Begin forwarded message:

> From: Peter Teeson <pteeson@me.com>
> Subject: Re: bug#13342: Errors trying to build Guile 2.0.7
> Date: 7 January, 2013 8:21:59 PM EST
> To: Ludovic Courtès <ludo@gnu.org>
> 
> Hi Ludo:
> 
> On 2013-01-04, at 12:23 PM, Ludovic Courtès wrote:
>>>>> bad return from expression `(f-sum -1 2000 -30000 40000000000)': expected 39999971999; got 39999972255
>>>>> FAIL: test-ffi
>>>> 
>>>> This is a known issue when building Guile with LLVM/Clang:
>>>> 
>>>> http://bugs.gnu.org/10015
>>>> http://bugs.gnu.org/10681
>>>> 
>>>> It would be great if you could investigate.
> 
> Here is the result of my investigation - do you agree?
> My hypothesis is that the scheme interpreter is not calculating the sum correctly based on the following:
> 
> (0) First observe this
> "In Apple's version of GCC, both cc and gcc are actually symbolic links to the llvm-gcc compiler.  Similarly, c++ and g++ are links to llvm-g++."
> 
> (1) Also we note that 39999972255 - 39999971999 = 256!
> 
> (2) This program
> //
> //  main.c
> //  testffi
> //
> //  Created by Peter Teeson on 13-01-07.
> //  Copyright (c) 2013 PHT Software. All rights reserved.
> //
> 
> #include <stdio.h>
> #include <inttypes.h>
> 
> int64_t test_ffi_sum (int8_t a, int16_t b,
>                           int32_t c, int64_t d);
> int64_t test_ffi_sum (int8_t a, int16_t b,
>                       int32_t c, int64_t d)
> {
>     printf("int64 d %" PRId64 " %#llX \n", d,d);
>     printf("int32 c %" PRId32 " %#X \n", c,c);
>     printf("int16 b %" PRId16 " %#X \n", b,b);
>     printf("int08 a %" PRId8 " %#X \n", a,a);
> 
>     int64_t sum = d + c + b + a;
>     printf("int64 sum %" PRId64 " %#llX \n", sum,sum);
> 
>     return sum;
> }
> int main(int argc, const char * argv[])
> {
>     test_ffi_sum(-1, 2000, -30000, 40000000000);
>     return 0;
> }
> 
> (3) produces this output
> 
> int64 d 40000000000 0X9502F9000 
> int32 c -30000 0XFFFF8AD0 
> int16 b 2000 0X7D0 
> int08 a -1 0XFFFFFFFF 
> int64 sum 39999971999 0X9502F229F 
> 
> (4) This function in  /guile-2.0.7/test-suite/standalone/test-ffi 
> ;;
> ;; Multiple int args of differing types
> ;;
> (define f-sum
>   (pointer->procedure int64 (dynamic-func "test_ffi_sum" lib)
>                       (list int8 int16 int32 int64)))
> (test (f-sum -1 2000 -30000 40000000000)
>       (+ -1 2000 -30000 40000000000))
> 
> might be the culprit and I am guessing that it is this expression
> 
> (+ -1 2000 -30000 40000000000) 
> 
> which the scheme interpreter is calculating incorrectly. Probably related to -1;
> 
> Since I am not familiar with the scheme/guile language I can't go any further than this without help.
> Let me know if I can do more.
> 
> respect…..
> 
> Peter