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target/i386: fix fscale handling of invalid exponent encodings

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The fscale implementation does not check for invalid encodings in the
exponent operand, thus treating them like INT_MIN (the value returned
for invalid encodings by floatx80_to_int32_round_to_zero).  Fix it to
treat them similarly to signaling NaN exponents, thus generating a
quiet NaN result.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Message-Id: <alpine.DEB.2.21.2005070044190.18350@digraph.polyomino.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Joseph Myers 2020-05-07 00:44:57 +00:00 committed by Paolo Bonzini
parent 0d48b43632
commit b40eec96b2
2 changed files with 33 additions and 1 deletions
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5
target/i386/fpu_helper.c
View File

@ -968,7 +968,10 @@ void helper_frndint(CPUX86State *env)
void helper_fscale(CPUX86State *env)
{
if (floatx80_is_any_nan(ST1)) {
if (floatx80_invalid_encoding(ST1)) {
float_raise(float_flag_invalid, &env->fp_status);
ST0 = floatx80_default_nan(&env->fp_status);
} else if (floatx80_is_any_nan(ST1)) {
ST0 = ST1;
if (floatx80_is_signaling_nan(ST0, &env->fp_status)) {
float_raise(float_flag_invalid, &env->fp_status);

29
tests/tcg/i386/test-i386-fscale.c
View File

@ -8,6 +8,11 @@ union u {
long double ld;
};
volatile union u ld_invalid_1 = { .s = { 1, 1234 } };
volatile union u ld_invalid_2 = { .s = { 0, 1234 } };
volatile union u ld_invalid_3 = { .s = { 0, 0x7fff } };
volatile union u ld_invalid_4 = { .s = { (UINT64_C(1) << 63) - 1, 0x7fff } };
volatile long double ld_res;
int isnan_ld(long double x)
@ -33,5 +38,29 @@ int main(void)
printf("FAIL: fscale snan\n");
ret = 1;
}
__asm__ volatile ("fscale" : "=t" (ld_res) :
"0" (2.5L), "u" (ld_invalid_1.ld));
if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
printf("FAIL: fscale invalid 1\n");
ret = 1;
}
__asm__ volatile ("fscale" : "=t" (ld_res) :
"0" (2.5L), "u" (ld_invalid_2.ld));
if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
printf("FAIL: fscale invalid 2\n");
ret = 1;
}
__asm__ volatile ("fscale" : "=t" (ld_res) :
"0" (2.5L), "u" (ld_invalid_3.ld));
if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
printf("FAIL: fscale invalid 3\n");
ret = 1;
}
__asm__ volatile ("fscale" : "=t" (ld_res) :
"0" (2.5L), "u" (ld_invalid_4.ld));
if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
printf("FAIL: fscale invalid 4\n");
ret = 1;
}
return ret;
}