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Re: GNU Guile 2.1.6 released (beta) [numbers.c]

From: Amirouche
Subject: Re: GNU Guile 2.1.6 released (beta) [numbers.c]
Date: Fri, 20 Jan 2017 20:15:07 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1

Le 20/01/2017 à 20:01, Matt Wette a écrit :

On Jan 19, 2017, at 7:01 PM, Matt Wette <address@hidden> wrote:

On Jan 18, 2017, at 6:26 PM, Andy Wingo <address@hidden> wrote:

We are pleased to announce GNU Guile release 2.1.6.

Guile 2.1.6 is the sixth pre-release in what will eventually become the
2.2 release series.  We encourage you to test this release and provide
feedback to address@hidden.

Saw this one last round.  Mac OS, now gcc-6.3.0:

;;; ("address@hidden" 1.0 -0.0)
FAIL: numbers.test: string->number: valid complex number strings

I am going to see if I can generate the assembly.

Short story: scm_c_make_polar is broken for the Mac.  Guile needs to decide if it want to use __sincos() on Mac, or suppress optimization, or ...

I was able to get the above to work (guile-2.1.5) by using
+#ifdef __APPLE__
 scm_c_make_polar (double mag, double ang)

In scm_c_make_polar, “gcc -O2”  turns sin(), cos() into cexp(), since cexp(i*x) = cos(x) + i*sin(x):

gcc -O0 =>
movq -32(%rbp), %rax
movd %rax, %xmm0
call _sin
movd %xmm0, %rax
movq %rax, -8(%rbp)
movq -32(%rbp), %rax
movd %rax, %xmm0
call _cos
movd %xmm0, %rax
movq %rax, -16(%rbp)

gcc -O2 =>
pxor %xmm0, %xmm0
call _cexp

I wrote a little C program to show that cexp() does not preserve the zero-signed-ness:

 cos,sin: +1.000000 -0.000000
__sincos: +1.000000 -0.000000
    cexp: +1.000000 +0.000000

The scm_c_make_polar will use sincos() if available, but macOS does not have sincos(), it has __sincos().

#include <stdio.h>
#include <stdint.h>
#include <math.h>
#include <complex.h>

extern double z, p, n;

int main() {
  double complex c;
  double d, sine, cosine;

  d = z*n;
  printf(" cos,sin: %+f %+f\n", cos(d), sin(d));
  __sincos(d, &sine, &cosine);
  printf("__sincos: %+f %+f\n", cosine, sine);
  c = cexp(CMPLX(0.0, d));
  printf("    cexp: %+f %+f\n", creal(c), cimag(c));

double z = 0.0, p = +1.0, n = -1.0;

Incidentally, the above program will not compile on my machine w/ gcc-6.3.0.  “gcc -std=c11” or “gcc -std=c99” will not recognize the standard macro CMPLX().


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