Remove num_traits dependency

components/segmenter/Cargo.toml

@@ -38,7 +38,7 @@ zerovec = { version = "0.9.4", path = "../../utils/zerovec", features = ["yoke"]
 databake = { version = "0.1.3", path = "../../utils/databake", optional = true, features = ["derive"] }
 serde = { version = "1.0", default-features = false, features = ["derive", "alloc"], optional = true }
 
-num-traits = { version = "0.2", default-features = false, features = ["libm"], optional = true }
+libm = { version = "0.2", default-features = false, optional = true }
 
 [dev-dependencies]
 criterion = "0.4"
@@ -56,7 +56,7 @@ default = ["auto"]
 std = ["icu_collections/std", "icu_locid/std", "icu_provider/std"]
 serde = ["dep:serde", "zerovec/serde", "icu_collections/serde", "icu_provider/serde"]
 datagen = ["serde", "dep:databake", "zerovec/databake", "icu_collections/databake"]
-lstm = ["dep:num-traits"]
+lstm = ["dep:libm"]
 auto = ["lstm"] # Enabled try_new_auto_unstable constructors
 
 [lib]

components/segmenter/src/complex/lstm/matrix.rs

@@ -8,20 +8,24 @@ use core::ops::Range;
 use zerovec::ule::AsULE;
 use zerovec::ZeroSlice;
 
-// Polyfill float operations with libm in case we're no_std.
-#[allow(unused_imports)]
-use num_traits::Float;
-
-/// `tanh` computes the tanh function for a scalar value.
-#[inline]
-fn tanh(x: f32) -> f32 {
-    x.tanh()
+// This will be used in #[no_std] as f32::exp/f32::tanh are not in core.
+trait CoreFloat {
+    fn exp(self) -> Self;
+    fn tanh(self) -> Self;
 }
 
-/// `sigmoid` computes the sigmoid function for a scalar value.
-#[inline]
-fn sigmoid(x: f32) -> f32 {
-    1.0 / (1.0 + (-x).exp())
+// TODO: Find a way to do this without libm. There's an intrinsic
+// that produces `llvm.exp.f32`, but that's not exposed through
+// f32. Another option would be to declare `extern "Rust"` and
+// let clients provide these functions.
+impl CoreFloat for f32 {
+    fn exp(self) -> Self {
+        libm::expf(self)
+    }
+
+    fn tanh(self) -> Self {
+        libm::tanhf(self)
+    }
 }
 
 /// A `D`-dimensional, heap-allocated matrix.
@@ -209,21 +213,24 @@ impl<'a, const D: usize> MatrixBorrowedMut<'a, D> {
 
     /// Mutates this matrix by applying a softmax transformation.
     pub(super) fn softmax_transform(&mut self) {
-        let sm = self.data.iter().map(|v| v.exp()).sum::<f32>();
-        self.data.iter_mut().for_each(|v| {
-            *v = v.exp() / sm;
-        });
+        for v in self.data.iter_mut() {
+            *v = v.exp();
+        }
+        let sm = 1.0 / self.data.iter().sum::<f32>();
+        for v in self.data.iter_mut() {
+            *v *= sm;
+        }
     }
 
     pub(super) fn sigmoid_transform(&mut self) {
         for x in &mut self.data.iter_mut() {
-            *x = sigmoid(*x);
+            *x = 1.0 / (1.0 + (-*x).exp());
         }
     }
 
     pub(super) fn tanh_transform(&mut self) {
         for x in &mut self.data.iter_mut() {
-            *x = tanh(*x);
+            *x = x.tanh();
         }
     }
 
@@ -262,7 +269,7 @@ impl<'a, const D: usize> MatrixBorrowedMut<'a, D> {
             // Safety: The lengths are all the same (checked above)
             unsafe {
                 *self.data.get_unchecked_mut(idx) =
-                    o.get_unchecked(idx) * tanh(*c.get_unchecked(idx));
+                    o.get_unchecked(idx) * c.get_unchecked(idx).tanh();
             }
         }
     }

ffi/gn/Cargo.toml

@@ -36,9 +36,6 @@ rustflags = []
 [gn.package.syn."1.0.109"]
 rustflags = ["--cfg=syn_disable_nightly_tests"]
 
-[gn.package.num-traits."0.2.15"]
-rustflags = ["--cfg=has_i128"]
-
 [gn.package.libm."0.2.6"]
 rustflags = []
 

ffi/gn/icu4x/BUILD.gn

@@ -628,7 +628,7 @@ rust_library("icu_segmenter-v1_2_1") {
   deps += [ ":icu_collections-v1_2_0" ]
   deps += [ ":icu_locid-v1_2_0" ]
   deps += [ ":icu_provider-v1_2_0" ]
-  deps += [ ":num-traits-v0_2_15" ]
+  deps += [ ":libm-v0_2_6" ]
   deps += [ ":utf8_iter-v1_0_3" ]
   deps += [ ":zerovec-v0_9_4" ]
 
@@ -752,7 +752,6 @@ rust_library("libm-v0_2_6") {
     "--edition=2018",
     "-Cmetadata=6b5214f2031c6f9e",
     "-Cextra-filename=-6b5214f2031c6f9e",
-    "--cfg=feature=\"default\"",
   ]
 
   visibility = [ ":*" ]
@@ -820,28 +819,6 @@ rust_library("memchr-v2_5_0") {
   visibility = [ ":*" ]
 }
 
-rust_library("num-traits-v0_2_15") {
-  crate_name = "num_traits"
-  crate_root = "//ffi/gn/vendor/num-traits/src/lib.rs"
-  output_name = "num_traits-64c0e09f0f13aa66"
-
-  deps = []
-  deps += [ ":libm-v0_2_6" ]
-
-  rustenv = []
-
-  rustflags = [
-    "--cap-lints=allow",
-    "--edition=2015",
-    "-Cmetadata=64c0e09f0f13aa66",
-    "-Cextra-filename=-64c0e09f0f13aa66",
-    "--cfg=feature=\"libm\"",
-    "--cfg=has_i128",
-  ]
-
-  visibility = [ ":*" ]
-}
-
 rust_library("proc-macro2-v1_0_56") {
   crate_name = "proc_macro2"
   crate_root = "//ffi/gn/vendor/proc-macro2/src/lib.rs"

tools/depcheck/src/allowlist.rs

@@ -72,7 +72,7 @@ pub const EXTRA_EXPERIMENTAL_DEPS: &[&str] = &[
 ];
 
 /// Dependencies allowed when opting in to LSTM segmenter
-pub const EXTRA_LSTM_DEPS: &[&str] = &["libm", "num-traits"];
+pub const EXTRA_LSTM_DEPS: &[&str] = &["libm"];
 
 /// Dependencies allowed when opting in to fixed_decimal's `ryu` backend
 /// This should never change
@@ -122,6 +122,7 @@ pub const EXTRA_DATAGEN_DEPS: &[&str] = &[
     "ndarray",
     "num-complex",
     "num-integer",
+    "num-traits",
     "rawpointer",
     "regex-syntax",
     "rust-format",