Backport LLVM apfloat commit to rustc_apfloat
Backports LLVM commit: e34bd1e0b0
Fixes #69532
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@ -1511,6 +1511,18 @@ impl<S: Semantics, T: Semantics> FloatConvert<IeeeFloat<T>> for IeeeFloat<S> {
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sig::set_bit(&mut r.sig, T::PRECISION - 1);
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sig::set_bit(&mut r.sig, T::PRECISION - 1);
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}
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}
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// If we are truncating NaN, it is possible that we shifted out all of the
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// set bits in a signalling NaN payload. But NaN must remain NaN, so some
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// bit in the significand must be set (otherwise it is Inf).
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// This can only happen with sNaN. Set the 1st bit after the quiet bit,
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// so that we still have an sNaN.
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if r.sig[0] == 0 {
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assert!(shift < 0, "Should not lose NaN payload on extend");
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assert!(T::PRECISION >= 3, "Unexpectedly narrow significand");
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assert!(*loses_info, "Missing payload should have set lost info");
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sig::set_bit(&mut r.sig, T::PRECISION - 3);
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}
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// gcc forces the Quiet bit on, which means (float)(double)(float_sNan)
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// gcc forces the Quiet bit on, which means (float)(double)(float_sNan)
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// does not give you back the same bits. This is dubious, and we
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// does not give you back the same bits. This is dubious, and we
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// don't currently do it. You're really supposed to get
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// don't currently do it. You're really supposed to get
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@ -566,6 +566,15 @@ fn fma() {
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}
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}
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}
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}
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#[test]
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fn issue_69532() {
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let f = Double::from_bits(0x7FF0_0000_0000_0001u64 as u128);
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let mut loses_info = false;
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let r: Single = f.convert(&mut loses_info).value;
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assert!(loses_info);
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assert!(r.is_nan());
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}
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#[test]
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#[test]
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fn min_num() {
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fn min_num() {
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let f1 = Double::from_f64(1.0);
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let f1 = Double::from_f64(1.0);
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@ -0,0 +1,24 @@
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// run-pass
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#![feature(const_fn_transmute)]
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const fn make_nans() -> (f64, f64, f32, f32) {
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let nan1: f64 = unsafe { std::mem::transmute(0x7FF0_0001_0000_0001u64) };
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let nan2: f64 = unsafe { std::mem::transmute(0x7FF0_0000_0000_0001u64) };
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let nan1_32 = nan1 as f32;
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let nan2_32 = nan2 as f32;
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(nan1, nan2, nan1_32, nan2_32)
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}
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static NANS: (f64, f64, f32, f32) = make_nans();
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fn main() {
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let (nan1, nan2, nan1_32, nan2_32) = NANS;
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assert!(nan1.is_nan());
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assert!(nan2.is_nan());
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assert!(nan1_32.is_nan());
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assert!(nan2_32.is_nan());
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}
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