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From: Bo Persson <bo@bo-persson.se>
Newsgroups: comp.lang.c++
Subject: Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ?
Date: Wed, 1 Sep 2021 10:05:53 +0200
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Xref: csiph.com comp.lang.c++:80946

On 2021-09-01 at 08:55, Christian Gollwitzer wrote:
> Am 01.09.21 um 08:43 schrieb Bonita Montero:
>> Am 01.09.2021 um 08:34 schrieb Christian Gollwitzer:
>>> Am 01.09.21 um 08:03 schrieb Bonita Montero:
>>>> Am 01.09.2021 um 07:41 schrieb Christian Gollwitzer:
>>>>> Am 01.09.21 um 07:26 schrieb Bonita Montero:
>>>>>> Am 01.09.2021 um 06:42 schrieb Juha Nieminen:
>>>>>>> Bonita Montero <Bonita.Montero@gmail.com> wrote:
>>>>>>>> Am 29.08.2021 um 20:57 schrieb Alf P. Steinbach:
>>>>>>>>> Are there any examples of current platforms/architectures where
>>>>>>>>> sizeof(void*) > sizeof(int*) ?
>>>>>>>>
>>>>>>>> Why should there be such an architecture ?
>>>>>>>> On such an architecture you won't be able
>>>>>>>> to cast the result of malloc() to an int *
>>>>>>>
>>>>>>> Why not? If void* is larger than int*, why couldn't you cast a
>>>>>>> void* to an int*?
>>>>>>
>>>>>> Because it would drop information and f.e. you won't be able to
>>>>>> access the int-arrray behind the int *.
>>>>>>
>>>>>
>>>>> I think you misunderstand how that works. The int pointer would not 
>>>>> count in bytes, but in ints. So if you do ptr++, then it would 
>>>>> actually increase by 1 - not by 4 or 8 as it does on the usual 
>>>>> platforms, where there is no difference between int*, char*, void* 
>>>>> on the machine code level.
>>>>
>>>> Name an architecture of the last three decades that behaves like that.
>>>
>>> You are repeating Alf's original question. Read the whole thread for 
>>> an answer.
>>
>> You have too much phantasy. You're ideas would make the design of a
>> CPU more complex - without any benefit.
> 
> On the contrary. It makes the hardware design simpler. You can address 
> more memory with a smaller number of bits in the registers. For 
> non-aligned addresses, you need to load two words and then assemble them 
> back with shifts etc. Modern Intel-like CPUs do this in hardware, but it 
> is still slower than aligned access, earlier machines simply had no way 
> to do this.
> 

The 8088 in the original IBM PC had an 8-bit external data bus, so 
always loaded one byte at a time. Intel's designs are still cursed by this.