[vm/ffi] Rewrite Pointer.elementAt calls in CFE

This rewrites `elementAt` calls in the CFE to skip the runtime entry for `sizeOf` when the type argument is constant. The runtime entry is still used when the type argument is generic. Forcing the type argument to be constant and removing the runtime entry will be done in follow up CLs. Bug: #44621 Bug: #38721 TEST=tests/ffi/data_test.dart Change-Id: I480db43e7c115c24bd45f0ddab0cfea7eb8cfa58 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/182263 Reviewed-by: Clement Skau <[email protected]>
dart-lang · Feb 2, 2021 · 1fff52a · 1fff52a
1 parent 64bf734
commit 1fff52a
Show file tree

Hide file tree

Showing 2 changed files with 18 additions and 11 deletions.
diff --git a/pkg/vm/lib/transformations/ffi.dart b/pkg/vm/lib/transformations/ffi.dart
@@ -206,6 +206,7 @@ class FfiTransformer extends Transformer {
   final Field pragmaOptions;
   final Procedure listElementAt;
   final Procedure numAddition;
+  final Procedure numMultiplication;
 
   final Library ffiLibrary;
   final Class allocatorClass;
@@ -267,6 +268,7 @@ class FfiTransformer extends Transformer {
         pragmaOptions = coreTypes.pragmaOptions,
         listElementAt = coreTypes.index.getMember('dart:core', 'List', '[]'),
         numAddition = coreTypes.index.getMember('dart:core', 'num', '+'),
+        numMultiplication = coreTypes.index.getMember('dart:core', 'num', '*'),
         ffiLibrary = index.getLibrary('dart:ffi'),
         allocatorClass = index.getClass('dart:ffi', 'Allocator'),
         nativeFunctionClass = index.getClass('dart:ffi', 'NativeFunction'),

diff --git a/pkg/vm/lib/transformations/ffi_use_sites.dart b/pkg/vm/lib/transformations/ffi_use_sites.dart
@@ -31,7 +31,6 @@ import 'ffi.dart'
         FfiTransformerData,
         NativeType,
         FfiTransformer,
-        optimizedTypes,
         nativeTypeSizes,
         WORD_SIZE,
         UNKNOWN,
@@ -432,20 +431,26 @@ class _FfiUseSiteTransformer extends FfiTransformer {
 
         _warningNativeTypeValid(nativeType, node);
 
+        // TODO(http://dartbug.com/38721): Change this to an error.
         if (nativeType is TypeParameterType) {
           // Do not rewire generic invocations.
           return node;
         }
-        final Class nativeClass = (nativeType as InterfaceType).classNode;
-        final NativeType nt = getType(nativeClass);
-        if (optimizedTypes.contains(nt)) {
-          final typeArguments = [
-            if (nt == NativeType.kPointer) _pointerTypeGetTypeArg(nativeType)
-          ];
-          return StaticInvocation(
-              elementAtMethods[nt],
-              Arguments([node.receiver, node.arguments.positional[0]],
-                  types: typeArguments));
+
+        Expression inlineSizeOf = _inlineSizeOf(nativeType);
+        if (inlineSizeOf != null) {
+          // Generates `receiver.offsetBy(inlineSizeOfExpression)`.
+          return MethodInvocation(
+              node.receiver,
+              offsetByMethod.name,
+              Arguments([
+                MethodInvocation(
+                    node.arguments.positional.single,
+                    numMultiplication.name,
+                    Arguments([inlineSizeOf]),
+                    numMultiplication)
+              ], types: node.arguments.types),
+              offsetByMethod);
         }
       }
     } on _FfiStaticTypeError {