Re: [PATCH 1/2] simplify-rtx: The truncation of an IOR can have all bits set (PR81423)

[Mike Stump <mikestump at comcast dot net>]

On Jul 25, 2017, at 3:10 PM, Segher Boessenkool <segher@kernel.crashing.org> wrote:
> 
> On Tue, Jul 25, 2017 at 12:30:13PM +0100, Kyrill Tkachov wrote:
>> We sometimes use the __mode__ attribute to force certain sizes in C types.
>> For example: typedef int ditype __attribute__ ((mode (DI)));
>> Maybe you can do this to force the right sizes. I don't know if there are 
>> any targets
>> that don't support DImode ops though :)
> 
> DImode isn't necessarily the same size on all targets, a byte isn't
> always eight bits.

As a practical matter, presently a byte is always eight bits and a DI is always 8 bytes in gcc.  :-)

Pretending otherwise is a fool's errand.  We like to kid ourselves that a character isn't always 8 bits, but the first person to want to do that will discover the lie it is.

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