From c415f2c58296d86e9abb7e4a133111acf7031da3 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Thu, 7 May 2020 00:43:30 +0000 Subject: [PATCH] target/i386: implement special cases for fxtract MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 --- target/i386/fpu_helper.c | 25 +++++++- tests/tcg/i386/test-i386-fxtract.c | 120 +++++++++++++++++++++++++++++++++++++ 2 files changed, 144 insertions(+), 1 deletion(-) create mode 100644 tests/tcg/i386/test-i386-fxtract.c 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; +} -- 2.11.0