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Re: gcc moving memory reference across call
Richard Guenther wrote:
> On Fri, Oct 10, 2008 at 7:55 PM, Andrew Haley <aph@redhat.com> wrote:
>> I have some broken code, compiled from Java source.
>>
>> It looks like:
>>
>> D.843 = &java.text.Collator.class$$;
>> _Jv_InitClass (D.843);
>> D.845 = &_CD_java_text_Collator;
>>
>> is being turned into:
>>
>> D.843 = &java.text.Collator.class$$;
>> D.845 = &_CD_java_text_Collator;
>> _Jv_InitClass (D.843);
>
> This is always a valid transformation.
>
>> i.e. the memory reference is moved to before the call to _Jv_InitClass.
>
> There is no memory reference in the above case, it seems just the address
> of _CD_java_text_Collator is taken.
>
> Or maybe I'm missing sth?
In the RTL code it moves the mem ref, not just the address:
(call (mem:QI (symbol_ref:DI ("_Jv_InitClass") [flags 0x41]
(set (reg/f:DI 95 [ #ref#8#1 ])
(mem/s/u/f/j:DI (const:DI (plus:DI (symbol_ref:DI ("_CD_java_text_Collator")
(const_int 16 [0x10])))
is turned to:
(set (reg/f:DI 162 [ #ref#8#1 ])
(mem/s/u/f/j:DI (const:DI (plus:DI (symbol_ref:DI ("_CD_java_text_Collator")
(const_int 16 [0x10])))
...
(call (mem:QI (symbol_ref:DI ("_Jv_InitClass")
Andrew.