[compiler-rt] [compiler-rt][AArch64][Android] Use getauxval on Android. (PR #102979)

[Saleem Abdulrasool via llvm-commits]

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@@ -20,11 +21,15 @@ _Bool __aarch64_has_sme_and_tpidr2_el0;
 #define HWCAP2_SME (1 << 23)
 #endif
 
+#ifdef __ANDROID__
+extern unsigned long int getauxval(unsigned long int);
+#define GETAUXVAL(x) getauxval(x)
+#else
 extern unsigned long int __getauxval (unsigned long int);
+#define GETAUXVAL(x) __getauxval(x)
+#endif
 
-static _Bool has_sme(void) {
-  return __getauxval(AT_HWCAP2) & HWCAP2_SME;
-}
+static _Bool has_sme(void) { return GETAUXVAL(AT_HWCAP2) & HWCAP2_SME; }
----------------
compnerd wrote:

I think that I would rather that we inline the use of `__getauxval`. `getauxval` is a GNU "standard" interface, but was introduced in glibc only in 2.16. I don't know if anyone is targeting an older glibc, but we can do something like:

```suggestion
static _Bool has_sme(void) {
#if defined(__GLIBC__) && !__GLIBC_PREREQ(2,16)
  unsigned long int auxval = __getauxval(AT_HWCAP2);
#else
  unsigned long int auxval = getauxval(AT_HWCAP2);
#endif
  return auxval & HWCAP2_SME;
}
```

https://github.com/llvm/llvm-project/pull/102979