First step towards making JumpTarget work on ARM. Instead...

src/arm/jump-target-arm.cc

 // Copyright 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 29 matching lines @@
 
 #define __ ACCESS_MASM(cgen()->masm())
 
 void JumpTarget::DoJump() {
   ASSERT(cgen()->has_valid_frame());
   // Live non-frame registers are not allowed at unconditional jumps
   // because we have no way of invalidating the corresponding results
   // which are still live in the C++ code.
   ASSERT(cgen()->HasValidEntryRegisters());
 
-  if (is_bound()) {
-    // Backward jump.  There already a frame expectation at the target.
-    ASSERT(direction_ == BIDIRECTIONAL);
-    cgen()->frame()->MergeTo(entry_frame_);
+  if (entry_frame_set_) {
+    // There already a frame expectation at the target.
+    cgen()->frame()->MergeTo(&entry_frame_);
     cgen()->DeleteFrame();
   } else {
     // Use the current frame as the expected one at the target if necessary.

[Søren Thygesen Gjesse, 2010/05/06 07:48:11]

Use the same comment "// Clone the current frame to use as the expected one at
the target." as is used below.

-    if (entry_frame_ == NULL) {
-      entry_frame_ = cgen()->frame();
-      RegisterFile empty;
-      cgen()->SetFrame(NULL, &empty);
-    } else {
-      cgen()->frame()->MergeTo(entry_frame_);
-      cgen()->DeleteFrame();
-    }
-
-    // The predicate is_linked() should be made true.  Its implementation
-    // detects the presence of a frame pointer in the reaching_frames_ list.
-    if (!is_linked()) {
-      reaching_frames_.Add(NULL);
-      ASSERT(is_linked());
-    }
+    entry_frame_ = *cgen()->frame();

[Søren Thygesen Gjesse, 2010/05/06 07:48:11]

How about adding a function SetEntryFrame doing

  entry_frame_ = *cgen()->frame();
  entry_frame_set_ = true;

As this is done several times below?

+    entry_frame_set_ = true;
+    RegisterFile empty;
+    cgen()->SetFrame(NULL, &empty);
   }
   __ jmp(&entry_label_);
 }
 
 
 void JumpTarget::DoBranch(Condition cc, Hint ignored) {
   ASSERT(cgen()->has_valid_frame());
 
-  if (is_bound()) {
-    ASSERT(direction_ == BIDIRECTIONAL);
+  if (entry_frame_set_) {
     // Backward branch.  We have an expected frame to merge to on the
     // backward edge.
-    cgen()->frame()->MergeTo(entry_frame_);
+    if (cc == al) {
+      cgen()->frame()->MergeTo(&entry_frame_);
+    } else {
+      // We can't do conditional merges yet so you have to ensure that all
+      // conditional branches to the JumpTarget have the same virtual frame.
+      ASSERT(cgen()->frame()->Equals(&entry_frame_));
+    }
   } else {
-    // Clone the current frame to use as the expected one at the target if
-    // necessary.
-    if (entry_frame_ == NULL) {
-      entry_frame_ = new VirtualFrame(cgen()->frame());
-    }
-    // The predicate is_linked() should be made true.  Its implementation
-    // detects the presence of a frame pointer in the reaching_frames_ list.
-    if (!is_linked()) {
-      reaching_frames_.Add(NULL);
-      ASSERT(is_linked());
-    }
+    // Clone the current frame to use as the expected one at the target.
+    entry_frame_ = *cgen()->frame();
+    entry_frame_set_ = true;
   }
   __ b(cc, &entry_label_);
 }
 
 
 void JumpTarget::Call() {
   // Call is used to push the address of the catch block on the stack as
   // a return address when compiling try/catch and try/finally.  We
   // fully spill the frame before making the call.  The expected frame
   // at the label (which should be the only one) is the spilled current
   // frame plus an in-memory return address.  The "fall-through" frame
   // at the return site is the spilled current frame.
   ASSERT(cgen()->has_valid_frame());
   // There are no non-frame references across the call.
   ASSERT(cgen()->HasValidEntryRegisters());
   ASSERT(!is_linked());
 
   // Calls are always 'forward' so we use a copy of the current frame (plus
   // one for a return address) as the expected frame.
-  ASSERT(entry_frame_ == NULL);
-  VirtualFrame* target_frame = new VirtualFrame(cgen()->frame());
-  target_frame->Adjust(1);
+  ASSERT(!entry_frame_set_);
+  VirtualFrame target_frame = *cgen()->frame();
+  target_frame.Adjust(1);
   entry_frame_ = target_frame;
-
-  // The predicate is_linked() should now be made true.  Its implementation
-  // detects the presence of a frame pointer in the reaching_frames_ list.
-  reaching_frames_.Add(NULL);
-  ASSERT(is_linked());
+  entry_frame_set_ = true;
 
   __ bl(&entry_label_);
 }
 
 
 void JumpTarget::DoBind() {
   ASSERT(!is_bound());
 
   // Live non-frame registers are not allowed at the start of a basic
   // block.
   ASSERT(!cgen()->has_valid_frame() || cgen()->HasValidEntryRegisters());
 
   if (cgen()->has_valid_frame()) {
     // If there is a current frame we can use it on the fall through.
-    if (entry_frame_ == NULL) {
-      entry_frame_ = new VirtualFrame(cgen()->frame());
+    if (!entry_frame_set_) {
+      entry_frame_ = *cgen()->frame();
+      entry_frame_set_ = true;
     } else {
-      ASSERT(cgen()->frame()->Equals(entry_frame_));
+      cgen()->frame()->MergeTo(&entry_frame_);
     }
   } else {
     // If there is no current frame we must have an entry frame which we can
     // copy.
-    ASSERT(entry_frame_ != NULL);
+    ASSERT(entry_frame_set_);
     RegisterFile empty;
-    cgen()->SetFrame(new VirtualFrame(entry_frame_), &empty);
-  }
-
-  // The predicate is_linked() should be made false.  Its implementation
-  // detects the presence (or absence) of frame pointers in the
-  // reaching_frames_ list.  If we inserted a bogus frame to make
-  // is_linked() true, remove it now.
-  if (is_linked()) {
-    reaching_frames_.Clear();
+    cgen()->SetFrame(new VirtualFrame(&entry_frame_), &empty);
   }
 
   __ bind(&entry_label_);
 }
 
 
-void BreakTarget::Jump() {
-  // On ARM we do not currently emit merge code for jumps, so we need to do
-  // it explicitly here.  The only merging necessary is to drop extra
-  // statement state from the stack.
-  ASSERT(cgen()->has_valid_frame());
-  int count = cgen()->frame()->height() - expected_height_;
-  cgen()->frame()->Drop(count);
-  DoJump();
-}
-
-
-void BreakTarget::Jump(Result* arg) {
-  UNIMPLEMENTED();
-}
-
-
-void BreakTarget::Bind() {
-#ifdef DEBUG
-  // All the forward-reaching frames should have been adjusted at the
-  // jumps to this target.
-  for (int i = 0; i < reaching_frames_.length(); i++) {
-    ASSERT(reaching_frames_[i] == NULL ||
-           reaching_frames_[i]->height() == expected_height_);
-  }
-#endif
-  // Drop leftover statement state from the frame before merging, even
-  // on the fall through.  This is so we can bind the return target
-  // with state on the frame.
-  if (cgen()->has_valid_frame()) {
-    int count = cgen()->frame()->height() - expected_height_;
-    // On ARM we do not currently emit merge code at binding sites, so we need
-    // to do it explicitly here.  The only merging necessary is to drop extra
-    // statement state from the stack.
-    cgen()->frame()->Drop(count);
-  }
-
-  DoBind();
-}
-
-
-void BreakTarget::Bind(Result* arg) {
-  UNIMPLEMENTED();
-}
-
-
 #undef __
 
 
 } }  // namespace v8::internal