/* FPU-related code for x86 and x86_64 processors.
- Copyright (C) 2005-2014 Free Software Foundation, Inc.
+ Copyright (C) 2005-2018 Free Software Foundation, Inc.
Contributed by Francois-Xavier Coudert <coudert@clipper.ens.fr>
This file is part of the GNU Fortran 95 runtime library (libgfortran).
#define _FPU_RC_MASK 0x3
+/* Enable flush to zero mode. */
+
+#define MXCSR_FTZ (1 << 15)
+
+
+/* This structure corresponds to the layout of the block
+ written by FSTENV. */
+typedef struct
+{
+ unsigned short int __control_word;
+ unsigned short int __unused1;
+ unsigned short int __status_word;
+ unsigned short int __unused2;
+ unsigned short int __tags;
+ unsigned short int __unused3;
+ unsigned int __eip;
+ unsigned short int __cs_selector;
+ unsigned short int __opcode;
+ unsigned int __data_offset;
+ unsigned short int __data_selector;
+ unsigned short int __unused5;
+ unsigned int __mxcsr;
+}
+my_fenv_t;
+
+/* Check we can actually store the FPU state in the allocated size. */
+_Static_assert (sizeof(my_fenv_t) <= (size_t) GFC_FPE_STATE_BUFFER_SIZE,
+ "GFC_FPE_STATE_BUFFER_SIZE is too small");
+
+
+/* Raise the supported floating-point exceptions from EXCEPTS. Other
+ bits in EXCEPTS are ignored. Code originally borrowed from
+ libatomic/config/x86/fenv.c. */
+
+static void
+local_feraiseexcept (int excepts)
+{
+ if (excepts & _FPU_MASK_IM)
+ {
+ float f = 0.0f;
+#ifdef __SSE_MATH__
+ volatile float r __attribute__ ((unused));
+ __asm__ __volatile__ ("%vdivss\t{%0, %d0|%d0, %0}" : "+x" (f));
+ r = f; /* Needed to trigger exception. */
+#else
+ __asm__ __volatile__ ("fdiv\t{%y0, %0|%0, %y0}" : "+t" (f));
+ /* No need for fwait, exception is triggered by emitted fstp. */
+#endif
+ }
+ if (excepts & _FPU_MASK_DM)
+ {
+ my_fenv_t temp;
+ __asm__ __volatile__ ("fnstenv\t%0" : "=m" (temp));
+ temp.__status_word |= _FPU_MASK_DM;
+ __asm__ __volatile__ ("fldenv\t%0" : : "m" (temp));
+ __asm__ __volatile__ ("fwait");
+ }
+ if (excepts & _FPU_MASK_ZM)
+ {
+ float f = 1.0f, g = 0.0f;
+#ifdef __SSE_MATH__
+ volatile float r __attribute__ ((unused));
+ __asm__ __volatile__ ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
+ r = f; /* Needed to trigger exception. */
+#else
+ __asm__ __volatile__ ("fdivs\t%1" : "+t" (f) : "m" (g));
+ /* No need for fwait, exception is triggered by emitted fstp. */
+#endif
+ }
+ if (excepts & _FPU_MASK_OM)
+ {
+ my_fenv_t temp;
+ __asm__ __volatile__ ("fnstenv\t%0" : "=m" (temp));
+ temp.__status_word |= _FPU_MASK_OM;
+ __asm__ __volatile__ ("fldenv\t%0" : : "m" (temp));
+ __asm__ __volatile__ ("fwait");
+ }
+ if (excepts & _FPU_MASK_UM)
+ {
+ my_fenv_t temp;
+ __asm__ __volatile__ ("fnstenv\t%0" : "=m" (temp));
+ temp.__status_word |= _FPU_MASK_UM;
+ __asm__ __volatile__ ("fldenv\t%0" : : "m" (temp));
+ __asm__ __volatile__ ("fwait");
+ }
+ if (excepts & _FPU_MASK_PM)
+ {
+ float f = 1.0f, g = 3.0f;
+#ifdef __SSE_MATH__
+ volatile float r __attribute__ ((unused));
+ __asm__ __volatile__ ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
+ r = f; /* Needed to trigger exception. */
+#else
+ __asm__ __volatile__ ("fdivs\t%1" : "+t" (f) : "m" (g));
+ /* No need for fwait, exception is triggered by emitted fstp. */
+#endif
+ }
+}
+
void
-set_fpu (void)
+set_fpu_trap_exceptions (int trap, int notrap)
{
- int excepts = 0;
+ int exc_set = 0, exc_clr = 0;
unsigned short cw;
- __asm__ __volatile__ ("fstcw\t%0" : "=m" (cw));
+ if (trap & GFC_FPE_INVALID) exc_set |= _FPU_MASK_IM;
+ if (trap & GFC_FPE_DENORMAL) exc_set |= _FPU_MASK_DM;
+ if (trap & GFC_FPE_ZERO) exc_set |= _FPU_MASK_ZM;
+ if (trap & GFC_FPE_OVERFLOW) exc_set |= _FPU_MASK_OM;
+ if (trap & GFC_FPE_UNDERFLOW) exc_set |= _FPU_MASK_UM;
+ if (trap & GFC_FPE_INEXACT) exc_set |= _FPU_MASK_PM;
+
+ if (notrap & GFC_FPE_INVALID) exc_clr |= _FPU_MASK_IM;
+ if (notrap & GFC_FPE_DENORMAL) exc_clr |= _FPU_MASK_DM;
+ if (notrap & GFC_FPE_ZERO) exc_clr |= _FPU_MASK_ZM;
+ if (notrap & GFC_FPE_OVERFLOW) exc_clr |= _FPU_MASK_OM;
+ if (notrap & GFC_FPE_UNDERFLOW) exc_clr |= _FPU_MASK_UM;
+ if (notrap & GFC_FPE_INEXACT) exc_clr |= _FPU_MASK_PM;
- if (options.fpe & GFC_FPE_INVALID) excepts |= _FPU_MASK_IM;
- if (options.fpe & GFC_FPE_DENORMAL) excepts |= _FPU_MASK_DM;
- if (options.fpe & GFC_FPE_ZERO) excepts |= _FPU_MASK_ZM;
- if (options.fpe & GFC_FPE_OVERFLOW) excepts |= _FPU_MASK_OM;
- if (options.fpe & GFC_FPE_UNDERFLOW) excepts |= _FPU_MASK_UM;
- if (options.fpe & GFC_FPE_INEXACT) excepts |= _FPU_MASK_PM;
+ __asm__ __volatile__ ("fstcw\t%0" : "=m" (cw));
- cw |= _FPU_MASK_ALL;
- cw &= ~excepts;
+ cw |= exc_clr;
+ cw &= ~exc_set;
__asm__ __volatile__ ("fnclex\n\tfldcw\t%0" : : "m" (cw));
__asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (cw_sse));
/* The SSE exception masks are shifted by 7 bits. */
- cw_sse |= _FPU_MASK_ALL << 7;
- cw_sse &= ~(excepts << 7);
+ cw_sse |= (exc_clr << 7);
+ cw_sse &= ~(exc_set << 7);
/* Clear stalled exception flags. */
cw_sse &= ~_FPU_EX_ALL;
}
}
+void
+set_fpu (void)
+{
+ set_fpu_trap_exceptions (options.fpe, 0);
+}
+
+int
+get_fpu_trap_exceptions (void)
+{
+ unsigned short cw;
+ int mask;
+ int res = 0;
+
+ __asm__ __volatile__ ("fstcw\t%0" : "=m" (cw));
+ mask = cw;
+
+ if (has_sse())
+ {
+ unsigned int cw_sse;
+
+ __asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (cw_sse));
+
+ /* The SSE exception masks are shifted by 7 bits. */
+ mask |= (cw_sse >> 7);
+ }
+
+ mask = ~mask & _FPU_MASK_ALL;
+
+ if (mask & _FPU_MASK_IM) res |= GFC_FPE_INVALID;
+ if (mask & _FPU_MASK_DM) res |= GFC_FPE_DENORMAL;
+ if (mask & _FPU_MASK_ZM) res |= GFC_FPE_ZERO;
+ if (mask & _FPU_MASK_OM) res |= GFC_FPE_OVERFLOW;
+ if (mask & _FPU_MASK_UM) res |= GFC_FPE_UNDERFLOW;
+ if (mask & _FPU_MASK_PM) res |= GFC_FPE_INEXACT;
+
+ return res;
+}
+
+int
+support_fpu_trap (int flag __attribute__((unused)))
+{
+ return 1;
+}
+
int
get_fpu_except_flags (void)
{
unsigned short cw;
int excepts;
- int result = 0;
+ int res = 0;
- __asm__ __volatile__ ("fnstsw\t%0" : "=a" (cw));
+ __asm__ __volatile__ ("fnstsw\t%0" : "=am" (cw));
excepts = cw;
if (has_sse())
excepts &= _FPU_EX_ALL;
- if (excepts & _FPU_MASK_IM) result |= GFC_FPE_INVALID;
- if (excepts & _FPU_MASK_DM) result |= GFC_FPE_DENORMAL;
- if (excepts & _FPU_MASK_ZM) result |= GFC_FPE_ZERO;
- if (excepts & _FPU_MASK_OM) result |= GFC_FPE_OVERFLOW;
- if (excepts & _FPU_MASK_UM) result |= GFC_FPE_UNDERFLOW;
- if (excepts & _FPU_MASK_PM) result |= GFC_FPE_INEXACT;
+ if (excepts & _FPU_MASK_IM) res |= GFC_FPE_INVALID;
+ if (excepts & _FPU_MASK_DM) res |= GFC_FPE_DENORMAL;
+ if (excepts & _FPU_MASK_ZM) res |= GFC_FPE_ZERO;
+ if (excepts & _FPU_MASK_OM) res |= GFC_FPE_OVERFLOW;
+ if (excepts & _FPU_MASK_UM) res |= GFC_FPE_UNDERFLOW;
+ if (excepts & _FPU_MASK_PM) res |= GFC_FPE_INEXACT;
- return result;
+ return res;
+}
+
+void
+set_fpu_except_flags (int set, int clear)
+{
+ my_fenv_t temp;
+ int exc_set = 0, exc_clr = 0;
+
+ /* Translate from GFC_PE_* values to _FPU_MASK_* values. */
+ if (set & GFC_FPE_INVALID)
+ exc_set |= _FPU_MASK_IM;
+ if (clear & GFC_FPE_INVALID)
+ exc_clr |= _FPU_MASK_IM;
+
+ if (set & GFC_FPE_DENORMAL)
+ exc_set |= _FPU_MASK_DM;
+ if (clear & GFC_FPE_DENORMAL)
+ exc_clr |= _FPU_MASK_DM;
+
+ if (set & GFC_FPE_ZERO)
+ exc_set |= _FPU_MASK_ZM;
+ if (clear & GFC_FPE_ZERO)
+ exc_clr |= _FPU_MASK_ZM;
+
+ if (set & GFC_FPE_OVERFLOW)
+ exc_set |= _FPU_MASK_OM;
+ if (clear & GFC_FPE_OVERFLOW)
+ exc_clr |= _FPU_MASK_OM;
+
+ if (set & GFC_FPE_UNDERFLOW)
+ exc_set |= _FPU_MASK_UM;
+ if (clear & GFC_FPE_UNDERFLOW)
+ exc_clr |= _FPU_MASK_UM;
+
+ if (set & GFC_FPE_INEXACT)
+ exc_set |= _FPU_MASK_PM;
+ if (clear & GFC_FPE_INEXACT)
+ exc_clr |= _FPU_MASK_PM;
+
+
+ /* Change the flags. This is tricky on 387 (unlike SSE), because we have
+ FNSTSW but no FLDSW instruction. */
+ __asm__ __volatile__ ("fnstenv\t%0" : "=m" (temp));
+ temp.__status_word &= ~exc_clr;
+ __asm__ __volatile__ ("fldenv\t%0" : : "m" (temp));
+
+ /* Change the flags on SSE. */
+
+ if (has_sse())
+ {
+ unsigned int cw_sse;
+
+ __asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (cw_sse));
+ cw_sse &= ~exc_clr;
+ __asm__ __volatile__ ("%vldmxcsr\t%0" : : "m" (cw_sse));
+ }
+
+ local_feraiseexcept (exc_set);
+}
+
+int
+support_fpu_flag (int flag __attribute__((unused)))
+{
+ return 1;
}
void
case _FPU_RC_ZERO:
return GFC_FPE_TOWARDZERO;
default:
- return GFC_FPE_INVALID; /* Should be unreachable. */
+ return 0; /* Should be unreachable. */
}
}
+
+int
+support_fpu_rounding_mode (int mode __attribute__((unused)))
+{
+ return 1;
+}
+
+void
+get_fpu_state (void *state)
+{
+ my_fenv_t *envp = state;
+
+ __asm__ __volatile__ ("fnstenv\t%0" : "=m" (*envp));
+
+ /* fnstenv has the side effect of masking all exceptions, so we need
+ to restore the control word after that. */
+ __asm__ __volatile__ ("fldcw\t%0" : : "m" (envp->__control_word));
+
+ if (has_sse())
+ __asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (envp->__mxcsr));
+}
+
+void
+set_fpu_state (void *state)
+{
+ my_fenv_t *envp = state;
+
+ /* glibc sources (sysdeps/x86_64/fpu/fesetenv.c) do something more
+ complex than this, but I think it suffices in our case. */
+ __asm__ __volatile__ ("fldenv\t%0" : : "m" (*envp));
+
+ if (has_sse())
+ __asm__ __volatile__ ("%vldmxcsr\t%0" : : "m" (envp->__mxcsr));
+}
+
+
+int
+support_fpu_underflow_control (int kind)
+{
+ if (!has_sse())
+ return 0;
+
+ return (kind == 4 || kind == 8) ? 1 : 0;
+}
+
+
+int
+get_fpu_underflow_mode (void)
+{
+ unsigned int cw_sse;
+
+ if (!has_sse())
+ return 1;
+
+ __asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (cw_sse));
+
+ /* Return 0 for abrupt underflow (flush to zero), 1 for gradual underflow. */
+ return (cw_sse & MXCSR_FTZ) ? 0 : 1;
+}
+
+
+void
+set_fpu_underflow_mode (int gradual)
+{
+ unsigned int cw_sse;
+
+ if (!has_sse())
+ return;
+
+ __asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (cw_sse));
+
+ if (gradual)
+ cw_sse &= ~MXCSR_FTZ;
+ else
+ cw_sse |= MXCSR_FTZ;
+
+ __asm__ __volatile__ ("%vldmxcsr\t%0" : : "m" (cw_sse));
+}
+
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