RFC: Start refactoring to provide more than a single backend.

lib/compiler/implementation/ssa/builder.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class Interceptors {
   Compiler compiler;
   Interceptors(Compiler this.compiler);
 
   SourceString mapOperatorToMethodName(Operator op) {
     String name = op.source.stringValue;
@@ skipping 763 matching lines @@
   // The most recently opened block. Has the same value as [current] while
   // the block is open, but unlike [current], it isn't cleared when the current
   // block is closed.
   HBasicBlock lastOpenedBlock;
 
   LibraryElement get currentLibrary() => work.element.getLibrary();
 
   SsaBuilder(Compiler compiler, WorkItem work)
     : this.compiler = compiler,
       this.work = work,
-      interceptors = compiler.builder.interceptors,
+      interceptors = compiler.backend.builder.interceptors,

[ahe, 2012/05/11 11:39:48]

I think this will cause a type warning. compiler.backend is a Backend which
doesn't have a builder.

[Anton Muhin, 2012/05/12 15:48:43]

I am sorry I probably missed something, what kind of warning it will cause? 
While being run, it shouldn't be an issue (I hope) as backend will have
necessary methods.  What I am missing? 

[ngeoffray, 2012/05/13 17:02:47]

It will create a static type warning, eg: "interface backend has no field named
'builder'". We want to be warning free. Indeed, at runtime, the backend object
will have a 'builder' field, but Peter is referring to compile-time.

[Anton Muhin, 2012/05/14 14:36:45]

Thanks a lot for explanation, Nicolas!

Q: how do I test my changes?  Currently I use:


./tools/build.py --mode=release create_sdk && ./tools/test.py --mode=release
--compiler=dart2js --runtime=d8 --time --use-sdk --report --shards=4 --shard=1

but that didn't show any warning.

I remember you used to have a presubmit script.

Any advice?

And to solve the problem I try to pass proper instances, e.g. JavaScriptBackend,
etc.
On 2012/05/13 17:02:47, ngeoffray wrote:

[ahe, 2012/05/14 15:56:41]

If you want to make sure you run all the tests, you should remove the "shard"
related options. If you just want to run a quarter of the tests, then the shard
options are fine. When making changes to the infrastructure (like you are)
running only a subset of tests is probably sufficient.

Also, if you remove --use-sdk, you don't have to run build.py.

You should also make sure that the unit tests still run. These are likely to
break when refactoring:

./tools/test.py -mrelease -rvm leg

The unit tests must be run on the VM because dart2js is not self-hosted, and
because they are *unit* tests, not *integration* tests. Side note: we should
probably start looking into getting the unit tests running on dart2js as well,
but I don't think that can replace running them on the VM.

       methodInterceptionEnabled = true,
       elements = work.resolutionTree,
       graph = new HGraph(),
       stack = new List<HInstruction>(),
       jumpTargets = new Map<TargetElement, JumpHandler>() {
     localsHandler = new LocalsHandler(this);
   }
 
   void disableMethodInterception() {
     assert(methodInterceptionEnabled);
@@ skipping 663 matching lines @@
             wrapExpressionGraph(conditionExpression),
             wrapStatementGraph(bodyGraph),
             null,
             loopEntryBlock.loopInformation.target,
             loopEntryBlock.loopInformation.labels);
     loopEntryBlock.setBlockFlow(loopBlockInfo, current);
     loopInfo.loopBlockInformation = loopBlockInfo;
   }
 
   visitFunctionExpression(FunctionExpression node) {
-    ClosureData nestedClosureData = compiler.builder.closureDataCache[node];
+    ClosureData nestedClosureData = compiler.backend.builder.closureDataCache[node];
     if (nestedClosureData === null) {
       // TODO(floitsch): we can only assume that the reason for not having a
       // closure data here is, because the function is inside an initializer.
       compiler.unimplemented("Closures inside initializers", node: node);
     }
     assert(nestedClosureData !== null);
     assert(nestedClosureData.closureClassElement !== null);
     ClassElement closureClassElement =
         nestedClosureData.closureClassElement;
     FunctionElement callElement = nestedClosureData.callElement;
@@ skipping 1841 matching lines @@
                                    <HInstruction>[target, input],
                                    HType.STRING));
     return builder.pop();
   }
 
   HInstruction result() {
     flushLiterals();
     return prefix;
   }
 }