From e1b76386b7e323054d5e8844366ebad86bba693e Mon Sep 17 00:00:00 2001
From: Henry Gressmann <mail@henrygressmann.de>
Date: Sat, 26 Apr 2025 17:43:23 +0200
Subject: feat: add canonicalize_nans feature

Signed-off-by: Henry Gressmann <mail@henrygressmann.de>
---
 crates/tinywasm/Cargo.toml                     | 10 ++++++++-
 crates/tinywasm/src/interpreter/num_helpers.rs | 29 ++++++++++++++++++++++----
 2 files changed, 34 insertions(+), 5 deletions(-)

(limited to 'crates')

diff --git a/crates/tinywasm/Cargo.toml b/crates/tinywasm/Cargo.toml
index 3281476..10a3099 100644
--- a/crates/tinywasm/Cargo.toml
+++ b/crates/tinywasm/Cargo.toml
@@ -32,12 +32,20 @@ serde_json={version="1.0"}
 serde={version="1.0", features=["derive"]}
 
 [features]
-default=["std", "parser", "logging", "archive"]
+default=["std", "parser", "logging", "archive", "canonicalize_nans"]
+
 logging=["log", "tinywasm-parser?/logging", "tinywasm-types/logging"]
 std=["tinywasm-parser?/std", "tinywasm-types/std"]
+
+# support for parsing WebAssembly
 parser=["dep:tinywasm-parser"]
+
+# support for "archiving" tinywasm bytecode
 archive=["tinywasm-types/archive"]
 
+# canonicalize all NaN values to a single representation
+canonicalize_nans=[]
+
 # enable simd support (unstable / unfinished)
 __simd=[]
 
diff --git a/crates/tinywasm/src/interpreter/num_helpers.rs b/crates/tinywasm/src/interpreter/num_helpers.rs
index 678c32e..7e8a461 100644
--- a/crates/tinywasm/src/interpreter/num_helpers.rs
+++ b/crates/tinywasm/src/interpreter/num_helpers.rs
@@ -72,9 +72,12 @@ macro_rules! impl_wasm_float_ops {
     ($($t:ty)*) => ($(
         impl TinywasmFloatExt for $t {
             // https://webassembly.github.io/spec/core/exec/numerics.html#op-fnearest
+            #[inline]
             fn tw_nearest(self) -> Self {
                 match self {
-                    // x if x.is_nan() => x, // preserve NaN
+                    #[cfg(not(feature = "canonicalize_nans"))]
+                    x if x.is_nan() => x, // preserve NaN
+                    #[cfg(feature = "canonicalize_nans")]
                     x if x.is_nan() => Self::NAN, // Do not preserve NaN
                     x if x.is_infinite() || x == 0.0 => x, // preserve infinities and zeros
                     x if (0.0..=0.5).contains(&x) => 0.0,
@@ -100,7 +103,9 @@ macro_rules! impl_wasm_float_ops {
                     Some(core::cmp::Ordering::Less) => self,
                     Some(core::cmp::Ordering::Greater) => other,
                     Some(core::cmp::Ordering::Equal) => if self.is_sign_negative() && other.is_sign_positive() { self } else { other },
-                    // None => self + other, // At least one input is NaN. Use `+` to perform NaN propagation and quieting.
+                    #[cfg(not(feature = "canonicalize_nans"))]
+                    None => self + other, // At least one input is NaN. Use `+` to perform NaN propagation and quieting.
+                    #[cfg(feature = "canonicalize_nans")]
                     None => Self::NAN, // Do not preserve NaN
                 }
             }
@@ -113,7 +118,9 @@ macro_rules! impl_wasm_float_ops {
                     Some(core::cmp::Ordering::Greater) => self,
                     Some(core::cmp::Ordering::Less) => other,
                     Some(core::cmp::Ordering::Equal) => if self.is_sign_negative() && other.is_sign_positive() { other } else { self },
-                    // None => self + other, // At least one input is NaN. Use `+` to perform NaN propagation and quieting.
+                    #[cfg(not(feature = "canonicalize_nans"))]
+                    None => self + other, // At least one input is NaN. Use `+` to perform NaN propagation and quieting.
+                    #[cfg(feature = "canonicalize_nans")]
                     None => Self::NAN, // Do not preserve NaN
                 }
             }
@@ -184,8 +191,15 @@ macro_rules! impl_checked_wrapping_rem {
 
 impl_checked_wrapping_rem! { i32 i64 u32 u64 }
 
-#[cfg(feature = "__simd")]
+#[cfg(all(feature = "__simd", not(feature = "canonicalize_nans")))]
+#[inline]
+pub(crate) fn canonicalize_f32x4(x: core::simd::f32x4) -> core::simd::f32x4 {
+    x // No need to do anything, as we are not replacing NaNs
+}
+
+#[cfg(all(feature = "__simd", feature = "canonicalize_nans"))]
 /// replace all NaNs in a f32x4 with f32::NAN
+#[inline]
 pub(crate) fn canonicalize_f32x4(x: core::simd::f32x4) -> core::simd::f32x4 {
     use core::simd::{Simd, num::SimdFloat};
     let nan = Simd::splat(f32::NAN);
@@ -193,8 +207,15 @@ pub(crate) fn canonicalize_f32x4(x: core::simd::f32x4) -> core::simd::f32x4 {
     mask.select(nan, x)
 }
 
+#[cfg(all(feature = "__simd", not(feature = "canonicalize_nans")))]
+#[inline]
+pub(crate) fn canonicalize_f64x2(x: core::simd::f64x2) -> core::simd::f64x2 {
+    x // No need to do anything, as we are not replacing NaNs
+}
+
 #[cfg(feature = "__simd")]
 /// replace all NaNs in a f64x2 with f64::NAN
+#[inline]
 pub(crate) fn canonicalize_f64x2(x: core::simd::f64x2) -> core::simd::f64x2 {
     use core::simd::{Simd, num::SimdFloat};
     let nan = Simd::splat(f64::NAN);
-- 
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