Amend build script to handle more platforms.

Signed-off-by: Toby Lawrence <[email protected]>

bytecheck/build.rs

@@ -1,19 +1,33 @@
 use std::env;
 
 fn main() {
+    let mut has_atomic32 = true;
+    let mut has_atomic64 = true;
+
     let target = env::var("TARGET").unwrap();
 
-    let is_wasm = target == "asmjs-unknown-emscripten"
-        || target == "wasm32-unknown-emscripten"
-        || target == "wasm32-unknown-unknown";
+    // Full target triples that have specific limitations:
+    match target.as_str() {
+        "arm-linux-androideabi"
+        | "asmjs-unknown-emscripten"
+        | "wasm32-unknown-emscripten"
+        | "wasm32-unknown-unknown" => has_atomic64 = false,
+        _ => {}
+    }
 
-    let has_atomic64 = target.starts_with("x86_64")
-        || target.starts_with("i686")
-        || target.starts_with("aarch64")
-        || target.starts_with("powerpc64")
-        || target.starts_with("sparc64")
-        || target.starts_with("mips64el");
-    let has_atomic32 = has_atomic64 || is_wasm;
+    // Architecture-specific limitations:
+    let arch = target.split("-").next().unwrap_or(&target);
+    match arch {
+        // NOTE: Not all ARMv7 variants are listed here, as certain variants do actually provide
+        // 64-bit atomics. (`armv7`, `armv7a`, and `armv7s`, specifically)
+        "armv5te" | "mips" | "mipsel" | "powerpc" | "riscv32imac" | "thumbv7em" | "thumbv7m"
+        | "thumbv8m.base" | "thumbv8m.main" | "armebv7r" | "armv7r" => has_atomic64 = false,
+        "avr" | "riscv32i" | "riscv32imc" | "thumbv6m" => {
+            has_atomic32 = false;
+            has_atomic64 = false;
+        }
+        _ => {}
+    }
 
     if has_atomic64 {
         println!("cargo:rustc-cfg=has_atomics_64");