Add crate that enables the full float APIs in #[no_std]

Cargo.toml

@@ -70,6 +70,7 @@ members = [
 
     # Utils
     "utils/calendrical_calculations",
+    "utils/core_math",
     "utils/crlify",
     "utils/databake",
     "utils/databake/derive",
@@ -199,6 +200,7 @@ icu_provider_macros = { version = "~1.2.0", path = "provider/macros", default-fe
 
 # Utils
 calendrical_calculations = { version = "0.1.0", path = "utils/calendrical_calculations", default-features = false }
+core_math = { version = "0.0.0", path = "utils/core_math", default-features = false }
 crlify = { version = "1.0.1", path = "utils/crlify", default-features = false }
 databake = { version = "0.1.3", path = "utils/databake", default-features = false }
 databake-derive = { version = "0.1.3", path = "utils/databake/derive", default-features = false }

components/segmenter/Cargo.toml

@@ -30,7 +30,7 @@ zerovec = { workspace = true, features = ["yoke"] }
 databake = { workspace = true, optional = true, features = ["derive"] }
 serde = { version = "1.0", default-features = false, features = ["derive", "alloc"], optional = true }
 
-libm = { version = "0.2", default-features = false, optional = true }
+core_math = { workspace = true, optional = true }
 
 icu_segmenter_data = { workspace = true, optional = true }
 icu_locid_transform = { workspace = true, optional = true, features = ["compiled_data"] }
@@ -49,7 +49,7 @@ default = ["compiled_data", "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:libm"]
+lstm = ["dep:core_math"]
 auto = ["lstm"] # Enabled try_new_auto_unstable constructors
 compiled_data = ["dep:icu_segmenter_data"]
 bench = []

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

@@ -5,29 +5,11 @@
 use alloc::vec;
 use alloc::vec::Vec;
 use core::ops::Range;
+#[allow(unused_imports)]
+use core_math::*;
 use zerovec::ule::AsULE;
 use zerovec::ZeroSlice;
 
-// 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;
-}
-
-// 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.
 ///
 /// This matrix implementation supports slicing matrices into tightly-packed

docs/tutorials/testing/patch.toml

@@ -73,6 +73,7 @@ databake-derive = { path = "../../utils/databake/derive" }
 deduplicating_array = { path = "../../utils/deduplicating_array" }
 fixed_decimal = { path = "../../utils/fixed_decimal" }
 litemap = { path = "../../utils/litemap" }
+core_math = { path = "../../utils/core_math" }
 icu_pattern = { path = "../../utils/pattern" }
 tinystr = { path = "../../utils/tinystr" }
 tzif = { path = "../../utils/tzif" }

ffi/gn/icu4x/BUILD.gn

@@ -37,6 +37,28 @@ rust_library("calendrical_calculations-v0_1_0") {
   visibility = [ ":*" ]
 }
 
+rust_library("core_math-v0_0_0") {
+  crate_name = "core_math"
+  crate_root = "//utils/core_math/src/lib.rs"
+  output_name = "core_math-73cb7218c03e07b7"
+
+  deps = []
+  if (false) {
+    deps += [ ":libm-v0_2_6" ]
+  }
+
+  rustenv = []
+
+  rustflags = [
+    "--cap-lints=allow",
+    "--edition=2021",
+    "-Cmetadata=73cb7218c03e07b7",
+    "-Cextra-filename=-73cb7218c03e07b7",
+  ]
+
+  visibility = [ ":*" ]
+}
+
 rust_proc_macro("diplomat-v0_5_2") {
   crate_name = "diplomat"
   crate_root = "//ffi/gn/vendor/diplomat/src/lib.rs"
@@ -652,11 +674,11 @@ rust_library("icu_segmenter-v1_2_1") {
   output_name = "icu_segmenter-9c67817750522b21"
 
   deps = []
+  deps += [ ":core_math-v0_0_0" ]
   deps += [ ":displaydoc-v0_2_4($host_toolchain)" ]
   deps += [ ":icu_collections-v1_2_0" ]
   deps += [ ":icu_locid-v1_2_0" ]
   deps += [ ":icu_provider-v1_2_0" ]
-  deps += [ ":libm-v0_2_6" ]
   deps += [ ":utf8_iter-v1_0_3" ]
   deps += [ ":zerovec-v0_9_4" ]
 
@@ -732,6 +754,7 @@ rust_library("libm-v0_2_6") {
     "--edition=2018",
     "-Cmetadata=6b5214f2031c6f9e",
     "-Cextra-filename=-6b5214f2031c6f9e",
+    "--cfg=feature=\"default\"",
   ]
 
   visibility = [ ":*" ]

tools/depcheck/src/allowlist.rs

@@ -26,6 +26,7 @@ pub const BASIC_RUNTIME_DEPS: &[&str] = &[
     // ICU4X utils
     "calendrical_calculations",
     "fixed_decimal",
+    "core_math",
     "icu_provider_adapters", // not included in icu, but needed generally
     "icu_provider",
     "litemap",
@@ -102,7 +103,7 @@ pub const EXTRA_EXPERIMENTAL_DATA_DEPS: &[&str] = &[
 ];
 
 /// Dependencies allowed when opting in to LSTM segmenter
-pub const EXTRA_LSTM_DEPS: &[&str] = &["libm"];
+pub const EXTRA_LSTM_DEPS: &[&str] = &[];
 
 /// Dependencies allowed when opting in to fixed_decimal's `ryu` backend
 /// This should never change

utils/core_math/Cargo.toml

@@ -0,0 +1,23 @@
+# This file is part of ICU4X. For terms of use, please see the file
+# called LICENSE at the top level of the ICU4X source tree
+# (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
+
+[package]
+name = "core_math"
+version = "0.0.0"
+description = "Extension trait for full float functionality in `#[no_std]` backed by `libm`."
+
+rust-version.workspace = true
+authors.workspace = true
+edition.workspace = true
+repository.workspace = true
+homepage.workspace = true
+license-file.workspace = true
+categories.workspace = true
+include.workspace = true
+
+[lib]
+name = "core_math"
+
+[dependencies]
+libm = "0.2"

utils/core_math/LICENSE

@@ -0,0 +1,44 @@
+UNICODE LICENSE V3
+
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+
+Copyright © 2020-2023 Unicode, Inc.
+
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+SOFTWARE, YOU UNEQUIVOCALLY ACCEPT, AND AGREE TO BE BOUND BY, ALL OF THE
+TERMS AND CONDITIONS OF THIS AGREEMENT. IF YOU DO NOT AGREE, DO NOT
+DOWNLOAD, INSTALL, COPY, DISTRIBUTE OR USE THE DATA FILES OR SOFTWARE.
+
+Permission is hereby granted, free of charge, to any person obtaining a
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+software and any associated documentation (the "Software") to deal in the
+Data Files or Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, and/or sell
+copies of the Data Files or Software, and to permit persons to whom the
+Data Files or Software are furnished to do so, provided that either (a)
+this copyright and permission notice appear with all copies of the Data
+Files or Software, or (b) this copyright and permission notice appear in
+associated Documentation.
+
+THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF
+THIRD PARTY RIGHTS.
+
+IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE
+BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES,
+OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THE DATA
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+
+Except as contained in this notice, the name of a copyright holder shall
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+
+—
+
+Portions of ICU4X may have been adapted from ICU4C and/or ICU4J.
+ICU 1.8.1 to ICU 57.1 © 1995-2016 International Business Machines Corporation and others.