================
@@ -2002,6 +2003,76 @@ bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
return true;
}
+#elif defined(__linux__) && defined(__riscv)
+// struct riscv_hwprobe
+struct RISCVHwProbe {
+ int64_t Key;
+ uint64_t Value;
+};
+bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
+ RISCVHwProbe Query[]{{/*RISCV_HWPROBE_KEY_BASE_BEHAVIOR=*/3, 0},
+ {/*RISCV_HWPROBE_KEY_IMA_EXT_0=*/4, 0}};
+ int Ret = syscall(/*__NR_riscv_hwprobe=*/258, /*pairs=*/Query,
+ /*pair_count=*/std::size(Query), /*cpu_count=*/0,
+ /*cpus=*/0, /*flags=*/0);
+ if (Ret != 0)
+ return false;
+
+ uint64_t BaseMask = Query[0].Value;
+ // Check whether RISCV_HWPROBE_BASE_BEHAVIOR_IMA is set.
+ if (BaseMask & 1) {
+ Features["i"] = true;
+ Features["m"] = true;
+ Features["a"] = true;
+ }
+
+ uint64_t ExtMask = Query[1].Value;
----------------
preames wrote:
I think this is likely to be fine in practice.
>From https://docs.kernel.org/arch/riscv/hwprobe.html, I see "If a key is
>unknown to the kernel, its key field will be cleared to -1, and its value set
>to 0. " If I'm reading that properly, if RISCV_HWPROBE_KEY_IMA_EXT_0 isn't a
>valid key, it is the kernel's responsible for clearing all bits to zero, so
>this code should work.
https://github.com/llvm/llvm-project/pull/94352
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