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-rw-r--r--src/tools/rustfmt/tests/source/cfg_if/detect/os/linux/arm.rs49
1 files changed, 49 insertions, 0 deletions
diff --git a/src/tools/rustfmt/tests/source/cfg_if/detect/os/linux/arm.rs b/src/tools/rustfmt/tests/source/cfg_if/detect/os/linux/arm.rs
new file mode 100644
index 000000000..0d58a847c
--- /dev/null
+++ b/src/tools/rustfmt/tests/source/cfg_if/detect/os/linux/arm.rs
@@ -0,0 +1,49 @@
+//! Run-time feature detection for ARM on Linux.
+
+use crate::detect::{Feature, cache, bit};
+use super::{auxvec, cpuinfo};
+
+/// Performs run-time feature detection.
+#[inline]
+pub fn check_for(x: Feature) -> bool {
+ cache::test(x as u32, detect_features)
+}
+
+/// Try to read the features from the auxiliary vector, and if that fails, try
+/// to read them from /proc/cpuinfo.
+fn detect_features() -> cache::Initializer {
+ let mut value = cache::Initializer::default();
+ let enable_feature = |value: &mut cache::Initializer, f, enable| {
+ if enable {
+ value.set(f as u32);
+ }
+ };
+
+ // The values are part of the platform-specific [asm/hwcap.h][hwcap]
+ //
+ // [hwcap]: https://github.com/torvalds/linux/blob/master/arch/arm64/include/uapi/asm/hwcap.h
+ if let Ok(auxv) = auxvec::auxv() {
+ enable_feature(&mut value, Feature::neon, bit::test(auxv.hwcap, 12));
+ enable_feature(&mut value, Feature::pmull, bit::test(auxv.hwcap2, 1));
+ return value;
+ }
+
+ if let Ok(c) = cpuinfo::CpuInfo::new() {
+ enable_feature(&mut value, Feature::neon, c.field("Features").has("neon") &&
+ !has_broken_neon(&c));
+ enable_feature(&mut value, Feature::pmull, c.field("Features").has("pmull"));
+ return value;
+ }
+ value
+}
+
+/// Is the CPU known to have a broken NEON unit?
+///
+/// See https://crbug.com/341598.
+fn has_broken_neon(cpuinfo: &cpuinfo::CpuInfo) -> bool {
+ cpuinfo.field("CPU implementer") == "0x51"
+ && cpuinfo.field("CPU architecture") == "7"
+ && cpuinfo.field("CPU variant") == "0x1"
+ && cpuinfo.field("CPU part") == "0x04d"
+ && cpuinfo.field("CPU revision") == "0"
+}