Re: [PATCH 1/2] x86/math-emu: Add support for FCMOVcc and F[U]COMI[P] insns

From: Denys Vlasenko
Date: Wed Sep 16 2015 - 15:51:41 EST

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On 09/16/2015 09:48 PM, Denys Vlasenko wrote:
> Run-tested by booting with "no387 nofxsr" and running test programs:
>
> # ./test_FCMOV
> [RUN] Testing fcmovCC instructions
> [OK] fcmovCC
> # ./test_FCOMI
> [RUN] Testing f[u]comi[p] instructions
> [OK] f[u]comi[p]

The sources for these test programs are in this email.

Ingo, let me know if you want a patch which adds them
to tools/testing/selftests/x86/*

#undef _GNU_SOURCE
#define _GNU_SOURCE 1
#undef __USE_GNU
#define __USE_GNU 1
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/time.h>
//#include <sys/ptrace.h>
#include <sys/wait.h>

#define TEST(insn) \
long double __attribute__((noinline)) insn(long flags) \
{ \
long double out; \
asm ("\n" \
" push %1""\n" \
" popf""\n" \
" fldpi""\n" \
" fld1""\n" \
" " #insn " %%st(1), %%st" "\n" \
" ffree %%st(1)" "\n" \
: "=t" (out) \
: "r" (flags) \
); \
return out; \
}

TEST(fcmovb)
TEST(fcmove)
TEST(fcmovbe)
TEST(fcmovu)
TEST(fcmovnb)
TEST(fcmovne)
TEST(fcmovnbe)
TEST(fcmovnu)

enum {
CF = 1 << 0,
PF = 1 << 2,
ZF = 1 << 6,
};

int main(int argc, char **argv, char **envp)
{
int err = 0;

printf("[RUN]\tTesting fcmovCC instructions\n");
/* If fcmovCC() returns 1.0, the move wasn't done */
err |= !(fcmovb(0) == 1.0); err |= !(fcmovnb(0) != 1.0);
err |= !(fcmove(0) == 1.0); err |= !(fcmovne(0) != 1.0);
err |= !(fcmovbe(0) == 1.0); err |= !(fcmovnbe(0) != 1.0);
err |= !(fcmovu(0) == 1.0); err |= !(fcmovnu(0) != 1.0);

err |= !(fcmovb(CF) != 1.0); err |= !(fcmovnb(CF) == 1.0);
err |= !(fcmove(CF) == 1.0); err |= !(fcmovne(CF) != 1.0);
err |= !(fcmovbe(CF) != 1.0); err |= !(fcmovnbe(CF) == 1.0);
err |= !(fcmovu(CF) == 1.0); err |= !(fcmovnu(CF) != 1.0);

err |= !(fcmovb(ZF) == 1.0); err |= !(fcmovnb(ZF) != 1.0);
err |= !(fcmove(ZF) != 1.0); err |= !(fcmovne(ZF) == 1.0);
err |= !(fcmovbe(ZF) != 1.0); err |= !(fcmovnbe(ZF) == 1.0);
err |= !(fcmovu(ZF) == 1.0); err |= !(fcmovnu(ZF) != 1.0);

err |= !(fcmovb(PF) == 1.0); err |= !(fcmovnb(PF) != 1.0);
err |= !(fcmove(PF) == 1.0); err |= !(fcmovne(PF) != 1.0);
err |= !(fcmovbe(PF) == 1.0); err |= !(fcmovnbe(PF) != 1.0);
err |= !(fcmovu(PF) != 1.0); err |= !(fcmovnu(PF) == 1.0);

if (!err)
printf("[OK]\tfcmovCC\n");
else
printf("[FAIL]\tfcmovCC errors: %d\n", err);

return err;
}
#undef _GNU_SOURCE
#define _GNU_SOURCE 1
#undef __USE_GNU
#define __USE_GNU 1
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/time.h>
//#include <sys/ptrace.h>
#include <sys/wait.h>
#include <fenv.h>

enum {
CF = 1 << 0,
PF = 1 << 2,
ZF = 1 << 6,
ARITH = CF | PF | ZF,
};

long res_fcomi_pi_1;
long res_fcomi_1_pi;
long res_fcomi_1_1;
long res_fcomi_nan_1;
/* sNaN is s|111 1111 1|1xx xxxx xxxx xxxx xxxx xxxx */
/* qNaN is s|111 1111 1|0xx xxxx xxxx xxxx xxxx xxxx (some x must be nonzero) */
int snan = 0x7fc11111;
int qnan = 0x7f811111;
unsigned short snan1[5];
/* sNaN80 is s|111 1111 1111 1111 |10xx xx...xx (some x must be nonzero) */
unsigned short snan80[5] = { 0x1111, 0x1111, 0x1111, 0x8111, 0x7fff };

int test(long flags)
{
feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);

asm ("\n"

" push %0""\n"
" popf""\n"
" fld1""\n"
" fldpi""\n"
" fcomi %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" ffree %%st(1)" "\n"
" pushf""\n"
" pop res_fcomi_1_pi""\n"

" push %0""\n"
" popf""\n"
" fldpi""\n"
" fld1""\n"
" fcomi %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" ffree %%st(1)" "\n"
" pushf""\n"
" pop res_fcomi_pi_1""\n"

" push %0""\n"
" popf""\n"
" fld1""\n"
" fld1""\n"
" fcomi %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" ffree %%st(1)" "\n"
" pushf""\n"
" pop res_fcomi_1_1""\n"
:
: "r" (flags)
);
if ((res_fcomi_1_pi & ARITH) != (0)) {
printf("[BAD]\tfcomi_1_pi with flags:%lx\n", flags);
return 1;
}
if ((res_fcomi_pi_1 & ARITH) != (CF)) {
printf("[BAD]\tfcomi_pi_1 with flags:%lx->%lx\n", flags, res_fcomi_pi_1 & ARITH);
return 1;
}
if ((res_fcomi_1_1 & ARITH) != (ZF)) {
printf("[BAD]\tfcomi_1_1 with flags:%lx\n", flags);
return 1;
}
if (fetestexcept(FE_INVALID) != 0) {
printf("[BAD]\tFE_INVALID is set in %s\n", __func__);
return 1;
}
return 0;
}

int test_qnan(long flags)
{
feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);

asm ("\n"
" push %0""\n"
" popf""\n"
" flds qnan""\n"
" fld1""\n"
" fnclex""\n" // fld of a qnan raised FE_INVALID, clear it
" fcomi %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" ffree %%st(1)" "\n"
" pushf""\n"
" pop res_fcomi_nan_1""\n"
:
: "r" (flags)
);
if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
return 1;
}
if (fetestexcept(FE_INVALID) != FE_INVALID) {
printf("[BAD]\tFE_INVALID is not set in %s\n", __func__);
return 1;
}
return 0;
}

int testu_qnan(long flags)
{
feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);

asm ("\n"
" push %0""\n"
" popf""\n"
" flds qnan""\n"
" fld1""\n"
" fnclex""\n" // fld of a qnan raised FE_INVALID, clear it
" fucomi %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" ffree %%st(1)" "\n"
" pushf""\n"
" pop res_fcomi_nan_1""\n"
:
: "r" (flags)
);
if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
return 1;
}
if (fetestexcept(FE_INVALID) != 0) {
printf("[BAD]\tFE_INVALID is set in %s\n", __func__);
return 1;
}
return 0;
}

int testu_snan(long flags)
{
feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);

asm ("\n"
" push %0""\n"
" popf""\n"
// " flds snan""\n" // WRONG, this will convert 32-bit fp snan to a *qnan* in 80-bit fp register!
// " fstpt snan1""\n" // if uncommented, it prints "snan1:7fff c111 1100 0000 0000" - c111, not 8111!
// " fnclex""\n" // flds of a snan raised FE_INVALID, clear it
" fldt snan80""\n" // fldt never raise FE_INVALID
" fld1""\n"
" fucomi %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" ffree %%st(1)" "\n"
" pushf""\n"
" pop res_fcomi_nan_1""\n"
:
: "r" (flags)
);
if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
return 1;
}
// printf("snan:%x snan1:%04x %04x %04x %04x %04x\n", snan, snan1[4], snan1[3], snan1[2], snan1[1], snan1[0]);
if (fetestexcept(FE_INVALID) != FE_INVALID) {
printf("[BAD]\tFE_INVALID is not set in %s\n", __func__);
return 1;
}
return 0;
}

int testp(long flags)
{
feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);

asm ("\n"

" push %0""\n"
" popf""\n"
" fld1""\n"
" fldpi""\n"
" fcomip %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" pushf""\n"
" pop res_fcomi_1_pi""\n"

" push %0""\n"
" popf""\n"
" fldpi""\n"
" fld1""\n"
" fcomip %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" pushf""\n"
" pop res_fcomi_pi_1""\n"

" push %0""\n"
" popf""\n"
" fld1""\n"
" fld1""\n"
" fcomip %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" pushf""\n"
" pop res_fcomi_1_1""\n"
:
: "r" (flags)
);
if ((res_fcomi_1_pi & ARITH) != (0)) {
printf("[BAD]\tfcomi_1_pi with flags:%lx\n", flags);
return 1;
}
if ((res_fcomi_pi_1 & ARITH) != (CF)) {
printf("[BAD]\tfcomi_pi_1 with flags:%lx->%lx\n", flags, res_fcomi_pi_1 & ARITH);
return 1;
}
if ((res_fcomi_1_1 & ARITH) != (ZF)) {
printf("[BAD]\tfcomi_1_1 with flags:%lx\n", flags);
return 1;
}
if (fetestexcept(FE_INVALID) != 0) {
printf("[BAD]\tFE_INVALID is set in %s\n", __func__);
return 1;
}
return 0;
}

int testp_qnan(long flags)
{
feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);

asm ("\n"
" push %0""\n"
" popf""\n"
" flds qnan""\n"
" fld1""\n"
" fnclex""\n" // fld of a qnan raised FE_INVALID, clear it
" fcomip %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" pushf""\n"
" pop res_fcomi_nan_1""\n"
:
: "r" (flags)
);
if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
return 1;
}
if (fetestexcept(FE_INVALID) != FE_INVALID) {
printf("[BAD]\tFE_INVALID is not set in %s\n", __func__);
return 1;
}
return 0;
}

int testup_qnan(long flags)
{
feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);

asm ("\n"
" push %0""\n"
" popf""\n"
" flds qnan""\n"
" fld1""\n"
" fnclex""\n" // fld of a qnan raised FE_INVALID, clear it
" fucomip %%st(1), %%st" "\n"
" ffree %%st(0)" "\n"
" pushf""\n"
" pop res_fcomi_nan_1""\n"
:
: "r" (flags)
);
if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
return 1;
}
if (fetestexcept(FE_INVALID) != 0) {
printf("[BAD]\tFE_INVALID is set in %s\n", __func__);
return 1;
}
return 0;
}

int main(int argc, char **argv, char **envp)
{
int err = 0;

printf("[RUN]\tTesting f[u]comi[p] instructions\n");
err |= test(0);
err |= test_qnan(0);
err |= testu_qnan(0);
err |= testu_snan(0);
err |= test(CF|ZF|PF);
err |= test_qnan(CF|ZF|PF);
err |= testu_qnan(CF|ZF|PF);
err |= testu_snan(CF|ZF|PF);
err |= testp(0);
err |= testp_qnan(0);
err |= testup_qnan(0);
err |= testp(CF|ZF|PF);
err |= testp_qnan(CF|ZF|PF);
err |= testup_qnan(CF|ZF|PF);
if (!err)
printf("[OK]\tf[u]comi[p]\n");
else
printf("[FAIL]\tf[u]comi[p] errors: %d\n", err);

return err;
}

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Previous message: Denys Vlasenko: "[PATCH 2/2] x86/math-emu: Remove define layer for undocumented opcodes"
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Next in thread: Ingo Molnar: "Re: [PATCH 1/2] x86/math-emu: Add support for FCMOVcc and F[U]COMI[P] insns"
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