Reland Allow normal function results of @yield_once coroutines (#71645)

* Allow normal function results of @yield_once coroutines

* Address review comments

* Workaround LLVM coroutine codegen problem: it assumes that unwind path never returns.
This is not true to Swift coroutines as unwind path should end with error result.

Author: asl

docs/SIL.rst

@@ -6100,6 +6100,14 @@ executing the ``begin_apply``) were being "called" by the ``yield``:
   or move the value from that position before ending or aborting the
   coroutine.
 
+A coroutine optionally may produce normal results. These do not have
+``@yields`` annotation in the result type tuple.
+::
+  (%float, %token) = begin_apply %0() : $@yield_once () -> (@yields Float, Int)
+
+Normal results of a coroutine are produced by the corresponding ``end_apply``
+instruction.
+
 A ``begin_apply`` must be uniquely either ended or aborted before
 exiting the function or looping to an earlier portion of the function.
 
@@ -6129,9 +6137,9 @@ end_apply
 `````````
 ::
 
-  sil-instruction ::= 'end_apply' sil-value
+  sil-instruction ::= 'end_apply' sil-value 'as' sil-type
 
-  end_apply %token
+  end_apply %token as $()
 
 Ends the given coroutine activation, which is currently suspended at
 a ``yield`` instruction.  Transfers control to the coroutine and takes
@@ -6141,8 +6149,8 @@ when the coroutine reaches a ``return`` instruction.
 The operand must always be the token result of a ``begin_apply``
 instruction, which is why it need not specify a type.
 
-``end_apply`` currently has no instruction results.  If coroutines were
-allowed to have normal results, they would be producted by ``end_apply``.
+The result of ``end_apply`` is the normal result of the coroutine function (the
+operand of the ``return`` instruction)."
 
 When throwing coroutines are supported, there will need to be a
 ``try_end_apply`` instruction.

include/swift/AST/Types.h

@@ -4789,24 +4789,27 @@ class SILFunctionType final
   using Representation = SILExtInfoBuilder::Representation;
 
 private:
-  unsigned NumParameters;
+  unsigned NumParameters = 0;
 
-  // These are *normal* results if this is not a coroutine and *yield* results
-  // otherwise.
-  unsigned NumAnyResults;         // Not including the ErrorResult.
-  unsigned NumAnyIndirectFormalResults; // Subset of NumAnyResults.
-  unsigned NumPackResults; // Subset of NumAnyIndirectFormalResults.
+  // These are *normal* results
+  unsigned NumAnyResults = 0;         // Not including the ErrorResult.
+  unsigned NumAnyIndirectFormalResults = 0; // Subset of NumAnyResults.
+  unsigned NumPackResults = 0; // Subset of NumAnyIndirectFormalResults.
+  // These are *yield* results
+  unsigned NumAnyYieldResults = 0;  // Not including the ErrorResult.
+  unsigned NumAnyIndirectFormalYieldResults = 0; // Subset of NumAnyYieldResults.
+  unsigned NumPackYieldResults = 0; // Subset of NumAnyIndirectFormalYieldResults.
 
   // [NOTE: SILFunctionType-layout]
   // The layout of a SILFunctionType in memory is:
   //   SILFunctionType
   //   SILParameterInfo[NumParameters]
-  //   SILResultInfo[isCoroutine() ? 0 : NumAnyResults]
+  //   SILResultInfo[NumAnyResults]
   //   SILResultInfo?    // if hasErrorResult()
-  //   SILYieldInfo[isCoroutine() ? NumAnyResults : 0]
+  //   SILYieldInfo[NumAnyYieldResults]
   //   SubstitutionMap[HasPatternSubs + HasInvocationSubs]
-  //   CanType?          // if !isCoro && NumAnyResults > 1, formal result cache
-  //   CanType?          // if !isCoro && NumAnyResults > 1, all result cache
+  //   CanType?          // if NumAnyResults > 1, formal result cache
+  //   CanType?          // if NumAnyResults > 1, all result cache
 
   CanGenericSignature InvocationGenericSig;
   ProtocolConformanceRef WitnessMethodConformance;
@@ -4845,7 +4848,7 @@ class SILFunctionType final
 
   /// Do we have slots for caches of the normal-result tuple type?
   bool hasResultCache() const {
-    return NumAnyResults > 1 && !isCoroutine();
+    return NumAnyResults > 1;
   }
 
   CanType &getMutableFormalResultsCache() const {
@@ -4945,14 +4948,14 @@ class SILFunctionType final
   ArrayRef<SILYieldInfo> getYields() const {
     return const_cast<SILFunctionType *>(this)->getMutableYields();
   }
-  unsigned getNumYields() const { return isCoroutine() ? NumAnyResults : 0; }
+  unsigned getNumYields() const { return NumAnyYieldResults; }
 
   /// Return the array of all result information. This may contain inter-mingled
   /// direct and indirect results.
   ArrayRef<SILResultInfo> getResults() const {
     return const_cast<SILFunctionType *>(this)->getMutableResults();
   }
-  unsigned getNumResults() const { return isCoroutine() ? 0 : NumAnyResults; }
+  unsigned getNumResults() const { return NumAnyResults; }
 
   ArrayRef<SILResultInfo> getResultsWithError() const {
     return const_cast<SILFunctionType *>(this)->getMutableResultsWithError();
@@ -4989,17 +4992,17 @@ class SILFunctionType final
   // indirect property, not the SIL indirect property, should be consulted to
   // determine whether function reabstraction is necessary.
   unsigned getNumIndirectFormalResults() const {
-    return isCoroutine() ? 0 : NumAnyIndirectFormalResults;
+    return NumAnyIndirectFormalResults;
   }
   /// Does this function have any formally indirect results?
   bool hasIndirectFormalResults() const {
     return getNumIndirectFormalResults() != 0;
   }
   unsigned getNumDirectFormalResults() const {
-    return isCoroutine() ? 0 : NumAnyResults - NumAnyIndirectFormalResults;
+    return NumAnyResults - NumAnyIndirectFormalResults;
   }
   unsigned getNumPackResults() const {
-    return isCoroutine() ? 0 : NumPackResults;
+    return NumPackResults;
   }
   bool hasIndirectErrorResult() const {
     return hasErrorResult() && getErrorResult().isFormalIndirect();
@@ -5057,17 +5060,17 @@ class SILFunctionType final
                                      TypeExpansionContext expansion);
 
   unsigned getNumIndirectFormalYields() const {
-    return isCoroutine() ? NumAnyIndirectFormalResults : 0;
+    return NumAnyIndirectFormalYieldResults;
   }
   /// Does this function have any formally indirect yields?
   bool hasIndirectFormalYields() const {
     return getNumIndirectFormalYields() != 0;
   }
   unsigned getNumDirectFormalYields() const {
-    return isCoroutine() ? NumAnyResults - NumAnyIndirectFormalResults : 0;
+    return NumAnyYieldResults - NumAnyIndirectFormalYieldResults;
   }
   unsigned getNumPackYields() const {
-    return isCoroutine() ? NumPackResults : 0;
+    return NumPackYieldResults;
   }
 
   struct IndirectFormalYieldFilter {

include/swift/SIL/SILBuilder.h

@@ -589,11 +589,11 @@ class SILBuilder {
                                                    beginApply));
   }
 
-  EndApplyInst *createEndApply(SILLocation loc, SILValue beginApply) {
+  EndApplyInst *createEndApply(SILLocation loc, SILValue beginApply, SILType ResultType) {
     return insert(new (getModule()) EndApplyInst(getSILDebugLocation(loc),
-                                                 beginApply));
+                                                 beginApply, ResultType));
   }
-
+  
   BuiltinInst *createBuiltin(SILLocation Loc, Identifier Name, SILType ResultTy,
                              SubstitutionMap Subs,
                              ArrayRef<SILValue> Args) {

include/swift/SIL/SILCloner.h

@@ -1077,7 +1077,8 @@ SILCloner<ImplClass>::visitEndApplyInst(EndApplyInst *Inst) {
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   recordClonedInstruction(
       Inst, getBuilder().createEndApply(getOpLocation(Inst->getLoc()),
-                                        getOpValue(Inst->getOperand())));
+                                        getOpValue(Inst->getOperand()),
+                                        getOpType(Inst->getType())));
 }
 
 template<typename ImplClass>

include/swift/SIL/SILInstruction.h

@@ -3253,11 +3253,12 @@ class AbortApplyInst
 /// normally.
 class EndApplyInst
     : public UnaryInstructionBase<SILInstructionKind::EndApplyInst,
-                                  NonValueInstruction> {
+                                  SingleValueInstruction> {
   friend SILBuilder;
 
-  EndApplyInst(SILDebugLocation debugLoc, SILValue beginApplyToken)
-      : UnaryInstructionBase(debugLoc, beginApplyToken) {
+  EndApplyInst(SILDebugLocation debugLoc, SILValue beginApplyToken,
+               SILType Ty)
+    : UnaryInstructionBase(debugLoc, beginApplyToken, Ty) {
     assert(isaResultOf<BeginApplyInst>(beginApplyToken) &&
            isaResultOf<BeginApplyInst>(beginApplyToken)->isBeginApplyToken());
   }

include/swift/SIL/SILNodes.def

@@ -568,6 +568,8 @@ ABSTRACT_VALUE_AND_INST(SingleValueInstruction, ValueBase, SILInstruction)
                     SingleValueInstruction, MayHaveSideEffects, MayRelease)
   SINGLE_VALUE_INST(PartialApplyInst, partial_apply,
                     SingleValueInstruction, MayHaveSideEffects, DoesNotRelease)
+  SINGLE_VALUE_INST(EndApplyInst, end_apply,
+                    SILInstruction, MayHaveSideEffects, MayRelease)  
   SINGLE_VALUE_INST(FunctionExtractIsolationInst, function_extract_isolation,
                     SingleValueInstruction, None, DoesNotRelease)
 
@@ -873,8 +875,6 @@ NON_VALUE_INST(UncheckedRefCastAddrInst, unchecked_ref_cast_addr,
                SILInstruction, MayHaveSideEffects, DoesNotRelease)
 NON_VALUE_INST(AllocGlobalInst, alloc_global,
                SILInstruction, MayHaveSideEffects, DoesNotRelease)
-NON_VALUE_INST(EndApplyInst, end_apply,
-               SILInstruction, MayHaveSideEffects, MayRelease)
 NON_VALUE_INST(AbortApplyInst, abort_apply,
                SILInstruction, MayHaveSideEffects, MayRelease)
 NON_VALUE_INST(PackElementSetInst, pack_element_set,

lib/AST/ASTContext.cpp

@@ -4546,29 +4546,29 @@ SILFunctionType::SILFunctionType(
       !ext.getLifetimeDependenceInfo().empty();
   Bits.SILFunctionType.CoroutineKind = unsigned(coroutineKind);
   NumParameters = params.size();
-  if (coroutineKind == SILCoroutineKind::None) {
-    assert(yields.empty());
-    NumAnyResults = normalResults.size();
-    NumAnyIndirectFormalResults = 0;
-    NumPackResults = 0;
-    for (auto &resultInfo : normalResults) {
-      if (resultInfo.isFormalIndirect())
-        NumAnyIndirectFormalResults++;
-      if (resultInfo.isPack())
-        NumPackResults++;
-    }
-    memcpy(getMutableResults().data(), normalResults.data(),
-           normalResults.size() * sizeof(SILResultInfo));
-  } else {
-    assert(normalResults.empty());
-    NumAnyResults = yields.size();
-    NumAnyIndirectFormalResults = 0;
+  assert((coroutineKind == SILCoroutineKind::None && yields.empty()) ||
+         coroutineKind != SILCoroutineKind::None);
+
+  NumAnyResults = normalResults.size();
+  NumAnyIndirectFormalResults = 0;
+  NumPackResults = 0;
+  for (auto &resultInfo : normalResults) {
+    if (resultInfo.isFormalIndirect())
+      NumAnyIndirectFormalResults++;
+    if (resultInfo.isPack())
+      NumPackResults++;
+  }
+  memcpy(getMutableResults().data(), normalResults.data(),
+         normalResults.size() * sizeof(SILResultInfo));
+  if (coroutineKind != SILCoroutineKind::None) {
+    NumAnyYieldResults = yields.size();
+    NumAnyIndirectFormalYieldResults = 0;
     NumPackResults = 0;
     for (auto &yieldInfo : yields) {
       if (yieldInfo.isFormalIndirect())
-        NumAnyIndirectFormalResults++;
+        NumAnyIndirectFormalYieldResults++;
       if (yieldInfo.isPack())
-        NumPackResults++;
+        NumPackYieldResults++;
     }
     memcpy(getMutableYields().data(), yields.data(),
            yields.size() * sizeof(SILYieldInfo));
@@ -4740,7 +4740,6 @@ CanSILFunctionType SILFunctionType::get(
     std::optional<SILResultInfo> errorResult, SubstitutionMap patternSubs,
     SubstitutionMap invocationSubs, const ASTContext &ctx,
     ProtocolConformanceRef witnessMethodConformance) {
-  assert(coroutineKind == SILCoroutineKind::None || normalResults.empty());
   assert(coroutineKind != SILCoroutineKind::None || yields.empty());
   assert(!ext.isPseudogeneric() || genericSig ||
          coroutineKind != SILCoroutineKind::None);