Add some regression tests for libm's exponential functions. These

mostly just test corner cases rather than accuracy. Some of the
tests don't pass right now if you compile libm at -O2 due to gcc
constant-folding some things that it shouldn't. I'll fix that
shortly.

tools/regression/lib/msun/Makefile

@@ -1,6 +1,6 @@
 # $FreeBSD$
 
-TESTS=	test-csqrt test-fenv test-ilogb test-lrint \
+TESTS=	test-csqrt test-exponential test-fenv test-ilogb test-lrint \
 	test-lround test-nan test-next test-rem
 CFLAGS+= -O0 -lm
 

tools/regression/lib/msun/test-exponential.c

@@ -0,0 +1,170 @@
+/*-
+ * Copyright (c) 2008 David Schultz <das@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Tests for corner cases in exp*().
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <assert.h>
+#include <fenv.h>
+#include <float.h>
+#include <math.h>
+#include <stdio.h>
+
+#ifdef __i386__
+#include <ieeefp.h>
+#endif
+
+#define	ALL_STD_EXCEPT	(FE_DIVBYZERO | FE_INEXACT | FE_INVALID | \
+			 FE_OVERFLOW | FE_UNDERFLOW)
+
+#pragma STDC FENV_ACCESS ON
+
+/*
+ * Test that a function returns the correct value and sets the
+ * exception flags correctly. The exceptmask specifies which
+ * exceptions we should check. We need to be lenient for several
+ * reasoons, but mainly because on some architectures it's impossible
+ * to raise FE_OVERFLOW without raising FE_INEXACT.
+ *
+ * These are macros instead of functions so that assert provides more
+ * meaningful error messages.
+ *
+ * XXX The volatile here is to avoid gcc's bogus constant folding and work
+ *     around the lack of support for the FENV_ACCESS pragma.
+ */
+#define	test(func, x, result, exceptmask, excepts)	do {		\
+	volatile long double _d = x;					\
+	assert(feclearexcept(FE_ALL_EXCEPT) == 0);			\
+	assert(fpequal((func)(_d), (result)));				 \
+	assert(((func), fetestexcept(exceptmask) == (excepts)));	\
+} while (0)
+
+/* Test all the functions that compute b^x. */
+#define	testall0(x, result, exceptmask, excepts)	do {		\
+	test(exp, x, result, exceptmask, excepts);			\
+	test(expf, x, result, exceptmask, excepts);			\
+	test(exp2, x, result, exceptmask, excepts);			\
+	test(exp2f, x, result, exceptmask, excepts);			\
+	test(exp2l, x, result, exceptmask, excepts);			\
+} while (0)
+
+/* Test all the functions that compute b^x - 1. */
+#define	testall1(x, result, exceptmask, excepts)	do {		\
+	test(expm1, x, result, exceptmask, excepts);			\
+	test(expm1f, x, result, exceptmask, excepts);			\
+} while (0)
+
+/*
+ * Determine whether x and y are equal, with two special rules:
+ *	+0.0 != -0.0
+ *	 NaN == NaN
+ */
+int
+fpequal(long double x, long double y)
+{
+	return ((x == y && signbit(x) == signbit(y)) || isnan(x) && isnan(y));
+}
+
+void
+run_generic_tests(void)
+{
+
+	/* exp(0) == 1, no exceptions raised */
+	testall0(0.0, 1.0, ALL_STD_EXCEPT, 0);
+	testall1(0.0, 0.0, ALL_STD_EXCEPT, 0);
+	testall0(-0.0, 1.0, ALL_STD_EXCEPT, 0);
+	testall1(-0.0, -0.0, ALL_STD_EXCEPT, 0);
+
+	/* exp(NaN) == NaN, no exceptions raised */
+	testall0(NAN, NAN, ALL_STD_EXCEPT, 0);
+	testall1(NAN, NAN, ALL_STD_EXCEPT, 0);
+
+	/* exp(Inf) == Inf, no exceptions raised */
+	testall0(INFINITY, INFINITY, ALL_STD_EXCEPT, 0);
+	testall1(INFINITY, INFINITY, ALL_STD_EXCEPT, 0);
+
+	/* exp(-Inf) == 0, no exceptions raised */
+	testall0(-INFINITY, 0.0, ALL_STD_EXCEPT, 0);
+	testall1(-INFINITY, -1.0, ALL_STD_EXCEPT, 0);
+
+	/* exp(big) == Inf, overflow exception */
+	testall0(50000.0, INFINITY, ALL_STD_EXCEPT & ~FE_INEXACT, FE_OVERFLOW);
+	testall1(50000.0, INFINITY, ALL_STD_EXCEPT & ~FE_INEXACT, FE_OVERFLOW);
+
+	/* exp(small) == 0, underflow and inexact exceptions */
+	testall0(-50000.0, 0.0, ALL_STD_EXCEPT, FE_UNDERFLOW | FE_INEXACT);
+	testall1(-50000.0, -1.0, ALL_STD_EXCEPT, FE_UNDERFLOW | FE_INEXACT);
+}
+
+void
+run_exp2_tests(void)
+{
+	int i;
+
+	/*
+	 * We should insist that exp2() return exactly the correct
+	 * result and not raise an inexact exception for integer
+	 * arguments.
+	 */
+	feclearexcept(FE_ALL_EXCEPT);
+	for (i = FLT_MIN_EXP - FLT_MANT_DIG; i < FLT_MAX_EXP; i++) {
+		assert(exp2f(i) == ldexpf(1.0, i));
+		assert(fetestexcept(ALL_STD_EXCEPT) == 0);
+	}
+	for (i = DBL_MIN_EXP - DBL_MANT_DIG; i < DBL_MAX_EXP; i++) {
+		assert(exp2(i) == ldexp(1.0, i));
+		assert(fetestexcept(ALL_STD_EXCEPT) == 0);
+	}
+	for (i = LDBL_MIN_EXP - LDBL_MANT_DIG; i < LDBL_MAX_EXP; i++) {
+		assert(exp2l(i) == ldexpl(1.0, i));
+		assert(fetestexcept(ALL_STD_EXCEPT) == 0);
+	}
+}
+
+int
+main(int argc, char *argv[])
+{
+
+	printf("1..2\n");
+
+	run_generic_tests();
+	printf("ok 1 - exponential\n");
+
+#ifdef __i386__
+	fpsetprec(FP_PE);
+	run_generic_tests();
+#endif
+	printf("ok 2 - exponential\n");
+
+	run_exp2_tests();
+	printf("ok 3 - exponential\n");
+
+	return (0);
+}

tools/regression/lib/msun/test-exponential.t

@@ -0,0 +1,10 @@
+#!/bin/sh
+# $FreeBSD$
+
+cd `dirname $0`
+
+executable=`basename $0 .t`
+
+make $executable 2>&1 > /dev/null
+
+exec ./$executable