[SIL Opaque Value] Fix some SILGen issues for closures when opaque values are enabled

docs/SIL.rst

@@ -6777,9 +6777,9 @@ Checked Conversions
 
 Some user-level cast operations can fail and thus require runtime checking.
 
-The `unconditional_checked_cast_addr`_, `unconditional_checked_cast_value`_ and `unconditional_checked_cast`_
+The `unconditional_checked_cast_addr` and `unconditional_checked_cast`_
 instructions performs an unconditional checked cast; it is a runtime failure
-if the cast fails. The `checked_cast_addr_br`_, `checked_cast_value_br`_ and `checked_cast_br`_
+if the cast fails. The `checked_cast_addr_br`_ and `checked_cast_br`_
 terminator instruction performs a conditional checked cast; it branches to one
 of two destinations based on whether the cast succeeds or not.
 
@@ -6814,25 +6814,6 @@ unconditional_checked_cast_addr
 Performs a checked indirect conversion, causing a runtime failure if the
 conversion fails.
 
-unconditional_checked_cast_value
-````````````````````````````````
-::
-
-  sil-instruction ::= 'unconditional_checked_cast_value'
-                       sil-operand 'to' sil-type
-
-  %1 = unconditional_checked_cast_value %0 : $A to $B
-  // $A must not be an address
-  // $B must not be an address
-  // %1 will be of type $B
-  // $A is destroyed during the conversion. There is no implicit copy.
-
-Performs a checked conversion, causing a runtime failure if the conversion
-fails. Unlike `unconditional_checked_cast`, this destroys its operand and
-creates a new value. Consequently, this supports bridging objects to values, as
-well as casting to a different ownership classification such as `$AnyObject` to
-`$T.Type`.
-
 Runtime Failures
 ~~~~~~~~~~~~~~~~
 
@@ -7213,26 +7194,6 @@ An exact cast checks whether the dynamic type is exactly the target
 type, not any possible subtype of it.  The source and target types
 must be class types.
 
-checked_cast_value_br
-`````````````````````
-::
-
-  sil-terminator ::= 'checked_cast_value_br'
-                      sil-operand 'to' sil-type ','
-                      sil-identifier ',' sil-identifier
-  sil-checked-cast-exact ::= '[' 'exact' ']'
-
-  checked_cast_value_br %0 : $A to $B, bb1, bb2
-  // $A must be not be an address
-  // $B must be an opaque value
-  // bb1 must take a single argument of type $B
-  // bb2 must take no arguments
-
-Performs a checked opaque conversion from ``$A`` to ``$B``. If the conversion
-succeeds, control is transferred to ``bb1``, and the result of the cast is
-passed into ``bb1`` as an argument. If the conversion fails, control is
-transferred to ``bb2``.
-
 checked_cast_addr_br
 ````````````````````
 ::

lib/SILGen/SILGenEpilog.cpp

@@ -29,10 +29,12 @@ void SILGenFunction::prepareEpilog(Optional<Type> directResultType,
     // Set NeedsReturn for indirect or direct results. This ensures that SILGen
     // emits unreachable if there is no source level return.
     NeedsReturn = !(*directResultType)->isEqual(TupleType::getEmpty(getASTContext()));
-    for (auto directResult : fnConv.getDirectSILResults()) {
-      SILType resultType = F.getLoweredType(F.mapTypeIntoContext(
-          fnConv.getSILType(directResult, getTypeExpansionContext())));
-      epilogBB->createPhiArgument(resultType, OwnershipKind::Owned);
+    if (NeedsReturn) {
+      for (auto directResult : fnConv.getDirectSILResults()) {
+        SILType resultType = F.getLoweredType(F.mapTypeIntoContext(
+            fnConv.getSILType(directResult, getTypeExpansionContext())));
+        epilogBB->createPhiArgument(resultType, OwnershipKind::Owned);
+      }
     }
   }
 

lib/SILGen/SILGenProlog.cpp

@@ -458,7 +458,11 @@ static void emitCaptureArguments(SILGenFunction &SGF,
     // Non-escaping stored decls are captured as the address of the value.
     auto type = getVarTypeInCaptureContext();
     SILType ty = SGF.getLoweredType(type);
-    if (SGF.SGM.M.useLoweredAddresses()) {
+    auto argConv = SGF.F.getConventions().getSILArgumentConvention(
+        SGF.F.begin()->getNumArguments());
+    bool isInOut = (argConv == SILArgumentConvention::Indirect_Inout ||
+                    argConv == SILArgumentConvention::Indirect_InoutAliasable);
+    if (isInOut || SGF.SGM.M.useLoweredAddresses()) {
       ty = ty.getAddressType();
     }
     SILValue arg = SGF.F.begin()->createFunctionArgument(ty, VD);

test/SILGen/opaque_values_silgen.swift

@@ -367,3 +367,20 @@ extension Array where Element == Int {
     }
   }
 }
+
+// CHECK-LABEL: sil private [ossa] @$s20opaque_values_silgen22anon_read_only_captureyS2iFSiyXEfU_ : $@convention(thin) (@inout_aliasable Int) -> Int {
+// CHECK-LABEL: } // end sil function '$s20opaque_values_silgen22anon_read_only_captureyS2iFSiyXEfU_'
+func anon_read_only_capture(_ x: Int) -> Int {
+  var x = x
+  return ({ x })()
+}
+
+
+// CHECK-LABEL: sil private [ossa] @$s20opaque_values_silgen22testEmptyReturnClosureyyFyycyKXEfu_yycfU_ : $@convention(thin) @substituted <τ_0_0> () -> @out τ_0_0 for <()> {
+// CHECK-NOT: bb1 
+// CHECK-LABEL: } // end sil function '$s20opaque_values_silgen22testEmptyReturnClosureyyFyycyKXEfu_yycfU_'
+func testEmptyReturnClosure() {
+  func bar() {}
+  let b = nil ?? { bar() }
+}
+