@@ -2718,16 +2718,15 @@ int main (int argc, char *argv[])
@node _gfortran_set_fpe
-@subsection @code{_gfortran_set_fpe} --- Set when a Floating Point Exception should be raised
+@subsection @code{_gfortran_set_fpe} --- Enable floating point exception traps
@fnindex _gfortran_set_fpe
@cindex libgfortran initialization, set_fpe
@table @asis
@item @emph{Description}:
-@code{_gfortran_set_fpe} sets the IEEE exceptions for which a
-Floating Point Exception (FPE) should be raised. On most systems,
-this will result in a SIGFPE signal being sent and the program
-being interrupted.
+@code{_gfortran_set_fpe} enables floating point exception traps for
+the specified exceptions. On most systems, this will result in a
+SIGFPE signal being sent and the program being aborted.
@item @emph{Syntax}:
@code{void _gfortran_set_fpe (int val)}
@@ -2738,7 +2737,7 @@ being interrupted.
(bitwise or-ed) zero (0, default) no trapping,
@code{GFC_FPE_INVALID} (1), @code{GFC_FPE_DENORMAL} (2),
@code{GFC_FPE_ZERO} (4), @code{GFC_FPE_OVERFLOW} (8),
-@code{GFC_FPE_UNDERFLOW} (16), and @code{GFC_FPE_PRECISION} (32).
+@code{GFC_FPE_UNDERFLOW} (16), and @code{GFC_FPE_INEXACT} (32).
@end multitable
@item @emph{Example}:
@@ -919,21 +919,31 @@ GNU Fortran compiler itself. This option is deprecated; use
@item -ffpe-trap=@var{list}
@opindex @code{ffpe-trap=}@var{list}
-Specify a list of IEEE exceptions when a Floating Point Exception
-(FPE) should be raised. On most systems, this will result in a SIGFPE
-signal being sent and the program being interrupted, producing a core
-file useful for debugging. @var{list} is a (possibly empty) comma-separated
-list of the following IEEE exceptions: @samp{invalid} (invalid floating
-point operation, such as @code{SQRT(-1.0)}), @samp{zero} (division by
-zero), @samp{overflow} (overflow in a floating point operation),
-@samp{underflow} (underflow in a floating point operation),
-@samp{precision} (loss of precision during operation) and @samp{denormal}
-(operation produced a denormal value).
-
-Some of the routines in the Fortran runtime library, like
-@samp{CPU_TIME}, are likely to trigger floating point exceptions when
-@code{ffpe-trap=precision} is used. For this reason, the use of
-@code{ffpe-trap=precision} is not recommended.
+Specify a list of floating point exception traps to enable. On most
+systems, if a floating point exception occurs and the trap for that
+exception is enabled, a SIGFPE signal will be sent and the program
+being aborted, producing a core file useful for debugging. @var{list}
+is a (possibly empty) comma-separated list of the following
+exceptions: @samp{invalid} (invalid floating point operation, such as
+@code{SQRT(-1.0)}), @samp{zero} (division by zero), @samp{overflow}
+(overflow in a floating point operation), @samp{underflow} (underflow
+in a floating point operation), @samp{inexact} (loss of precision
+during operation), and @samp{denormal} (operation performed on a
+denormal value). The first five exceptions correspond to the five
+IEEE 754 exceptions, whereas the last one (@samp{denormal}) is not
+part of the IEEE 754 standard but is available on some common
+architectures such as x86.
+
+The first three exceptions (@samp{invalid}, @samp{zero}, and
+@samp{overflow}) often indicate serious errors, and unless the program
+has provisions for dealing with these exceptions, enabling traps for
+these three exceptions is probably a good idea.
+
+Many, if not most, floating point operations incur loss of precision
+due to rounding, and hence the @code{ffpe-trap=inexact} is likely to
+be uninteresting in practice.
+
+By default no exception traps are enabled.
@item -fno-backtrace
@opindex @code{fno-backtrace}
@@ -42,7 +42,7 @@ along with GCC; see the file COPYING3. If not see
#define GFC_FPE_ZERO (1<<2)
#define GFC_FPE_OVERFLOW (1<<3)
#define GFC_FPE_UNDERFLOW (1<<4)
-#define GFC_FPE_PRECISION (1<<5)
+#define GFC_FPE_INEXACT (1<<5)
/* Bitmasks for the various runtime checks that can be enabled. */
@@ -492,12 +492,14 @@ static void
gfc_handle_fpe_trap_option (const char *arg)
{
int result, pos = 0, n;
+ /* precision is a backwards compatibility alias for inexact. */
static const char * const exception[] = { "invalid", "denormal", "zero",
"overflow", "underflow",
- "precision", NULL };
+ "inexact", "precision", NULL };
static const int opt_exception[] = { GFC_FPE_INVALID, GFC_FPE_DENORMAL,
GFC_FPE_ZERO, GFC_FPE_OVERFLOW,
- GFC_FPE_UNDERFLOW, GFC_FPE_PRECISION,
+ GFC_FPE_UNDERFLOW, GFC_FPE_INEXACT,
+ GFC_FPE_INEXACT,
0 };
while (*arg)
@@ -110,7 +110,7 @@ void set_fpu (void)
if (options.fpe & GFC_FPE_ZERO) cw &= ~_FPU_MASK_ZM;
if (options.fpe & GFC_FPE_OVERFLOW) cw &= ~_FPU_MASK_OM;
if (options.fpe & GFC_FPE_UNDERFLOW) cw &= ~_FPU_MASK_UM;
- if (options.fpe & GFC_FPE_PRECISION) cw &= ~_FPU_MASK_PM;
+ if (options.fpe & GFC_FPE_INEXACT) cw &= ~_FPU_MASK_PM;
asm volatile ("fldcw %0" : : "m" (cw));
@@ -129,7 +129,7 @@ void set_fpu (void)
if (options.fpe & GFC_FPE_ZERO) cw_sse &= ~(_FPU_MASK_ZM << 7);
if (options.fpe & GFC_FPE_OVERFLOW) cw_sse &= ~(_FPU_MASK_OM << 7);
if (options.fpe & GFC_FPE_UNDERFLOW) cw_sse &= ~(_FPU_MASK_UM << 7);
- if (options.fpe & GFC_FPE_PRECISION) cw_sse &= ~(_FPU_MASK_PM << 7);
+ if (options.fpe & GFC_FPE_INEXACT) cw_sse &= ~(_FPU_MASK_PM << 7);
asm volatile ("ldmxcsr %0" : : "m" (cw_sse));
}
@@ -43,7 +43,7 @@ set_fpu (void)
#endif
if (options.fpe & GFC_FPE_DENORMAL)
- estr_write ("Fortran runtime warning: IEEE 'denormal number' "
+ estr_write ("Fortran runtime warning: Floating point 'denormal operand' "
"exception not supported.\n");
if (options.fpe & GFC_FPE_ZERO)
@@ -70,11 +70,11 @@ set_fpu (void)
"exception not supported.\n");
#endif
- if (options.fpe & GFC_FPE_PRECISION)
-#ifdef TRP_UNDERFLOW
- mode |= TRP_UNDERFLOW;
+ if (options.fpe & GFC_FPE_INEXACT)
+#ifdef TRP_INEXACT
+ mode |= TRP_INEXACT;
#else
- estr_write ("Fortran runtime warning: IEEE 'loss of precision' "
+ estr_write ("Fortran runtime warning: IEEE 'inexact' "
"exception not supported.\n");
#endif
@@ -35,7 +35,7 @@ set_fpu (void)
estr_write ("Fortran runtime warning: IEEE 'invalid operation' "
"exception not supported.\n");
if (options.fpe & GFC_FPE_DENORMAL)
- estr_write ("Fortran runtime warning: IEEE 'denormal number' "
+ estr_write ("Fortran runtime warning: Floating point 'denormal operand' "
"exception not supported.\n");
if (options.fpe & GFC_FPE_ZERO)
estr_write ("Fortran runtime warning: IEEE 'division by zero' "
@@ -46,7 +46,7 @@ set_fpu (void)
if (options.fpe & GFC_FPE_UNDERFLOW)
estr_write ("Fortran runtime warning: IEEE 'underflow' "
"exception not supported.\n");
- if (options.fpe & GFC_FPE_PRECISION)
- estr_write ("Fortran runtime warning: IEEE 'loss of precision' "
+ if (options.fpe & GFC_FPE_INEXACT)
+ estr_write ("Fortran runtime warning: IEEE 'inexact' "
"exception not supported.\n");
}
@@ -49,7 +49,7 @@ void set_fpu (void)
#ifdef FE_DENORMAL
feenableexcept (FE_DENORMAL);
#else
- estr_write ("Fortran runtime warning: IEEE 'denormal number' "
+ estr_write ("Fortran runtime warning: Floating point 'denormal operand' "
"exception not supported.\n");
#endif
@@ -77,11 +77,11 @@ void set_fpu (void)
"exception not supported.\n");
#endif
- if (options.fpe & GFC_FPE_PRECISION)
+ if (options.fpe & GFC_FPE_INEXACT)
#ifdef FE_INEXACT
feenableexcept (FE_INEXACT);
#else
- estr_write ("Fortran runtime warning: IEEE 'loss of precision' "
+ estr_write ("Fortran runtime warning: IEEE 'inexact' "
"exception not supported.\n");
#endif
}
@@ -42,7 +42,7 @@ set_fpu (void)
#ifdef FP_X_DNML
cw |= FP_X_DNML;
#else
- estr_write ("Fortran runtime warning: IEEE 'denormal number' "
+ estr_write ("Fortran runtime warning: Floating point 'denormal operand' "
"exception not supported.\n");
#endif
@@ -70,11 +70,11 @@ set_fpu (void)
"exception not supported.\n");
#endif
- if (options.fpe & GFC_FPE_PRECISION)
+ if (options.fpe & GFC_FPE_INEXACT)
#ifdef FP_X_IMP
cw |= FP_X_IMP;
#else
- estr_write ("Fortran runtime warning: IEEE 'loss of precision' "
+ estr_write ("Fortran runtime warning: IEEE 'inexact' "
"exception not supported.\n");
#endif