From: Joseph Myers Date: Thu, 7 May 2020 00:43:30 +0000 (+0000) Subject: target/i386: implement special cases for fxtract X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c415f2c58296d86e9abb7e4a133111acf7031da3;p=qemu.git target/i386: implement special cases for fxtract The implementation of the fxtract instruction treats all nonzero operands as normal numbers, so yielding incorrect results for invalid formats, infinities, NaNs and subnormal and pseudo-denormal operands. Implement appropriate handling of all those cases. Signed-off-by: Joseph Myers Acked-by: Alex Bennée Message-Id: Signed-off-by: Paolo Bonzini --- diff --git a/target/i386/fpu_helper.c b/target/i386/fpu_helper.c index b34fa784eb..568bd3b359 100644 --- a/target/i386/fpu_helper.c +++ b/target/i386/fpu_helper.c @@ -767,10 +767,33 @@ void helper_fxtract(CPUX86State *env) &env->fp_status); fpush(env); ST0 = temp.d; + } else if (floatx80_invalid_encoding(ST0)) { + float_raise(float_flag_invalid, &env->fp_status); + ST0 = floatx80_default_nan(&env->fp_status); + fpush(env); + ST0 = ST1; + } else if (floatx80_is_any_nan(ST0)) { + if (floatx80_is_signaling_nan(ST0, &env->fp_status)) { + float_raise(float_flag_invalid, &env->fp_status); + ST0 = floatx80_silence_nan(ST0, &env->fp_status); + } + fpush(env); + ST0 = ST1; + } else if (floatx80_is_infinity(ST0)) { + fpush(env); + ST0 = ST1; + ST1 = floatx80_infinity; } else { int expdif; - expdif = EXPD(temp) - EXPBIAS; + if (EXPD(temp) == 0) { + int shift = clz64(temp.l.lower); + temp.l.lower <<= shift; + expdif = 1 - EXPBIAS - shift; + float_raise(float_flag_input_denormal, &env->fp_status); + } else { + expdif = EXPD(temp) - EXPBIAS; + } /* DP exponent bias */ ST0 = int32_to_floatx80(expdif, &env->fp_status); fpush(env); diff --git a/tests/tcg/i386/test-i386-fxtract.c b/tests/tcg/i386/test-i386-fxtract.c new file mode 100644 index 0000000000..64fd93d333 --- /dev/null +++ b/tests/tcg/i386/test-i386-fxtract.c @@ -0,0 +1,120 @@ +/* Test fxtract instruction. */ + +#include +#include + +union u { + struct { uint64_t sig; uint16_t sign_exp; } s; + long double ld; +}; + +volatile union u ld_pseudo_m16382 = { .s = { UINT64_C(1) << 63, 0 } }; +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_sig, ld_exp; + +int isnan_ld(long double x) +{ + union u tmp = { .ld = x }; + return ((tmp.s.sign_exp & 0x7fff) == 0x7fff && + (tmp.s.sig >> 63) != 0 && + (tmp.s.sig << 1) != 0); +} + +int issignaling_ld(long double x) +{ + union u tmp = { .ld = x }; + return isnan_ld(x) && (tmp.s.sig & UINT64_C(0x4000000000000000)) == 0; +} + +int main(void) +{ + int ret = 0; + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : "0" (2.5L)); + if (ld_sig != 1.25L || ld_exp != 1.0L) { + printf("FAIL: fxtract 2.5\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : "0" (0.0L)); + if (ld_sig != 0.0L || __builtin_copysignl(1.0L, ld_sig) != 1.0L || + ld_exp != -__builtin_infl()) { + printf("FAIL: fxtract 0.0\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : "0" (-0.0L)); + if (ld_sig != -0.0L || __builtin_copysignl(1.0L, ld_sig) != -1.0L || + ld_exp != -__builtin_infl()) { + printf("FAIL: fxtract -0.0\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (__builtin_infl())); + if (ld_sig != __builtin_infl() || ld_exp != __builtin_infl()) { + printf("FAIL: fxtract inf\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (-__builtin_infl())); + if (ld_sig != -__builtin_infl() || ld_exp != __builtin_infl()) { + printf("FAIL: fxtract -inf\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (__builtin_nanl(""))); + if (!isnan_ld(ld_sig) || issignaling_ld(ld_sig) || + !isnan_ld(ld_exp) || issignaling_ld(ld_exp)) { + printf("FAIL: fxtract qnan\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (__builtin_nansl(""))); + if (!isnan_ld(ld_sig) || issignaling_ld(ld_sig) || + !isnan_ld(ld_exp) || issignaling_ld(ld_exp)) { + printf("FAIL: fxtract snan\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (0x1p-16445L)); + if (ld_sig != 1.0L || ld_exp != -16445.0L) { + printf("FAIL: fxtract subnormal\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (ld_pseudo_m16382.ld)); + if (ld_sig != 1.0L || ld_exp != -16382.0L) { + printf("FAIL: fxtract pseudo\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (ld_invalid_1.ld)); + if (!isnan_ld(ld_sig) || issignaling_ld(ld_sig) || + !isnan_ld(ld_exp) || issignaling_ld(ld_exp)) { + printf("FAIL: fxtract invalid 1\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (ld_invalid_2.ld)); + if (!isnan_ld(ld_sig) || issignaling_ld(ld_sig) || + !isnan_ld(ld_exp) || issignaling_ld(ld_exp)) { + printf("FAIL: fxtract invalid 2\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (ld_invalid_3.ld)); + if (!isnan_ld(ld_sig) || issignaling_ld(ld_sig) || + !isnan_ld(ld_exp) || issignaling_ld(ld_exp)) { + printf("FAIL: fxtract invalid 3\n"); + ret = 1; + } + __asm__ volatile ("fxtract" : "=t" (ld_sig), "=u" (ld_exp) : + "0" (ld_invalid_4.ld)); + if (!isnan_ld(ld_sig) || issignaling_ld(ld_sig) || + !isnan_ld(ld_exp) || issignaling_ld(ld_exp)) { + printf("FAIL: fxtract invalid 4\n"); + ret = 1; + } + return ret; +}