Declare parameters of the bailout version in beginGraph, instead of setting them up in endGraph.

lib/compiler/implementation/ssa/codegen.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 SsaCodeGeneratorTask extends CompilerTask {
   final JavaScriptBackend backend;
   SsaCodeGeneratorTask(JavaScriptBackend backend)
       : this.backend = backend,
         super(backend.compiler);
   String get name() => 'SSA code generator';
@@ skipping 2621 matching lines @@
   void endLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
   }
 }
 
 class SsaUnoptimizedCodeGenerator extends SsaCodeGenerator {
 
   final StringBuffer setup;
   final StringBuffer newParameters;
   final List<String> labels;
   int labelId = 0;
-  int maxBailoutParameters = 0;
 
   SsaBailoutPropagator propagator;
   HInstruction savedFirstInstruction;
 
   SsaUnoptimizedCodeGenerator(backend, work, parameters, parameterNames)
     : super(backend, work, parameters, parameterNames),
       setup = new StringBuffer(),
       newParameters = new StringBuffer(),
       labels = <String>[];
 
   String pushLabel() {
     String label = 'L${labelId++}';
     labels.addLast(label);
     return label;
   }
 
   String popLabel() {
     return labels.removeLast();
   }
 
   String currentLabel() {
     return labels.last();
   }
 
   HBasicBlock beginGraph(HGraph graph) {
     propagator = new SsaBailoutPropagator(compiler, generateAtUseSite);
     propagator.visitGraph(graph);
+    // TODO(ngeoffray): We could avoid generating the state at the
+    // call site for non-complex bailout methods.
+    newParameters.add('state');
 
     if (propagator.hasComplexTypeGuards) {
       startBailoutSwitch();
+     
+      // Use generic parameters that will be assign to

[floitsch, 2012/06/14 15:29:39]

assigned

[ngeoffray, 2012/06/14 15:31:47]

Done.

+      // the right variables in the setup phase.
+      for (int i = 0; i < propagator.maxBailoutParameters; i++) {
+        String name = 'env$i';
+        declaredVariables.add(name);
+        newParameters.add(', $name');
+      }
 
       // The setup phase of a bailout function sets up the environment for
       // each bailout target. Each bailout target will populate this
       // setup phase. It is put at the beginning of the function.
       setup.add('  switch (state) {\n');
       return graph.entry;
     } else {
+      // We have a simple type guard, so we can reuse the names that
+      // the type guard expects.
+      for (HInstruction input in propagator.firstTypeGuard.inputs) {
+        input = unwrap(input);
+        String name = variableNames.getName(input);
+        declaredVariables.add(name);
+        newParameters.add(', $name');
+      }
+
       // We change the first instruction of the first guard to be the
       // guard. We will change it back in the call to [endGraph].
       HBasicBlock block = propagator.firstTypeGuard.block;
       savedFirstInstruction = block.first;
       block.first = propagator.firstTypeGuard;
       return block;
     }
   }
 
   // If argument is a [HCheck] and it does not have a name, we try to
   // find the name of its checked input. Note that there must be a
   // name, otherwise the instruction would not be in the live
   // environment.
   HInstruction unwrap(HInstruction argument) {
     while (argument is HCheck && !variableNames.hasName(argument)) {
       argument = argument.checkedInput;
     }
     assert(variableNames.hasName(argument));
     return argument;
   }
 
   void endGraph(HGraph graph) {
-    // TODO(ngeoffray): We could avoid generating the state at the
-    // call site for non-complex bailout methods.
-    newParameters.add('state');
-
-    // TODO(ngeoffray): We should declare the parameters in
-    // beginGraph, to avoid potentially redeclaring them with 'var'
-    // in the method body.
-    if (!propagator.hasComplexTypeGuards) {
-      propagator.firstTypeGuard.block.first = savedFirstInstruction;
-      for (HInstruction input in propagator.firstTypeGuard.inputs) {
-        input = unwrap(input);
-        newParameters.add(', ${variableNames.getName(input)}');
-      }
-    } else {
-      for (int i = 0; i < maxBailoutParameters; i++) {
-        newParameters.add(', env$i');
-      }
+    if (propagator.hasComplexTypeGuards) {
       indent--; // Close original case.
       indent--;
       addIndented('}\n');  // Close 'switch'.
       setup.add('  }\n');
+    } else {
+      // Put back the original first instruction of the block.
+      propagator.firstTypeGuard.block.first = savedFirstInstruction;
     }
   }
 
   bool visitAndOrInfo(HAndOrBlockInformation info) => false;
 
   bool visitIfInfo(HIfBlockInformation info) {
     if (info.thenGraph.start.hasGuards()) return false;
     if (info.elseGraph.start.hasGuards()) return false;
     return super.visitIfInfo(info);
   }
@@ skipping 21 matching lines @@
       input = unwrap(input);
       String name = variableNames.getName(input);
       setup.add('      ');
       if (!isVariableDeclared(name)) {
         declaredVariables.add(name);
         setup.add('var ');
       }
       setup.add('$name = env$i;\n');
       i++;
     }
-    if (i > maxBailoutParameters) maxBailoutParameters = i;
     setup.add('      break;\n');
   }
 
   void startBailoutCase(List<HTypeGuard> bailouts1,
                         List<HTypeGuard> bailouts2) {
     indent--;
     handleBailoutCase(bailouts1);
     handleBailoutCase(bailouts2);
     indent++;
   }
@@ skipping 119 matching lines @@
       startBailoutSwitch();
     }
   }
 
   void endLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     if (labeledBlockInfo.body.start.hasGuards()) {
       endBailoutSwitch();
     }
   }
 }