Merge pull request swiftlang#78837 from gottesmm/rdar-142661388

[rbi] Change Region Based Isolation for closures to not use the AST and instead just use SIL.

Author: gottesmm

SwiftCompilerSources/Sources/SIL/Instruction.swift

@@ -1736,3 +1736,6 @@ final public class ThunkInst : Instruction {
 
 final public class MergeIsolationRegionInst : Instruction {
 }
+
+final public class IgnoredUseInst : Instruction, UnaryInstruction {
+}

SwiftCompilerSources/Sources/SIL/Registration.swift

@@ -258,4 +258,5 @@ public func registerSILClasses() {
   register(CheckedCastAddrBranchInst.self)
   register(ThunkInst.self)
   register(MergeIsolationRegionInst.self)
+  register(IgnoredUseInst.self)
 }

docs/SIL/Instructions.md

@@ -5551,3 +5551,21 @@ sil-instruction ::= 'has_symbol' sil-decl-ref
 Returns true if each of the underlying symbol addresses associated with
 the given declaration are non-null. This can be used to determine
 whether a weakly-imported declaration is available at runtime.
+
+## Miscellaneous instructions
+
+### ignored_use
+
+```none
+sil-instruction ::= 'ignored_use'
+```
+
+This instruction acts as a synthetic use instruction that suppresses unused
+variable warnings. In Swift the equivalent operation is '_ = x'. This
+importantly also provides a way to find the source location for '_ = x' when
+emitting SIL diagnostics. It is only legal in Raw SIL and is removed as dead
+code when we convert to Canonical SIL.
+
+DISCUSSION: Before the introduction of this instruction, in certain cases,
+SILGen would just not emit anything for '_ = x'... so one could not emit
+diagnostics upon this case.

include/swift/AST/DiagnosticsSIL.def

@@ -1056,6 +1056,12 @@ NOTE(regionbasedisolation_typed_tns_passed_to_sending_closure_helper_have_value_
 NOTE(regionbasedisolation_typed_tns_passed_to_sending_closure_helper_multiple_value, none,
      "closure captures non-Sendable %0",
      (DeclName))
+NOTE(regionbasedisolation_closure_captures, none,
+     "closure captures %0",
+     (DeclName))
+NOTE(regionbasedisolation_closure_captures_actor, none,
+     "closure captures %0 allowing access to %1 state within the closure",
+     (DeclName, StringRef))
 
 NOTE(regionbasedisolation_typed_tns_passed_to_sending_callee, none,
      "Passing %0 value of non-Sendable type %1 as a 'sending' parameter to %2 %3 risks causing races inbetween %0 uses and uses reachable from %3",

include/swift/SIL/InstructionUtils.h

@@ -129,6 +129,11 @@ bool isEndOfScopeMarker(SILInstruction *user);
 /// only used in recognizable patterns without otherwise "escaping".
 bool isIncidentalUse(SILInstruction *user);
 
+/// Returns true if this is a move only wrapper use.
+///
+/// E.x.: moveonlywrapper_to_copyable_addr, copyable_to_moveonlywrapper_value
+bool isMoveOnlyWrapperUse(SILInstruction *user);
+
 /// Return true if the given `user` instruction modifies the value's refcount
 /// without propagating the value or having any other effect aside from
 /// potentially destroying the value itself (and executing associated cleanups).

include/swift/SIL/SILBuilder.h

@@ -3089,6 +3089,15 @@ class SILBuilder {
         getModule(), getSILDebugLocation(Loc), Decl));
   }
 
+  //===--------------------------------------------------------------------===//
+  // Misc Uses
+  //===--------------------------------------------------------------------===//
+
+  IgnoredUseInst *createIgnoredUse(SILLocation loc, SILValue value) {
+    return insert(new (getModule())
+                      IgnoredUseInst(getSILDebugLocation(loc), value));
+  }
+
   //===--------------------------------------------------------------------===//
   // Private Helper Methods
   //===--------------------------------------------------------------------===//

include/swift/SIL/SILCloner.h

@@ -3796,6 +3796,14 @@ void SILCloner<ImplClass>::visitHasSymbolInst(HasSymbolInst *Inst) {
                                          Inst->getDecl()));
 }
 
+template <typename ImplClass>
+void SILCloner<ImplClass>::visitIgnoredUseInst(IgnoredUseInst *Inst) {
+  getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
+  recordClonedInstruction(
+      Inst, getBuilder().createIgnoredUse(getOpLocation(Inst->getLoc()),
+                                          getOpValue(Inst->getOperand())));
+}
+
 } // end namespace swift
 
 #endif

include/swift/SIL/SILInstruction.h

@@ -11725,6 +11725,17 @@ class MergeIsolationRegionInst final
   }
 };
 
+/// An instruction that represents a semantic-less use that is used to
+/// suppresses unused value variable warnings. E.x.: _ = x.
+class IgnoredUseInst final
+    : public UnaryInstructionBase<SILInstructionKind::IgnoredUseInst,
+                                  NonValueInstruction> {
+  friend SILBuilder;
+
+  IgnoredUseInst(SILDebugLocation loc, SILValue operand)
+      : UnaryInstructionBase(loc, operand) {}
+};
+
 inline SILType *AllocRefInstBase::getTypeStorage() {
   // If the size of the subclasses are equal, then all of this compiles away.
   if (auto I = dyn_cast<AllocRefInst>(this))

include/swift/SIL/SILNodes.def

@@ -897,6 +897,9 @@ NON_VALUE_INST(MarkUnresolvedMoveAddrInst, mark_unresolved_move_addr,
 NON_VALUE_INST(MergeIsolationRegionInst, merge_isolation_region,
                SILInstruction, None, DoesNotRelease)
 
+NON_VALUE_INST(IgnoredUseInst, ignored_use,
+               SILInstruction, None, DoesNotRelease)
+
 NON_VALUE_INST(IncrementProfilerCounterInst, increment_profiler_counter,
                SILInstruction, MayReadWrite, DoesNotRelease)
 

include/swift/SILOptimizer/Utils/PartitionUtils.h

@@ -1374,6 +1374,12 @@ struct PartitionOpEvaluator {
       Region sentRegion = p.getRegion(sentElement);
       bool isClosureCapturedElt = false;
       SILDynamicMergedIsolationInfo sentRegionIsolation;
+
+      // TODO: Today we only return the first element in our region that has
+      // some form of isolation. This causes us to in the case of sending
+      // partial_applies to only emit a diagnostic for the first element in the
+      // capture list of the partial_apply. If we returned a list of potential
+      // errors... we could emit the error for each capture individually.
       auto pairOpt = getIsolationRegionInfo(sentRegion, op.getSourceOp());
       if (!pairOpt) {
         return handleError(UnknownCodePatternError(op));