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List:       netbsd-tech-toolchain
Subject:    Re: PCC LP64 compiler_rt ((mode (TI))) woe
From:       Anders Magnusson <ragge () ludd ! ltu ! se>
Date:       2016-04-02 9:10:01
Message-ID: 56FF8C69.3040002 () ludd ! ltu ! se
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Den 2016-04-02 kl. 03:26, skrev Toru Nishimura:
> Hi, list,
>
> I found PCC can not compile a piece of code.  In specific,
> it's GCC attribute ((mode (TI))) large size integer designation.
>
> The offending file is
> src/sys/external/bsd/compiler_rt/dist/lib/builtins/int_types.h
>
> #if __LP64__
> #define CRT_HAS_128BIT
> #endif
>
> #ifdef CRT_HAS_128BIT
> typedef int      ti_int __attribute__ ((mode (TI)));
> typedef unsigned tu_int __attribute__ ((mode (TI)));
>
> PCC has mode (TI) logic which is braced out with #ifdef and
> that part is not enabled probably due to the lack of code
> generator support.
>
I took a quick look at the TImode for pcc some time ago, and the
#ifdef TARGET_TIMODE  is the result of that.  This is a trivial
implementation and therefore very inefficient (and not well tested).

Currently it just allocates space on stack for variables (handling as a 
struct)
and calls the TI functions for evaluating expressions. Only tested on x86.

Doing a "correct" implementation would require much more work and since
it is a special non-standard case that is almost never used I have not spent
any time on it.

I just tested and at least it generated some code.  It might be a reason to
turn it on just to be able to compile compiler_rt, but it probably would 
be good
if someone checked the correctness of the generated code first.

-- Ragge

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