llvmpipe: add loongarch util_get_cpu_caps function

When use LA464(3A5000 pc), LLVM18 and kernel(which not supports lsx/lasx),
it will get a illegal instruction error. LA464 will return LA464 and
LA664 will return a generic when calling getHostCPUName(). Return LA464
name will add all feature(+f,+d,+lsx,+lasx,lvz) by default and generate
vector instruction, generic will add null. Hence we use util_get_cpu_caps
to judge if kernel supports lsx/lasx or not.

Set lsx and lasx by util_get_cpu_caps. Only LLVM 18 on loongarch
supports lsx and lasx completely. LLVM 16 isn't supported and
LLVM 17's LSX support is incomplete.

Signed-off-by: Jiale Zhao <zhaojiale@loongson.cn>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30220>

src/gallium/auxiliary/gallivm/lp_bld_misc.cpp

@@ -417,8 +417,6 @@ lp_build_fill_mattrs(std::vector<std::string> &MAttrs)
 
 #if DETECT_ARCH_LOONGARCH64 == 1
    /*
-    * TODO: Implement util_get_cpu_caps()
-    *
     * No FPU-less LoongArch64 systems are ever shipped yet, and LP64D is
     * the default ABI, so FPU is enabled here.
     *
@@ -427,9 +425,16 @@ lp_build_fill_mattrs(std::vector<std::string> &MAttrs)
     * https://github.com/loongson/la-softdev-convention/releases/download/v0.1/la-softdev-convention.pdf
     */
    MAttrs = {"+f","+d"};
-#if LLVM_VERSION_MAJOR == 17
-   /* LLVM 17's LSX support is incomplete, so explicitly mask it */
+#if LLVM_VERSION_MAJOR >= 18
+   MAttrs.push_back(util_get_cpu_caps()->has_lsx ? "+lsx" : "-lsx");
+   MAttrs.push_back(util_get_cpu_caps()->has_lasx ? "+lasx" : "-lasx");
+#else
+   /*
+    * LLVM 17's LSX support is incomplete, and LLVM 16 isn't supported
+    * LSX and LASX. So explicitly mask it.
+    */
    MAttrs.push_back("-lsx");
+   MAttrs.push_back("-lasx");
 #endif
 #endif
 }

src/gallium/drivers/llvmpipe/lp_screen.c

@@ -997,11 +997,11 @@ update_cache_sha1_cpu(struct mesa_sha1 *ctx)
    const struct util_cpu_caps_t *cpu_caps = util_get_cpu_caps();
    /*
     * Don't need the cpu cache affinity stuff. The rest
-    * is contained in first 5 dwords.
+    * is contained in first 6 dwords.
     */
    STATIC_ASSERT(offsetof(struct util_cpu_caps_t, num_L3_caches)
-                 == 5 * sizeof(uint32_t));
-   _mesa_sha1_update(ctx, cpu_caps, 5 * sizeof(uint32_t));
+                 == 6 * sizeof(uint32_t));
+   _mesa_sha1_update(ctx, cpu_caps, 6 * sizeof(uint32_t));
 }
 
 

src/util/u_cpu_detect.c

@@ -470,6 +470,31 @@ check_os_mips64_support(void)
 }
 #endif /* DETECT_ARCH_MIPS64 */
 
+#if DETECT_ARCH_LOONGARCH64
+static void
+check_os_loongarch64_support(void)
+{
+#if DETECT_OS_LINUX
+    Elf64_auxv_t aux;
+    int fd;
+
+    fd = open("/proc/self/auxv", O_RDONLY | O_CLOEXEC);
+    if (fd >= 0) {
+       while (read(fd, &aux, sizeof(Elf64_auxv_t)) == sizeof(Elf64_auxv_t)) {
+          if (aux.a_type == AT_HWCAP) {
+             uint64_t hwcap = aux.a_un.a_val;
+
+             util_cpu_caps.has_lsx = (hwcap >> 4) & 1;
+             util_cpu_caps.has_lasx = (hwcap >> 5) & 1;
+             break;
+          }
+       }
+       close (fd);
+    }
+#endif /* DETECT_OS_LINUX */
+}
+#endif /* DETECT_ARCH_LOONGARCH64 */
+
 
 static void
 get_cpu_topology(void)
@@ -943,6 +968,10 @@ _util_cpu_detect_once(void)
    check_os_mips64_support();
 #endif /* DETECT_ARCH_MIPS64 */
 
+#if DETECT_ARCH_LOONGARCH64
+   check_os_loongarch64_support();
+#endif /* DETECT_ARCH_LOONGARCH64 */
+
 #if DETECT_ARCH_S390
    util_cpu_caps.family = CPU_S390X;
 #endif
@@ -980,6 +1009,8 @@ _util_cpu_detect_once(void)
       printf("util_cpu_caps.has_neon = %u\n", util_cpu_caps.has_neon);
       printf("util_cpu_caps.has_msa = %u\n", util_cpu_caps.has_msa);
       printf("util_cpu_caps.has_daz = %u\n", util_cpu_caps.has_daz);
+      printf("util_cpu_caps.has_lsx = %u\n", util_cpu_caps.has_lsx);
+      printf("util_cpu_caps.has_lasx = %u\n", util_cpu_caps.has_lasx);
       printf("util_cpu_caps.has_avx512f = %u\n", util_cpu_caps.has_avx512f);
       printf("util_cpu_caps.has_avx512dq = %u\n", util_cpu_caps.has_avx512dq);
       printf("util_cpu_caps.has_avx512ifma = %u\n", util_cpu_caps.has_avx512ifma);

src/util/u_cpu_detect.h

@@ -109,6 +109,8 @@ struct util_cpu_caps_t {
    unsigned has_daz:1;
    unsigned has_neon:1;
    unsigned has_msa:1;
+   unsigned has_lsx:1;
+   unsigned has_lasx:1;
 
    unsigned has_avx512f:1;
    unsigned has_avx512dq:1;