[Info-vax] VMS x86-64 compilers

[Mark Daniel]

On 17/11/2023 06:20, Dan Cross wrote:
> In article <Hcu5N.206704$OPFb.159654 at fx15.ams4>,
> Mark Daniel  <mark.daniel at wasd.vsm.com.au> wrote:
>> On 17/11/2023 06:03, Dan Cross wrote:
>>> In article <m6u5N.135963$96D1.86705 at fx04.ams4>,
>>> Mark Daniel  <mark.daniel at wasd.vsm.com.au> wrote:
>>>> On 17/11/2023 05:50, Dan Cross wrote:
>>>>> In article <qdt5N.129064$ydda.38102 at fx13.ams4>,
>>>>> Mark Daniel  <mark.daniel at wasd.vsm.com.au> wrote:
>>>>>> On 16/11/2023 22:52, Arne Vajhøj wrote:
>>>>>>> Looks like new versions of C, Pascal and Fortran has just been released.
>>>>>>>
>>>>>>> Arne
>>>>>>
>>>>>> $ X86VMS$ cc/version
>>>>>> VSI C x86-64 X7.4-843 (GEM 50XB9) on OpenVMS x86_64 V9.2-1
>>>>>> $ CC /DECC /STAND=RELAXED_ANSI /PREFIX=ALL /NAMES=AS_IS /OPTIMIZE
>>>>>> /NODEBUG /WARNING=(NOINFORM,DISABLE=(PREOPTW)) /FLOAT=IEEE /IEEE=DENORM
>>>>>> /DEFINE(WASD_VMS_V7,SESOLA,WATCH_CAT=1,WATCH_MOD=0,WASD_ACME=1,WASD_GETSPI=1)
>>>>>> /OBJ=[.obj_X86_64]Error    Error.c
>>>>>> LLVM ERROR: Cannot encode high byte register in REX-prefixed instruction
>>>>>>
>>>>>> https://forum.vmssoftware.com/viewtopic.php?f=12&t=8900
>>>>>
>>>>> What's in `Error.c`?  It's neither here nor on the VSI forum.
>>>>
>>>> I have not bothered to isolate a simple reproducer in anticipation of a
>>>> Reagan-esque, "oh that means...", or "I'll add that to the list".  :-)
>>>>
>>>> https://wasd.vsm.com.au/wasd_root/src/httpd/error.c
>>>>
>>>> The error is reported across multiple modules and so relates to a common
>>>> header file construct or repeated code construct used individually.
>>>
>>> I see.  That program is, of course, somewhat long for a simple
>>> reproduction.  Out of curiousity, do you get a similar error
>>> with something very simple, like "Hello, World?"
>>
>> No.  And surely the product validation team would have the equivalent
>> test case in its suite ;-)
> 
> Well that's good, at least!  The error message means that the
> program is trying to store to one of the "high" "byte" registers
> (AH, BH, CH, DH) with a REX-prefixed instruction; I don't know,
> but this is almost certainly a MOV that requires a REX prefix
> for access to the source operand: `movb (%r8), %ah` or something
> like that.  This is architecturally forbidden.

Yes.  I had that gist from early search engine hits.

> Why is it doing that?  I'd imagine inline assembler would be the
> most likely culprit, but I'm guessing there.  I wonder if you
> can get the compiler to emit an assembler listing?

Excellent suggestion but unfortunately no.  The compile must quit very 
early.  The object file has zero content precluding 
ANA/OBJECT/DISASSEMBLE and while CC/LIST/MACHINE seems to be working 
with this release the .LIS is similarly empty.

> 	- Dan C.
> 

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