* Wrong insn length attribute
@ 2002-07-19 11:10 Momchil Velikov
2002-07-19 12:14 ` Richard Earnshaw
0 siblings, 1 reply; 2+ messages in thread
From: Momchil Velikov @ 2002-07-19 11:10 UTC (permalink / raw)
To: gcc
Is there any problem if an insn has length attribute greater than the
real one?
I have a case, where during insn output, the insn pattern generated
depends (hrm ..., will depend) upon results of ``find_reg_note (insn,
REG_UNUSED, ...)'' and the generated insns have different lengths.
~velco
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Wrong insn length attribute
2002-07-19 11:10 Wrong insn length attribute Momchil Velikov
@ 2002-07-19 12:14 ` Richard Earnshaw
0 siblings, 0 replies; 2+ messages in thread
From: Richard Earnshaw @ 2002-07-19 12:14 UTC (permalink / raw)
To: Momchil Velikov; +Cc: gcc, Richard.Earnshaw
> Is there any problem if an insn has length attribute greater than the
> real one?
>
> I have a case, where during insn output, the insn pattern generated
> depends (hrm ..., will depend) upon results of ``find_reg_note (insn,
> REG_UNUSED, ...)'' and the generated insns have different lengths.
I don't think anything in the MI part of the compiler relies on insn
lengths. There are passes that will calculate insn lengths and addresses
for you if you provide that information (so that you can use branch
shortening); but in the end, only the machine-dependent code will rely on
that information.
So the answer is, if you don't rely on this information being exact, just
a worse case value, then you will not have a problem.
R.
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