ArraySemantics: support "array.check_subscript" as a two-parameter function.

Support a version of Array._checkSubscript which has no wasNativeTypeChecked parameter.

Author: eeckstein

lib/SILOptimizer/Analysis/ArraySemantic.cpp

@@ -103,10 +103,12 @@ bool swift::ArraySemanticsCall::isValidSignature() {
   }
   case ArrayCallKind::kCheckSubscript: {
     // Int, Bool, Self
-    if (SemanticsCall->getNumArguments() != 3 ||
-        !SemanticsCall->getArgument(0)->getType().isTrivial(*F))
+    unsigned numArgs = SemanticsCall->getNumArguments();
+    if (numArgs != 2 && numArgs != 3)
+      return false;
+    if (!SemanticsCall->getArgument(0)->getType().isTrivial(*F))
       return false;
-    if (!SemanticsCall->getArgument(1)->getType().isTrivial(*F))
+    if (numArgs == 3 && !SemanticsCall->getArgument(1)->getType().isTrivial(*F))
       return false;
     auto SelfConvention = FnTy->getSelfParameter().getConvention();
     return SelfConvention == ParameterConvention::Direct_Guaranteed ||
@@ -326,23 +328,22 @@ bool swift::ArraySemanticsCall::canHoist(SILInstruction *InsertBefore,
     // Not implemented yet.
     return false;
 
-  case ArrayCallKind::kCheckSubscript: {
-    auto IsNativeArg = getArrayPropertyIsNativeTypeChecked();
-    ArraySemanticsCall IsNative(IsNativeArg,
-                                "array.props.isNativeTypeChecked", true);
-    if (!IsNative) {
-      // Do we have a constant parameter?
-      auto *SI = dyn_cast<StructInst>(IsNativeArg);
-      if (!SI)
-        return false;
-      if (!isa<IntegerLiteralInst>(SI->getOperand(0)))
+  case ArrayCallKind::kCheckSubscript:
+    if (SILValue IsNativeArg = getArrayPropertyIsNativeTypeChecked()) {
+      ArraySemanticsCall IsNative(IsNativeArg,
+                                  "array.props.isNativeTypeChecked", true);
+      if (!IsNative) {
+        // Do we have a constant parameter?
+        auto *SI = dyn_cast<StructInst>(IsNativeArg);
+        if (!SI)
+          return false;
+        if (!isa<IntegerLiteralInst>(SI->getOperand(0)))
+          return false;
+      } else if (!IsNative.canHoist(InsertBefore, DT))
+        // Otherwise, we must be able to hoist the function call.
         return false;
-    } else if (!IsNative.canHoist(InsertBefore, DT))
-      // Otherwise, we must be able to hoist the function call.
-      return false;
-
+    }
     return canHoistArrayArgument(SemanticsCall, getSelf(), InsertBefore, DT);
-  }
 
   case ArrayCallKind::kMakeMutable:
   case ArrayCallKind::kEndMutation:
@@ -450,9 +451,8 @@ ApplyInst *swift::ArraySemanticsCall::hoistOrCopy(SILInstruction *InsertBefore,
         hoistOrCopySelf(SemanticsCall, InsertBefore, DT, LeaveOriginal);
 
     SILValue NewArrayProps;
-    if (Kind == ArrayCallKind::kCheckSubscript) {
+    if (SILValue IsNativeArg = getArrayPropertyIsNativeTypeChecked()) {
       // Copy the array.props argument call.
-      auto IsNativeArg = getArrayPropertyIsNativeTypeChecked();
       ArraySemanticsCall IsNative(IsNativeArg,
                                   "array.props.isNativeTypeChecked", true);
       if (!IsNative) {
@@ -517,14 +517,15 @@ void swift::ArraySemanticsCall::removeCall() {
 
   switch (getKind()) {
   default: break;
-  case ArrayCallKind::kCheckSubscript: {
-    // Remove all uses with the empty tuple ().
-    auto EmptyDep = SILBuilderWithScope(SemanticsCall)
-                        .createStruct(SemanticsCall->getLoc(),
-                                      SemanticsCall->getType(), {});
-    SemanticsCall->replaceAllUsesWith(EmptyDep);
-  }
-  break;
+  case ArrayCallKind::kCheckSubscript:
+    if (!SemanticsCall->getType().isVoid()){
+      // Remove all uses with the empty tuple ().
+      auto EmptyDep = SILBuilderWithScope(SemanticsCall)
+                          .createStruct(SemanticsCall->getLoc(),
+                                        SemanticsCall->getType(), {});
+      SemanticsCall->replaceAllUsesWith(EmptyDep);
+    }
+    break;
   case ArrayCallKind::kGetElement: {
     // Remove the matching isNativeTypeChecked and check_subscript call.
     ArraySemanticsCall IsNative(getTypeCheckedArgument(),
@@ -554,11 +555,13 @@ SILValue
 swift::ArraySemanticsCall::getArrayPropertyIsNativeTypeChecked() const {
   switch (getKind()) {
     case ArrayCallKind::kCheckSubscript:
-      return SemanticsCall->getArgument(1);
+      if (SemanticsCall->getNumArguments() == 3)
+        return SemanticsCall->getArgument(1);
+      return SILValue();
     case ArrayCallKind::kGetElement:
       return getTypeCheckedArgument();
     default:
-      llvm_unreachable("Must have an array.props argument");
+      return SILValue();
   }
 }