https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120158
Bug ID: 120158
Summary: Incorrect UNSIGNED maxval/maxloc etc.
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libfortran
Assignee: unassigned at gcc dot gnu.org
Reporter: jakub at gcc dot gnu.org
Target Milestone: ---
maxval/maxloc use
#if defined('atype_inf`)
maxval = -atype_inf;
#else
maxval = atype_min;
#endif',
compared to minval/minloc
#if defined('atype_inf`)
minval = atype_inf;
#else
minval = atype_max;
#endif',
Both of that is reasonable, but I think the atype_min definition for UNSIGNED
is incorrect.
The
../../../libgfortran/generated/maxloc0_8_m1.c:274:14: warning: unsigned
conversion from ‘int’ to ‘GFC_UINTEGER_1’ {aka ‘unsigned char’} changes value
from ‘-255’ to ‘1’ [-Woverflow]
../../../libgfortran/generated/maxloc0_4_m2.c:99:14: warning: unsigned
conversion from ‘int’ to ‘GFC_UINTEGER_2’ {aka ‘short unsigned int’} changes
value from ‘-65535’ to ‘1’ [-Woverflow]
etc. warnings are suspicious.
At least in C, minimum for unsigned is 0 and maximum 0xffffffff while signed
int have
minimum of -0x7fffffff - 1 and maximum 0x7fffffff. In Fortran for INTEGER I
believe maximum is 0x7fffffff and minimum -0x7fffffff, but it would really
surprise me if UNSIGNED maximum wasn't 0xffffffff and minimum 0.
So, I think we need to somehow arrange for atype_min to be ((GFC_UINTEGER_N) 0)
or so
(for N 1, 2, 4, 8 or 16), or predefine macros for it in libgfortran and just
arrange for
define(atype_min,ifelse(regexp(file,
`_\(.\)[0-9]*\.c$',`\1'),`i',`(-'atype_max`-1)',`-'atype_max))dnl
to be perhaps
--- libgfortran/m4/iparm.m4.jj 2024-09-25 17:25:07.201360961 +0200
+++ libgfortran/m4/iparm.m4 2025-05-07 15:53:42.940954331 +0200
@@ -28,7 +28,7 @@ define_type(rtype, rtype_tmp)dnl
define(rtype_qual,`_'rtype_kind)dnl
')dnl
define(atype_max, atype_name`_HUGE')dnl
-define(atype_min,ifelse(regexp(file, `_\(.\)[0-9]*\.c$',
`\1'),`i',`(-'atype_max`-1)',`-'atype_max))dnl
+define(atype_min,ifelse(index(atype_name,`UNSIGNED`),-1,ifelse(regexp(file,
`_\(.\)[0-9]*\.c$', `\1'),`i',`(-'atype_max`-1)',`-'atype_max),`((`atype_name`)
0)`))dnl
define(atype_inf, atype_name`_INFINITY')dnl
define(atype_nan, atype_name`_QUIET_NAN')dnl
define(name, regexp(regexp(file, `[^/]*$', `\&'), `^\([^_]*\)_', `\1'))dnl
? So far completely untested.
