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libfortran: fix conversion of UNSIGNED(kind=16) to decimal in output [PR118406]

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PR libfortran/118406

libgfortran/ChangeLog:

	* runtime/string.c (gfc_itoa): Handle unsigned integers larger than
	(10^19 * 2^64).

gcc/testsuite/ChangeLog:

	* gfortran.dg/unsigned_write.f90: New test.
This commit is contained in:
Harald Anlauf 2025-01-16 20:23:06 +01:00
parent 1ff85affe4
commit 99bcce0d89
2 changed files with 65 additions and 8 deletions
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40
gcc/testsuite/gfortran.dg/unsigned_write.f90 Normal file
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@ -0,0 +1,40 @@
! { dg-do run }
! This is a libgfortran (runtime library) test, need to run only once!
!
! { dg-require-effective-target fortran_integer_16 }
! { dg-additional-options "-funsigned" }
!
! PR libfortran/118406 - printing large UNSIGNED(kind=16) crashes
program print_large_unsigned
unsigned(16), parameter :: u16_max = huge(0U_16)
unsigned(16), parameter :: u8_max = uint(huge(0U_8),16) ! UINT64_MAX
unsigned(16), parameter :: ten19 = uint(10_8 ** 18,16)*10U_16 ! 10**19
character(42) :: s
! Reference: signed integer
write(s,*) huge(0_16)
if (adjustl (s) /= "170141183460469231731687303715884105727") stop 1
! Same value as unsigned
write(s,*) uint (huge(0_16),16)
if (adjustl (s) /= "170141183460469231731687303715884105727") stop 2
! Extreme and intermediate values
write(s,*) u16_max
if (adjustl (s) /= "340282366920938463463374607431768211455") stop 3
write(s,*) (u16_max - 3U_16) / 4U_16 * 3U_16
if (adjustl (s) /= "255211775190703847597530955573826158589") stop 4
! Test branches of implementation in string.c::gfc_itoa
write(s,*) u8_max * ten19
if (adjustl (s) /= "184467440737095516150000000000000000000") stop 5
write(s,*) u8_max * ten19 - 1U_16
if (adjustl (s) /= "184467440737095516149999999999999999999") stop 6
write(s,*) u8_max * ten19 + 1U_16
if (adjustl (s) /= "184467440737095516150000000000000000001") stop 7
end

33
libgfortran/runtime/string.c
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@ -241,18 +241,35 @@ gfc_itoa (GFC_UINTEGER_LARGEST n, char *buffer, size_t len)
the uint64_t function are not sufficient for all 128-bit unsigned
integers (we would need three calls), but they do suffice for all
values up to 2^127, which is the largest that Fortran can produce
(-HUGE(0_16)-1) with its signed integer types. */
(-HUGE(0_16)-1) with its signed integer types.
With the introduction of UNSIGNED integers, we must treat the case
of unsigned ints larger than (10^19 * 2^64) by adding one step. */
_Static_assert (sizeof(GFC_UINTEGER_LARGEST) <= 2 * sizeof(uint64_t),
"integer too large");
GFC_UINTEGER_LARGEST r;
r = n % TEN19;
n = n / TEN19;
assert (r <= UINT64_MAX);
p = itoa64_pad19 (r, p);
if (n <= TEN19 * UINT64_MAX)
{
GFC_UINTEGER_LARGEST r;
r = n % TEN19;
n = n / TEN19;
assert (r <= UINT64_MAX);
p = itoa64_pad19 (r, p);
assert(n <= UINT64_MAX);
return itoa64 (n, p);
assert(n <= UINT64_MAX);
return itoa64 (n, p);
}
else
{
/* Here n > (10^19 * 2^64). */
GFC_UINTEGER_LARGEST d1, r1, d2, r2;
d1 = n / (TEN19 * TEN19);
r1 = n % (TEN19 * TEN19);
d2 = r1 / TEN19;
r2 = r1 % TEN19;
p = itoa64_pad19 (r2, p);
p = itoa64_pad19 (d2, p);
return itoa64 (d1, p);
}
}
#else
/* On targets where the largest integer is 64-bit, just use that. */