Add hint to value() (#48)

danlehmann · Dec 2, 2024 · 680553d · 680553d
1 parent 0a54994
commit 680553d
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diff --git a/Cargo.toml b/Cargo.toml
@@ -31,6 +31,10 @@ borsh = ["dep:borsh"]
 
 schemars = ["dep:schemars", "std"]
 
+# Provide a soundness promixe to the compiler that the unerlying value is always within range
+# This optimizes e.g. indexing range checks when passed in an API
+hint = []
+
 [dependencies]
 num-traits = { version = "0.2.19", default-features = false, optional = true }
 defmt = { version = "0.3.8", optional = true }

diff --git a/src/lib.rs b/src/lib.rs
@@ -190,6 +190,11 @@ macro_rules! uint_impl_num {
 
                 #[inline]
                 fn value(self) -> $type {
+                    #[cfg(feature = "hint")]
+                    unsafe {
+                        core::hint::assert_unchecked(self.value <= Self::MAX.value);
+                    }
+
                     self.value
                 }
             }
@@ -230,6 +235,11 @@ macro_rules! uint_impl_num {
 
                 #[inline]
                 fn value(self) -> $type {
+                    #[cfg(feature = "hint")]
+                    unsafe {
+                        core::hint::assert_unchecked(self.value <= Self::MAX.value);
+                    }
+
                     self.value
                 }
             }