not be passing trivial values to this api. Use instead "
+           "emitCopyValueOperation");
+    return insert(new (getModule())
+                      ExplicitCopyValueInst(getSILDebugLocation(Loc), operand));
+  }
+
   DestroyValueInst *createDestroyValue(SILLocation Loc, SILValue operand,
                                        bool poisonRefs = false) {
     assert(isLoadableOrOpaque(operand->getType()));

include/swift/SIL/SILCloner.h

@@ -1713,6 +1713,21 @@ void SILCloner<ImplClass>::visitCopyValueInst(CopyValueInst *Inst) {
                                          getOpValue(Inst->getOperand())));
 }
 
+template <typename ImplClass>
+void SILCloner<ImplClass>::visitExplicitCopyValueInst(
+    ExplicitCopyValueInst *Inst) {
+  getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
+  if (!getBuilder().hasOwnership()) {
+    SILValue newValue = getBuilder().emitCopyValueOperation(
+        getOpLocation(Inst->getLoc()), getOpValue(Inst->getOperand()));
+    return recordFoldedValue(Inst, newValue);
+  }
+
+  recordClonedInstruction(
+      Inst, getBuilder().createExplicitCopyValue(
+                getOpLocation(Inst->getLoc()), getOpValue(Inst->getOperand())));
+}
+
 template <typename ImplClass>
 void SILCloner<ImplClass>::visitMoveValueInst(MoveValueInst *Inst) {
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));

include/swift/SIL/SILInstruction.h

@@ -7267,6 +7267,15 @@ class CopyValueInst
       : UnaryInstructionBase(DebugLoc, operand, operand->getType()) {}
 };
 
+class ExplicitCopyValueInst
+    : public UnaryInstructionBase<SILInstructionKind::ExplicitCopyValueInst,
+                                  SingleValueInstruction> {
+  friend class SILBuilder;
+
+  ExplicitCopyValueInst(SILDebugLocation DebugLoc, SILValue operand)
+      : UnaryInstructionBase(DebugLoc, operand, operand->getType()) {}
+};
+
 #define UNCHECKED_REF_STORAGE(Name, ...)                                       \
   class StrongCopy##Name##ValueInst                                            \
       : public UnaryInstructionBase<                                           \

include/swift/SIL/SILNodes.def

@@ -575,6 +575,10 @@ ABSTRACT_VALUE_AND_INST(SingleValueInstruction, ValueBase, SILInstruction)
   // A copy_value's retain semantics are fully encapsulated in OSSA
   // invariants. It has no side effects relative to other OSSA values.
   BRIDGED_SINGLE_VALUE_INST(CopyValueInst, copy_value,
+                            SingleValueInstruction, None, DoesNotRelease)
+  // A copy_value instruction that was explicitly asked for by the user. Left
+  // alone by OSSA optimizations.
+  SINGLE_VALUE_INST(ExplicitCopyValueInst, explicit_copy_value,
                     SingleValueInstruction, None, DoesNotRelease)
 #define UNCHECKED_REF_STORAGE(Name, name, ...) \
   SINGLE_VALUE_INST(StrongCopy##Name##ValueInst, strong_copy_##name##_value, \

lib/AST/ASTPrinter.cpp

@@ -2816,6 +2816,8 @@ static bool usesFeatureBuiltinMove(Decl *decl) {
   return false;
 }
 
+static bool usesFeatureBuiltinCopy(Decl *decl) { return false; }
+
 static bool usesFeatureInheritActorContext(Decl *decl) {
   if (auto func = dyn_cast<AbstractFunctionDecl>(decl)) {
     for (auto param : *func->getParameters()) {