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[Patch] Fix libstdc++/13450


Hi,

so, here it is. Basically, I have adapted and tested submitter's patch,
which brings us back to the 3.2.x behavior + the optimization introduced
by Gaby for 3.3, carried out only when absolutely safe.

The important tweak wrt the original patch is the following:

 if (__x.imag() == _Tp() && __x.real() > _Tp())
                                       ^--------- instead of >=
   return pow(__x.real(), __y);

Without it, we may end up calling cmath's pow also when __x.real == -0
and, in general, this isn't safe (it's ok for C99 libcs, F.9.4.4).

An interesting twist of the work is that I have noticed that we weren't
running two testcases (!) due to a wrong suffix, the second particularly
important in order to verify that we are not regressing on 10689:
26_numerics/cmath/overloads.C and 26_numerics/complex/pow.C.

Tested x86-linux, I mean to double check the fix immediately on x86-64
too, and, if nobody objects, commit the work tomorrow.

Paolo.

///////////////
2004-03-09  Paul Kienzle  <pkienzle@nist.gov>
	    Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/13450
	* include/std/std_complex.h (pow(const complex&, const _Tp&),
	pow(const _Tp&, const complex&)): Use cmath pow only when safe.
	* testsuite/26_numerics/complex/13450.cc: New.

	* testsuite/26_numerics/cmath/overloads.C: Rename to overloads.cc.
	* testsuite/26_numerics/complex/pow.C: Rename to pow.cc and fix.
diff -urN libstdc++-v3-orig/include/std/std_complex.h libstdc++-v3/include/std/std_complex.h
--- libstdc++-v3-orig/include/std/std_complex.h	2004-01-27 03:58:06.000000000 +0100
+++ libstdc++-v3/include/std/std_complex.h	2004-03-09 18:06:14.000000000 +0100
@@ -705,7 +705,7 @@
     complex<_Tp>
     pow(const complex<_Tp>& __x, const _Tp& __y)
     {
-      if (__x.imag() == _Tp())
+      if (__x.imag() == _Tp() && __x.real() > _Tp())
         return pow(__x.real(), __y);
 
       complex<_Tp> __t = log(__x);
@@ -723,9 +723,8 @@
     inline complex<_Tp>
     pow(const _Tp& __x, const complex<_Tp>& __y)
     {
-      return __x == _Tp()
-        ? _Tp()
-        : std::polar(pow(__x, __y.real()), __y.imag() * log(__x));
+      return __x > _Tp() ? polar(pow(__x, __y.real()), __y.imag() * log(__x))
+	                 : pow(complex<_Tp>(__x, _Tp()), __y);
     }
 
   // 26.2.3  complex specializations
diff -urN libstdc++-v3-orig/testsuite/26_numerics/cmath/overloads.C libstdc++-v3/testsuite/26_numerics/cmath/overloads.C
--- libstdc++-v3-orig/testsuite/26_numerics/cmath/overloads.C	2003-05-11 11:07:17.000000000 +0200
+++ libstdc++-v3/testsuite/26_numerics/cmath/overloads.C	1970-01-01 01:00:00.000000000 +0100
@@ -1,27 +0,0 @@
-// PR 3181
-// Origin: pete@toyon.com
-
-#include <cmath>
-
-int main()
-{
-  int i = -1;
-  int j = 9;
-  double ans;
-  ans = std::acos(i);
-  ans = std::asin(i);
-  ans = std::atan(i);
-  ans = std::atan2(i, j);
-  ans = std::cos(i);
-  ans = std::cosh(i);
-  ans = std::exp(i);
-  ans = std::fabs(i);
-  ans = std::floor(i);
-  ans = std::log(i);
-  ans = std::log10(i);
-  ans = std::sqrt(i);
-  ans = std::sin(i);
-  ans = std::sinh(j);
-  ans = std::tan(i);
-  ans = std::tanh(i);
-}
diff -urN libstdc++-v3-orig/testsuite/26_numerics/cmath/overloads.cc libstdc++-v3/testsuite/26_numerics/cmath/overloads.cc
--- libstdc++-v3-orig/testsuite/26_numerics/cmath/overloads.cc	1970-01-01 01:00:00.000000000 +0100
+++ libstdc++-v3/testsuite/26_numerics/cmath/overloads.cc	2003-05-11 11:07:17.000000000 +0200
@@ -0,0 +1,27 @@
+// PR 3181
+// Origin: pete@toyon.com
+
+#include <cmath>
+
+int main()
+{
+  int i = -1;
+  int j = 9;
+  double ans;
+  ans = std::acos(i);
+  ans = std::asin(i);
+  ans = std::atan(i);
+  ans = std::atan2(i, j);
+  ans = std::cos(i);
+  ans = std::cosh(i);
+  ans = std::exp(i);
+  ans = std::fabs(i);
+  ans = std::floor(i);
+  ans = std::log(i);
+  ans = std::log10(i);
+  ans = std::sqrt(i);
+  ans = std::sin(i);
+  ans = std::sinh(j);
+  ans = std::tan(i);
+  ans = std::tanh(i);
+}
diff -urN libstdc++-v3-orig/testsuite/26_numerics/complex/13450.cc libstdc++-v3/testsuite/26_numerics/complex/13450.cc
--- libstdc++-v3-orig/testsuite/26_numerics/complex/13450.cc	1970-01-01 01:00:00.000000000 +0100
+++ libstdc++-v3/testsuite/26_numerics/complex/13450.cc	2004-03-09 17:59:31.000000000 +0100
@@ -0,0 +1,75 @@
+// Copyright (C) 2004 Free Software Foundation
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING.  If not, write to the Free
+// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// 26.2.8 complex transcendentals
+
+#include <complex>
+#include <limits>
+#include <testsuite_hooks.h>
+
+template<typename T>
+  void test01_do(T a, T b)
+  {
+    using namespace std;
+    bool test __attribute__((unused)) = true;
+    typedef complex<T> cplx;
+
+    T eps = numeric_limits<T>::epsilon() * 10;
+    
+    cplx ref = pow(cplx(a, T()), cplx(b, T()));
+    cplx res1 = pow(a, cplx(b, T()));
+    cplx res2 = pow(cplx(a, T()), b);
+    
+    VERIFY( abs(ref - res1) < eps );
+    VERIFY( abs(ref - res2) < eps );
+    VERIFY( abs(res1 - res2) < eps );
+  }
+
+// libstdc++/13450
+void test01()
+{
+  float f1 = -1.0f;
+  float f2 = 0.5f;
+  test01_do(f1, f2);
+
+  f1 = -3.2f;
+  f2 = 1.4f;
+  test01_do(f1, f2);
+
+  double d1 = -1.0;
+  double d2 = 0.5;
+  test01_do(d1, d2);
+
+  d1 = -3.2;
+  d2 = 1.4;
+  test01_do(d1, d2);
+
+  long double ld1 = -1.0l;
+  long double ld2 = 0.5l;
+  test01_do(ld1, ld2);
+
+  ld1 = -3.2l;
+  ld2 = 1.4l;
+  test01_do(ld1, ld2);
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
diff -urN libstdc++-v3-orig/testsuite/26_numerics/complex/pow.C libstdc++-v3/testsuite/26_numerics/complex/pow.C
--- libstdc++-v3-orig/testsuite/26_numerics/complex/pow.C	2003-05-20 08:52:11.000000000 +0200
+++ libstdc++-v3/testsuite/26_numerics/complex/pow.C	1970-01-01 01:00:00.000000000 +0100
@@ -1,14 +0,0 @@
-// PR libbstdc++/10689
-// Origin: Daniel.Levine@jhuaph.edu
-
-#include <complex>
-#include <testsuite_hooks.h>
-
-int main()
-{
-   std::complex<double> z(0, 1) ;
-
-   VERIFY(pow(z, 1.0/3.0) == 0.0);
-
-   return 0;
-}
diff -urN libstdc++-v3-orig/testsuite/26_numerics/complex/pow.cc libstdc++-v3/testsuite/26_numerics/complex/pow.cc
--- libstdc++-v3-orig/testsuite/26_numerics/complex/pow.cc	1970-01-01 01:00:00.000000000 +0100
+++ libstdc++-v3/testsuite/26_numerics/complex/pow.cc	2004-03-09 16:10:29.000000000 +0100
@@ -0,0 +1,14 @@
+// PR libbstdc++/10689
+// Origin: Daniel.Levine@jhuaph.edu
+
+#include <complex>
+#include <testsuite_hooks.h>
+
+int main()
+{
+   std::complex<double> z;
+
+   VERIFY( pow(z, 1.0/3.0) == 0.0 );
+
+   return 0;
+}

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