Andrew Pinski wrote:
> On Fri, Oct 10, 2008 at 11:14 AM, Andrew Haley <[EMAIL PROTECTED]> wrote:
>> Richard Guenther wrote:
>>> On Fri, Oct 10, 2008 at 7:55 PM, Andrew Haley <[EMAIL PROTECTED]> 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")
>
> Well the mem has a /u on it so it is being marked as MEM_READONLY_P so
> it is valid optimization. Why it is being marked with MEM_READONLY_P,
> I don't know.
I've found the code that's incorrectly marking the decl as TREE_READONLY.
It's here:
/* If the variable is never written, we can set the TREE_READONLY
flag. Additionally if it has a DECL_INITIAL that is made up of
constants we can treat the entire global as a constant. */
bitmap_and_compl (module_statics_readonly, all_module_statics,
module_statics_written);
EXECUTE_IF_SET_IN_BITMAP (module_statics_readonly, 0, index, bi)
{
tree var = get_static_decl (index);
/* Ignore variables in named sections - changing TREE_READONLY
changes the section flags, potentially causing conflicts with
other variables in the same named section. */
if (DECL_SECTION_NAME (var) == NULL_TREE)
{
TREE_READONLY (var) = 1;
The decl (called _CD_ppp) is not written by the code we generate, that's true.
However, there is a global struct class$, which contains a field which points to
_CD_ppp:
ppp::class$:
.quad vtable for java::lang::Class+16
.quad 1074145824
.quad _Utf6
.value 33
.zero 6
.quad java::lang::Object::class$
.long 2
.zero 4
.quad _CT_ppp
.quad _CD_ppp
...
.type _CD_ppp, @object
.size _CD_ppp, 16
_CD_ppp:
.quad 0
.quad _Utf5
I would expect that this would mean that _CD_ppp has its address taken, and
therefore should not be marked as TREE_READONLY.
Andrew.
