On Tue, 24 May 2016, Matt Turner wrote:
> Some implementations of truncf(x) add 2**23 to x with the rounding mode
> set to truncate before subtracting 2**23 to produce the truncated
> result. Unfortunately this doesn't work for odd values of x greater than
> 2**23, since the result of the addition is inexact and the parity bit is
> lost by the rounding step. The same problems apply to implementations of
> trunc on other floating-point data types.
I think the same tests should be added for all of ceil, floor, round,
trunc if not already present.
> + TEST_f_f (trunc, 0x1p63 + 1, 0x1p63 + 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
> TEST_f_f (trunc, 0x1p64, 0x1p64, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
> TEST_f_f (trunc, 0x1p65, 0x1p65, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
> TEST_f_f (trunc, 0x1p105, 0x1p105, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
> + TEST_f_f (trunc, 0x1p105 + 1, 0x1p105 + 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
> TEST_f_f (trunc, 0x1p106, 0x1p106, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
> TEST_f_f (trunc, 0x1p107, 0x1p107, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
> TEST_f_f (trunc, 0x1p112, 0x1p112, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
> + TEST_f_f (trunc, 0x1p112 + 1, 0x1p112 + 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
These need to suffix the constants with 'L' so that they actually test
what's intended for long double. And doing arithmetic like that in
libm-test.inc makes manipulation to change suffixes, as in
<https://sourceware.org/ml/libc-alpha/2016-05/msg00474.html>, harder. So
I think it's better to write all the constants explicitly without
arithmetic (0x1.000002p23L, 0x1.0000000000001p52L,
0x1.0000000000000002p63L, 0x1.000000000000000000000000008p105L,
0x1.0000000000000000000000000001p112L).
@@ -11413,18 +11413,23 @@ static const struct test_f_f_data trunc_test_data[] =
TEST_f_f (trunc, 1, 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 2, 2, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p23, 0x1p23, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, 0x1p23 + 1, 0x1p23 + 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p24, 0x1p24, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p25, 0x1p25, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p52, 0x1p52, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, 0x1p52 + 1, 0x1p52 + 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p53, 0x1p53, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p54, 0x1p54, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p63, 0x1p63, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, 0x1p63 + 1, 0x1p63 + 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p64, 0x1p64, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p65, 0x1p65, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p105, 0x1p105, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, 0x1p105 + 1, 0x1p105 + 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p106, 0x1p106, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p107, 0x1p107, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p112, 0x1p112, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, 0x1p112 + 1, 0x1p112 + 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p113, 0x1p113, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 0x1p114, 0x1p114, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, max_value, max_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
@@ -11433,18 +11438,23 @@ static const struct test_f_f_data trunc_test_data[] =
TEST_f_f (trunc, -1, -1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -2, -2, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p23, -0x1p23, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, -0x1p23 - 1, -0x1p23 - 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p24, -0x1p24, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p25, -0x1p25, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p52, -0x1p52, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, -0x1p52 - 1, -0x1p52 - 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p53, -0x1p53, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p54, -0x1p54, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p63, -0x1p63, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, -0x1p63 - 1, -0x1p63 - 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p64, -0x1p64, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p65, -0x1p65, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p105, -0x1p105, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, -0x1p105 - 1, -0x1p105 - 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p106, -0x1p106, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p107, -0x1p107, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p112, -0x1p112, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, -0x1p112 - 1, -0x1p112 - 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p113, -0x1p113, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -0x1p114, -0x1p114, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, -max_value, -max_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),