[Bug c++/16607] New: Incorrect FP code generated in member data initialization

["npr1 at suomi24 dot fi" <gcc-bugzilla at gcc dot gnu dot org>]

In some conditions a member initializer of double data is handled in single 
precision.

Attached is a quite fragile minimized test program. In it, the bug only surfaces 
in inlined code, i.e. compiled with -O.

At least GCC 3.3, 3.3.3 and 3.4.1 are affected. A test on GCC 2.95.4 on i686-pc-
linux-gnu didn't show the bug. It might be x86 only, as the test program doesn't 
show it with GCC 3.3 on sparc-sun-solaris2.8.

For example, "gcc -v" of the 3.3.3:
Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/3.3.3/specs
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/
usr/share/info --enable-shared --enable-threads=posix --disable-checking --
disable-libunwind-exceptions --with-system-zlib --enable-__cxa_atexit --
host=i386-redhat-linux
Thread model: posix
gcc version 3.3.3 20040412 (Red Hat Linux 3.3.3-7)

/* $ g++ -Wall -O gccbug.cpp && ./a.out
 *  -1.19209e-07 0
 *  0 1.19209e-07
 * $ g++ -Wall -O0 gccbug.cpp && ./a.out
 *  0 1.19209e-07
 *  0 1.19209e-07
 */

int printf(const char*, ...);

struct C {
	double x;
	C(double x_) : x(x_) {
		printf(" ");
		printf("%g %g\n", x - x_, x - float(x_));
	}
};

void f(float x) {
	const double y = x * .9f;
	if (x) {
		new C(y);
		new C(y);
	}
}

int main() {
	f(3);
	return 0;
}

-- 
           Summary: Incorrect FP code generated in member data
                    initialization
           Product: gcc
           Version: 3.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: npr1 at suomi24 dot fi
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16607