Reduce the number of iterations on emulated aarch64 Linux

CI for aarch64 Linux is significantly slower than the others. Adjust how
iteration selection is done to better handle this case, which also
simplifies things.

Also set the `EMULATED` environment variable in Docker to be more
accurate, and reindents run-docker.sh.

library/compiler-builtins/libm/ci/run-docker.sh

@@ -5,39 +5,49 @@
 
 set -euxo pipefail
 
+host_arch="$(uname -m | sed 's/arm64/aarch64/')"
+
 run() {
     local target=$1
 
     echo "testing target: $target"
 
+    target_arch="$(echo "$target" | cut -d'-' -f1)"
+
+    emulated=""
+    if [ "$target_arch" != "$host_arch" ]; then
+        emulated=1
+        echo "target is emulated"
+    fi
+
     # This directory needs to exist before calling docker, otherwise docker will create it but it
     # will be owned by root
     mkdir -p target
 
     docker build -t "$target" "ci/docker/$target"
     docker run \
-           --rm \
-           --user "$(id -u):$(id -g)" \
-           -e RUSTFLAGS \
-           -e CARGO_HOME=/cargo \
-           -e CARGO_TARGET_DIR=/target \
-           -e EMULATED=1 \
-           -v "${HOME}/.cargo:/cargo" \
-           -v "$(pwd)/target:/target" \
-           -v "$(pwd):/checkout:ro" \
-           -v "$(rustc --print sysroot):/rust:ro" \
-           --init \
-           -w /checkout \
-           "$target" \
-           sh -c "HOME=/tmp PATH=\$PATH:/rust/bin exec ci/run.sh $target"
+        --rm \
+        --user "$(id -u):$(id -g)" \
+        -e RUSTFLAGS \
+        -e CARGO_HOME=/cargo \
+        -e CARGO_TARGET_DIR=/target \
+        -e "EMULATED=$emulated" \
+        -v "${HOME}/.cargo:/cargo" \
+        -v "$(pwd)/target:/target" \
+        -v "$(pwd):/checkout:ro" \
+        -v "$(rustc --print sysroot):/rust:ro" \
+        --init \
+        -w /checkout \
+        "$target" \
+        sh -c "HOME=/tmp PATH=\$PATH:/rust/bin exec ci/run.sh $target"
 }
 
 if [ -z "$1" ]; then
-  echo "running tests for all targets"
+    echo "running tests for all targets"
 
-  for d in ci/docker/*; do
-    run $d
-  done
+    for d in ci/docker/*; do
+        run $d
+    done
 else
-  run $1
+    run $1
 fi

library/compiler-builtins/libm/crates/libm-test/src/gen/random.rs

@@ -13,31 +13,21 @@ const SEED: [u8; 32] = *b"3.141592653589793238462643383279";
 
 /// Number of tests to run.
 const NTESTS: usize = {
-    let ntests = if cfg!(optimizations_enabled) {
-        if cfg!(target_arch = "x86_64") || cfg!(target_arch = "aarch64") {
-            5_000_000
-        } else if !cfg!(target_pointer_width = "64")
+    if cfg!(optimizations_enabled) {
+        if crate::emulated()
+            || !cfg!(target_pointer_width = "64")
             || cfg!(all(target_arch = "x86_64", target_vendor = "apple"))
-            || option_env!("EMULATED").is_some()
-                && cfg!(any(target_arch = "aarch64", target_arch = "powerpc64"))
         {
-            // Tests are pretty slow on:
-            // - Non-64-bit targets
-            // - Emulated ppc
-            // - Emulated aarch64
-            // - x86 MacOS
-            // So reduce the number of iterations
+            // Tests are pretty slow on non-64-bit targets, x86 MacOS, and targets that run
+            // in QEMU.
             100_000
         } else {
-            // Most everything else gets tested in docker and works okay, but we still
-            // don't need 20 minutes of tests.
-            1_000_000
+            5_000_000
         }
     } else {
+        // Without optimizations just run a quick check
         800
-    };
-
-    ntests
+    }
 };
 
 /// Tested inputs.

library/compiler-builtins/libm/crates/libm-test/src/lib.rs

@@ -62,3 +62,12 @@ pub fn canonical_name(name: &str) -> &str {
             .unwrap_or(name),
     }
 }
+
+/// True if `EMULATED` is set and nonempty. Used to determine how many iterations to run.
+pub const fn emulated() -> bool {
+    match option_env!("EMULATED") {
+        Some(s) if s.is_empty() => false,
+        None => false,
+        Some(_) => true,
+    }
+}