[CoroutineAccessors] Dedicate bit to dealloc time.

Don't rely on the kind for this.  Allow each allocator to decide for
itself for future compatibility.

Author: nate-chandler

include/swift/ABI/Coro.h

@@ -39,6 +39,8 @@ class CoroAllocatorFlags : public FlagSet<uint32_t> {
     Kind           = 0,
     Kind_width     = 8,
 
+    ShouldDeallocateImmediately = 8,
+
     // 24 reserved bits
   };
   // clang-format on
@@ -49,6 +51,9 @@ class CoroAllocatorFlags : public FlagSet<uint32_t> {
 
   FLAGSET_DEFINE_FIELD_ACCESSORS(Kind, Kind_width, CoroAllocatorKind, getKind,
                                  setKind)
+  FLAGSET_DEFINE_FLAG_ACCESSORS(ShouldDeallocateImmediately,
+                                shouldDeallocateImmediately,
+                                setShouldDeallocateImmediately)
 };
 
 using CoroAllocation = void *;
@@ -62,16 +67,16 @@ struct CoroAllocator {
 
   /// Whether the allocator should deallocate memory on calls to
   /// swift_coro_dealloc.
-  constexpr bool shouldDeallocateImmediately() {
-    // Only the "mallocator" should immediately deallocate in
+  bool shouldDeallocateImmediately() {
+    // Currently, only the "mallocator" should immediately deallocate in
     // swift_coro_dealloc.  It must because the ABI does not provide a means for
     // the callee to return its allocations to the caller.
     //
     // Async allocations can be deferred until the first non-coroutine caller
     // from where swift_task_dealloc_through can be called and passed the
     // caller-allocated fixed-per-callee-sized-frame.
     // Stack allocations just pop the stack.
-    return flags.getKind() == CoroAllocatorKind::Malloc;
+    return flags.shouldDeallocateImmediately();
   }
 };
 

lib/IRGen/GenCall.cpp

@@ -5230,16 +5230,17 @@ Address irgen::emitAllocYieldManyCoroutineBuffer(IRGenFunction &IGF) {
                                  getYieldManyCoroutineBufferAlignment(IGF.IGM));
 }
 
-static llvm::Constant *getAddrOfGlobalCoroAllocator(IRGenModule &IGM,
-                                                    CoroAllocatorKind kind,
-                                                    llvm::Constant *allocFn,
-                                                    llvm::Constant *deallocFn) {
+static llvm::Constant *getAddrOfGlobalCoroAllocator(
+    IRGenModule &IGM, CoroAllocatorKind kind, bool shouldDeallocateImmediately,
+    llvm::Constant *allocFn, llvm::Constant *deallocFn) {
   auto entity = LinkEntity::forCoroAllocator(kind);
   auto taskAllocator = IGM.getOrCreateLazyGlobalVariable(
       entity,
       [&](ConstantInitBuilder &builder) -> ConstantInitFuture {
         auto allocator = builder.beginStruct(IGM.CoroAllocatorTy);
-        allocator.addInt32(CoroAllocatorFlags(kind).getOpaqueValue());
+        auto flags = CoroAllocatorFlags(kind);
+        flags.setShouldDeallocateImmediately(shouldDeallocateImmediately);
+        allocator.addInt32(flags.getOpaqueValue());
         allocator.add(allocFn);
         allocator.add(deallocFn);
         return allocator.finishAndCreateFuture();
@@ -5249,10 +5250,12 @@ static llvm::Constant *getAddrOfGlobalCoroAllocator(IRGenModule &IGM,
 }
 llvm::Constant *IRGenModule::getAddrOfGlobalCoroMallocAllocator() {
   return getAddrOfGlobalCoroAllocator(*this, CoroAllocatorKind::Malloc,
+                                      /*shouldDeallocateImmediately=*/true,
                                       getMallocFn(), getFreeFn());
 }
 llvm::Constant *IRGenModule::getAddrOfGlobalCoroAsyncTaskAllocator() {
   return getAddrOfGlobalCoroAllocator(*this, CoroAllocatorKind::Async,
+                                      /*shouldDeallocateImmediately=*/false,
                                       getTaskAllocFn(), getTaskDeallocFn());
 }
 llvm::Value *

test/IRGen/coroutine_accessors.swift

@@ -14,7 +14,7 @@
 // CHECK-SAME:  }>
 
 // CHECK-LABEL: _swift_coro_malloc_allocator = linkonce_odr hidden constant %swift.coro_allocator {
-// CHECK-SAME:       i32 2,
+// CHECK-SAME:       i32 258,
 // CHECK-SAME:       malloc,
 // CHECK-SAME:       free
 // CHECK-SAME:  }

test/IRGen/coroutine_accessors_popless.swift

@@ -23,7 +23,7 @@
 // CHECK-SAME:      swift_task_dealloc
 // CHECK-SAME:  }
 // CHECK-LABEL: _swift_coro_malloc_allocator = linkonce_odr hidden constant %swift.coro_allocator {
-// CHECK-SAME:       i32 2,
+// CHECK-SAME:       i32 258,
 // CHECK-SAME:       malloc,
 // CHECK-SAME:       free
 // CHECK-SAME:  }