Begin forwarded message:
> From: Peter Teeson <ptee...@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 <l...@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
