Skip to content

NaN non-determinism for intrinsics and libm functions #3244

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 5 commits into from
Dec 28, 2023
Merged

NaN non-determinism for intrinsics and libm functions #3244

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
56ec38f
fast_math: detect non-finite results
RalfJung Dec 27, 2023
2e78b9f
make float intrinsics return non-deterministic NaN
RalfJung Dec 28, 2023
1586fa5
add NaN-nondet to libm functions
RalfJung Dec 28, 2023
08e6b30
NaN non-determinism for SIMD intrinsics
RalfJung Dec 28, 2023
2d4f580
don't test unspecified case
RalfJung Dec 28, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
45 changes: 45 additions & 0 deletions src/helpers.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ use std::time::Duration;
use log::trace;

use rustc_apfloat::ieee::{Double, Single};
use rustc_apfloat::Float;
use rustc_hir::def::{DefKind, Namespace};
use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
use rustc_index::IndexVec;
Expand Down Expand Up @@ -117,6 +118,50 @@ fn try_resolve_did(tcx: TyCtxt<'_>, path: &[&str], namespace: Option<Namespace>)
}
}

/// Convert a softfloat type to its corresponding hostfloat type.
pub trait ToHost {
type HostFloat;
fn to_host(self) -> Self::HostFloat;
}

/// Convert a hostfloat type to its corresponding softfloat type.
pub trait ToSoft {
type SoftFloat;
fn to_soft(self) -> Self::SoftFloat;
}

impl ToHost for rustc_apfloat::ieee::Double {
type HostFloat = f64;

fn to_host(self) -> Self::HostFloat {
f64::from_bits(self.to_bits().try_into().unwrap())
}
}

impl ToSoft for f64 {
type SoftFloat = rustc_apfloat::ieee::Double;

fn to_soft(self) -> Self::SoftFloat {
Float::from_bits(self.to_bits().into())
}
}

impl ToHost for rustc_apfloat::ieee::Single {
type HostFloat = f32;

fn to_host(self) -> Self::HostFloat {
f32::from_bits(self.to_bits().try_into().unwrap())
}
}

impl ToSoft for f32 {
type SoftFloat = rustc_apfloat::ieee::Single;

fn to_soft(self) -> Self::SoftFloat {
Float::from_bits(self.to_bits().into())
}
}

impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
/// Checks if the given crate/module exists.
Expand Down
4 changes: 4 additions & 0 deletions src/operator.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -118,4 +118,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
nan
}
}

fn adjust_nan<F1: Float + FloatConvert<F2>, F2: Float>(&self, f: F2, inputs: &[F1]) -> F2 {
if f.is_nan() { self.generate_nan(inputs) } else { f }
}
}
108 changes: 61 additions & 47 deletions src/shims/foreign_items.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ use rustc_target::{

use super::backtrace::EvalContextExt as _;
use crate::*;
use helpers::{ToHost, ToSoft};

/// Type of dynamic symbols (for `dlsym` et al)
#[derive(Debug, Copy, Clone)]
Expand Down Expand Up @@ -886,23 +887,26 @@ trait EvalContextExtPriv<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
| "tgammaf"
=> {
let [f] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
let f = this.read_scalar(f)?.to_f32()?;
// FIXME: Using host floats.
let f = f32::from_bits(this.read_scalar(f)?.to_u32()?);
let f_host = f.to_host();
let res = match link_name.as_str() {
"cbrtf" => f.cbrt(),
"coshf" => f.cosh(),
"sinhf" => f.sinh(),
"tanf" => f.tan(),
"tanhf" => f.tanh(),
"acosf" => f.acos(),
"asinf" => f.asin(),
"atanf" => f.atan(),
"log1pf" => f.ln_1p(),
"expm1f" => f.exp_m1(),
"tgammaf" => f.gamma(),
"cbrtf" => f_host.cbrt(),
"coshf" => f_host.cosh(),
"sinhf" => f_host.sinh(),
"tanf" => f_host.tan(),
"tanhf" => f_host.tanh(),
"acosf" => f_host.acos(),
"asinf" => f_host.asin(),
"atanf" => f_host.atan(),
"log1pf" => f_host.ln_1p(),
"expm1f" => f_host.exp_m1(),
"tgammaf" => f_host.gamma(),
_ => bug!(),
};
this.write_scalar(Scalar::from_u32(res.to_bits()), dest)?;
let res = res.to_soft();
let res = this.adjust_nan(res, &[f]);
this.write_scalar(res, dest)?;
}
#[rustfmt::skip]
| "_hypotf"
Expand All @@ -911,19 +915,20 @@ trait EvalContextExtPriv<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
| "fdimf"
=> {
let [f1, f2] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
let f1 = this.read_scalar(f1)?.to_f32()?;
let f2 = this.read_scalar(f2)?.to_f32()?;
// underscore case for windows, here and below
// (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
// FIXME: Using host floats.
let f1 = f32::from_bits(this.read_scalar(f1)?.to_u32()?);
let f2 = f32::from_bits(this.read_scalar(f2)?.to_u32()?);
let res = match link_name.as_str() {
"_hypotf" | "hypotf" => f1.hypot(f2),
"atan2f" => f1.atan2(f2),
"_hypotf" | "hypotf" => f1.to_host().hypot(f2.to_host()).to_soft(),
"atan2f" => f1.to_host().atan2(f2.to_host()).to_soft(),
#[allow(deprecated)]
"fdimf" => f1.abs_sub(f2),
"fdimf" => f1.to_host().abs_sub(f2.to_host()).to_soft(),
_ => bug!(),
};
this.write_scalar(Scalar::from_u32(res.to_bits()), dest)?;
let res = this.adjust_nan(res, &[f1, f2]);
this.write_scalar(res, dest)?;
}
#[rustfmt::skip]
| "cbrt"
Expand All @@ -939,23 +944,26 @@ trait EvalContextExtPriv<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
| "tgamma"
=> {
let [f] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
let f = this.read_scalar(f)?.to_f64()?;
// FIXME: Using host floats.
let f = f64::from_bits(this.read_scalar(f)?.to_u64()?);
let f_host = f.to_host();
let res = match link_name.as_str() {
"cbrt" => f.cbrt(),
"cosh" => f.cosh(),
"sinh" => f.sinh(),
"tan" => f.tan(),
"tanh" => f.tanh(),
"acos" => f.acos(),
"asin" => f.asin(),
"atan" => f.atan(),
"log1p" => f.ln_1p(),
"expm1" => f.exp_m1(),
"tgamma" => f.gamma(),
"cbrt" => f_host.cbrt(),
"cosh" => f_host.cosh(),
"sinh" => f_host.sinh(),
"tan" => f_host.tan(),
"tanh" => f_host.tanh(),
"acos" => f_host.acos(),
"asin" => f_host.asin(),
"atan" => f_host.atan(),
"log1p" => f_host.ln_1p(),
"expm1" => f_host.exp_m1(),
"tgamma" => f_host.gamma(),
_ => bug!(),
};
this.write_scalar(Scalar::from_u64(res.to_bits()), dest)?;
let res = res.to_soft();
let res = this.adjust_nan(res, &[f]);
this.write_scalar(res, dest)?;
}
#[rustfmt::skip]
| "_hypot"
Expand All @@ -964,17 +972,20 @@ trait EvalContextExtPriv<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
| "fdim"
=> {
let [f1, f2] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
let f1 = this.read_scalar(f1)?.to_f64()?;
let f2 = this.read_scalar(f2)?.to_f64()?;
// underscore case for windows, here and below
// (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
// FIXME: Using host floats.
let f1 = f64::from_bits(this.read_scalar(f1)?.to_u64()?);
let f2 = f64::from_bits(this.read_scalar(f2)?.to_u64()?);
let res = match link_name.as_str() {
"_hypot" | "hypot" => f1.hypot(f2),
"atan2" => f1.atan2(f2),
"_hypot" | "hypot" => f1.to_host().hypot(f2.to_host()).to_soft(),
"atan2" => f1.to_host().atan2(f2.to_host()).to_soft(),
#[allow(deprecated)]
"fdim" => f1.abs_sub(f2),
"fdim" => f1.to_host().abs_sub(f2.to_host()).to_soft(),
_ => bug!(),
};
this.write_scalar(Scalar::from_u64(res.to_bits()), dest)?;
let res = this.adjust_nan(res, &[f1, f2]);
this.write_scalar(res, dest)?;
}
#[rustfmt::skip]
| "_ldexp"
Expand All @@ -987,27 +998,30 @@ trait EvalContextExtPriv<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
let exp = this.read_scalar(exp)?.to_i32()?;

let res = x.scalbn(exp);
this.write_scalar(Scalar::from_f64(res), dest)?;
let res = this.adjust_nan(res, &[x]);
this.write_scalar(res, dest)?;
}
"lgammaf_r" => {
let [x, signp] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
// FIXME: Using host floats.
let x = f32::from_bits(this.read_scalar(x)?.to_u32()?);
let x = this.read_scalar(x)?.to_f32()?;
let signp = this.deref_pointer(signp)?;

let (res, sign) = x.ln_gamma();
// FIXME: Using host floats.
let (res, sign) = x.to_host().ln_gamma();
this.write_int(sign, &signp)?;
this.write_scalar(Scalar::from_u32(res.to_bits()), dest)?;
let res = this.adjust_nan(res.to_soft(), &[x]);
this.write_scalar(res, dest)?;
}
"lgamma_r" => {
let [x, signp] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
// FIXME: Using host floats.
let x = f64::from_bits(this.read_scalar(x)?.to_u64()?);
let x = this.read_scalar(x)?.to_f64()?;
let signp = this.deref_pointer(signp)?;

let (res, sign) = x.ln_gamma();
// FIXME: Using host floats.
let (res, sign) = x.to_host().ln_gamma();
this.write_int(sign, &signp)?;
this.write_scalar(Scalar::from_u64(res.to_bits()), dest)?;
let res = this.adjust_nan(res.to_soft(), &[x]);
this.write_scalar(res, dest)?;
}

// LLVM intrinsics
Expand Down
Loading