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target/i386: fix floating-point load-constant rounding 

The implementations of the fldl2t, fldl2e, fldpi, fldlg2 and fldln2
instructions load fixed constants independent of the rounding mode.
Fix them to load a value correctly rounded for the current rounding
mode (but always rounded to 64-bit precision independent of the
precision control, and without setting "inexact") as specified.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <alpine.DEB.2.21.2005132348310.11687@digraph.polyomino.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Joseph Myers 2020-05-13 23:49:27 +00:00 committed by Paolo Bonzini
parent 5579b524b0
commit 80b4008c80
2 changed files with 248 additions and 5 deletions
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54
target/i386/fpu_helper.c
View File

@ -59,8 +59,13 @@
#define FPUC_EM 0x3f
#define floatx80_lg2 make_floatx80(0x3ffd, 0x9a209a84fbcff799LL)
#define floatx80_lg2_d make_floatx80(0x3ffd, 0x9a209a84fbcff798LL)
#define floatx80_l2e make_floatx80(0x3fff, 0xb8aa3b295c17f0bcLL)
#define floatx80_l2e_d make_floatx80(0x3fff, 0xb8aa3b295c17f0bbLL)
#define floatx80_l2t make_floatx80(0x4000, 0xd49a784bcd1b8afeLL)
#define floatx80_l2t_u make_floatx80(0x4000, 0xd49a784bcd1b8affLL)
#define floatx80_ln2_d make_floatx80(0x3ffe, 0xb17217f7d1cf79abLL)
#define floatx80_pi_d make_floatx80(0x4000, 0xc90fdaa22168c234LL)
#if !defined(CONFIG_USER_ONLY)
static qemu_irq ferr_irq;
@ -544,27 +549,66 @@ void helper_fld1_ST0(CPUX86State *env)
void helper_fldl2t_ST0(CPUX86State *env)
{
ST0 = floatx80_l2t;
switch (env->fpuc & FPU_RC_MASK) {
case FPU_RC_UP:
ST0 = floatx80_l2t_u;
break;
default:
ST0 = floatx80_l2t;
break;
}
}
void helper_fldl2e_ST0(CPUX86State *env)
{
ST0 = floatx80_l2e;
switch (env->fpuc & FPU_RC_MASK) {
case FPU_RC_DOWN:
case FPU_RC_CHOP:
ST0 = floatx80_l2e_d;
break;
default:
ST0 = floatx80_l2e;
break;
}
}
void helper_fldpi_ST0(CPUX86State *env)
{
ST0 = floatx80_pi;
switch (env->fpuc & FPU_RC_MASK) {
case FPU_RC_DOWN:
case FPU_RC_CHOP:
ST0 = floatx80_pi_d;
break;
default:
ST0 = floatx80_pi;
break;
}
}
void helper_fldlg2_ST0(CPUX86State *env)
{
ST0 = floatx80_lg2;
switch (env->fpuc & FPU_RC_MASK) {
case FPU_RC_DOWN:
case FPU_RC_CHOP:
ST0 = floatx80_lg2_d;
break;
default:
ST0 = floatx80_lg2;
break;
}
}
void helper_fldln2_ST0(CPUX86State *env)
{
ST0 = floatx80_ln2;
switch (env->fpuc & FPU_RC_MASK) {
case FPU_RC_DOWN:
case FPU_RC_CHOP:
ST0 = floatx80_ln2_d;
break;
default:
ST0 = floatx80_ln2;
break;
}
}
void helper_fldz_ST0(CPUX86State *env)

199
tests/tcg/i386/test-i386-fldcst.c Normal file
View File

@ -0,0 +1,199 @@
/* Test instructions loading floating-point constants. */
#include <stdint.h>
#include <stdio.h>
volatile long double ld_res;
int main(void)
{
short cw;
int ret = 0;
/* Round to nearest. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x000;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldl2t" : "=t" (ld_res));
if (ld_res != 0x3.5269e12f346e2bf8p+0L) {
printf("FAIL: fldl2t N\n");
ret = 1;
}
/* Round downward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x400;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldl2t" : "=t" (ld_res));
if (ld_res != 0x3.5269e12f346e2bf8p+0L) {
printf("FAIL: fldl2t D\n");
ret = 1;
}
/* Round toward zero. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0xc00;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldl2t" : "=t" (ld_res));
if (ld_res != 0x3.5269e12f346e2bf8p+0L) {
printf("FAIL: fldl2t Z\n");
ret = 1;
}
/* Round upward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x800;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldl2t" : "=t" (ld_res));
if (ld_res != 0x3.5269e12f346e2bfcp+0L) {
printf("FAIL: fldl2t U\n");
ret = 1;
}
/* Round to nearest. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x000;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldl2e" : "=t" (ld_res));
if (ld_res != 0x1.71547652b82fe178p+0L) {
printf("FAIL: fldl2e N\n");
ret = 1;
}
/* Round downward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x400;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldl2e" : "=t" (ld_res));
if (ld_res != 0x1.71547652b82fe176p+0L) {
printf("FAIL: fldl2e D\n");
ret = 1;
}
/* Round toward zero. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0xc00;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldl2e" : "=t" (ld_res));
if (ld_res != 0x1.71547652b82fe176p+0L) {
printf("FAIL: fldl2e Z\n");
ret = 1;
}
/* Round upward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x800;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldl2e" : "=t" (ld_res));
if (ld_res != 0x1.71547652b82fe178p+0L) {
printf("FAIL: fldl2e U\n");
ret = 1;
}
/* Round to nearest. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x000;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldpi" : "=t" (ld_res));
if (ld_res != 0x3.243f6a8885a308d4p+0L) {
printf("FAIL: fldpi N\n");
ret = 1;
}
/* Round downward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x400;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldpi" : "=t" (ld_res));
if (ld_res != 0x3.243f6a8885a308dp+0L) {
printf("FAIL: fldpi D\n");
ret = 1;
}
/* Round toward zero. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0xc00;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldpi" : "=t" (ld_res));
if (ld_res != 0x3.243f6a8885a308dp+0L) {
printf("FAIL: fldpi Z\n");
ret = 1;
}
/* Round upward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x800;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldpi" : "=t" (ld_res));
if (ld_res != 0x3.243f6a8885a308d4p+0L) {
printf("FAIL: fldpi U\n");
ret = 1;
}
/* Round to nearest. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x000;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldlg2" : "=t" (ld_res));
if (ld_res != 0x4.d104d427de7fbcc8p-4L) {
printf("FAIL: fldlg2 N\n");
ret = 1;
}
/* Round downward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x400;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldlg2" : "=t" (ld_res));
if (ld_res != 0x4.d104d427de7fbccp-4L) {
printf("FAIL: fldlg2 D\n");
ret = 1;
}
/* Round toward zero. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0xc00;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldlg2" : "=t" (ld_res));
if (ld_res != 0x4.d104d427de7fbccp-4L) {
printf("FAIL: fldlg2 Z\n");
ret = 1;
}
/* Round upward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x800;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldlg2" : "=t" (ld_res));
if (ld_res != 0x4.d104d427de7fbcc8p-4L) {
printf("FAIL: fldlg2 U\n");
ret = 1;
}
/* Round to nearest. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x000;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldln2" : "=t" (ld_res));
if (ld_res != 0xb.17217f7d1cf79acp-4L) {
printf("FAIL: fldln2 N\n");
ret = 1;
}
/* Round downward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x400;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldln2" : "=t" (ld_res));
if (ld_res != 0xb.17217f7d1cf79abp-4L) {
printf("FAIL: fldln2 D\n");
ret = 1;
}
/* Round toward zero. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0xc00;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldln2" : "=t" (ld_res));
if (ld_res != 0xb.17217f7d1cf79abp-4L) {
printf("FAIL: fldln2 Z\n");
ret = 1;
}
/* Round upward. */
__asm__ volatile ("fnstcw %0" : "=m" (cw));
cw = (cw & ~0xc00) | 0x800;
__asm__ volatile ("fldcw %0" : : "m" (cw));
__asm__ volatile ("fldln2" : "=t" (ld_res));
if (ld_res != 0xb.17217f7d1cf79acp-4L) {
printf("FAIL: fldln2 U\n");
ret = 1;
}
return ret;
}