Remove the redundant flags is_bound_ and is_linked_ from the

JumpTarget class in favor of using other internal state.

Review URL: http://codereview.chromium.org/113456

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1966 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/jump-target-arm.cc

@@ -62,8 +62,6 @@ void JumpTarget::DoJump() {
     cgen_->SetFrame(NULL, &empty);
     __ jmp(&merge_labels_.last());
   }
-
-  is_linked_ = !is_bound_;
 }
 
 
@@ -124,7 +122,6 @@ void JumpTarget::DoBranch(Condition cc, Hint ignored) {
     // the merge code is emitted.
     AddReachingFrame(new VirtualFrame(cgen_->frame()));
     __ b(cc, &merge_labels_.last());
-    is_linked_ = true;
   }
 }
 
@@ -149,8 +146,6 @@ void JumpTarget::Call() {
   ASSERT(entry_frame_ == NULL);
   AddReachingFrame(target_frame);
   __ bl(&merge_labels_.last());
-
-  is_linked_ = !is_bound_;
 }
 
 
@@ -175,8 +170,7 @@ void JumpTarget::DoBind(int mergable_elements) {
         frame->stack_pointer_ -= difference;
         __ add(sp, sp, Operand(difference * kPointerSize));
       }
-
-      is_bound_ = true;
+      __ bind(&entry_label_);
       return;
     }
 
@@ -199,9 +193,7 @@ void JumpTarget::DoBind(int mergable_elements) {
         frame->stack_pointer_ -= difference;
         __ add(sp, sp, Operand(difference * kPointerSize));
       }
-
-      is_linked_ = false;
-      is_bound_ = true;
+      __ bind(&entry_label_);
       return;
     }
   }
@@ -298,10 +290,6 @@ void JumpTarget::DoBind(int mergable_elements) {
       cgen_->SetFrame(new VirtualFrame(entry_frame_), &reserved_registers);
     }
 
-    // There is certainly a current frame equal to the entry frame.
-    // Bind the entry frame label.
-    __ bind(&entry_label_);
-
     // There may be unprocessed reaching frames that did not need
     // merge code.  They will have unbound merge labels.  Bind their
     // merge labels to be the same as the entry label and deallocate
@@ -328,11 +316,9 @@ void JumpTarget::DoBind(int mergable_elements) {
     cgen_->SetFrame(new VirtualFrame(reaching_frames_[0]), &reserved);
     __ bind(&merge_labels_[0]);
     cgen_->frame()->MergeTo(entry_frame_);
-    __ bind(&entry_label_);
   }
 
-  is_linked_ = false;
-  is_bound_ = true;
+  __ bind(&entry_label_);
 }
 
 #undef __

src/ia32/jump-target-ia32.cc

@@ -65,8 +65,6 @@ void JumpTarget::DoJump() {
     cgen_->SetFrame(NULL, &empty);
     __ jmp(&merge_labels_.last());
   }
-
-  is_linked_ = !is_bound_;
 }
 
 
@@ -123,18 +121,20 @@ void JumpTarget::DoBranch(Condition cc, Hint hint) {
     // Forward branch with a preconfigured entry frame.  Assert the
     // current frame matches the expected one and branch to the block.
     ASSERT(cgen_->frame()->Equals(entry_frame_));
-    // Use masm_-> instead of __ as forward branches are expected to
-    // be a fixed size (no inserted coverage-checking instructions
-    // please).  This is used in Reference::GetValue.
+    // Explicitly use the macro assembler instead of __ as forward
+    // branches are expected to be a fixed size (no inserted
+    // coverage-checking instructions please).  This is used in
+    // Reference::GetValue.
     masm_->j(cc, &entry_label_, hint);
-    is_linked_ = true;
 
   } else {
     // Forward branch.  A copy of the current frame is remembered and
-    // a branch to the merge code is emitted.
+    // a branch to the merge code is emitted.  Explicitly use the
+    // macro assembler instead of __ as forward branches are expected
+    // to be a fixed size (no inserted coverage-checking instructions
+    // please).  This is used in Reference::GetValue.
     AddReachingFrame(new VirtualFrame(cgen_->frame()));
     masm_->j(cc, &merge_labels_.last(), hint);
-    is_linked_ = true;
   }
 }
 
@@ -159,8 +159,6 @@ void JumpTarget::Call() {
   ASSERT(entry_frame_ == NULL);
   AddReachingFrame(target_frame);
   __ call(&merge_labels_.last());
-
-  is_linked_ = !is_bound_;
 }
 
 
@@ -190,8 +188,6 @@ void JumpTarget::DoBind(int mergable_elements) {
       entry_frame_ = NULL;
     }
     __ bind(&entry_label_);
-    is_linked_ = false;
-    is_bound_ = true;
     return;
   }
 
@@ -208,7 +204,6 @@ void JumpTarget::DoBind(int mergable_elements) {
         frame->stack_pointer_ -= difference;
         __ add(Operand(esp), Immediate(difference * kPointerSize));
       }
-
     } else {
       ASSERT(direction_ == BIDIRECTIONAL);
       // Fast case: no forward jumps, possible backward ones.  Remove
@@ -216,9 +211,8 @@ void JumpTarget::DoBind(int mergable_elements) {
       // frame and use it as the entry frame.
       cgen_->frame()->MakeMergable(mergable_elements);
       entry_frame_ = new VirtualFrame(cgen_->frame());
-      __ bind(&entry_label_);
     }
-    is_bound_ = true;
+    __ bind(&entry_label_);
     return;
   }
 
@@ -243,8 +237,7 @@ void JumpTarget::DoBind(int mergable_elements) {
       __ add(Operand(esp), Immediate(difference * kPointerSize));
     }
 
-    is_linked_ = false;
-    is_bound_ = true;
+    __ bind(&entry_label_);
     return;
   }
 
@@ -338,10 +331,6 @@ void JumpTarget::DoBind(int mergable_elements) {
       cgen_->SetFrame(new VirtualFrame(entry_frame_), &reserved_registers);
     }
 
-    // There is certainly a current frame equal to the entry frame.
-    // Bind the entry frame label.
-    __ bind(&entry_label_);
-
     // There may be unprocessed reaching frames that did not need
     // merge code.  They will have unbound merge labels.  Bind their
     // merge labels to be the same as the entry label and deallocate
@@ -368,11 +357,9 @@ void JumpTarget::DoBind(int mergable_elements) {
     cgen_->SetFrame(new VirtualFrame(reaching_frames_[0]), &reserved);
     __ bind(&merge_labels_[0]);
     cgen_->frame()->MergeTo(entry_frame_);
-    __ bind(&entry_label_);
   }
 
-  is_linked_ = false;
-  is_bound_ = true;
+  __ bind(&entry_label_);
 }
 
 #undef __

src/jump-target.cc

@@ -42,8 +42,6 @@ bool JumpTarget::compiling_deferred_code_ = false;
 JumpTarget::JumpTarget(CodeGenerator* cgen, Directionality direction)
     : cgen_(cgen),
       direction_(direction),
-      is_bound_(false),
-      is_linked_(false),
       reaching_frames_(0),
       merge_labels_(0),
       entry_frame_(NULL) {
@@ -56,8 +54,6 @@ JumpTarget::JumpTarget()
     : cgen_(NULL),
       masm_(NULL),
       direction_(FORWARD_ONLY),
-      is_bound_(false),
-      is_linked_(false),
       reaching_frames_(0),
       merge_labels_(0),
       entry_frame_(NULL) {
@@ -78,8 +74,6 @@ void JumpTarget::Unuse() {
   merge_labels_.Clear();
   entry_frame_ = NULL;
   entry_label_.Unuse();
-  is_bound_ = false;
-  is_linked_ = false;
 }
 
 
@@ -547,8 +541,6 @@ void BreakTarget::CopyTo(BreakTarget* destination) {
   }
   destination->entry_frame_ = entry_frame_;
   destination->entry_label_ = entry_label_;
-  destination->is_bound_ = is_bound_;
-  destination->is_linked_ = is_linked_;
   destination->expected_height_ = expected_height_;
 }
 

src/jump-target.h

@@ -90,9 +90,14 @@ class JumpTarget : public ZoneObject {  // Shadows are dynamically allocated.
   }
 
   // Predicates testing the state of the encapsulated label.
-  bool is_bound() const { return is_bound_; }
-  bool is_linked() const { return is_linked_; }
-  bool is_unused() const { return !is_bound() && !is_linked(); }
+  bool is_bound() const { return entry_label_.is_bound(); }
+  bool is_linked() const {
+    return !is_bound() && !reaching_frames_.is_empty();
+  }
+  bool is_unused() const {
+    // This is !is_bound() && !is_linked().
+    return !is_bound() && reaching_frames_.is_empty();
+  }
 
   // Emit a jump to the target.  There must be a current frame at the
   // jump and there will be no current frame after the jump.
@@ -167,12 +172,6 @@ class JumpTarget : public ZoneObject {  // Shadows are dynamically allocated.
   // Directionality flag set at initialization time.
   Directionality direction_;
 
-  // A target is bound if its Bind member function has been called.
-  // It is linked if it is not bound but its Jump, Branch, or Call
-  // member functions have been called.
-  bool is_bound_;
-  bool is_linked_;
-
   // A list of frames reaching this block via forward jumps.
   ZoneList<VirtualFrame*> reaching_frames_;