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-rw-r--r--compiler/rustc_apfloat/src/ppc.rs434
1 files changed, 434 insertions, 0 deletions
diff --git a/compiler/rustc_apfloat/src/ppc.rs b/compiler/rustc_apfloat/src/ppc.rs
new file mode 100644
index 000000000..65a0f6664
--- /dev/null
+++ b/compiler/rustc_apfloat/src/ppc.rs
@@ -0,0 +1,434 @@
+use crate::ieee;
+use crate::{Category, ExpInt, Float, FloatConvert, ParseError, Round, Status, StatusAnd};
+
+use core::cmp::Ordering;
+use core::fmt;
+use core::ops::Neg;
+
+#[must_use]
+#[derive(Copy, Clone, PartialEq, PartialOrd, Debug)]
+pub struct DoubleFloat<F>(F, F);
+pub type DoubleDouble = DoubleFloat<ieee::Double>;
+
+// These are legacy semantics for the Fallback, inaccurate implementation of
+// IBM double-double, if the accurate DoubleDouble doesn't handle the
+// operation. It's equivalent to having an IEEE number with consecutive 106
+// bits of mantissa and 11 bits of exponent.
+//
+// It's not equivalent to IBM double-double. For example, a legit IBM
+// double-double, 1 + epsilon:
+//
+// 1 + epsilon = 1 + (1 >> 1076)
+//
+// is not representable by a consecutive 106 bits of mantissa.
+//
+// Currently, these semantics are used in the following way:
+//
+// DoubleDouble -> (Double, Double) ->
+// DoubleDouble's Fallback -> IEEE operations
+//
+// FIXME: Implement all operations in DoubleDouble, and delete these
+// semantics.
+// FIXME(eddyb) This shouldn't need to be `pub`, it's only used in bounds.
+pub struct FallbackS<F>(#[allow(unused)] F);
+type Fallback<F> = ieee::IeeeFloat<FallbackS<F>>;
+impl<F: Float> ieee::Semantics for FallbackS<F> {
+ // Forbid any conversion to/from bits.
+ const BITS: usize = 0;
+ const PRECISION: usize = F::PRECISION * 2;
+ const MAX_EXP: ExpInt = F::MAX_EXP as ExpInt;
+ const MIN_EXP: ExpInt = F::MIN_EXP as ExpInt + F::PRECISION as ExpInt;
+}
+
+// Convert number to F. To avoid spurious underflows, we re-
+// normalize against the F exponent range first, and only *then*
+// truncate the mantissa. The result of that second conversion
+// may be inexact, but should never underflow.
+// FIXME(eddyb) This shouldn't need to be `pub`, it's only used in bounds.
+pub struct FallbackExtendedS<F>(#[allow(unused)] F);
+type FallbackExtended<F> = ieee::IeeeFloat<FallbackExtendedS<F>>;
+impl<F: Float> ieee::Semantics for FallbackExtendedS<F> {
+ // Forbid any conversion to/from bits.
+ const BITS: usize = 0;
+ const PRECISION: usize = Fallback::<F>::PRECISION;
+ const MAX_EXP: ExpInt = F::MAX_EXP as ExpInt;
+}
+
+impl<F: Float> From<Fallback<F>> for DoubleFloat<F>
+where
+ F: FloatConvert<FallbackExtended<F>>,
+ FallbackExtended<F>: FloatConvert<F>,
+{
+ fn from(x: Fallback<F>) -> Self {
+ let mut status;
+ let mut loses_info = false;
+
+ let extended: FallbackExtended<F> = unpack!(status=, x.convert(&mut loses_info));
+ assert_eq!((status, loses_info), (Status::OK, false));
+
+ let a = unpack!(status=, extended.convert(&mut loses_info));
+ assert_eq!(status - Status::INEXACT, Status::OK);
+
+ // If conversion was exact or resulted in a special case, we're done;
+ // just set the second double to zero. Otherwise, re-convert back to
+ // the extended format and compute the difference. This now should
+ // convert exactly to double.
+ let b = if a.is_finite_non_zero() && loses_info {
+ let u: FallbackExtended<F> = unpack!(status=, a.convert(&mut loses_info));
+ assert_eq!((status, loses_info), (Status::OK, false));
+ let v = unpack!(status=, extended - u);
+ assert_eq!(status, Status::OK);
+ let v = unpack!(status=, v.convert(&mut loses_info));
+ assert_eq!((status, loses_info), (Status::OK, false));
+ v
+ } else {
+ F::ZERO
+ };
+
+ DoubleFloat(a, b)
+ }
+}
+
+impl<F: FloatConvert<Self>> From<DoubleFloat<F>> for Fallback<F> {
+ fn from(DoubleFloat(a, b): DoubleFloat<F>) -> Self {
+ let mut status;
+ let mut loses_info = false;
+
+ // Get the first F and convert to our format.
+ let a = unpack!(status=, a.convert(&mut loses_info));
+ assert_eq!((status, loses_info), (Status::OK, false));
+
+ // Unless we have a special case, add in second F.
+ if a.is_finite_non_zero() {
+ let b = unpack!(status=, b.convert(&mut loses_info));
+ assert_eq!((status, loses_info), (Status::OK, false));
+
+ (a + b).value
+ } else {
+ a
+ }
+ }
+}
+
+float_common_impls!(DoubleFloat<F>);
+
+impl<F: Float> Neg for DoubleFloat<F> {
+ type Output = Self;
+ fn neg(self) -> Self {
+ if self.1.is_finite_non_zero() {
+ DoubleFloat(-self.0, -self.1)
+ } else {
+ DoubleFloat(-self.0, self.1)
+ }
+ }
+}
+
+impl<F: FloatConvert<Fallback<F>>> fmt::Display for DoubleFloat<F> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ fmt::Display::fmt(&Fallback::from(*self), f)
+ }
+}
+
+impl<F: FloatConvert<Fallback<F>>> Float for DoubleFloat<F>
+where
+ Self: From<Fallback<F>>,
+{
+ const BITS: usize = F::BITS * 2;
+ const PRECISION: usize = Fallback::<F>::PRECISION;
+ const MAX_EXP: ExpInt = Fallback::<F>::MAX_EXP;
+ const MIN_EXP: ExpInt = Fallback::<F>::MIN_EXP;
+
+ const ZERO: Self = DoubleFloat(F::ZERO, F::ZERO);
+
+ const INFINITY: Self = DoubleFloat(F::INFINITY, F::ZERO);
+
+ // FIXME(eddyb) remove when qnan becomes const fn.
+ const NAN: Self = DoubleFloat(F::NAN, F::ZERO);
+
+ fn qnan(payload: Option<u128>) -> Self {
+ DoubleFloat(F::qnan(payload), F::ZERO)
+ }
+
+ fn snan(payload: Option<u128>) -> Self {
+ DoubleFloat(F::snan(payload), F::ZERO)
+ }
+
+ fn largest() -> Self {
+ let status;
+ let mut r = DoubleFloat(F::largest(), F::largest());
+ r.1 = r.1.scalbn(-(F::PRECISION as ExpInt + 1));
+ r.1 = unpack!(status=, r.1.next_down());
+ assert_eq!(status, Status::OK);
+ r
+ }
+
+ const SMALLEST: Self = DoubleFloat(F::SMALLEST, F::ZERO);
+
+ fn smallest_normalized() -> Self {
+ DoubleFloat(F::smallest_normalized().scalbn(F::PRECISION as ExpInt), F::ZERO)
+ }
+
+ // Implement addition, subtraction, multiplication and division based on:
+ // "Software for Doubled-Precision Floating-Point Computations",
+ // by Seppo Linnainmaa, ACM TOMS vol 7 no 3, September 1981, pages 272-283.
+
+ fn add_r(mut self, rhs: Self, round: Round) -> StatusAnd<Self> {
+ match (self.category(), rhs.category()) {
+ (Category::Infinity, Category::Infinity) => {
+ if self.is_negative() != rhs.is_negative() {
+ Status::INVALID_OP.and(Self::NAN.copy_sign(self))
+ } else {
+ Status::OK.and(self)
+ }
+ }
+
+ (_, Category::Zero) | (Category::NaN, _) | (Category::Infinity, Category::Normal) => {
+ Status::OK.and(self)
+ }
+
+ (Category::Zero, _) | (_, Category::NaN | Category::Infinity) => Status::OK.and(rhs),
+
+ (Category::Normal, Category::Normal) => {
+ let mut status = Status::OK;
+ let (a, aa, c, cc) = (self.0, self.1, rhs.0, rhs.1);
+ let mut z = a;
+ z = unpack!(status|=, z.add_r(c, round));
+ if !z.is_finite() {
+ if !z.is_infinite() {
+ return status.and(DoubleFloat(z, F::ZERO));
+ }
+ status = Status::OK;
+ let a_cmp_c = a.cmp_abs_normal(c);
+ z = cc;
+ z = unpack!(status|=, z.add_r(aa, round));
+ if a_cmp_c == Ordering::Greater {
+ // z = cc + aa + c + a;
+ z = unpack!(status|=, z.add_r(c, round));
+ z = unpack!(status|=, z.add_r(a, round));
+ } else {
+ // z = cc + aa + a + c;
+ z = unpack!(status|=, z.add_r(a, round));
+ z = unpack!(status|=, z.add_r(c, round));
+ }
+ if !z.is_finite() {
+ return status.and(DoubleFloat(z, F::ZERO));
+ }
+ self.0 = z;
+ let mut zz = aa;
+ zz = unpack!(status|=, zz.add_r(cc, round));
+ if a_cmp_c == Ordering::Greater {
+ // self.1 = a - z + c + zz;
+ self.1 = a;
+ self.1 = unpack!(status|=, self.1.sub_r(z, round));
+ self.1 = unpack!(status|=, self.1.add_r(c, round));
+ self.1 = unpack!(status|=, self.1.add_r(zz, round));
+ } else {
+ // self.1 = c - z + a + zz;
+ self.1 = c;
+ self.1 = unpack!(status|=, self.1.sub_r(z, round));
+ self.1 = unpack!(status|=, self.1.add_r(a, round));
+ self.1 = unpack!(status|=, self.1.add_r(zz, round));
+ }
+ } else {
+ // q = a - z;
+ let mut q = a;
+ q = unpack!(status|=, q.sub_r(z, round));
+
+ // zz = q + c + (a - (q + z)) + aa + cc;
+ // Compute a - (q + z) as -((q + z) - a) to avoid temporary copies.
+ let mut zz = q;
+ zz = unpack!(status|=, zz.add_r(c, round));
+ q = unpack!(status|=, q.add_r(z, round));
+ q = unpack!(status|=, q.sub_r(a, round));
+ q = -q;
+ zz = unpack!(status|=, zz.add_r(q, round));
+ zz = unpack!(status|=, zz.add_r(aa, round));
+ zz = unpack!(status|=, zz.add_r(cc, round));
+ if zz.is_zero() && !zz.is_negative() {
+ return Status::OK.and(DoubleFloat(z, F::ZERO));
+ }
+ self.0 = z;
+ self.0 = unpack!(status|=, self.0.add_r(zz, round));
+ if !self.0.is_finite() {
+ self.1 = F::ZERO;
+ return status.and(self);
+ }
+ self.1 = z;
+ self.1 = unpack!(status|=, self.1.sub_r(self.0, round));
+ self.1 = unpack!(status|=, self.1.add_r(zz, round));
+ }
+ status.and(self)
+ }
+ }
+ }
+
+ fn mul_r(mut self, rhs: Self, round: Round) -> StatusAnd<Self> {
+ // Interesting observation: For special categories, finding the lowest
+ // common ancestor of the following layered graph gives the correct
+ // return category:
+ //
+ // NaN
+ // / \
+ // Zero Inf
+ // \ /
+ // Normal
+ //
+ // e.g., NaN * NaN = NaN
+ // Zero * Inf = NaN
+ // Normal * Zero = Zero
+ // Normal * Inf = Inf
+ match (self.category(), rhs.category()) {
+ (Category::NaN, _) => Status::OK.and(self),
+
+ (_, Category::NaN) => Status::OK.and(rhs),
+
+ (Category::Zero, Category::Infinity) | (Category::Infinity, Category::Zero) => {
+ Status::OK.and(Self::NAN)
+ }
+
+ (Category::Zero | Category::Infinity, _) => Status::OK.and(self),
+
+ (_, Category::Zero | Category::Infinity) => Status::OK.and(rhs),
+
+ (Category::Normal, Category::Normal) => {
+ let mut status = Status::OK;
+ let (a, b, c, d) = (self.0, self.1, rhs.0, rhs.1);
+ // t = a * c
+ let mut t = a;
+ t = unpack!(status|=, t.mul_r(c, round));
+ if !t.is_finite_non_zero() {
+ return status.and(DoubleFloat(t, F::ZERO));
+ }
+
+ // tau = fmsub(a, c, t), that is -fmadd(-a, c, t).
+ let mut tau = a;
+ tau = unpack!(status|=, tau.mul_add_r(c, -t, round));
+ // v = a * d
+ let mut v = a;
+ v = unpack!(status|=, v.mul_r(d, round));
+ // w = b * c
+ let mut w = b;
+ w = unpack!(status|=, w.mul_r(c, round));
+ v = unpack!(status|=, v.add_r(w, round));
+ // tau += v + w
+ tau = unpack!(status|=, tau.add_r(v, round));
+ // u = t + tau
+ let mut u = t;
+ u = unpack!(status|=, u.add_r(tau, round));
+
+ self.0 = u;
+ if !u.is_finite() {
+ self.1 = F::ZERO;
+ } else {
+ // self.1 = (t - u) + tau
+ t = unpack!(status|=, t.sub_r(u, round));
+ t = unpack!(status|=, t.add_r(tau, round));
+ self.1 = t;
+ }
+ status.and(self)
+ }
+ }
+ }
+
+ fn mul_add_r(self, multiplicand: Self, addend: Self, round: Round) -> StatusAnd<Self> {
+ Fallback::from(self)
+ .mul_add_r(Fallback::from(multiplicand), Fallback::from(addend), round)
+ .map(Self::from)
+ }
+
+ fn div_r(self, rhs: Self, round: Round) -> StatusAnd<Self> {
+ Fallback::from(self).div_r(Fallback::from(rhs), round).map(Self::from)
+ }
+
+ fn c_fmod(self, rhs: Self) -> StatusAnd<Self> {
+ Fallback::from(self).c_fmod(Fallback::from(rhs)).map(Self::from)
+ }
+
+ fn round_to_integral(self, round: Round) -> StatusAnd<Self> {
+ Fallback::from(self).round_to_integral(round).map(Self::from)
+ }
+
+ fn next_up(self) -> StatusAnd<Self> {
+ Fallback::from(self).next_up().map(Self::from)
+ }
+
+ fn from_bits(input: u128) -> Self {
+ let (a, b) = (input, input >> F::BITS);
+ DoubleFloat(F::from_bits(a & ((1 << F::BITS) - 1)), F::from_bits(b & ((1 << F::BITS) - 1)))
+ }
+
+ fn from_u128_r(input: u128, round: Round) -> StatusAnd<Self> {
+ Fallback::from_u128_r(input, round).map(Self::from)
+ }
+
+ fn from_str_r(s: &str, round: Round) -> Result<StatusAnd<Self>, ParseError> {
+ Fallback::from_str_r(s, round).map(|r| r.map(Self::from))
+ }
+
+ fn to_bits(self) -> u128 {
+ self.0.to_bits() | (self.1.to_bits() << F::BITS)
+ }
+
+ fn to_u128_r(self, width: usize, round: Round, is_exact: &mut bool) -> StatusAnd<u128> {
+ Fallback::from(self).to_u128_r(width, round, is_exact)
+ }
+
+ fn cmp_abs_normal(self, rhs: Self) -> Ordering {
+ self.0.cmp_abs_normal(rhs.0).then_with(|| {
+ let result = self.1.cmp_abs_normal(rhs.1);
+ if result != Ordering::Equal {
+ let against = self.0.is_negative() ^ self.1.is_negative();
+ let rhs_against = rhs.0.is_negative() ^ rhs.1.is_negative();
+ (!against)
+ .cmp(&!rhs_against)
+ .then_with(|| if against { result.reverse() } else { result })
+ } else {
+ result
+ }
+ })
+ }
+
+ fn bitwise_eq(self, rhs: Self) -> bool {
+ self.0.bitwise_eq(rhs.0) && self.1.bitwise_eq(rhs.1)
+ }
+
+ fn is_negative(self) -> bool {
+ self.0.is_negative()
+ }
+
+ fn is_denormal(self) -> bool {
+ self.category() == Category::Normal
+ && (self.0.is_denormal() || self.0.is_denormal() ||
+ // (double)(Hi + Lo) == Hi defines a normal number.
+ !(self.0 + self.1).value.bitwise_eq(self.0))
+ }
+
+ fn is_signaling(self) -> bool {
+ self.0.is_signaling()
+ }
+
+ fn category(self) -> Category {
+ self.0.category()
+ }
+
+ fn get_exact_inverse(self) -> Option<Self> {
+ Fallback::from(self).get_exact_inverse().map(Self::from)
+ }
+
+ fn ilogb(self) -> ExpInt {
+ self.0.ilogb()
+ }
+
+ fn scalbn_r(self, exp: ExpInt, round: Round) -> Self {
+ DoubleFloat(self.0.scalbn_r(exp, round), self.1.scalbn_r(exp, round))
+ }
+
+ fn frexp_r(self, exp: &mut ExpInt, round: Round) -> Self {
+ let a = self.0.frexp_r(exp, round);
+ let mut b = self.1;
+ if self.category() == Category::Normal {
+ b = b.scalbn_r(-*exp, round);
+ }
+ DoubleFloat(a, b)
+ }
+}
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