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Auto merge of rust-lang#3244 - RalfJung:nan-nondet, r=RalfJung
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NaN non-determinism for intrinsics and libm functions
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@bors
bors committed Dec 28, 2023
2 parents 0c2c93e + 771e479 commit a63fd5e
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Showing 14 changed files with 488 additions and 197 deletions.
45 changes: 45 additions & 0 deletions src/tools/miri/src/helpers.rs
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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/tools/miri/src/operator.rs
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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/tools/miri/src/shims/foreign_items.rs
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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
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