linux: use getauxval() for RISC-V CPU detection

src/linux/cpu.c

@@ -82,71 +82,24 @@ unsigned vlc_CPU_raw(void)
     return flags;
 }
 
-#else
-#undef CPU_FLAGS
-#if defined (__i386__) || defined (__x86_64__)
-# define CPU_FLAGS "flags"
-
 #elif defined (__riscv)
-# include <vlc_strings.h>
-# define CPU_FLAGS "isa"
+# define HWCAP_RV(letter) (1LU << ((letter) - 'A'))
 
-static unsigned vlc_CPU_RV_isa_parse(const char *isa)
+unsigned vlc_CPU_raw(void)
 {
-    unsigned caps = 0;
-    int c;
-
-    if (vlc_ascii_tolower((unsigned char)isa[0]) != 'r'
-     || vlc_ascii_tolower((unsigned char)isa[1]) != 'v')
-        return 0;
-
-    isa += 2;
-
-    if (strncmp(isa, "32", 2) == 0 || strncmp(isa, "64", 2) == 0)
-        isa += 2;
-    else if (strncmp(isa, "128", 3) == 0)
-        isa += 3;
-    else
-        return 0;
-
-    while ((c = vlc_ascii_tolower((unsigned char)*isa)) != '\0') {
-        size_t extlen = 1;
-
-        switch (c) {
-            case '_':
-                break;
-
-            case 'z':
-            case 's':
-            case 'h':
-            case 'x':
-                extlen = 1 + strcspn(isa + 1, "_");
-                break;
-
-            default:
-                if (((unsigned)(c - 'a')) > 'y')
-                    return 0;
-
-                while (isa[extlen] && ((unsigned)(isa[extlen] - '0')) < 10)
-                    extlen++;
-
-                if (vlc_ascii_tolower(isa[extlen]) == 'p') {
-                    extlen++;
-
-                    while (isa[extlen] && ((unsigned)(isa[extlen] - '0')) < 10)
-                        extlen++;
-                }
-        }
-
-        /* TODO: Zve extensions */
-        if (c == 'v')
-            caps |= VLC_CPU_RV_V;
+    const unsigned long hwcap = getauxval(AT_HWCAP);
+    unsigned int flags = 0;
 
-        isa += extlen;
-    }
+    if (hwcap & HWCAP_RV('V'))
+        flags |= VLC_CPU_RV_V;
 
-    return caps;
+    return flags;
 }
+
+#else
+#undef CPU_FLAGS
+#if defined (__i386__) || defined (__x86_64__)
+# define CPU_FLAGS "flags"
 #endif
 
 #ifdef CPU_FLAGS
@@ -173,10 +126,6 @@ unsigned vlc_CPU_raw(void)
         if (*p != ':')
             continue;
 
-#if defined (__riscv)
-        p += strspn(p, "\t ");
-        core_caps = vlc_CPU_RV_isa_parse(p);
-#else
         while ((cap = strsep (&p, " ")) != NULL)
         {
 #if defined (__i386__) || defined (__x86_64__)
@@ -208,7 +157,6 @@ unsigned vlc_CPU_raw(void)
                 core_caps |= VLC_CPU_FMA4;
 #endif
         }
-#endif
 
         /* Take the intersection of capabilities of each processor */
         all_caps &= core_caps;