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Re: [patch i386]: Expand sibling-tail-calls via accumulator register

On 05/28/2014 02:54 PM, Jeff Law wrote:
> On 05/28/14 15:52, Jakub Jelinek wrote:
>> On Wed, May 28, 2014 at 05:28:31PM -0400, Kai Tietz wrote:
>>> Yes, I missed the plus-part.
>>> I am just running bootstrap with regression testing for altering predicate to:
>>> (define_predicate "sibcall_memory_operand"
>>>    (match_operand 0 "memory_operand")
>>> {
>>>    op = XEXP (op, 0);
>>>    if (GET_CODE (op) == CONST)
>>>      op = XEXP (op, 0);
>>>    if (GET_CODE (op) == PLUS && CONSTANT_P (XEXP (op, 0)))
>>>      op = XEXP (op, 1);
>> Why not get rid of all the above 4 lines and just keep:
>>>    return CONSTANT_P (op);
>> ?  CONST matches CONSTANT_P, and what is inside of CONST should be
>> fine, and (plus (symbol_ref) (const_int)) not surrounded by CONST
>> ir invalid.
> Haven't we recently had problems with being overly accepting of stuff inside
> CONST when using the CONST for address expressions.  ISTM we should only accept
> what the processor supports here.

Recall that it has just satisfied memory_operand, where all the real checks
should have been done.  I think just the CONSTANT_P check is sufficient.


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