Bug #3723: Remove unused control frame variable: rb_control_frame_t.block_iseq

• Status: Rejected
• Assignee: ko1 (Koichi Sasada)
• Target version: 2.0.0
• ruby -v: ruby 1.9.3dev (2010-08-19 trunk 29056) [i386-mswin32_100]

[pweldon (Peter Weldon)]

=begin
rb_control_frame_t.block_iseq does not appear to serve any purpose and can possibly be removed.
=end

[naruse (Yui NARUSE)]

• Status changed from Open to Assigned
• Assignee set to ko1 (Koichi Sasada)

=begin
As you said, it seems useless variable.

But if block_iseq of rb_control_frame_t is simply removed, it breaks ABI compatibility.

I assign this to ko1.
=end

[naruse (Yui NARUSE)]

• Status changed from Assigned to Rejected

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I talked this with ko1.
It is used from rb_block_t.iseq, so it can't be removed.
=end

[pweldon (Peter Weldon)]

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I apologise, I did not understand the connection between rb_control_frame_t and rb_block_t. I see now that these macros are used to access rb_control_frame_t members via a rb_block_t:

vm_core.h:
#define RUBY_VM_GET_BLOCK_PTR_IN_CFP(cfp) ((rb_block_t *)(&(cfp)->self))
#define RUBY_VM_GET_CFP_FROM_BLOCK_PTR(b)
((rb_control_frame_t *)((VALUE *)(b) - 5))

The rb_control_frame_t comments in vm_core.h now also make sense to me. Thank you for helping me understand.

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