Re: [Tinycc-devel] core dump because stack overwritten

[Christian Jullien]

Yes, it's fixed now. Thanks.

There are different ways to build tcc for Windows.
I personally wrote and maintain https://sourceforge.net/projects/wintcc/

Which makes a reproducible native build on Windows with both 32/64 backend.

It requires Cygwin only for first step bootstrap with gcc.

C.

-----Original Message-----
From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=address@hidden] On 
Behalf Of Herman ten Brugge via Tinycc-devel
Sent: Wednesday, October 23, 2019 13:20
To: address@hidden; address@hidden
Cc: Herman ten Brugge
Subject: Re: [Tinycc-devel] core dump because stack overwritten

I updated the Makefile. I hope it now works on all targets.
How do I test the Windows port. I do not have any compilers installed. I 
use linux 99.999% of the time.

     Herman

On 2019-10-23 11:50, Christian Jullien wrote:
> Again I've no idea of the best patch to apply, but two remarks:
>
> * First, 106_pthread.c fails on Windows because of:
> Test: 106_pthread...
> --- 106_pthread.expect  2019-10-22 20:47:55.982574300 +0200
> +++ 106_pthread.output  2019-10-23 11:40:46.742218000 +0200
> @@ -1 +1,2 @@
> -ok
> +In file included from 106_pthread.c:2:
> +106_pthread.c:2: error: include file 'pthread.h' not found
> You should run this test only on Linux systems
>
> * Your new patch test TCC_TARGET_X86_64, how do you explain that with or 
> without this patch your test case looks to work on Windows x64 and produces 
> "42 42"?
>
>
> -----Original Message-----
> From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=address@hidden] On 
> Behalf Of Herman ten Brugge via Tinycc-devel
> Sent: Wednesday, October 23, 2019 11:23
> To: address@hidden; address@hidden
> Cc: Herman ten Brugge
> Subject: Re: [Tinycc-devel] core dump because stack overwritten
>
> How about this patch:
>
> --------------------------
> --- a/tccgen.c        2019-10-22 19:52:48.761977245 +0200
> +++ b/tccgen.c  2019-10-23 11:18:14.871290060 +0200
> @@ -2627,7 +2627,9 @@ static void gen_cvt_ftoi1(int t)
>            gfunc_call(1);
>            vpushi(0);
>            vtop->r = REG_IRET;
> +#if !defined(TCC_TARGET_X86_64) /* REG_LRET only for VT_QLONG */
>            vtop->r2 = REG_LRET;
> +#endif
>        } else {
>            gen_cvt_ftoi(t);
>        }
> --------------------------
> According to https://en.wikipedia.org/wiki/X86_calling_conventions the
> x86_64 only uses rax for 64 bits returns.
>
>       Herman
>
>
> On 2019-10-23 07:20, Christian Jullien wrote:
>> I confirm your test case fails on Linux x64. It looks your patch pay 
>> attention to PTR_SIZE == 4 (i.e. it now enters if only with 32bit processor).
>> However, w.o. the patch I can't reproduce the core dump on aarch64 Linux nor 
>> with Windows x64 which are also a 64bit processors. They both correctly 
>> display "42 42"
>> No core dumps does not mean it works, memory may be corrupted somewhere else.
>>
>> Either your patch is only required for Linux x64 or there is something to 
>> investigate more carefully.
>>
>> I can only test on different platforms but I'm unable to give you further 
>> advices.
>>
>> M2c
>>
>> C.
>>
>> -----Original Message-----
>> From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=address@hidden] On 
>> Behalf Of Herman ten Brugge via Tinycc-devel
>> Sent: Tuesday, October 22, 2019 22:15
>> To: address@hidden
>> Cc: Herman ten Brugge
>> Subject: [Tinycc-devel] core dump because stack overwritten
>>
>> I have a small testcase:
>>
>> --------------
>> #include <stdio.h>
>> #include <stdlib.h>
>> #include <inttypes.h>
>>
>> int
>> main(void)
>> {
>>      struct tst_struct { uint64_t cnt; } *tst =
>>        (struct tst_struct *) malloc (sizeof (struct tst_struct));
>>
>>      tst->cnt = 42;
>>      printf ("%" PRIu64 " %" PRIu64 "\n", tst->cnt, (uint64_t) (tst->cnt /
>> 1.0));
>>      return 0;
>> }
>> ----------------
>> when I compile this with tcc and run it I get a core dump. The problem
>> is that the stack is overwritten.
>> I have a fix.
>>
>> ------------------------
>> --- a/tccgen.c  2019-10-22 19:52:48.761977245 +0200
>> +++ b/tccgen.c  2019-10-22 22:08:08.465825842 +0200
>> @@ -1203,7 +1203,7 @@ ST_FUNC void save_reg_upstack(int r, int
>>                     }
>>     #endif
>>                     /* special long long case */
>> -                if ((p->r2 & VT_VALMASK) < VT_CONST) {
>> +                if (PTR_SIZE == 4 && (p->r2 & VT_VALMASK) < VT_CONST) {
>>                         sv.c.i += PTR_SIZE;
>>                         store(p->r2, &sv);
>>                     }
>> ---------------------
>> But am not sure if this is the correct fix. The code generator is quite
>> complex.
>>
>>        Herman
>>
>>
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>
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