Experimental: fix two issues with ARM fast (jump table) switches....

src/codegen-arm.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1430 matching lines @@
 
 
 void CodeGenerator::GenerateFastCaseSwitchJumpTable(
     SwitchStatement* node,
     int min_index,
     int range,
     Label* default_label,
     Vector<Label*> case_targets,
     Vector<Label> case_labels) {
   VirtualFrame::SpilledScope spilled_scope(this);
+  JumpTarget setup_default(this);
+  JumpTarget is_smi(this);
+
+  // A non-null default label pointer indicates a default case among
+  // the case labels.  Otherwise we use the break target as a
+  // "default".
+  JumpTarget* default_target =
+      (default_label == NULL) ? node->break_target() : &setup_default;
+
   ASSERT(kSmiTag == 0 && kSmiTagSize <= 2);
-
   frame_->EmitPop(r0);
 
   // Test for a Smi value in a HeapNumber.
-  JumpTarget is_smi(this);
   __ tst(r0, Operand(kSmiTagMask));
   is_smi.Branch(eq);
   __ ldr(r1, MemOperand(r0, HeapObject::kMapOffset - kHeapObjectTag));
   __ ldrb(r1, MemOperand(r1, Map::kInstanceTypeOffset - kHeapObjectTag));
   __ cmp(r1, Operand(HEAP_NUMBER_TYPE));
-  __ b(ne, default_label);
+  default_target->Branch(ne);
   frame_->EmitPush(r0);
   frame_->CallRuntime(Runtime::kNumberToSmi, 1);
   is_smi.Bind();
 
   if (min_index != 0) {
     // Small positive numbers can be immediate operands.
     if (min_index < 0) {
       // If min_index is Smi::kMinValue, -min_index is not a Smi.
       if (Smi::IsValid(-min_index)) {
         __ add(r0, r0, Operand(Smi::FromInt(-min_index)));
       } else {
         __ add(r0, r0, Operand(Smi::FromInt(-min_index - 1)));
         __ add(r0, r0, Operand(Smi::FromInt(1)));
       }
     } else {
       __ sub(r0, r0, Operand(Smi::FromInt(min_index)));
     }
   }
   __ tst(r0, Operand(0x80000000 | kSmiTagMask));
-  __ b(ne, default_label);
+  default_target->Branch(ne);
   __ cmp(r0, Operand(Smi::FromInt(range)));
-  __ b(ge, default_label);
+  default_target->Branch(ge);
+  VirtualFrame* start_frame = new VirtualFrame(frame_);
   __ SmiJumpTable(r0, case_targets);
 
-  VirtualFrame* start_frame = new VirtualFrame(frame_);
-  // Table containing branch operations.
-  for (int i = 0; i < range; i++) {
-    __ jmp(case_targets[i]);
+  GenerateFastCaseSwitchCases(node, case_labels, start_frame);
+
+  // If there was a default case, we need to emit the code to match
+  // it.

[Lasse Reichstein, 2009/02/24 11:55:06]

This comment should be more descriptive.

[Kevin Millikin (Chromium), 2009/02/24 12:33:19]

Descriptified.

+  if (default_label != NULL) {
+    node->break_target()->Jump();
+    setup_default.Bind();
+    frame_->MergeTo(start_frame);
+    __ b(default_label);
+    DeleteFrame();
   }
-  GenerateFastCaseSwitchCases(node, case_labels, start_frame);
+  node->break_target()->Bind();
+
   delete start_frame;
 }
 
 
 void CodeGenerator::VisitSwitchStatement(SwitchStatement* node) {
 #ifdef DEBUG
   int original_height = frame_->height();
 #endif
   VirtualFrame::SpilledScope spilled_scope(this);
   Comment cmnt(masm_, "[ SwitchStatement");
@@ skipping 3536 matching lines @@
   __ mov(r2, Operand(0));
   __ GetBuiltinEntry(r3, Builtins::CALL_NON_FUNCTION);
   __ Jump(Handle<Code>(Builtins::builtin(Builtins::ArgumentsAdaptorTrampoline)),
           RelocInfo::CODE_TARGET);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal