[debbugs-tracker] bug#13386: closed (Fwd: bug#13342: Errors trying to bu

Begin forwarded message:

From: Peter Teeson <address@hidden>
Subject: Re: bug#13342: Errors trying to build Guile 2.0.7
Date: 7 January, 2013 8:21:59 PM EST
To: Ludovic Courtès <address@hidden>

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

From:	GNU bug Tracking System
Subject:	[debbugs-tracker] bug#13386: closed (Fwd: bug#13342: Errors trying to build Guile 2.0.7)
Date:	Wed, 30 Jan 2013 21:38:03 +0000