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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/extend.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/extend.rs | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/src/float/extend.rs b/vendor/compiler_builtins/src/float/extend.rs new file mode 100644 index 000000000..39633773b --- /dev/null +++ b/vendor/compiler_builtins/src/float/extend.rs @@ -0,0 +1,83 @@ +use float::Float; +use int::{CastInto, Int}; + +/// Generic conversion from a narrower to a wider IEEE-754 floating-point type +fn extend<F: Float, R: Float>(a: F) -> R +where + F::Int: CastInto<u64>, + u64: CastInto<F::Int>, + u32: CastInto<R::Int>, + R::Int: CastInto<u32>, + R::Int: CastInto<u64>, + u64: CastInto<R::Int>, + F::Int: CastInto<R::Int>, +{ + let src_zero = F::Int::ZERO; + let src_one = F::Int::ONE; + let src_bits = F::BITS; + let src_sign_bits = F::SIGNIFICAND_BITS; + let src_exp_bias = F::EXPONENT_BIAS; + let src_min_normal = F::IMPLICIT_BIT; + let src_infinity = F::EXPONENT_MASK; + let src_sign_mask = F::SIGN_MASK as F::Int; + let src_abs_mask = src_sign_mask - src_one; + let src_qnan = F::SIGNIFICAND_MASK; + let src_nan_code = src_qnan - src_one; + + let dst_bits = R::BITS; + let dst_sign_bits = R::SIGNIFICAND_BITS; + let dst_inf_exp = R::EXPONENT_MAX; + let dst_exp_bias = R::EXPONENT_BIAS; + let dst_min_normal = R::IMPLICIT_BIT; + + let sign_bits_delta = dst_sign_bits - src_sign_bits; + let exp_bias_delta = dst_exp_bias - src_exp_bias; + let a_abs = a.repr() & src_abs_mask; + let mut abs_result = R::Int::ZERO; + + if a_abs.wrapping_sub(src_min_normal) < src_infinity.wrapping_sub(src_min_normal) { + // a is a normal number. + // Extend to the destination type by shifting the significand and + // exponent into the proper position and rebiasing the exponent. + let abs_dst: R::Int = a_abs.cast(); + let bias_dst: R::Int = exp_bias_delta.cast(); + abs_result = abs_dst.wrapping_shl(sign_bits_delta); + abs_result += bias_dst.wrapping_shl(dst_sign_bits); + } else if a_abs >= src_infinity { + // a is NaN or infinity. + // Conjure the result by beginning with infinity, then setting the qNaN + // bit (if needed) and right-aligning the rest of the trailing NaN + // payload field. + let qnan_dst: R::Int = (a_abs & src_qnan).cast(); + let nan_code_dst: R::Int = (a_abs & src_nan_code).cast(); + let inf_exp_dst: R::Int = dst_inf_exp.cast(); + abs_result = inf_exp_dst.wrapping_shl(dst_sign_bits); + abs_result |= qnan_dst.wrapping_shl(sign_bits_delta); + abs_result |= nan_code_dst.wrapping_shl(sign_bits_delta); + } else if a_abs != src_zero { + // a is denormal. + // Renormalize the significand and clear the leading bit, then insert + // the correct adjusted exponent in the destination type. + let scale = a_abs.leading_zeros() - src_min_normal.leading_zeros(); + let abs_dst: R::Int = a_abs.cast(); + let bias_dst: R::Int = (exp_bias_delta - scale + 1).cast(); + abs_result = abs_dst.wrapping_shl(sign_bits_delta + scale); + abs_result = (abs_result ^ dst_min_normal) | (bias_dst.wrapping_shl(dst_sign_bits)); + } + + let sign_result: R::Int = (a.repr() & src_sign_mask).cast(); + R::from_repr(abs_result | (sign_result.wrapping_shl(dst_bits - src_bits))) +} + +intrinsics! { + #[aapcs_on_arm] + #[arm_aeabi_alias = __aeabi_f2d] + pub extern "C" fn __extendsfdf2(a: f32) -> f64 { + extend(a) + } + + #[cfg(target_arch = "arm")] + pub extern "C" fn __extendsfdf2vfp(a: f32) -> f64 { + a as f64 // LLVM generate 'fcvtds' + } +} |