Add pass to remove empty blocks and recompute fall-through targets.

runtime/vm/intermediate_language_ia32.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 714 matching lines @@
     default:
       break;
   }
   ASSERT(hi_cond != OVERFLOW && lo_cond != OVERFLOW);
   Label is_true, is_false;
   // Compare upper halves first.
   __ pextrd(left_tmp, left, Immediate(1));
   __ pextrd(right_tmp, right, Immediate(1));
   __ cmpl(left_tmp, right_tmp);
   if (branch != NULL) {
-    __ j(hi_cond, compiler->GetBlockLabel(branch->true_successor()));
+    __ j(hi_cond, compiler->GetJumpLabel(branch->true_successor()));
     __ j(FlowGraphCompiler::FlipCondition(hi_cond),
-         compiler->GetBlockLabel(branch->false_successor()));
+         compiler->GetJumpLabel(branch->false_successor()));
   } else {
     __ j(hi_cond, &is_true);
     __ j(FlowGraphCompiler::FlipCondition(hi_cond), &is_false);
   }
 
   // If upper is equal, compare lower half.
   __ pextrd(left_tmp, left, Immediate(0));
   __ pextrd(right_tmp, right, Immediate(0));
   __ cmpl(left_tmp, right_tmp);
   if (branch != NULL) {
@@ skipping 2538 matching lines @@
                                    GetDeoptId(),
                                    0);  // No token position.
   }
 
   if (HasParallelMove()) {
     compiler->parallel_move_resolver()->EmitNativeCode(parallel_move());
   }
 
   // We can fall through if the successor is the next block in the list.
   // Otherwise, we need a jump.
-  if (!compiler->IsNextBlock(successor())) {
-    __ jmp(compiler->GetBlockLabel(successor()));
+  if (!compiler->CanFallThroughTo(successor())) {
+    __ jmp(compiler->GetJumpLabel(successor()));
   }
 }
 
 
 static Condition NegateCondition(Condition condition) {
   switch (condition) {
     case EQUAL:         return NOT_EQUAL;
     case NOT_EQUAL:     return EQUAL;
     case LESS:          return GREATER_EQUAL;
     case LESS_EQUAL:    return GREATER;
     case GREATER:       return LESS_EQUAL;
     case GREATER_EQUAL: return LESS;
     case BELOW:         return ABOVE_EQUAL;
     case BELOW_EQUAL:   return ABOVE;
     case ABOVE:         return BELOW_EQUAL;
     case ABOVE_EQUAL:   return BELOW;
     default:
       OS::Print("Error %d\n", condition);
       UNIMPLEMENTED();
       return EQUAL;
   }
 }
 
 
 void ControlInstruction::EmitBranchOnValue(FlowGraphCompiler* compiler,
                                            bool value) {
-  if (value && compiler->IsNextBlock(false_successor())) {
-    __ jmp(compiler->GetBlockLabel(true_successor()));
-  } else if (!value && compiler->IsNextBlock(true_successor())) {
-    __ jmp(compiler->GetBlockLabel(false_successor()));
+  if (value && !compiler->CanFallThroughTo(true_successor())) {
+    __ jmp(compiler->GetJumpLabel(true_successor()));
+  } else if (!value && !compiler->CanFallThroughTo(false_successor())) {
+    __ jmp(compiler->GetJumpLabel(false_successor()));
   }
 }
 
 
 void ControlInstruction::EmitBranchOnCondition(FlowGraphCompiler* compiler,
                                                Condition true_condition) {
-  if (compiler->IsNextBlock(false_successor())) {
+  if (compiler->CanFallThroughTo(false_successor())) {
     // If the next block is the false successor we will fall through to it.
-    __ j(true_condition, compiler->GetBlockLabel(true_successor()));
+    __ j(true_condition, compiler->GetJumpLabel(true_successor()));
   } else {
     // If the next block is the true successor we negate comparison and fall
     // through to it.
-    ASSERT(compiler->IsNextBlock(true_successor()));
     Condition false_condition = NegateCondition(true_condition);
-    __ j(false_condition, compiler->GetBlockLabel(false_successor()));
+    __ j(false_condition, compiler->GetJumpLabel(false_successor()));
+
+    // Fall through or jump to the true successor.
+    if (!compiler->CanFallThroughTo(true_successor())) {
+      __ jmp(compiler->GetJumpLabel(true_successor()));
+    }
   }
 }
 
 
 LocationSummary* CurrentContextInstr::MakeLocationSummary() const {
   return LocationSummary::Make(0,
                                Location::RequiresRegister(),
                                LocationSummary::kNoCall);
 }
 
@@ skipping 202 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_IA32