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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /vendor/compiler_builtins/src/float/add.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | vendor/compiler_builtins/src/float/add.rs | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/src/float/add.rs b/vendor/compiler_builtins/src/float/add.rs new file mode 100644 index 000000000..67f6c2c14 --- /dev/null +++ b/vendor/compiler_builtins/src/float/add.rs @@ -0,0 +1,213 @@ +use float::Float; +use int::{CastInto, Int}; + +/// Returns `a + b` +fn add<F: Float>(a: F, b: F) -> F +where + u32: CastInto<F::Int>, + F::Int: CastInto<u32>, + i32: CastInto<F::Int>, + F::Int: CastInto<i32>, +{ + let one = F::Int::ONE; + let zero = F::Int::ZERO; + + let bits = F::BITS.cast(); + let significand_bits = F::SIGNIFICAND_BITS; + let max_exponent = F::EXPONENT_MAX; + + let implicit_bit = F::IMPLICIT_BIT; + let significand_mask = F::SIGNIFICAND_MASK; + let sign_bit = F::SIGN_MASK as F::Int; + let abs_mask = sign_bit - one; + let exponent_mask = F::EXPONENT_MASK; + let inf_rep = exponent_mask; + let quiet_bit = implicit_bit >> 1; + let qnan_rep = exponent_mask | quiet_bit; + + let mut a_rep = a.repr(); + let mut b_rep = b.repr(); + let a_abs = a_rep & abs_mask; + let b_abs = b_rep & abs_mask; + + // Detect if a or b is zero, infinity, or NaN. + if a_abs.wrapping_sub(one) >= inf_rep - one || b_abs.wrapping_sub(one) >= inf_rep - one { + // NaN + anything = qNaN + if a_abs > inf_rep { + return F::from_repr(a_abs | quiet_bit); + } + // anything + NaN = qNaN + if b_abs > inf_rep { + return F::from_repr(b_abs | quiet_bit); + } + + if a_abs == inf_rep { + // +/-infinity + -/+infinity = qNaN + if (a.repr() ^ b.repr()) == sign_bit { + return F::from_repr(qnan_rep); + } else { + // +/-infinity + anything remaining = +/- infinity + return a; + } + } + + // anything remaining + +/-infinity = +/-infinity + if b_abs == inf_rep { + return b; + } + + // zero + anything = anything + if a_abs == Int::ZERO { + // but we need to get the sign right for zero + zero + if b_abs == Int::ZERO { + return F::from_repr(a.repr() & b.repr()); + } else { + return b; + } + } + + // anything + zero = anything + if b_abs == Int::ZERO { + return a; + } + } + + // Swap a and b if necessary so that a has the larger absolute value. + if b_abs > a_abs { + // Don't use mem::swap because it may generate references to memcpy in unoptimized code. + let tmp = a_rep; + a_rep = b_rep; + b_rep = tmp; + } + + // Extract the exponent and significand from the (possibly swapped) a and b. + let mut a_exponent: i32 = ((a_rep & exponent_mask) >> significand_bits).cast(); + let mut b_exponent: i32 = ((b_rep & exponent_mask) >> significand_bits).cast(); + let mut a_significand = a_rep & significand_mask; + let mut b_significand = b_rep & significand_mask; + + // normalize any denormals, and adjust the exponent accordingly. + if a_exponent == 0 { + let (exponent, significand) = F::normalize(a_significand); + a_exponent = exponent; + a_significand = significand; + } + if b_exponent == 0 { + let (exponent, significand) = F::normalize(b_significand); + b_exponent = exponent; + b_significand = significand; + } + + // The sign of the result is the sign of the larger operand, a. If they + // have opposite signs, we are performing a subtraction; otherwise addition. + let result_sign = a_rep & sign_bit; + let subtraction = ((a_rep ^ b_rep) & sign_bit) != zero; + + // Shift the significands to give us round, guard and sticky, and or in the + // implicit significand bit. (If we fell through from the denormal path it + // was already set by normalize(), but setting it twice won't hurt + // anything.) + a_significand = (a_significand | implicit_bit) << 3; + b_significand = (b_significand | implicit_bit) << 3; + + // Shift the significand of b by the difference in exponents, with a sticky + // bottom bit to get rounding correct. + let align = a_exponent.wrapping_sub(b_exponent).cast(); + if align != Int::ZERO { + if align < bits { + let sticky = + F::Int::from_bool(b_significand << bits.wrapping_sub(align).cast() != Int::ZERO); + b_significand = (b_significand >> align.cast()) | sticky; + } else { + b_significand = one; // sticky; b is known to be non-zero. + } + } + if subtraction { + a_significand = a_significand.wrapping_sub(b_significand); + // If a == -b, return +zero. + if a_significand == Int::ZERO { + return F::from_repr(Int::ZERO); + } + + // If partial cancellation occured, we need to left-shift the result + // and adjust the exponent: + if a_significand < implicit_bit << 3 { + let shift = + a_significand.leading_zeros() as i32 - (implicit_bit << 3).leading_zeros() as i32; + a_significand <<= shift; + a_exponent -= shift; + } + } else { + // addition + a_significand += b_significand; + + // If the addition carried up, we need to right-shift the result and + // adjust the exponent: + if a_significand & implicit_bit << 4 != Int::ZERO { + let sticky = F::Int::from_bool(a_significand & one != Int::ZERO); + a_significand = a_significand >> 1 | sticky; + a_exponent += 1; + } + } + + // If we have overflowed the type, return +/- infinity: + if a_exponent >= max_exponent as i32 { + return F::from_repr(inf_rep | result_sign); + } + + if a_exponent <= 0 { + // Result is denormal before rounding; the exponent is zero and we + // need to shift the significand. + let shift = (1 - a_exponent).cast(); + let sticky = + F::Int::from_bool((a_significand << bits.wrapping_sub(shift).cast()) != Int::ZERO); + a_significand = a_significand >> shift.cast() | sticky; + a_exponent = 0; + } + + // Low three bits are round, guard, and sticky. + let a_significand_i32: i32 = a_significand.cast(); + let round_guard_sticky: i32 = a_significand_i32 & 0x7; + + // Shift the significand into place, and mask off the implicit bit. + let mut result = a_significand >> 3 & significand_mask; + + // Insert the exponent and sign. + result |= a_exponent.cast() << significand_bits; + result |= result_sign; + + // Final rounding. The result may overflow to infinity, but that is the + // correct result in that case. + if round_guard_sticky > 0x4 { + result += one; + } + if round_guard_sticky == 0x4 { + result += result & one; + } + + F::from_repr(result) +} + +intrinsics! { + #[aapcs_on_arm] + #[arm_aeabi_alias = __aeabi_fadd] + pub extern "C" fn __addsf3(a: f32, b: f32) -> f32 { + add(a, b) + } + + #[aapcs_on_arm] + #[arm_aeabi_alias = __aeabi_dadd] + pub extern "C" fn __adddf3(a: f64, b: f64) -> f64 { + add(a, b) + } + + #[cfg(target_arch = "arm")] + pub extern "C" fn __addsf3vfp(a: f32, b: f32) -> f32 { + a + b + } + + #[cfg(target_arch = "arm")] + pub extern "C" fn __adddf3vfp(a: f64, b: f64) -> f64 { + a + b + } +} |