Date: 2021-03-03T22:25:40+00:00

Actual source code: fp.c
petsc-3.14.5 2021-03-03
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      2: /*
      3: *   IEEE error handler for all machines. Since each OS has
      4: *   enough slight differences we have completely separate codes for each one.
      5: *
      6: */

      8: /*
      9:   This feature test macro provides FE_NOMASK_ENV on GNU.  It must be defined
     10:   at the top of the file because other headers may pull in fenv.h even when
     11:   not strictly necessary.  Strictly speaking, we could include ONLY petscconf.h,
     12:   check PETSC_HAVE_FENV_H, and only define _GNU_SOURCE in that case, but such
     13:   shenanigans ought to be unnecessary.
     14: */
     15: #if !defined(_GNU_SOURCE)
     16: #define _GNU_SOURCE
     17: #endif

     19: #include <petscsys.h>
     20: #include <signal.h>

     22: struct PetscFPTrapLink {
     23:   PetscFPTrap            trapmode;
     24:   struct PetscFPTrapLink *next;
     25: };
     26: static PetscFPTrap            _trapmode = PETSC_FP_TRAP_OFF; /* Current trapping mode; see PetscDetermineInitialFPTrap() */
     27: static struct PetscFPTrapLink *_trapstack;                   /* Any pushed states of _trapmode */

     29: /*@
     30:    PetscFPTrapPush - push a floating point trapping mode, restored using PetscFPTrapPop()

     32:    Not Collective

     34:    Input Arguments:
     35: .    trap - PETSC_FP_TRAP_ON or PETSC_FP_TRAP_OFF

     37:    Level: advanced

     39:    Notes:
     40:      This only changes the trapping if the new mode is different than the current mode.

     42:      This routine is called to turn off trapping for certain LAPACK routines that assume that dividing
     43:      by zero is acceptable. In particular the routine ieeeck().

     45:      Most systems by default have all trapping turned off, but certain Fortran compilers have
     46:      link flags that turn on trapping before the program begins.
     47: $       gfortran -ffpe-trap=invalid,zero,overflow,underflow,denormal
     48: $       ifort -fpe0

     50: .seealso: PetscFPTrapPop(), PetscSetFPTrap(), PetscDetermineInitialFPTrap()
     51: @*/
     52: PetscErrorCode PetscFPTrapPush(PetscFPTrap trap)
     53: {
     54:   PetscErrorCode         ierr;
     55:   struct PetscFPTrapLink *link;

     58:   PetscNew(&link);
     59:   link->trapmode = _trapmode;
     60:   link->next     = _trapstack;
     61:   _trapstack     = link;
     62:   if (trap != _trapmode) {PetscSetFPTrap(trap);}
     63:   return(0);
     64: }

     66: /*@
     67:    PetscFPTrapPop - push a floating point trapping mode, to be restored using PetscFPTrapPop()

     69:    Not Collective

     71:    Level: advanced

     73: .seealso: PetscFPTrapPush(), PetscSetFPTrap(), PetscDetermineInitialFPTrap()
     74: @*/
     75: PetscErrorCode PetscFPTrapPop(void)
     76: {
     77:   PetscErrorCode         ierr;
     78:   struct PetscFPTrapLink *link;

     81:   if (_trapstack->trapmode != _trapmode) {PetscSetFPTrap(_trapstack->trapmode);}
     82:   link       = _trapstack;
     83:   _trapstack = _trapstack->next;
     84:   PetscFree(link);
     85:   return(0);
     86: }

     88: /*--------------------------------------- ---------------------------------------------------*/
     89: #if defined(PETSC_HAVE_SUN4_STYLE_FPTRAP)
     90: #include <floatingpoint.h>

     92: PETSC_EXTERN PetscErrorCode ieee_flags(char*,char*,char*,char**);
     93: PETSC_EXTERN PetscErrorCode ieee_handler(char*,char*,sigfpe_handler_type(int,int,struct sigcontext*,char*));

     95: static struct { int code_no; char *name; } error_codes[] = {
     96:   { FPE_INTDIV_TRAP    ,"integer divide" },
     97:   { FPE_FLTOPERR_TRAP  ,"IEEE operand error" },
     98:   { FPE_FLTOVF_TRAP    ,"floating point overflow" },
     99:   { FPE_FLTUND_TRAP    ,"floating point underflow" },
    100:   { FPE_FLTDIV_TRAP    ,"floating pointing divide" },
    101:   { FPE_FLTINEX_TRAP   ,"inexact floating point result" },
    102:   { 0                  ,"unknown error" }
    103: };
    104: #define SIGPC(scp) (scp->sc_pc)

    106: sigfpe_handler_type PetscDefaultFPTrap(int sig,int code,struct sigcontext *scp,char *addr)
    107: {
    109:   int            err_ind = -1,j;

    112:   for (j = 0; error_codes[j].code_no; j++) {
    113:     if (error_codes[j].code_no == code) err_ind = j;
    114:   }

    116:   if (err_ind >= 0) (*PetscErrorPrintf)("*** %s occurred at pc=%X ***\n",error_codes[err_ind].name,SIGPC(scp));
    117:   else              (*PetscErrorPrintf)("*** floating point error 0x%x occurred at pc=%X ***\n",code,SIGPC(scp));

    119:   PetscError(PETSC_COMM_SELF,PETSC_ERR_FP,"User provided function","Unknown file",PETSC_ERR_FP,PETSC_ERROR_REPEAT,"floating point error");
    120:   PETSCABORT(MPI_COMM_WORLD,PETSC_ERR_FP);
    121:   return(0);
    122: }

    124: /*@
    125:    PetscSetFPTrap - Enables traps/exceptions on common floating point errors.
    126:                     This option may not work on certain systems.

    128:    Not Collective

    130:    Input Parameters:
    131: .  flag - PETSC_FP_TRAP_ON, PETSC_FP_TRAP_OFF.

    133:    Options Database Keys:
    134: .  -fp_trap - Activates floating point trapping

    136:    Level: advanced

    138:    Description:
    139:    On systems that support it, when called with PETSC_FP_TRAP_ON this routine causes floating point
    140:    underflow, overflow, divide-by-zero, and invalid-operand (e.g., a NaN) to
    141:    cause a message to be printed and the program to exit.

    143:    Note:
    144:    On many common systems, the floating
    145:    point exception state is not preserved from the location where the trap
    146:    occurred through to the signal handler.  In this case, the signal handler
    147:    will just say that an unknown floating point exception occurred and which
    148:    function it occurred in.  If you run with -fp_trap in a debugger, it will
    149:    break on the line where the error occurred.  On systems that support C99
    150:    floating point exception handling You can check which
    151:    exception occurred using fetestexcept(FE_ALL_EXCEPT).  See fenv.h
    152:    (usually at /usr/include/bits/fenv.h) for the enum values on your system.

    154:    Caution:
    155:    On certain machines, in particular the IBM PowerPC, floating point
    156:    trapping may be VERY slow!

    159: .seealso: PetscFPTrapPush(), PetscFPTrapPop(), PetscDetermineInitialFPTrap()
    160: @*/
    161: PetscErrorCode PetscSetFPTrap(PetscFPTrap flag)
    162: {
    163:   char *out;

    166:   /* Clear accumulated exceptions.  Used to suppress meaningless messages from f77 programs */
    167:   (void) ieee_flags("clear","exception","all",&out);
    168:   if (flag == PETSC_FP_TRAP_ON) {
    169:     /*
    170:       To trap more fp exceptions, including underflow, change the line below to
    171:       if (ieee_handler("set","all",PetscDefaultFPTrap)) {
    172:     */
    173:     if (ieee_handler("set","common",PetscDefaultFPTrap))        (*PetscErrorPrintf)("Can't set floatingpoint handler\n");
    174:   } else if (ieee_handler("clear","common",PetscDefaultFPTrap)) (*PetscErrorPrintf)("Can't clear floatingpoint handler\n");

    176:   _trapmode = flag;
    177:   return(0);
    178: }

    180: /*@
    181:    PetscDetermineInitialFPTrap - Attempts to determine the floating point trapping that exists when PetscInitialize() is called

    183:    Not Collective

    185:    Notes:
    186:       Currently only supported on Linux and MacOS. Checks if divide by zero is enable and if so declares that trapping is on.

    188:    Level: advanced

    190: .seealso: PetscFPTrapPush(), PetscFPTrapPop(), PetscDetermineInitialFPTrap()
    191: @*/
    192: PetscErrorCode  PetscDetermineInitialFPTrap(void)
    193: {

    197:   PetscInfo(NULL,"Unable to determine initial floating point trapping. Assuming it is off\n");
    198:   return(0);
    199: }

    201: /* -------------------------------------------------------------------------------------------*/
    202: #elif defined(PETSC_HAVE_SOLARIS_STYLE_FPTRAP)
    203: #include <sunmath.h>
    204: #include <floatingpoint.h>
    205: #include <siginfo.h>
    206: #include <ucontext.h>

    208: static struct { int code_no; char *name; } error_codes[] = {
    209:   { FPE_FLTINV,"invalid floating point operand"},
    210:   { FPE_FLTRES,"inexact floating point result"},
    211:   { FPE_FLTDIV,"division-by-zero"},
    212:   { FPE_FLTUND,"floating point underflow"},
    213:   { FPE_FLTOVF,"floating point overflow"},
    214:   { 0,         "unknown error"}
    215: };
    216: #define SIGPC(scp) (scp->si_addr)

    218: void PetscDefaultFPTrap(int sig,siginfo_t *scp,ucontext_t *uap)
    219: {
    220:   int            err_ind,j,code = scp->si_code;

    224:   err_ind = -1;
    225:   for (j = 0; error_codes[j].code_no; j++) {
    226:     if (error_codes[j].code_no == code) err_ind = j;
    227:   }

    229:   if (err_ind >= 0) (*PetscErrorPrintf)("*** %s occurred at pc=%X ***\n",error_codes[err_ind].name,SIGPC(scp));
    230:   else              (*PetscErrorPrintf)("*** floating point error 0x%x occurred at pc=%X ***\n",code,SIGPC(scp));

    232:   PetscError(PETSC_COMM_SELF,0,"User provided function","Unknown file",PETSC_ERR_FP,PETSC_ERROR_REPEAT,"floating point error");
    233:   PETSCABORT(MPI_COMM_WORLD,PETSC_ERR_FP);
    234: }

    236: PetscErrorCode PetscSetFPTrap(PetscFPTrap flag)
    237: {
    238:   char *out;

    241:   /* Clear accumulated exceptions.  Used to suppress meaningless messages from f77 programs */
    242:   (void) ieee_flags("clear","exception","all",&out);
    243:   if (flag == PETSC_FP_TRAP_ON) {
    244:     if (ieee_handler("set","common",(sigfpe_handler_type)PetscDefaultFPTrap))        (*PetscErrorPrintf)("Can't set floating point handler\n");
    245:   } else {
    246:     if (ieee_handler("clear","common",(sigfpe_handler_type)PetscDefaultFPTrap)) (*PetscErrorPrintf)("Can't clear floatingpoint handler\n");
    247:   }
    248:   _trapmode = flag;
    249:   return(0);
    250: }

    252: PetscErrorCode  PetscDetermineInitialFPTrap(void)
    253: {

    257:   PetscInfo(NULL,"Unable to determine initial floating point trapping. Assuming it is off\n");
    258:   return(0);
    259: }

    261: /* ------------------------------------------------------------------------------------------*/
    262: #elif defined(PETSC_HAVE_IRIX_STYLE_FPTRAP)
    263: #include <sigfpe.h>
    264: static struct { int code_no; char *name; } error_codes[] = {
    265:   { _INVALID   ,"IEEE operand error" },
    266:   { _OVERFL    ,"floating point overflow" },
    267:   { _UNDERFL   ,"floating point underflow" },
    268:   { _DIVZERO   ,"floating point divide" },
    269:   { 0          ,"unknown error" }
    270: } ;
    271: void PetscDefaultFPTrap(unsigned exception[],int val[])
    272: {
    273:   int err_ind,j,code;

    276:   code    = exception[0];
    277:   err_ind = -1;
    278:   for (j = 0; error_codes[j].code_no; j++) {
    279:     if (error_codes[j].code_no == code) err_ind = j;
    280:   }
    281:   if (err_ind >= 0) (*PetscErrorPrintf)("*** %s occurred ***\n",error_codes[err_ind].name);
    282:   else              (*PetscErrorPrintf)("*** floating point error 0x%x occurred ***\n",code);

    284:   PetscError(PETSC_COMM_SELF,0,"User provided function","Unknown file",PETSC_ERR_FP,PETSC_ERROR_REPEAT,"floating point error");
    285:   PETSCABORT(MPI_COMM_WORLD,PETSC_ERR_FP);
    286: }

    288: PetscErrorCode PetscSetFPTrap(PetscFPTrap flag)
    289: {
    291:   if (flag == PETSC_FP_TRAP_ON) handle_sigfpes(_ON,,_EN_UNDERFL|_EN_OVERFL|_EN_DIVZERO|_EN_INVALID,PetscDefaultFPTrap,_ABORT_ON_ERROR,0);
    292:   else                          handle_sigfpes(_OFF,_EN_UNDERFL|_EN_OVERFL|_EN_DIVZERO|_EN_INVALID,0,_ABORT_ON_ERROR,0);
    293:   _trapmode = flag;
    294:   return(0);
    295: }

    297: PetscErrorCode  PetscDetermineInitialFPTrap(void)
    298: {

    302:   PetscInfo(NULL,"Unable to determine initial floating point trapping. Assuming it is off\n");
    303:   return(0);
    304: }

    306: /* -------------------------------------------------------------------------------------------*/
    307: #elif defined(PETSC_HAVE_SOLARIS_STYLE_FPTRAP)
    308: #include <sunmath.h>
    309: #include <floatingpoint.h>
    310: #include <siginfo.h>
    311: #include <ucontext.h>

    313: static struct { int code_no; char *name; } error_codes[] = {
    314:   { FPE_FLTINV,"invalid floating point operand"},
    315:   { FPE_FLTRES,"inexact floating point result"},
    316:   { FPE_FLTDIV,"division-by-zero"},
    317:   { FPE_FLTUND,"floating point underflow"},
    318:   { FPE_FLTOVF,"floating point overflow"},
    319:   { 0,         "unknown error"}
    320: };
    321: #define SIGPC(scp) (scp->si_addr)

    323: void PetscDefaultFPTrap(int sig,siginfo_t *scp,ucontext_t *uap)
    324: {
    325:   int            err_ind,j,code = scp->si_code;

    329:   err_ind = -1;
    330:   for (j = 0; error_codes[j].code_no; j++) {
    331:     if (error_codes[j].code_no == code) err_ind = j;
    332:   }

    334:   if (err_ind >= 0) (*PetscErrorPrintf)("*** %s occurred at pc=%X ***\n",error_codes[err_ind].name,SIGPC(scp));
    335:   else              (*PetscErrorPrintf)("*** floating point error 0x%x occurred at pc=%X ***\n",code,SIGPC(scp));

    337:   PetscError(PETSC_COMM_SELF,0,"User provided function","Unknown file",PETSC_ERR_FP,PETSC_ERROR_REPEAT,"floating point error");
    338:   PETSCABORT(MPI_COMM_WORLD,PETSC_ERR_FP);
    339: }

    341: PetscErrorCode PetscSetFPTrap(PetscFPTrap flag)
    342: {
    343:   char *out;

    346:   /* Clear accumulated exceptions.  Used to suppress meaningless messages from f77 programs */
    347:   (void) ieee_flags("clear","exception","all",&out);
    348:   if (flag == PETSC_FP_TRAP_ON) {
    349:     if (ieee_handler("set","common",(sigfpe_handler_type)PetscDefaultFPTrap))        (*PetscErrorPrintf)("Can't set floating point handler\n");
    350:   } else {
    351:     if (ieee_handler("clear","common",(sigfpe_handler_type)PetscDefaultFPTrap)) (*PetscErrorPrintf)("Can't clear floatingpoint handler\n");
    352:   }
    353:   _trapmode = flag;
    354:   return(0);
    355: }

    357: PetscErrorCode  PetscDetermineInitialFPTrap(void)
    358: {

    362:   PetscInfo(NULL,"Unable to determine initial floating point trapping. Assuming it is off\n");
    363:   return(0);
    364: }

    366: /*----------------------------------------------- --------------------------------------------*/
    367: #elif defined(PETSC_HAVE_RS6000_STYLE_FPTRAP)
    368: /* In "fast" mode, floating point traps are imprecise and ignored.
    369:    This is the reason for the fptrap(FP_TRAP_SYNC) call */
    370: struct sigcontext;
    371: #include <fpxcp.h>
    372: #include <fptrap.h>
    373: #define FPE_FLTOPERR_TRAP (fptrap_t)(0x20000000)
    374: #define FPE_FLTOVF_TRAP   (fptrap_t)(0x10000000)
    375: #define FPE_FLTUND_TRAP   (fptrap_t)(0x08000000)
    376: #define FPE_FLTDIV_TRAP   (fptrap_t)(0x04000000)
    377: #define FPE_FLTINEX_TRAP  (fptrap_t)(0x02000000)

    379: static struct { int code_no; char *name; } error_codes[] = {
    380:   {FPE_FLTOPERR_TRAP   ,"IEEE operand error" },
    381:   { FPE_FLTOVF_TRAP    ,"floating point overflow" },
    382:   { FPE_FLTUND_TRAP    ,"floating point underflow" },
    383:   { FPE_FLTDIV_TRAP    ,"floating point divide" },
    384:   { FPE_FLTINEX_TRAP   ,"inexact floating point result" },
    385:   { 0                  ,"unknown error" }
    386: } ;
    387: #define SIGPC(scp) (0) /* Info MIGHT be in scp->sc_jmpbuf.jmp_context.iar */
    388: /*
    389:    For some reason, scp->sc_jmpbuf does not work on the RS6000, even though
    390:    it looks like it should from the include definitions.  It is probably
    391:    some strange interaction with the "POSIX_SOURCE" that we require.
    392: */

    394: void PetscDefaultFPTrap(int sig,int code,struct sigcontext *scp)
    395: {
    397:   int            err_ind,j;
    398:   fp_ctx_t       flt_context;

    401:   fp_sh_trap_info(scp,&flt_context);

    403:   err_ind = -1;
    404:   for (j = 0; error_codes[j].code_no; j++) {
    405:     if (error_codes[j].code_no == flt_context.trap) err_ind = j;
    406:   }

    408:   if (err_ind >= 0) (*PetscErrorPrintf)("*** %s occurred ***\n",error_codes[err_ind].name);
    409:   else              (*PetscErrorPrintf)("*** floating point error 0x%x occurred ***\n",flt_context.trap);

    411:   PetscError(PETSC_COMM_SELF,0,"User provided function","Unknown file",PETSC_ERR_FP,PETSC_ERROR_REPEAT,"floating point error");
    412:   PETSCABORT(MPI_COMM_WORLD,PETSC_ERR_FP);
    413: }

    415: PetscErrorCode PetscSetFPTrap(PetscFPTrap on)
    416: {
    418:   if (on == PETSC_FP_TRAP_ON) {
    419:     signal(SIGFPE,(void (*)(int))PetscDefaultFPTrap);
    420:     fp_trap(FP_TRAP_SYNC);
    421:     fp_enable(TRP_INVALID | TRP_DIV_BY_ZERO | TRP_OVERFLOW | TRP_UNDERFLOW);
    422:     /* fp_enable(mask) for individual traps.  Values are:
    423:        TRP_INVALID
    424:        TRP_DIV_BY_ZERO
    425:        TRP_OVERFLOW
    426:        TRP_UNDERFLOW
    427:        TRP_INEXACT
    428:        Can OR then together.
    429:        fp_enable_all(); for all traps.
    430:     */
    431:   } else {
    432:     signal(SIGFPE,SIG_DFL);
    433:     fp_disable(TRP_INVALID | TRP_DIV_BY_ZERO | TRP_OVERFLOW | TRP_UNDERFLOW);
    434:     fp_trap(FP_TRAP_OFF);
    435:   }
    436:   _trapmode = on;
    437:   return(0);
    438: }

    440: PetscErrorCode  PetscDetermineInitialFPTrap(void)
    441: {

    445:   PetscInfo(NULL,"Unable to determine initial floating point trapping. Assuming it is off\n");
    446:   return(0);
    447: }

    449: /* ------------------------------------------------------------*/
    450: #elif defined(PETSC_HAVE_WINDOWS_COMPILERS)
    451: #include <float.h>
    452: void PetscDefaultFPTrap(int sig)
    453: {
    455:   (*PetscErrorPrintf)("*** floating point error occurred ***\n");
    456:   PetscError(PETSC_COMM_SELF,0,"User provided function","Unknown file",PETSC_ERR_FP,PETSC_ERROR_REPEAT,"floating point error");
    457:   PETSCABORT(MPI_COMM_WORLD,PETSC_ERR_FP);
    458: }

    460: PetscErrorCode  PetscSetFPTrap(PetscFPTrap on)
    461: {
    462:   unsigned int cw;

    465:   if (on == PETSC_FP_TRAP_ON) {
    466:     cw = _EM_INVALID | _EM_ZERODIVIDE | _EM_OVERFLOW | _EM_UNDERFLOW;
    467:     if (SIG_ERR == signal(SIGFPE,PetscDefaultFPTrap)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Can't set floating point handler\n");
    468:   } else {
    469:     cw = 0;
    470:     if (SIG_ERR == signal(SIGFPE,SIG_DFL)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Can't clear floating point handler\n");
    471:   }
    472:   (void)_controlfp(0, cw);
    473:   _trapmode = on;
    474:   return(0);
    475: }

    477: PetscErrorCode  PetscDetermineInitialFPTrap(void)
    478: {

    482:   PetscInfo(NULL,"Unable to determine initial floating point trapping. Assuming it is off\n");
    483:   return(0);
    484: }

    486: /* ------------------------------------------------------------*/
    487: #elif defined(PETSC_HAVE_FENV_H) && !defined(__cplusplus)
    488: /*
    489:    C99 style floating point environment.

    491:    Note that C99 merely specifies how to save, restore, and clear the floating
    492:    point environment as well as defining an enumeration of exception codes.  In
    493:    particular, C99 does not specify how to make floating point exceptions raise
    494:    a signal.  Glibc offers this capability through FE_NOMASK_ENV (or with finer
    495:    granularity, feenableexcept()), xmmintrin.h offers _MM_SET_EXCEPTION_MASK().
    496: */
    497: #include <fenv.h>
    498: typedef struct {int code; const char *name;} FPNode;
    499: static const FPNode error_codes[] = {
    500:   {FE_DIVBYZERO,"divide by zero"},
    501:   {FE_INEXACT,  "inexact floating point result"},
    502:   {FE_INVALID,  "invalid floating point arguments (domain error)"},
    503:   {FE_OVERFLOW, "floating point overflow"},
    504:   {FE_UNDERFLOW,"floating point underflow"},
    505:   {0           ,"unknown error"}
    506: };

    508: void PetscDefaultFPTrap(int sig)
    509: {
    510:   const FPNode *node;
    511:   int          code;
    512:   PetscBool    matched = PETSC_FALSE;

    515:   /* Note: While it is possible for the exception state to be preserved by the
    516:    * kernel, this seems to be rare which makes the following flag testing almost
    517:    * useless.  But on a system where the flags can be preserved, it would provide
    518:    * more detail.
    519:    */
    520:   code = fetestexcept(FE_ALL_EXCEPT);
    521:   for (node=&error_codes[0]; node->code; node++) {
    522:     if (code & node->code) {
    523:       matched = PETSC_TRUE;
    524:       (*PetscErrorPrintf)("*** floating point error \"%s\" occurred ***\n",node->name);
    525:       code &= ~node->code; /* Unset this flag since it has been processed */
    526:     }
    527:   }
    528:   if (!matched || code) { /* If any remaining flags are set, or we didn't process any flags */
    529:     (*PetscErrorPrintf)("*** unknown floating point error occurred ***\n");
    530:     (*PetscErrorPrintf)("The specific exception can be determined by running in a debugger.  When the\n");
    531:     (*PetscErrorPrintf)("debugger traps the signal, the exception can be found with fetestexcept(0x%x)\n",FE_ALL_EXCEPT);
    532:     (*PetscErrorPrintf)("where the result is a bitwise OR of the following flags:\n");
    533:     (*PetscErrorPrintf)("FE_INVALID=0x%x FE_DIVBYZERO=0x%x FE_OVERFLOW=0x%x FE_UNDERFLOW=0x%x FE_INEXACT=0x%x\n",FE_INVALID,FE_DIVBYZERO,FE_OVERFLOW,FE_UNDERFLOW,FE_INEXACT);
    534:   }

    536:   (*PetscErrorPrintf)("Try option -start_in_debugger\n");
    537:   if (PetscDefined(USE_DEBUG)) {
    538:     if (!PetscStackActive()) (*PetscErrorPrintf)("  or try option -log_stack\n");
    539:     else {
    540:       (*PetscErrorPrintf)("likely location of problem given in stack below\n");
    541:       (*PetscErrorPrintf)("---------------------  Stack Frames ------------------------------------\n");
    542:       PetscStackView(PETSC_STDOUT);
    543:     }
    544:   } else {
    545:     (*PetscErrorPrintf)("configure using --with-debugging=yes, recompile, link, and run \n");
    546:     (*PetscErrorPrintf)("with -start_in_debugger to get more information on the crash.\n");
    547:   }
    548:   PetscError(PETSC_COMM_SELF,0,"User provided function","Unknown file",PETSC_ERR_FP,PETSC_ERROR_INITIAL,"trapped floating point error");
    549:   PETSCABORT(MPI_COMM_WORLD,PETSC_ERR_FP);
    550: }

    552: PetscErrorCode  PetscSetFPTrap(PetscFPTrap on)
    553: {
    555:   if (on == PETSC_FP_TRAP_ON) {
    556:     /* Clear any flags that are currently set so that activating trapping will not immediately call the signal handler. */
    557:     if (feclearexcept(FE_ALL_EXCEPT)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Cannot clear floating point exception flags\n");
    558: #if defined(FE_NOMASK_ENV)
    559:     /* Could use fesetenv(FE_NOMASK_ENV), but that causes spurious exceptions (like gettimeofday() -> PetscLogDouble). */
    560:     if (feenableexcept(FE_DIVBYZERO | FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW) == -1) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Cannot activate floating point exceptions\n");
    561: #elif defined PETSC_HAVE_XMMINTRIN_H
    562:    _MM_SET_EXCEPTION_MASK(_MM_GET_EXCEPTION_MASK() & ~_MM_MASK_DIV_ZERO);
    563:    _MM_SET_EXCEPTION_MASK(_MM_GET_EXCEPTION_MASK() & ~_MM_MASK_UNDERFLOW);
    564:    _MM_SET_EXCEPTION_MASK(_MM_GET_EXCEPTION_MASK() & ~_MM_MASK_OVERFLOW);
    565:    _MM_SET_EXCEPTION_MASK(_MM_GET_EXCEPTION_MASK() & ~_MM_MASK_INVALID);
    566: #else
    567:     /* C99 does not provide a way to modify the environment so there is no portable way to activate trapping. */
    568: #endif
    569:     if (SIG_ERR == signal(SIGFPE,PetscDefaultFPTrap)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Can't set floating point handler\n");
    570:   } else {
    571:     if (fesetenv(FE_DFL_ENV)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Cannot disable floating point exceptions");
    572:     /* can use _MM_SET_EXCEPTION_MASK(_MM_GET_EXCEPTION_MASK() | _MM_MASK_UNDERFLOW); if PETSC_HAVE_XMMINTRIN_H exists */
    573:     if (SIG_ERR == signal(SIGFPE,SIG_DFL)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Can't clear floating point handler\n");
    574:   }
    575:   _trapmode = on;
    576:   return(0);
    577: }

    579: PetscErrorCode  PetscDetermineInitialFPTrap(void)
    580: {
    581: #if defined(FE_NOMASK_ENV) || defined PETSC_HAVE_XMMINTRIN_H
    582:   unsigned int   flags;
    583: #endif

    587: #if defined(FE_NOMASK_ENV)
    588:   flags = fegetexcept();
    589:   if (flags & FE_DIVBYZERO) {
    590: #elif defined PETSC_HAVE_XMMINTRIN_H
    591:   flags = _MM_GET_EXCEPTION_MASK();
    592:   if (!(flags & _MM_MASK_DIV_ZERO)) {
    593: #else
    594:   PetscInfo(NULL,"Floating point trapping unknown, assuming off\n");
    595:   return(0);
    596: #endif
    597: #if defined(FE_NOMASK_ENV) || defined PETSC_HAVE_XMMINTRIN_H
    598:     _trapmode = PETSC_FP_TRAP_ON;
    599:     PetscInfo1(NULL,"Floating point trapping is on by default %d\n",flags);
    600:   } else {
    601:     _trapmode = PETSC_FP_TRAP_OFF;
    602:     PetscInfo1(NULL,"Floating point trapping is off by default %d\n",flags);
    603:   }
    604:   return(0);
    605: #endif
    606: }

    608: /* ------------------------------------------------------------*/
    609: #elif defined(PETSC_HAVE_IEEEFP_H)
    610: #include <ieeefp.h>
    611: void PetscDefaultFPTrap(int sig)
    612: {
    614:   (*PetscErrorPrintf)("*** floating point error occurred ***\n");
    615:   PetscError(PETSC_COMM_SELF,0,"User provided function","Unknown file",PETSC_ERR_FP,PETSC_ERROR_REPEAT,"floating point error");
    616:   PETSCABORT(MPI_COMM_WORLD,PETSC_ERR_FP);
    617: }

    619: PetscErrorCode  PetscSetFPTrap(PetscFPTrap on)
    620: {
    622:   if (on == PETSC_FP_TRAP_ON) {
    623: #if defined(PETSC_HAVE_FPPRESETSTICKY)
    624:     fpresetsticky(fpgetsticky());
    625: #elif defined(PETSC_HAVE_FPSETSTICKY)
    626:     fpsetsticky(fpgetsticky());
    627: #endif
    628:     fpsetmask(FP_X_INV | FP_X_DZ | FP_X_OFL |  FP_X_OFL);
    629:     if (SIG_ERR == signal(SIGFPE,PetscDefaultFPTrap)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Can't set floating point handler\n");
    630:   } else {
    631: #if defined(PETSC_HAVE_FPPRESETSTICKY)
    632:     fpresetsticky(fpgetsticky());
    633: #elif defined(PETSC_HAVE_FPSETSTICKY)
    634:     fpsetsticky(fpgetsticky());
    635: #endif
    636:     fpsetmask(0);
    637:     if (SIG_ERR == signal(SIGFPE,SIG_DFL)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Can't clear floating point handler\n");
    638:   }
    639:   _trapmode = on;
    640:   return(0);
    641: }

    643: PetscErrorCode  PetscDetermineInitialFPTrap(void)
    644: {

    648:   PetscInfo(NULL,"Unable to determine initial floating point trapping. Assuming it is off\n");
    649:   return(0);
    650: }

    652: /* -------------------------Default -----------------------------------*/
    653: #else

    655: void PetscDefaultFPTrap(int sig)
    656: {
    658:   (*PetscErrorPrintf)("*** floating point error occurred ***\n");
    659:   PetscError(PETSC_COMM_SELF,0,"User provided function","Unknown file",PETSC_ERR_FP,PETSC_ERROR_REPEAT,"floating point error");
    660:   PETSCABORT(MPI_COMM_WORLD,PETSC_ERR_FP);
    661: }

    663: PetscErrorCode  PetscSetFPTrap(PetscFPTrap on)
    664: {
    666:   if (on == PETSC_FP_TRAP_ON) {
    667:     if (SIG_ERR == signal(SIGFPE,PetscDefaultFPTrap)) (*PetscErrorPrintf)("Can't set floatingpoint handler\n");
    668:   } else if (SIG_ERR == signal(SIGFPE,SIG_DFL))       (*PetscErrorPrintf)("Can't clear floatingpoint handler\n");

    670:   _trapmode = on;
    671:   return(0);
    672: }

    674: PetscErrorCode  PetscDetermineInitialFPTrap(void)
    675: {

    679:   PetscInfo(NULL,"Unable to determine initial floating point trapping. Assuming it is off\n");
    680:   return(0);
    681: }
    682: #endif