diff options
| -rw-r--r-- | fpu/softfloat-specialize.c.inc | 225 | ||||
| -rw-r--r-- | include/fpu/softfloat-helpers.h | 11 | ||||
| -rw-r--r-- | include/fpu/softfloat-types.h | 42 |
3 files changed, 183 insertions, 95 deletions
diff --git a/fpu/softfloat-specialize.c.inc b/fpu/softfloat-specialize.c.inc index 4e279b9bc4..fae6794a15 100644 --- a/fpu/softfloat-specialize.c.inc +++ b/fpu/softfloat-specialize.c.inc @@ -390,118 +390,153 @@ bool float32_is_signaling_nan(float32 a_, float_status *status) static int pickNaN(FloatClass a_cls, FloatClass b_cls, bool aIsLargerSignificand, float_status *status) { -#if defined(TARGET_ARM) || defined(TARGET_MIPS) || defined(TARGET_HPPA) || \ - defined(TARGET_LOONGARCH64) || defined(TARGET_S390X) - /* ARM mandated NaN propagation rules (see FPProcessNaNs()), take - * the first of: - * 1. A if it is signaling - * 2. B if it is signaling - * 3. A (quiet) - * 4. B (quiet) - * A signaling NaN is always quietened before returning it. - */ - /* According to MIPS specifications, if one of the two operands is - * a sNaN, a new qNaN has to be generated. This is done in - * floatXX_silence_nan(). For qNaN inputs the specifications - * says: "When possible, this QNaN result is one of the operand QNaN - * values." In practice it seems that most implementations choose - * the first operand if both operands are qNaN. In short this gives - * the following rules: - * 1. A if it is signaling - * 2. B if it is signaling - * 3. A (quiet) - * 4. B (quiet) - * A signaling NaN is always silenced before returning it. + Float2NaNPropRule rule = status->float_2nan_prop_rule; + + /* + * We guarantee not to require the target to tell us how to + * pick a NaN if we're always returning the default NaN. */ - if (is_snan(a_cls)) { - return 0; - } else if (is_snan(b_cls)) { - return 1; - } else if (is_qnan(a_cls)) { - return 0; - } else { - return 1; - } + assert(!status->default_nan_mode); + + if (rule == float_2nan_prop_none) { + /* target didn't set the rule: fall back to old ifdef choices */ +#if defined(TARGET_AVR) || defined(TARGET_HEXAGON) \ + || defined(TARGET_RISCV) || defined(TARGET_SH4) \ + || defined(TARGET_TRICORE) + g_assert_not_reached(); +#elif defined(TARGET_ARM) || defined(TARGET_MIPS) || defined(TARGET_HPPA) || \ + defined(TARGET_LOONGARCH64) || defined(TARGET_S390X) + /* + * ARM mandated NaN propagation rules (see FPProcessNaNs()), take + * the first of: + * 1. A if it is signaling + * 2. B if it is signaling + * 3. A (quiet) + * 4. B (quiet) + * A signaling NaN is always quietened before returning it. + */ + /* + * According to MIPS specifications, if one of the two operands is + * a sNaN, a new qNaN has to be generated. This is done in + * floatXX_silence_nan(). For qNaN inputs the specifications + * says: "When possible, this QNaN result is one of the operand QNaN + * values." In practice it seems that most implementations choose + * the first operand if both operands are qNaN. In short this gives + * the following rules: + * 1. A if it is signaling + * 2. B if it is signaling + * 3. A (quiet) + * 4. B (quiet) + * A signaling NaN is always silenced before returning it. + */ + rule = float_2nan_prop_s_ab; #elif defined(TARGET_PPC) || defined(TARGET_M68K) - /* PowerPC propagation rules: - * 1. A if it sNaN or qNaN - * 2. B if it sNaN or qNaN - * A signaling NaN is always silenced before returning it. - */ - /* M68000 FAMILY PROGRAMMER'S REFERENCE MANUAL - * 3.4 FLOATING-POINT INSTRUCTION DETAILS - * If either operand, but not both operands, of an operation is a - * nonsignaling NaN, then that NaN is returned as the result. If both - * operands are nonsignaling NaNs, then the destination operand - * nonsignaling NaN is returned as the result. - * If either operand to an operation is a signaling NaN (SNaN), then the - * SNaN bit is set in the FPSR EXC byte. If the SNaN exception enable bit - * is set in the FPCR ENABLE byte, then the exception is taken and the - * destination is not modified. If the SNaN exception enable bit is not - * set, setting the SNaN bit in the operand to a one converts the SNaN to - * a nonsignaling NaN. The operation then continues as described in the - * preceding paragraph for nonsignaling NaNs. - */ - if (is_nan(a_cls)) { - return 0; - } else { - return 1; - } + /* + * PowerPC propagation rules: + * 1. A if it sNaN or qNaN + * 2. B if it sNaN or qNaN + * A signaling NaN is always silenced before returning it. + */ + /* + * M68000 FAMILY PROGRAMMER'S REFERENCE MANUAL + * 3.4 FLOATING-POINT INSTRUCTION DETAILS + * If either operand, but not both operands, of an operation is a + * nonsignaling NaN, then that NaN is returned as the result. If both + * operands are nonsignaling NaNs, then the destination operand + * nonsignaling NaN is returned as the result. + * If either operand to an operation is a signaling NaN (SNaN), then the + * SNaN bit is set in the FPSR EXC byte. If the SNaN exception enable bit + * is set in the FPCR ENABLE byte, then the exception is taken and the + * destination is not modified. If the SNaN exception enable bit is not + * set, setting the SNaN bit in the operand to a one converts the SNaN to + * a nonsignaling NaN. The operation then continues as described in the + * preceding paragraph for nonsignaling NaNs. + */ + rule = float_2nan_prop_ab; #elif defined(TARGET_SPARC) - /* Prefer SNaN over QNaN, order B then A. */ - if (is_snan(b_cls)) { - return 1; - } else if (is_snan(a_cls)) { - return 0; - } else if (is_qnan(b_cls)) { - return 1; - } else { - return 0; - } + /* Prefer SNaN over QNaN, order B then A. */ + rule = float_2nan_prop_s_ba; #elif defined(TARGET_XTENSA) - /* - * Xtensa has two NaN propagation modes. - * Which one is active is controlled by float_status::use_first_nan. - */ - if (status->use_first_nan) { - if (is_nan(a_cls)) { + /* + * Xtensa has two NaN propagation modes. + * Which one is active is controlled by float_status::use_first_nan. + */ + if (status->use_first_nan) { + rule = float_2nan_prop_ab; + } else { + rule = float_2nan_prop_ba; + } +#else + rule = float_2nan_prop_x87; +#endif + } + + switch (rule) { + case float_2nan_prop_s_ab: + if (is_snan(a_cls)) { + return 0; + } else if (is_snan(b_cls)) { + return 1; + } else if (is_qnan(a_cls)) { return 0; } else { return 1; } - } else { - if (is_nan(b_cls)) { + break; + case float_2nan_prop_s_ba: + if (is_snan(b_cls)) { + return 1; + } else if (is_snan(a_cls)) { + return 0; + } else if (is_qnan(b_cls)) { return 1; } else { return 0; } - } -#else - /* This implements x87 NaN propagation rules: - * SNaN + QNaN => return the QNaN - * two SNaNs => return the one with the larger significand, silenced - * two QNaNs => return the one with the larger significand - * SNaN and a non-NaN => return the SNaN, silenced - * QNaN and a non-NaN => return the QNaN - * - * If we get down to comparing significands and they are the same, - * return the NaN with the positive sign bit (if any). - */ - if (is_snan(a_cls)) { - if (is_snan(b_cls)) { - return aIsLargerSignificand ? 0 : 1; + break; + case float_2nan_prop_ab: + if (is_nan(a_cls)) { + return 0; + } else { + return 1; } - return is_qnan(b_cls) ? 1 : 0; - } else if (is_qnan(a_cls)) { - if (is_snan(b_cls) || !is_qnan(b_cls)) { + break; + case float_2nan_prop_ba: + if (is_nan(b_cls)) { + return 1; + } else { return 0; + } + break; + case float_2nan_prop_x87: + /* + * This implements x87 NaN propagation rules: + * SNaN + QNaN => return the QNaN + * two SNaNs => return the one with the larger significand, silenced + * two QNaNs => return the one with the larger significand + * SNaN and a non-NaN => return the SNaN, silenced + * QNaN and a non-NaN => return the QNaN + * + * If we get down to comparing significands and they are the same, + * return the NaN with the positive sign bit (if any). + */ + if (is_snan(a_cls)) { + if (is_snan(b_cls)) { + return aIsLargerSignificand ? 0 : 1; + } + return is_qnan(b_cls) ? 1 : 0; + } else if (is_qnan(a_cls)) { + if (is_snan(b_cls) || !is_qnan(b_cls)) { + return 0; + } else { + return aIsLargerSignificand ? 0 : 1; + } } else { - return aIsLargerSignificand ? 0 : 1; + return 1; } - } else { - return 1; + default: + g_assert_not_reached(); } -#endif } /*---------------------------------------------------------------------------- diff --git a/include/fpu/softfloat-helpers.h b/include/fpu/softfloat-helpers.h index 94cbe073ec..453188de70 100644 --- a/include/fpu/softfloat-helpers.h +++ b/include/fpu/softfloat-helpers.h @@ -75,6 +75,12 @@ static inline void set_floatx80_rounding_precision(FloatX80RoundPrec val, status->floatx80_rounding_precision = val; } +static inline void set_float_2nan_prop_rule(Float2NaNPropRule rule, + float_status *status) +{ + status->float_2nan_prop_rule = rule; +} + static inline void set_flush_to_zero(bool val, float_status *status) { status->flush_to_zero = val; @@ -126,6 +132,11 @@ get_floatx80_rounding_precision(float_status *status) return status->floatx80_rounding_precision; } +static inline Float2NaNPropRule get_float_2nan_prop_rule(float_status *status) +{ + return status->float_2nan_prop_rule; +} + static inline bool get_flush_to_zero(float_status *status) { return status->flush_to_zero; diff --git a/include/fpu/softfloat-types.h b/include/fpu/softfloat-types.h index 0884ec4ef7..5cd5a0d0ae 100644 --- a/include/fpu/softfloat-types.h +++ b/include/fpu/softfloat-types.h @@ -171,6 +171,47 @@ typedef enum __attribute__((__packed__)) { } FloatX80RoundPrec; /* + * 2-input NaN propagation rule. Individual architectures have + * different rules for which input NaN is propagated to the output + * when there is more than one NaN on the input. + * + * If default_nan_mode is enabled then it is valid not to set a + * NaN propagation rule, because the softfloat code guarantees + * not to try to pick a NaN to propagate in default NaN mode. + * + * For transition, currently the 'none' rule will cause us to + * fall back to picking the propagation rule based on the existing + * ifdef ladder. When all targets are converted it will be an error + * not to set the rule in float_status unless in default_nan_mode, + * and we will assert if we need to handle an input NaN and no + * rule was selected. + */ +typedef enum __attribute__((__packed__)) { + /* No propagation rule specified */ + float_2nan_prop_none = 0, + /* Prefer SNaN over QNaN, then operand A over B */ + float_2nan_prop_s_ab, + /* Prefer SNaN over QNaN, then operand B over A */ + float_2nan_prop_s_ba, + /* Prefer A over B regardless of SNaN vs QNaN */ + float_2nan_prop_ab, + /* Prefer B over A regardless of SNaN vs QNaN */ + float_2nan_prop_ba, + /* + * This implements x87 NaN propagation rules: + * SNaN + QNaN => return the QNaN + * two SNaNs => return the one with the larger significand, silenced + * two QNaNs => return the one with the larger significand + * SNaN and a non-NaN => return the SNaN, silenced + * QNaN and a non-NaN => return the QNaN + * + * If we get down to comparing significands and they are the same, + * return the NaN with the positive sign bit (if any). + */ + float_2nan_prop_x87, +} Float2NaNPropRule; + +/* * Floating Point Status. Individual architectures may maintain * several versions of float_status for different functions. The * correct status for the operation is then passed by reference to @@ -181,6 +222,7 @@ typedef struct float_status { uint16_t float_exception_flags; FloatRoundMode float_rounding_mode; FloatX80RoundPrec floatx80_rounding_precision; + Float2NaNPropRule float_2nan_prop_rule; bool tininess_before_rounding; /* should denormalised results go to zero and set the inexact flag? */ bool flush_to_zero; |