Merge pull request #1811 from bjorng/bjorn/disable-fpe-support

Disable the use of floating point exceptions

2 files changed, 8 insertions, 565 deletions

diff --git a/erts/configure.in b/erts/configure.in
index d1c5fe324b..f66445ec25 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -2701,570 +2701,13 @@ if test X${enable_hipe} = Xyes; then
 fi
 AC_SUBST(HIPEBEAMLDFLAGS)
 
-if test X${enable_fp_exceptions} = Xauto ; then
-   case $host_os in
-   	*linux*)
-	      enable_fp_exceptions=no
-	      AC_MSG_NOTICE([Floating point exceptions disabled by default on Linux]) ;;
-	darwin*)
-	      enable_fp_exceptions=no
-	      AC_MSG_NOTICE([Floating point exceptions disabled by default on MacOS X]) ;;
-	      *)
-	      ;;
-    esac
-fi
-
-if test X${enable_fp_exceptions} = Xauto ; then
-   if test X${enable_hipe} = Xyes; then
-      enable_fp_exceptions=yes
-   else
-      enable_fp_exceptions=no
-   AC_MSG_NOTICE([Floating point exceptions disabled by default in this configuration])
-   fi
-fi	 
-
-if test X${enable_fp_exceptions} != Xyes ; then
-    AC_DEFINE(NO_FPE_SIGNALS,[],[Define if floating points exceptions are non-existing/not reliable])
-    FPE=unreliable
-else
-
-    AC_MSG_CHECKING([for unreliable floating point exceptions])
-
-
-    AC_TRY_RUN([
-/* fpe-test.c */
-#include <stdio.h>
-#include <signal.h>
-#include <stdlib.h>
-
-#if defined(__clang__) || defined(__llvm__)
-#error "Clang/LLVM generates broken code for FP exceptions"
-#endif
-
-volatile int erl_fp_exception;
-
-/*
- * We expect a single SIGFPE in this test program.
- * Getting many more indicates an inadequate SIGFPE handler,
- * e.g. using the generic handler on x86.
- */
-static void new_fp_exception(void)
-{
-    if (++erl_fp_exception > 50) {
-	fprintf(stderr, "SIGFPE loop detected, bailing out\n");
-	exit(1);
-    }
-}
-
-/* Is there no standard identifier for Darwin/MacOSX ? */
-#if defined(__APPLE__) && defined(__MACH__) && !defined(__DARWIN__)
-#define __DARWIN__ 1
-#endif
-
-/*
- * Implement unmask_fpe() and check_fpe() based on CPU/OS combination
- */
-
-#if (defined(__i386__) || defined(__x86_64__)) && defined(__GNUC__) && !defined(__CYGWIN__) && !defined(__MINGW32__)
-
-static void unmask_x87(void)
-{
-    unsigned short cw;
-    __asm__ __volatile__("fstcw %0" : "=m"(cw));
-    cw &= ~(0x01|0x04|0x08);   /* unmask IM, ZM, OM */
-    __asm__ __volatile__("fldcw %0" : : "m"(cw));
-}
-
-static void unmask_sse2(void)
-{
-    unsigned int mxcsr;
-    __asm__ __volatile__("stmxcsr %0" : "=m"(mxcsr));
-    mxcsr &= ~(0x003F|0x0680); /* clear exn flags, unmask OM, ZM, IM (not PM, UM, DM) */
-    __asm__ __volatile__("ldmxcsr %0" : : "m"(mxcsr));
-}
-
-#if defined(__x86_64__)
-
-static inline int cpu_has_sse2(void) { return 1; }
-
-#else /* !__x86_64__ */
-
-/*
- * Check if an x86-32 processor has SSE2.
- */
-static unsigned int xor_eflags(unsigned int mask)
-{
-    unsigned int eax, edx;
-
-    eax = mask;			/* eax = mask */
-    __asm__("pushfl\n\t"
-	    "popl %0\n\t"	/* edx = original EFLAGS */
-	    "xorl %0, %1\n\t"	/* eax = mask ^ EFLAGS */
-	    "pushl %1\n\t"
-	    "popfl\n\t"		/* new EFLAGS = mask ^ original EFLAGS */
-	    "pushfl\n\t"
-	    "popl %1\n\t"	/* eax = new EFLAGS */
-	    "xorl %0, %1\n\t"	/* eax = new EFLAGS ^ old EFLAGS */
-	    "pushl %0\n\t"
-	    "popfl"		/* restore original EFLAGS */
-	    : "=d"(edx), "=a"(eax)
-	    : "1"(eax));
-    return eax;
-}
-
-static __inline__ unsigned int cpuid_eax(unsigned int op)
-{
-    unsigned int eax, save_ebx;
-
-    /* In PIC mode i386 reserves EBX. So we must save
-       and restore it ourselves to not upset gcc. */
-    __asm__(
-	"movl %%ebx, %1\n\t"
-	"cpuid\n\t"
-	"movl %1, %%ebx"
-	: "=a"(eax), "=m"(save_ebx)
-	: "0"(op)
-	: "cx", "dx");
-    return eax;
-}
-
-static __inline__ unsigned int cpuid_edx(unsigned int op)
-{
-    unsigned int eax, edx, save_ebx;
- 
-    /* In PIC mode i386 reserves EBX. So we must save
-       and restore it ourselves to not upset gcc. */
-    __asm__(
-	"movl %%ebx, %2\n\t"
-	"cpuid\n\t"
-	"movl %2, %%ebx"
-	: "=a"(eax), "=d"(edx), "=m"(save_ebx)
-	: "0"(op)
-	: "cx");
-    return edx;
-}
-
-/* The AC bit, bit #18, is a new bit introduced in the EFLAGS
- * register on the Intel486 processor to generate alignment
- * faults. This bit cannot be set on the Intel386 processor.
- */
-static __inline__ int is_386(void)
-{
-    return ((xor_eflags(1<<18) >> 18) & 1) == 0;
-}
-
-/* Newer x86 processors have a CPUID instruction, as indicated by
- * the ID bit (#21) in EFLAGS being modifiable.
- */
-static __inline__ int has_CPUID(void)
-{
-    return (xor_eflags(1<<21) >> 21) & 1;
-}
-
-static int cpu_has_sse2(void)
-{
-    unsigned int maxlev, features;
-    static int has_sse2 = -1;
-
-    if (has_sse2 >= 0)
-	return has_sse2;
-    has_sse2 = 0;
-
-    if (is_386())
-	return 0;
-    if (!has_CPUID())
-	return 0;
-    maxlev = cpuid_eax(0);
-    /* Intel A-step Pentium had a preliminary version of CPUID.
-       It also didn't have SSE2. */
-    if ((maxlev & 0xFFFFFF00) == 0x0500)
-	return 0;
-    /* If max level is zero then CPUID cannot report any features. */
-    if (maxlev == 0)
-	return 0;
-    features = cpuid_edx(1);
-    has_sse2 = (features & (1 << 26)) != 0;
-
-    return has_sse2;
-}
-#endif /* !__x86_64__ */
-
-static void unmask_fpe(void)
-{
-    unmask_x87();
-    if (cpu_has_sse2())
-	unmask_sse2();
-}
-
-static __inline__ int check_fpe(double f)
-{
-    __asm__ __volatile__("fwait" : "=m"(erl_fp_exception) : "m"(f));
-    if (!erl_fp_exception)
-       return 0;
-    __asm__ __volatile__("fninit");
-    unmask_fpe();
-    return 1;
-}
-
-#elif defined(__sparc__) && defined(__linux__)
-
-#if defined(__arch64__)
-#define LDX "ldx"
-#define STX "stx"
-#else
-#define LDX "ld"
-#define STX "st"
-#endif
-
-static void unmask_fpe(void)
-{
-    unsigned long fsr;
-
-    __asm__(STX " %%fsr, %0" : "=m"(fsr));
-    fsr &= ~(0x1FUL << 23);	/* clear FSR[TEM] field */
-    fsr |= (0x1AUL << 23);	/* enable NV, OF, DZ exceptions */
-    __asm__ __volatile__(LDX " %0, %%fsr" : : "m"(fsr));
-}
-
-static __inline__ int check_fpe(double f)
-{
-    __asm__ __volatile__("" : "=m"(erl_fp_exception) : "em"(f));
-    return erl_fp_exception;
-}
-
-#elif (defined(__powerpc__) && defined(__linux__)) || (defined(__ppc__) && defined(__DARWIN__))
-
-#if defined(__linux__)
-
-#include <sys/prctl.h>
-
-static void set_fpexc_precise(void)
-{
-    if (prctl(PR_SET_FPEXC, PR_FP_EXC_PRECISE) < 0) {
-	perror("PR_SET_FPEXC");
-	exit(1);
-    }
-}
-
-#elif defined(__DARWIN__)
-
-#include <mach/mach.h>
-#include <pthread.h>
-
-/*
- * FE0 FE1	MSR bits
- *  0   0	floating-point exceptions disabled
- *  0   1	floating-point imprecise nonrecoverable
- *  1   0	floating-point imprecise recoverable
- *  1   1	floating-point precise mode
- *
- * Apparently:
- * - Darwin 5.5 (MacOS X <= 10.1) starts with FE0 == FE1 == 0,
- *   and resets FE0 and FE1 to 0 after each SIGFPE.
- * - Darwin 6.0 (MacOS X 10.2) starts with FE0 == FE1 == 1,
- *   and does not reset FE0 or FE1 after a SIGFPE.
- */
-#define FE0_MASK	(1<<11)
-#define FE1_MASK	(1<<8)
-
-/* a thread cannot get or set its own MSR bits */
-static void *fpu_fpe_enable(void *arg)
-{
-    thread_t t = *(thread_t*)arg;
-    struct ppc_thread_state state;
-    unsigned int state_size = PPC_THREAD_STATE_COUNT;
-
-    if (thread_get_state(t, PPC_THREAD_STATE, (natural_t*)&state, &state_size) != KERN_SUCCESS) {
-	perror("thread_get_state");
-	exit(1);
-    }
-    if ((state.srr1 & (FE1_MASK|FE0_MASK)) != (FE1_MASK|FE0_MASK)) {
-#if 0
-	/* This would also have to be performed in the SIGFPE handler
-	   to work around the MSR reset older Darwin releases do. */
-	state.srr1 |= (FE1_MASK|FE0_MASK);
-	thread_set_state(t, PPC_THREAD_STATE, (natural_t*)&state, state_size);
-#else
-	fprintf(stderr, "srr1 == 0x%08x, your Darwin is too old\n", state.srr1);
-	exit(1);
-#endif
-    }
-    return NULL; /* Ok, we appear to be on Darwin 6.0 or later */
-}
-
-static void set_fpexc_precise(void)
-{
-    thread_t self = mach_thread_self();
-    pthread_t enabler;
-
-    if (pthread_create(&enabler, NULL, fpu_fpe_enable, &self)) {
-	perror("pthread_create");
-    } else if (pthread_join(enabler, NULL)) {
-	perror("pthread_join");
-    }
-}
-
-#endif
-
-static void set_fpscr(unsigned int fpscr)
-{
-    union {
-	double d;
-	unsigned int fpscr[2];
-    } u;
-    u.fpscr[0] = 0xFFF80000;
-    u.fpscr[1] = fpscr;
-    __asm__ __volatile__("mtfsf 255,%0" : : "f"(u.d));
-}
-
-static void unmask_fpe(void)
-{
-    set_fpexc_precise();
-    set_fpscr(0x80|0x40|0x10);	/* VE, OE, ZE; not UE or XE */
-}
-
-static __inline__ int check_fpe(double f)
-{
-    __asm__ __volatile__("" : "=m"(erl_fp_exception) : "fm"(f));
-    return erl_fp_exception;
-}
-
-#else
-
-#include <ieeefp.h>
-
-#define unmask_fpe()   fpsetmask(FP_X_INV | FP_X_OFL | FP_X_DZ)
-
-static __inline__ int check_fpe(double f)
-{
-    __asm__ __volatile__("" : "=m"(erl_fp_exception) : "g"(f));
-    return erl_fp_exception;
-}
-
-#endif
-
-/*
- * Implement SIGFPE handler based on CPU/OS combination
- */
-
-#if (defined(__linux__) && (defined(__i386__) || defined(__x86_64__) || defined(__sparc__) || defined(__powerpc__))) || (defined(__DARWIN__) && (defined(__i386__) || defined(__x86_64__) || defined(__ppc__))) || (defined(__FreeBSD__) && (defined(__i386__) || defined(__x86_64__))) || ((defined(__OpenBSD__) || defined(__NetBSD__)) && defined(__x86_64__)) || (defined(__sun__) && defined(__x86_64__))
-
-#if defined(__linux__) && defined(__i386__)
-#if !defined(X86_FXSR_MAGIC)
-#define X86_FXSR_MAGIC 0x0000
-#endif
-#elif defined(__FreeBSD__) && defined(__i386__)
-#include <sys/types.h>
-#include <machine/npx.h>
-#elif defined(__FreeBSD__) && defined(__x86_64__)
-#include <sys/types.h>
-#include <machine/fpu.h>
-#elif defined(__DARWIN__)
-#include <machine/signal.h>
-#elif defined(__OpenBSD__) && defined(__x86_64__)
-#include <sys/types.h>
-#include <machine/fpu.h>
-#endif
-#if !(defined(__OpenBSD__) && defined(__x86_64__))
-#include <ucontext.h>
-#endif
-#include <string.h>
-
-static void fpe_sig_action(int sig, siginfo_t *si, void *puc)
-{
-    ucontext_t *uc = puc;
-#if defined(__linux__)
-#if defined(__x86_64__)
-    mcontext_t *mc = &uc->uc_mcontext;
-    fpregset_t fpstate = mc->fpregs;
-    fpstate->mxcsr = 0x1F80;
-    fpstate->swd &= ~0xFF;
-#elif defined(__i386__)
-    mcontext_t *mc = &uc->uc_mcontext;
-    fpregset_t fpstate = mc->fpregs;
-    if ((fpstate->status >> 16) == X86_FXSR_MAGIC)
-	((struct _fpstate*)fpstate)->mxcsr = 0x1F80;
-    fpstate->sw &= ~0xFF;
-#elif defined(__sparc__) && defined(__arch64__)
-    /* on SPARC the 3rd parameter points to a sigcontext not a ucontext */
-    struct sigcontext *sc = (struct sigcontext*)puc;
-    sc->sigc_regs.tpc = sc->sigc_regs.tnpc;
-    sc->sigc_regs.tnpc += 4;
-#elif defined(__sparc__)
-    /* on SPARC the 3rd parameter points to a sigcontext not a ucontext */
-    struct sigcontext *sc = (struct sigcontext*)puc;
-    sc->si_regs.pc = sc->si_regs.npc;
-    sc->si_regs.npc = (unsigned long)sc->si_regs.npc + 4;
-#elif defined(__powerpc__)
-#if defined(__powerpc64__)
-    mcontext_t *mc = &uc->uc_mcontext;
-    unsigned long *regs = &mc->gp_regs[0];
-#else
-    mcontext_t *mc = uc->uc_mcontext.uc_regs;
-    unsigned long *regs = &mc->gregs[0];
-#endif
-    regs[PT_NIP] += 4;
-    regs[PT_FPSCR] = 0x80|0x40|0x10;	/* VE, OE, ZE; not UE or XE */
-#endif
-#elif defined(__DARWIN__)
-#if defined(DARWIN_MODERN_MCONTEXT)
-#if defined(__x86_64__)
-    mcontext_t mc = uc->uc_mcontext;
-    struct __darwin_x86_float_state64 *fpstate = &mc->__fs;
-    fpstate->__fpu_mxcsr = 0x1F80;
-    *(unsigned short *)&fpstate->__fpu_fsw &= ~0xFF;
-#elif defined(__i386__)
-    mcontext_t mc = uc->uc_mcontext;
-    struct __darwin_i386_float_state *fpstate = &mc->__fs;
-    fpstate->__fpu_mxcsr = 0x1F80;
-    *(unsigned short *)&fpstate->__fpu_fsw &= ~0xFF;
-#elif defined(__ppc__)
-    mcontext_t mc = uc->uc_mcontext;
-    mc->ss.srr0 += 4;
-    mc->fs.fpscr = 0x80|0x40|0x10;
-#endif
-#else
-#if defined(__x86_64__)
-    mcontext_t mc = uc->uc_mcontext;
-    struct x86_float_state64_t *fpstate = &mc->fs;
-    fpstate->fpu_mxcsr = 0x1F80;
-    *(unsigned short *)&fpstate->fpu_fsw &= ~0xFF;
-#elif defined(__i386__)
-    mcontext_t mc = uc->uc_mcontext;
-    x86_float_state32_t	*fpstate = &mc->fs;
-    fpstate->fpu_mxcsr = 0x1F80;
-    *(unsigned short *)&fpstate->fpu_fsw &= ~0xFF;
-#elif defined(__ppc__)
-    mcontext_t mc = uc->uc_mcontext;
-    mc->ss.srr0 += 4;
-    mc->fs.fpscr = 0x80|0x40|0x10;
-#endif
-#endif
-#elif defined(__FreeBSD__) && defined(__x86_64__)
-    mcontext_t *mc = &uc->uc_mcontext;
-    struct savefpu *savefpu = (struct savefpu*)&mc->mc_fpstate;
-    struct envxmm *envxmm = &savefpu->sv_env;
-    envxmm->en_mxcsr = 0x1F80;
-    envxmm->en_sw &= ~0xFF;
-#elif defined(__FreeBSD__) && defined(__i386__)
-    mcontext_t *mc = &uc->uc_mcontext;
-    union savefpu *savefpu = (union savefpu*)&mc->mc_fpstate;
-    if (mc->mc_fpformat == _MC_FPFMT_XMM) {
-	struct envxmm *envxmm = &savefpu->sv_xmm.sv_env;
-	envxmm->en_mxcsr = 0x1F80;
-	envxmm->en_sw &= ~0xFF;
-    } else {
-	struct env87 *env87 = &savefpu->sv_87.sv_env;
-	env87->en_sw &= ~0xFF;
-    }
-#elif defined(__OpenBSD__) && defined(__x86_64__)
-    struct fxsave64 *fxsave = uc->sc_fpstate;
-    fxsave->fx_mxcsr = 0x1F80;
-    fxsave->fx_fsw &= ~0xFF;
-#elif defined(__NetBSD__) && defined(__x86_64__)
-    mcontext_t *mc = &uc->uc_mcontext;
-    struct fxsave64 *fxsave = (struct fxsave64 *)&mc->__fpregs;
-    fxsave->fx_mxcsr = 0x1F80;
-    fxsave->fx_fsw &= ~0xFF;
-#elif defined(__sun__) && defined(__x86_64__)
-    mcontext_t *mc = &uc->uc_mcontext;
-    struct fpchip_state *fpstate = &mc->fpregs.fp_reg_set.fpchip_state;
-    fpstate->mxcsr = 0x1F80;
-    fpstate->sw &= ~0xFF;
-#endif
-    new_fp_exception();
-}
-
-static void catch_sigfpe(void)
-{
-    struct sigaction act;
-
-    memset(&act, 0, sizeof act);
-    act.sa_sigaction = fpe_sig_action;
-    act.sa_flags = SA_SIGINFO;
-    sigaction(SIGFPE, &act, NULL);
-}
-
-#else
-
-static void fpe_sig_handler(int sig)
-{
-    new_fp_exception();
-}
-
-static void catch_sigfpe(void)
-{
-    signal(SIGFPE, fpe_sig_handler);
-}
-
-#endif
-
-/*
- * Generic test code
- */
-
-static void do_init(void)
-{
-    catch_sigfpe();
-    unmask_fpe();
-}
-
-double a = 3.23e133;
-double b = 3.57e257;
-double res;
-
-void do_fmul(void)
-{
-    res = a * b;
-}
-
-int do_check(void)
-{
-    if (check_fpe(res)) {
-       fprintf(stderr, "res = %g, FPE worked\n", res);
-       return 0;
-    } else {
-       fprintf(stderr, "res = %g, FPE failed\n", res);
-       return 1;
-    }
-}
-
-int main(int argc, const char **argv)
-{
-    if (argc == 3) {
-       a = atof(argv[1]);
-       b = atof(argv[2]);
-    }
-    do_init();
-    do_fmul();
-    return do_check();
-}
-],
-erl_ok=yes,
-erl_ok=no,
-[
-case X$erl_xcomp_reliable_fpe in
-    X) erl_ok=cross;;
-    Xyes|Xno) erl_ok=$erl_xcomp_reliable_fpe;;
-    *) AC_MSG_ERROR([Bad erl_xcomp_reliable_fpe value: $erl_xcomp_reliable_fpe]);;
-esac
-])
-
-    if test $erl_ok = yes; then
-	FPE=reliable
-        AC_MSG_RESULT(reliable)
-    else
-	FPE=unreliable
-	AC_MSG_RESULT([unreliable; testing in software instead])
-	AC_DEFINE(NO_FPE_SIGNALS,[],[Define if floating points exceptions are non-existing/not reliable])
-	if test $erl_ok = cross; then
-	    AC_MSG_WARN([result unreliable guessed because of cross compilation])
-	fi
-    fi
-fi	
-
-AC_SUBST(FPE)
-
+dnl Permanently disable floating point exceptions.
+dnl On x86/amd64, floating points exceptions have
+dnl unresolved stability issues.
+AC_MSG_CHECKING([for unreliable floating point exceptions])
+FPE=unreliable
+AC_MSG_RESULT([unreliable])
+AC_DEFINE(NO_FPE_SIGNALS,[],[Define if floating points exceptions are non-existing/not reliable])
 
 dnl
 dnl Some operating systems allow you to redefine FD_SETSIZE to be able
diff --git a/erts/emulator/Makefile.in b/erts/emulator/Makefile.in
index 5dfa60ee74..221cf84622 100644
--- a/erts/emulator/Makefile.in
+++ b/erts/emulator/Makefile.in
@@ -570,7 +570,7 @@ $(TTF_DIR)/OPCODES-GENERATED: $(OPCODE_TABLES) utils/beam_makeops
 		-code-model @CODE_MODEL@ \
 		-outdir $(TTF_DIR) \
 		-DUSE_VM_PROBES=$(if $(USE_VM_PROBES),1,0) \
-		-DNO_FPE_SIGNALS=$(if $filter(unreliable,$(FPE)),1,0) \
+		-DNO_FPE_SIGNALS=$(if $(filter unreliable,$(FPE)),1,0) \
 		-emulator $(OPCODE_TABLES) && echo $? >$(TTF_DIR)/OPCODES-GENERATED
 GENERATE += $(TTF_DIR)/OPCODES-GENERATED