[silgen] Change silgen pattern to use destructure_tuple instead of borrow + tuple_extract + copy.

rdar://29791263

lib/SILGen/SILGenPattern.cpp

@@ -1394,33 +1394,18 @@ void PatternMatchEmission::emitTupleDispatchWithOwnership(
   }
 
   auto firstPat = rows[0].Pattern;
-  auto sourceType = cast<TupleType>(firstPat->getType()->getCanonicalType());
   SILLocation loc = firstPat;
 
-  // Final consumption here will be either CopyOnSuccess or AlwaysTake. Since we
+  // Final consumption here will be either BorrowAlways or TakeAlways.
-  // do not have a take operation, we treat it as copy on success always.
+  ManagedValue v = src.getFinalManagedValue();
-  //
+
-  // Once we get a take operation, we should consider allowing for the value to
+  SmallVector<ConsumableManagedValue, 8> destructured;
-  // be taken at this point.
+  SGF.B.emitDestructureValueOperation(
-  ManagedValue v = src.getFinalManagedValue().borrow(SGF, loc);
+      loc, v, [&](unsigned index, ManagedValue v) {
-  SmallVector<ConsumableManagedValue, 4> destructured;
+        destructured.push_back({v, src.getFinalConsumption()});
+      });
 
   // Break down the values.
-  auto tupleSILTy = v.getType();
-  for (unsigned i = 0, e = sourceType->getNumElements(); i < e; ++i) {
-    SILType fieldTy = tupleSILTy.getTupleElementType(i);
-    auto &fieldTL = SGF.getTypeLowering(fieldTy);
-
-    // This is a borrowed value, so we need to use copy on success.
-    ManagedValue member = SGF.B.createTupleExtract(loc, v, i, fieldTy);
-    // *NOTE* We leave this as getManagedSubobject so that when we get a
-    // destructure operation, we can pass in src.getFinalConsumption() here and
-    // get the correct behavior of performing the take.
-    auto memberCMV = getManagedSubobject(SGF, member.getValue(), fieldTL,
-                                         CastConsumptionKind::CopyOnSuccess);
-    destructured.push_back(memberCMV);
-  }
-
   // Recurse.
   handleCase(destructured, specializedRows, outerFailure);
 }

test/SILGen/switch_ownership.swift

@@ -0,0 +1,100 @@
+// RUN: %target-swift-emit-silgen -module-name switch -enable-sil-ownership %s | %FileCheck %s
+//
+// A temporary file for testing switch code around ownership. Once SILGenPattern
+// refactoring is complete, this will be merged into the normal pattern file.
+
+//////////////////
+// Declarations //
+//////////////////
+
+class Klass {
+  init() {}
+}
+
+enum Foo { case A, B }
+
+enum NonTrivialFoo {
+case A(Klass)
+case B(Klass)
+}
+
+func a() {}
+func b() {}
+func c() {}
+func d() {}
+func e() {}
+func f() {}
+func g() {}
+
+///////////
+// Tests //
+///////////
+
+// CHECK-LABEL: sil hidden @$s6switch05test_A19_two_trivial_unions1x1yyAA3FooO_AFtF : $@convention(thin) (Foo, Foo) -> () {
+func test_switch_two_trivial_unions(x: Foo, y: Foo) {
+  // CHECK:   [[T0:%.*]] = tuple (%0 : $Foo, %1 : $Foo)
+  // CHECK:   ([[X:%.*]], [[Y:%.*]]) = destructure_tuple [[T0]]
+  // CHECK:   switch_enum [[Y]] : $Foo, case #Foo.A!enumelt: [[IS_CASE1:bb[0-9]+]], default [[IS_NOT_CASE1:bb[0-9]+]]
+
+  switch (x, y) {
+  // CHECK: [[IS_CASE1]]:
+  case (_, Foo.A):
+  // CHECK:   function_ref @$s6switch1ayyF
+    a()
+
+  // CHECK: [[IS_NOT_CASE1]](
+  // CHECK:   switch_enum [[X]] : $Foo, case #Foo.B!enumelt: [[IS_CASE2:bb[0-9]+]], default [[IS_NOT_CASE2:bb[0-9]+]]
+  // CHECK: [[IS_CASE2]]:
+  case (Foo.B, _):
+  // CHECK:   function_ref @$s6switch1byyF
+    b()
+
+  // CHECK: [[IS_NOT_CASE2]](
+  // CHECK:   switch_enum [[Y]] : $Foo, case #Foo.B!enumelt: [[IS_CASE3:bb[0-9]+]], default [[UNREACHABLE:bb[0-9]+]]
+  // CHECK: [[IS_CASE3]]:
+  case (_, Foo.B):
+  // CHECK:   function_ref @$s6switch1cyyF
+    c()
+
+  // CHECK: [[UNREACHABLE]](
+  // CHECK:   unreachable
+  }
+}
+
+// CHECK-LABEL: sil hidden @$s6switch05test_A22_two_nontrivial_unions1x1yyAA13NonTrivialFooO_AFtF : $@convention(thin) (@guaranteed NonTrivialFoo, @guaranteed NonTrivialFoo) -> () {
+func test_switch_two_nontrivial_unions(x: NonTrivialFoo, y: NonTrivialFoo) {
+  // CHECK:   [[ARG0_COPY:%.*]] = copy_value %0
+  // CHECK:   [[ARG1_COPY:%.*]] = copy_value %1
+  // CHECK:   [[T0:%.*]] = tuple ([[ARG0_COPY]] : $NonTrivialFoo, [[ARG1_COPY]] : $NonTrivialFoo)
+  // CHECK:   ([[X:%.*]], [[Y:%.*]]) = destructure_tuple [[T0]]
+  // CHECK:   [[BORROWED_Y:%.*]] = begin_borrow [[Y]]
+  // CHECK:   [[BORROWED_Y_COPY:%.*]] = copy_value [[BORROWED_Y]]
+  // CHECK:   switch_enum [[BORROWED_Y_COPY]] : $NonTrivialFoo, case #NonTrivialFoo.A!enumelt.1: [[IS_CASE1:bb[0-9]+]], default [[IS_NOT_CASE1:bb[0-9]+]]
+
+  switch (x, y) {
+  // CHECK: [[IS_CASE1]]({{%.*}} : @owned $Klass)
+  case (_, NonTrivialFoo.A):
+  // CHECK:   function_ref @$s6switch1ayyF
+    a()
+
+  // CHECK: [[IS_NOT_CASE1]]({{%.*}} : @owned $NonTrivialFoo):
+  // CHECK:   [[BORROWED_X:%.*]] = begin_borrow [[X]]
+  // CHECK:   [[BORROWED_X_COPY:%.*]] = copy_value [[BORROWED_X]]
+  // CHECK:   switch_enum [[BORROWED_X_COPY]] : $NonTrivialFoo, case #NonTrivialFoo.B!enumelt.1: [[IS_CASE2:bb[0-9]+]], default [[IS_NOT_CASE2:bb[0-9]+]]
+  // CHECK: [[IS_CASE2]]({{%.*}} : @owned $Klass)
+  case (NonTrivialFoo.B, _):
+  // CHECK:   function_ref @$s6switch1byyF
+    b()
+
+  // CHECK: [[IS_NOT_CASE2]]({{%.*}} : @owned $NonTrivialFoo)
+  // CHECK:   [[Y_COPY:%.*]] = copy_value [[Y]]
+  // CHECK:   switch_enum [[Y_COPY]] : $NonTrivialFoo, case #NonTrivialFoo.B!enumelt.1: [[IS_CASE3:bb[0-9]+]], default [[UNREACHABLE:bb[0-9]+]]
+  // CHECK: [[IS_CASE3]]({{%.*}} : @owned $Klass):
+  case (_, NonTrivialFoo.B):
+  // CHECK:   function_ref @$s6switch1cyyF
+    c()
+
+  // CHECK: [[UNREACHABLE]]({{%.*}} : @owned $NonTrivialFoo):
+  // CHECK:   unreachable
+  }
+}