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Re: PA casesi questions
- To: grahams at rcp dot co dot uk
- Subject: Re: PA casesi questions
- From: John Wehle <john at feith dot com>
- Date: Thu, 6 Jan 2000 17:26:19 -0500 (EST)
- CC: gcc at gcc dot gnu dot org
> Are you handling the scenario where the variable is volatile?
I only track ranges associated with pseudo registers. Can a
pseudo register be volatile? How's that indicated in the RTL?
> Obviously value range propagation can't be used on volatile variables.
Yes and no. The min. and max. values can always be determined from
the mode used when accessing the variable.
> In you example if a is volatile you know nothing about the value of a
> when control reaches the switch.
If "a" is QImode then you know the possible bits patterns are from 0x00
through 0xff.
-- John
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