Strictness in data declaration not matched in assembler?

Tyson Whitehead twhitehead at
Wed Oct 15 10:58:47 EDT 2008

On Wednesday 15 October 2008 10:48:26 you wrote:
> Strictness does not imply unboxing.
> To see why not, think about the fact that unboxing breaks sharing. By
> keeping the pointer-indirection in place, we can share even strict
> fields between related values.

I believe I realize that.  What I was wondering about was the fact that it 
seemed to think the pointer might be to a thunk (instead of constructor 
closure).  Doesn't the strictness flag mean the following assembler would work

        movq 7(%rbx),%rbx
        movq $snj_info,(%rbp)
        jmp snj_info

(which could be cleaned up further by combining it with snj_info) instead of

        movq 7(%rbx),%rbx
        movq $snj_info,(%rbp)
        testq $7,%rbx
        jne snj_info
        jmp *(%rbx)

(i.e., the whole test if it is a thunk and conditionally evaluate it bit is 
unnecessary due to constructor the strictness flag).

Cheers!  -Tyson

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