Experimental: a quick hack to allow different live values to flow down...

src/jump-target-ia32.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 54 matching lines @@
   ASSERT(cgen_ != NULL);
 
   VirtualFrame* current_frame = cgen_->frame();
   ASSERT(current_frame != NULL);
   ASSERT(cgen_->HasValidEntryRegisters());
 
   if (expected_frame_ == NULL) {
     current_frame->MakeMergable();
     expected_frame_ = current_frame;
     ASSERT(cgen_->HasValidEntryRegisters());
-    cgen_->SetFrame(NULL);
+    RegisterFile ignored;
+    cgen_->SetFrame(NULL, &ignored);
   } else {
     current_frame->MergeTo(expected_frame_);
     ASSERT(cgen_->HasValidEntryRegisters());
     cgen_->DeleteFrame();
   }
 
   __ jmp(&label_);
   // Postcondition: there is no current frame but there is an expected frame
   // at the label.
 }
 
 
 void JumpTarget::Jump(Result* arg) {
   ASSERT(cgen_ != NULL);
   ASSERT(cgen_->has_valid_frame());
 
   cgen_->frame()->Push(arg);
   Jump();
 }
 
 
 void JumpTarget::Branch(Condition cc, Hint hint) {
   // Precondition: there is a current frame.  There may or may not be an
   // expected frame at the label.
   ASSERT(cgen_ != NULL);
   ASSERT(masm_ != NULL);
 
   VirtualFrame* current_frame = cgen_->frame();
   ASSERT(current_frame != NULL);
-  ASSERT(cgen_->HasValidEntryRegisters());
 
   if (expected_frame_ == NULL) {
     expected_frame_ = new VirtualFrame(current_frame);
     // For a branch, the frame at the fall-through basic block (not labeled)
     // does not need to be mergable, but only the other (labeled) one.  That
     // is achieved by reversing the condition and emitting the make mergable
     // code as the actual fall-through block.  This is necessary only when
     // MakeMergable will generate code.
     if (expected_frame_->RequiresMergeCode()) {
       Label original_fall_through;
       __ j(NegateCondition(cc), &original_fall_through, NegateHint(hint));
       expected_frame_->MakeMergable();
       __ jmp(&label_);
       __ bind(&original_fall_through);
     } else {
       expected_frame_->MakeMergable();
       ASSERT(cgen_->HasValidEntryRegisters());
       __ j(cc, &label_, hint);
     }
   } else {
     // We negate the condition and emit the code to merge to the expected
     // frame immediately.
     //
     // TODO(): This should be replaced with a solution that emits the
     // merge code for forward CFG edges at the appropriate entry to the
     // target block.
     Label original_fall_through;
     __ j(NegateCondition(cc), &original_fall_through, NegateHint(hint));
     VirtualFrame* working_frame = new VirtualFrame(current_frame);
-    cgen_->SetFrame(working_frame);
+
+    // Switch to the working frame for the merge code with only the reserved
+    // registers referenced outside the frame.  Explicitly setting
+    // references here is ugly, but temporary.
+    RegisterFile non_frame_registers;
+    non_frame_registers.Use(esi);
+    non_frame_registers.Use(ebp);
+    non_frame_registers.Use(esp);
+    cgen_->SetFrame(working_frame, &non_frame_registers);
+
     working_frame->MergeTo(expected_frame_);
     ASSERT(cgen_->HasValidEntryRegisters());
     __ jmp(&label_);
-    cgen_->SetFrame(current_frame);
+
+    // Restore the current frame and its associated non-frame registers.
+    cgen_->SetFrame(current_frame, &non_frame_registers);
     delete working_frame;
     __ bind(&original_fall_through);
   }
   // Postcondition: there is both a current frame and an expected frame at
   // the label and they match.
 }
 
 
 void JumpTarget::Branch(Condition cc, Result* arg, Hint hint) {
   ASSERT(cgen_ != NULL);
@@ skipping 77 matching lines @@
   ASSERT(!label_.is_bound());
 
   if (expected_frame_ == NULL) {
     ASSERT(cgen_->HasValidEntryRegisters());
     // When a label is bound the current frame becomes the expected frame at
     // the label.  This requires the current frame to be mergable.
     current_frame->MakeMergable();
     ASSERT(cgen_->HasValidEntryRegisters());
     expected_frame_ = new VirtualFrame(current_frame);
   } else if (current_frame == NULL) {
-    cgen_->SetFrame(new VirtualFrame(expected_frame_));
+    // Pick up the frame from the label.  No merge code is necessary.
+    // Manually setting the reserved register reference counts is clumsy but
+    // temporary.
+    RegisterFile non_frame_registers;
+    non_frame_registers.Use(esi);
+    non_frame_registers.Use(ebp);
+    non_frame_registers.Use(esp);
+    cgen_->SetFrame(new VirtualFrame(expected_frame_), &non_frame_registers);
     ASSERT(cgen_->HasValidEntryRegisters());
   } else {
     ASSERT(cgen_->HasValidEntryRegisters());
     current_frame->MergeTo(expected_frame_);
     ASSERT(cgen_->HasValidEntryRegisters());
   }
 
   __ bind(&label_);
   // Postcondition: there is both a current frame and an expected frame at
   // the label and they match.  The label is bound.
@@ skipping 98 matching lines @@
 
 #ifdef DEBUG
   is_shadowing_ = false;
 #endif
 }
 
 #undef __
 
 
 } }  // namespace v8::internal