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Date: Wed, 20 Apr 2016 23:53:27 +0200
From: "Juan Manuel Guerrero (juan DOT guerrero AT gmx DOT de) [via djgpp-workers AT delorie DOT com]" <djgpp-workers AT delorie DOT com>
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To: djgpp-workers AT delorie DOT com
Subject: Re: Test build of gcc-6.0.1-20160415
References: <5713789D DOT 8070708 AT iki DOT fi> <57152494 DOT 6040808 AT gmx DOT de> <57154DC1 DOT 2080907 AT iki DOT fi>
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Reply-To: djgpp-workers AT delorie DOT com

Am 18.04.2016 23:12, schrieb Andris Pavenis (andris DOT pavenis AT iki DOT fi) [via djgpp-workers AT delorie DOT com]:
> On 04/18/2016 09:16 PM, Juan Manuel Guerrero (juan DOT guerrero AT gmx DOT de) [via djgpp-workers AT delorie DOT com] wrote:
>> Am 17.04.2016 13:50, schrieb Andris Pavenis (andris DOT pavenis AT iki DOT fi) [via djgpp-workers AT delorie DOT com]:
>>> gcc-6.1.0 should not be very far any more:
>>>
>>> https://gcc.gnu.org/ml/gcc/2016-04/msg00103.html
>>> https://gcc.gnu.org/ml/gcc/2016-04/msg00109.html
>>>
>>> I built DJGPP port based on SVN revision r235040 (the same used for release candidate sources) checked out from git mirror (see https://gcc.gnu.org/wiki/GitMirror for details). Of course DJGPP related additional changes are merged.
>>>
>>> Files (both i686 and x86_64 rpms and native DJGPP build are available for testing at:
>>>
>>> http://ap1.pp.fi/djgpp/gcc/test/6.0.1-20160415/
>>>
>>> Andris
>>>
>>
>>
>> I have tried to build libc from repository using g[cc|pp]601_20160415b.zip.
>> It fails with the following error message:
>>
>> gcc ... -c strlen.c
>> strlen.c: In function 'strlen':
>> strlen.c:10:6: error: nonnull argument 'str' compared to NULL [-Werror=nonnull-compare]
>> if (str == NULL)
>> ^
>> cc1.exe: all warnings being treated as errors
>> ../../../makefile.inc:89: recipe for target 'strlen.o' failed
>> make.exe[3]: *** [strlen.o] Error 1
>> makefile.sub:2: recipe for target 'all_subs' failed
>> make.exe[2]: *** [all_subs] Error 2
>> ../makefile.lib:6: recipe for target 'all' failed
>> make.exe[1]: *** [all] Error 2
>> makefile:39: recipe for target 'subs' failed
>> make.exe: *** [subs] Error 2
>>
>> Inspecting the strlen code, it is clear that the offending code segment is:
>>
>> if (str == NULL)
>> return 0;
>>
>> It seems to be that for some reason, the compiler does assume that the passed
>> argument to the function can never be NULL. If I understood correctly, this
>> should only be the case if the function is specified like this:
>>
>> size_t strlen(const char *_s) __attribute__ ((__nonnull__ (1)));
>>
>> specifying that _s is never NULL, but this is certainly not the case in the
>> current versions of string.h.
>>
>> So the question arises if we have to remove all NULL pointer check from our
>> code and if this measure is really wise? IMHO, we should adjust the compiler
>> checks in such a way that NULL pointer checks are still possible.
>> BTW I have inspected http://pubs.opengroup.org/onlinepubs/009695399/functions/strlen.html
>> and I have seen no indication that a NULL pointer check is prohibited, but
>> also I have seen no indication that a NULL pointer check is allowed.
>>
> GCC new versions are known to be too wise for its own good when it commes to builtin functions.
>
> We have already had similar problem with cmalloc() in nmalloc.c where GCC infinite wisdom told it to recognize source as implementation of __builtin_cmalloc() and over-optimize it to infinite tail recursion. Specifying -fno-builtin-cmalloc for nmalloc.c work-arounded the problem then (present in DJGPP v2.05). See:
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67618
>
> (it was NOT DJGPP specific and could easily be reproduced on Linux)
>
> It seems that gcc current version recognizes DJGPP implementation of strlen as __builtin_strlen and assumes that __builtin_strlen should never have passed NULL argument with following messages.
> Specifying
>
> strlen.o: EXTRA_CFLAGS += -fno-builtin-strlen
>
> in src/libc/ansi/string/makefile causes error to disappear.
>
> Same problem with:
>
> libc/c99/math/nan*.c
> libc/compat/string/stpcpy.c
> libc/compat/string/stpncpy.c
> libc/compat/string/strdup.c
>
> and more (same approach as with strlen() works also for these).
>
> There are also other warnings interpreted as errors. Some examples:
>
> i586-pc-msdosdjgpp-gcc -pipe ... -c k_rem_pio2.c
> k_rem_pio2.c: In function '__kernel_rem_pio2':
> k_rem_pio2.c:190:6: error: this 'for' clause does not guard... [-Werror=misleading-indentation]
> for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j]; q[i] = fw;
> ^~~
> k_rem_pio2.c:190:54: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
> for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j]; q[i] = fw;
> ^
> cc1: all warnings being treated as errors
>
> i586-pc-msdosdjgpp-gcc -pipe ... -c s_scalbn.c
> s_scalbn.c:69:1: error: 'huge' defined but not used [-Werror=unused-const-variable=]
> huge = 1.0e+300,
> ^~~~
> cc1: all warnings being treated as errors
>
> And some similar...
>
> I'm not going to fix these now immediately (in late evening).
>
> About -Wmisleading-indentation: I guess it would be best to disable it for gcc-6+
>
> Andris
>

OFYI, I have committed the patch below to pacifiy the new gcc 6.0.1 compiler
when used to compile the libc repository code.  It only concernces unused variables
and -Werror=misleading-indentation.


Regards,
Juan M. Guerrero



2016-04-20  Juan Manuel Guerrero <juan DOT guerrero AT gmx DOT de>

	* djgpp/src/libm/math/e_asin.c:  Fixing -Werror=misleading-indentation for gcc 6.0.1.

	* djgpp/src/libm/math/ef_asin.c:  Fixing -Werror=misleading-indentation for gcc 6.0.1.

	* djgpp/src/libm/math/k_rem_pio2.c:  Fixing -Werror=misleading-indentation for gcc 6.0.1.

	* djgpp/src/libm/math/kf_rem_pio2.c:  Fixing -Werror=misleading-indentation for gcc 6.0.1.

	* djgpp/src/libm/math/ef_jn.c:  Unused variable removed.

	* djgpp/src/libm/math/s_scalbn.c:  Unused variable removed.

	* djgpp/src/libm/math/sf_scalbn.c:  Unused variable removed.

	* djgpp/src/libm/math/sf_cos.c:  Unused variable removed.

	* djgpp/src/utils/djtar/unlzh.c:  Fixing -Werror=misleading-indentation for gcc 6.0.1.






Index: djgpp/src/libm/math/e_asin.c
===================================================================
RCS file: /cvs/djgpp/djgpp/src/libm/math/e_asin.c,v
retrieving revision 1.1
diff -U 5 -r1.1 e_asin.c
--- djgpp/src/libm/math/e_asin.c	7 Feb 1998 13:18:28 -0000	1.1
+++ djgpp/src/libm/math/e_asin.c	20 Apr 2016 21:40:58 -0000
@@ -89,14 +89,14 @@
  	} else if (ix<0x3fe00000) {	/* |x|<0.5 */
  	    if(ix<0x3e400000) {		/* if |x| < 2**-27 */
  		if(huge+x>one) return x;/* return x with inexact if x!=0*/
  	    } else
  		t = x*x;
-		p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
-		q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
-		w = p/q;
-		return x+x*w;
+	    p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
+	    q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
+	    w = p/q;
+	    return x+x*w;
  	}
  	/* 1> |x|>= 0.5 */
  	w = one-fabs(x);
  	t = w*0.5;
  	p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
Index: djgpp/src/libm/math/ef_asin.c
===================================================================
RCS file: /cvs/djgpp/djgpp/src/libm/math/ef_asin.c,v
retrieving revision 1.1
diff -U 5 -r1.1 ef_asin.c
--- djgpp/src/libm/math/ef_asin.c	7 Feb 1998 14:13:26 -0000	1.1
+++ djgpp/src/libm/math/ef_asin.c	20 Apr 2016 21:40:58 -0000
@@ -56,14 +56,14 @@
  	} else if (ix<0x3f000000) {	/* |x|<0.5 */
  	    if(ix<0x32000000) {		/* if |x| < 2**-27 */
  		if(huge+x>one) return x;/* return x with inexact if x!=0*/
  	    } else
  		t = x*x;
-		p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
-		q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
-		w = p/q;
-		return x+x*w;
+	    p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
+	    q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
+	    w = p/q;
+	    return x+x*w;
  	}
  	/* 1> |x|>= 0.5 */
  	w = one-fabsf(x);
  	t = w*(float)0.5;
  	p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
Index: djgpp/src/libm/math/ef_jn.c
===================================================================
RCS file: /cvs/djgpp/djgpp/src/libm/math/ef_jn.c,v
retrieving revision 1.2
diff -U 5 -r1.2 ef_jn.c
--- djgpp/src/libm/math/ef_jn.c	16 Mar 2002 13:32:53 -0000	1.2
+++ djgpp/src/libm/math/ef_jn.c	20 Apr 2016 21:40:58 -0000
@@ -18,11 +18,10 @@
  #ifdef __STDC__
  static const float
  #else
  static float
  #endif
-invsqrtpi=  5.6418961287e-01, /* 0x3f106ebb */
  two   =  2.0000000000e+00, /* 0x40000000 */
  one   =  1.0000000000e+00; /* 0x3F800000 */

  #ifdef __STDC__
  static const float zero  =  0.0000000000e+00;
Index: djgpp/src/libm/math/k_rem_pio2.c
===================================================================
RCS file: /cvs/djgpp/djgpp/src/libm/math/k_rem_pio2.c,v
retrieving revision 1.1
diff -U 5 -r1.1 k_rem_pio2.c
--- djgpp/src/libm/math/k_rem_pio2.c	15 Apr 1997 08:39:48 -0000	1.1
+++ djgpp/src/libm/math/k_rem_pio2.c	20 Apr 2016 21:40:58 -0000
@@ -185,11 +185,12 @@
  	j = jv-jx; m = jx+jk;
  	for(i=0;i<=m;i++,j++) f[i] = (j<0)? zero : (double) ipio2[j];

      /* compute q[0],q[1],...q[jk] */
  	for (i=0;i<=jk;i++) {
-	    for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j]; q[i] = fw;
+	    for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j];
+	    q[i] = fw;
  	}

  	jz = jk;
  recompute:
      /* distill q[] into iq[] reversingly */
Index: djgpp/src/libm/math/kf_rem_pio2.c
===================================================================
RCS file: /cvs/djgpp/djgpp/src/libm/math/kf_rem_pio2.c,v
retrieving revision 1.1
diff -U 5 -r1.1 kf_rem_pio2.c
--- djgpp/src/libm/math/kf_rem_pio2.c	15 Apr 1997 08:39:48 -0000	1.1
+++ djgpp/src/libm/math/kf_rem_pio2.c	20 Apr 2016 21:40:58 -0000
@@ -75,11 +75,12 @@
  	j = jv-jx; m = jx+jk;
  	for(i=0;i<=m;i++,j++) f[i] = (j<0)? zero : (float) ipio2[j];

      /* compute q[0],q[1],...q[jk] */
  	for (i=0;i<=jk;i++) {
-	    for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j]; q[i] = fw;
+	    for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j];
+	    q[i] = fw;
  	}

  	jz = jk;
  recompute:
      /* distill q[] into iq[] reversingly */
Index: djgpp/src/libm/math/s_scalbn.c
===================================================================
RCS file: /cvs/djgpp/djgpp/src/libm/math/s_scalbn.c,v
retrieving revision 1.1
diff -U 5 -r1.1 s_scalbn.c
--- djgpp/src/libm/math/s_scalbn.c	4 Oct 1998 10:48:42 -0000	1.1
+++ djgpp/src/libm/math/s_scalbn.c	20 Apr 2016 21:40:58 -0000
@@ -64,11 +64,10 @@
  #else
  static double
  #endif
  two54   =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
  twom54  =  5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
-huge   = 1.0e+300,
  tiny   = 1.0e-300;

  #ifdef __STDC__
  	double scalbn (double x, int n)
  #else
Index: djgpp/src/libm/math/sf_cos.c
===================================================================
RCS file: /cvs/djgpp/djgpp/src/libm/math/sf_cos.c,v
retrieving revision 1.1
diff -U 5 -r1.1 sf_cos.c
--- djgpp/src/libm/math/sf_cos.c	15 Apr 1997 08:39:52 -0000	1.1
+++ djgpp/src/libm/math/sf_cos.c	20 Apr 2016 21:40:58 -0000
@@ -14,16 +14,10 @@
   */

  #include "fdlibm.h"

  #ifdef __STDC__
-static const float one=1.0;
-#else
-static float one=1.0;
-#endif
-
-#ifdef __STDC__
  	float cosf(float x)
  #else
  	float cosf(x)
  	float x;
  #endif
Index: djgpp/src/libm/math/sf_scalbn.c
===================================================================
RCS file: /cvs/djgpp/djgpp/src/libm/math/sf_scalbn.c,v
retrieving revision 1.1
diff -U 5 -r1.1 sf_scalbn.c
--- djgpp/src/libm/math/sf_scalbn.c	4 Oct 1998 10:48:42 -0000	1.1
+++ djgpp/src/libm/math/sf_scalbn.c	20 Apr 2016 21:40:58 -0000
@@ -27,11 +27,10 @@
  #else
  static float
  #endif
  two25   =  3.355443200e+07,	/* 0x4c000000 */
  twom25  =  2.9802322388e-08,	/* 0x33000000 */
-huge   = 1.0e+30,
  tiny   = 1.0e-30;

  #ifdef __STDC__
  	float scalbnf (float x, int n)
  #else
Index: djgpp/src/utils/djtar/unlzh.c
===================================================================
RCS file: /cvs/djgpp/djgpp/src/utils/djtar/unlzh.c,v
retrieving revision 1.5
diff -U 5 -r1.5 unlzh.c
--- djgpp/src/utils/djtar/unlzh.c	2 May 2015 07:32:38 -0000	1.5
+++ djgpp/src/utils/djtar/unlzh.c	20 Apr 2016 21:40:58 -0000
@@ -1,5 +1,6 @@
+/* Copyright (C) 2016 DJ Delorie, see COPYING.DJ for details */
  /* Copyright (C) 2015 DJ Delorie, see COPYING.DJ for details */
  /* Copyright (C) 2013 DJ Delorie, see COPYING.DJ for details */
  /* Copyright (C) 2012 DJ Delorie, see COPYING.DJ for details */
  /* Copyright (C) 2011 DJ Delorie, see COPYING.DJ for details */
  /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
@@ -234,11 +235,12 @@
        c = bitbuf >> (BITBUFSIZ - 3);
        if (c == 7)
        {
          mask = (unsigned) 1 << (BITBUFSIZ - 1 - 3);
          while (mask & bitbuf)
-          mask >>= 1;  c++;
+          mask >>= 1;
+        c++;
        }
        fillbuf((c < 7) ? 3 : c - 3);
        pt_len[i++] = c;
        if (i == i_special)
        {