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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/libm/src/math/floor.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 'vendor/compiler_builtins/libm/src/math/floor.rs')
-rw-r--r-- | vendor/compiler_builtins/libm/src/math/floor.rs | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/libm/src/math/floor.rs b/vendor/compiler_builtins/libm/src/math/floor.rs new file mode 100644 index 000000000..d09f9a1a1 --- /dev/null +++ b/vendor/compiler_builtins/libm/src/math/floor.rs @@ -0,0 +1,81 @@ +#![allow(unreachable_code)] +use core::f64; + +const TOINT: f64 = 1. / f64::EPSILON; + +/// Floor (f64) +/// +/// Finds the nearest integer less than or equal to `x`. +#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] +pub fn floor(x: f64) -> f64 { + // On wasm32 we know that LLVM's intrinsic will compile to an optimized + // `f64.floor` native instruction, so we can leverage this for both code size + // and speed. + llvm_intrinsically_optimized! { + #[cfg(target_arch = "wasm32")] { + return unsafe { ::core::intrinsics::floorf64(x) } + } + } + #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] + { + //use an alternative implementation on x86, because the + //main implementation fails with the x87 FPU used by + //debian i386, probablly due to excess precision issues. + //basic implementation taken from https://github.com/rust-lang/libm/issues/219 + use super::fabs; + if fabs(x).to_bits() < 4503599627370496.0_f64.to_bits() { + let truncated = x as i64 as f64; + if truncated > x { + return truncated - 1.0; + } else { + return truncated; + } + } else { + return x; + } + } + let ui = x.to_bits(); + let e = ((ui >> 52) & 0x7ff) as i32; + + if (e >= 0x3ff + 52) || (x == 0.) { + return x; + } + /* y = int(x) - x, where int(x) is an integer neighbor of x */ + let y = if (ui >> 63) != 0 { + x - TOINT + TOINT - x + } else { + x + TOINT - TOINT - x + }; + /* special case because of non-nearest rounding modes */ + if e < 0x3ff { + force_eval!(y); + return if (ui >> 63) != 0 { -1. } else { 0. }; + } + if y > 0. { + x + y - 1. + } else { + x + y + } +} + +#[cfg(test)] +mod tests { + use super::*; + use core::f64::*; + + #[test] + fn sanity_check() { + assert_eq!(floor(1.1), 1.0); + assert_eq!(floor(2.9), 2.0); + } + + /// The spec: https://en.cppreference.com/w/cpp/numeric/math/floor + #[test] + fn spec_tests() { + // Not Asserted: that the current rounding mode has no effect. + assert!(floor(NAN).is_nan()); + for f in [0.0, -0.0, INFINITY, NEG_INFINITY].iter().copied() { + assert_eq!(floor(f), f); + } + } +} |