Remove workaround for x86 ifunc

Test: bionic unit test
Change-Id: I539a42b01fac705aa342a8d1d79d3607c06fef68
diff --git a/libc/arch-x86/dynamic_function_dispatch.cpp b/libc/arch-x86/dynamic_function_dispatch.cpp
index 6624385..70f4b3e 100644
--- a/libc/arch-x86/dynamic_function_dispatch.cpp
+++ b/libc/arch-x86/dynamic_function_dispatch.cpp
@@ -30,33 +30,6 @@
 
 extern "C" {
 
-struct __processor_model {
-    unsigned int __cpu_vendor;
-    unsigned int __cpu_type;
-    unsigned int __cpu_subtype;
-    unsigned int __cpu_features[1];
-};
-
-__attribute__((visibility("hidden")))
-extern struct __processor_model __cpu_model;
-
-// These definitions have to match the values in
-// llvm/include/llvm/Support/X86TargetParser.def
-static constexpr int SSSE3  = 6;
-static constexpr int SSE4_1 = 7;
-static constexpr int ATOM   = 1;
-
-// __builtin_cpu_supports and __builtin_cpu_is can not be used here. They
-// don't access __cpu_model directly but use GOT.
-// See https://reviews.llvm.org/D53850
-static bool cpu_supports(unsigned int feature) {
-    return (__cpu_model.__cpu_features[0] & (1U << feature)) != 0;
-}
-
-static bool cpu_is(unsigned int type) {
-    return (__cpu_model.__cpu_type == type);
-}
-
 #define DEFINE_IFUNC_FOR(name) \
     name##_func name __attribute__((ifunc(#name "_resolver"))); \
     __attribute__((visibility("hidden"))) \
@@ -74,29 +47,29 @@
 typedef int memcmp_func(const void* __lhs, const void* __rhs, size_t __n);
 DEFINE_IFUNC_FOR(memcmp) {
     __builtin_cpu_init();
-    if (cpu_is(ATOM)) RETURN_FUNC(memcmp_func, memcmp_atom);
-    if (cpu_supports(SSE4_1)) RETURN_FUNC(memcmp_func, memcmp_sse4);
+    if (__builtin_cpu_is("atom")) RETURN_FUNC(memcmp_func, memcmp_atom);
+    if (__builtin_cpu_supports("sse4.1")) RETURN_FUNC(memcmp_func, memcmp_sse4);
     RETURN_FUNC(memcmp_func, memcmp_generic);
 }
 
 typedef void* memset_func(void* __dst, int __ch, size_t __n);
 DEFINE_IFUNC_FOR(memset) {
     __builtin_cpu_init();
-    if (cpu_is(ATOM)) RETURN_FUNC(memset_func, memset_atom);
+    if (__builtin_cpu_is("atom")) RETURN_FUNC(memset_func, memset_atom);
     RETURN_FUNC(memset_func, memset_generic);
 }
 
 typedef void* __memset_chk_func(void *s, int c, size_t n, size_t n2);
 DEFINE_IFUNC_FOR(__memset_chk) {
     __builtin_cpu_init();
-    if (cpu_is(ATOM)) RETURN_FUNC(__memset_chk_func, __memset_chk_atom);
+    if (__builtin_cpu_is("atom")) RETURN_FUNC(__memset_chk_func, __memset_chk_atom);
     RETURN_FUNC(__memset_chk_func, __memset_chk_generic);
 }
 
 typedef void* memmove_func(void* __dst, const void* __src, size_t __n);
 DEFINE_IFUNC_FOR(memmove) {
     __builtin_cpu_init();
-    if (cpu_is(ATOM)) RETURN_FUNC(memmove_func, memmove_atom);
+    if (__builtin_cpu_is("atom")) RETURN_FUNC(memmove_func, memmove_atom);
     RETURN_FUNC(memmove_func, memmove_generic);
 }
 
@@ -108,85 +81,85 @@
 typedef char* strcpy_func(char* __dst, const char* __src);
 DEFINE_IFUNC_FOR(strcpy) {
     __builtin_cpu_init();
-    if (cpu_is(ATOM)) RETURN_FUNC(strcpy_func, strcpy_atom);
+    if (__builtin_cpu_is("atom")) RETURN_FUNC(strcpy_func, strcpy_atom);
     RETURN_FUNC(strcpy_func, strcpy_generic);
 }
 
 typedef char* strncpy_func(char* __dst, const char* __src, size_t __n);
 DEFINE_IFUNC_FOR(strncpy) {
     __builtin_cpu_init();
-    if (cpu_is(ATOM)) RETURN_FUNC(strncpy_func, strncpy_atom);
+    if (__builtin_cpu_is("atom")) RETURN_FUNC(strncpy_func, strncpy_atom);
     RETURN_FUNC(strncpy_func, strncpy_generic);
 }
 
 typedef size_t strlen_func(const char* __s);
 DEFINE_IFUNC_FOR(strlen) {
     __builtin_cpu_init();
-    if (cpu_is(ATOM)) RETURN_FUNC(strlen_func, strlen_atom);
+    if (__builtin_cpu_is("atom")) RETURN_FUNC(strlen_func, strlen_atom);
     RETURN_FUNC(strlen_func, strlen_generic);
 }
 
 typedef int wmemcmp_func(const wchar_t* __lhs, const wchar_t* __rhs, size_t __n);
 DEFINE_IFUNC_FOR(wmemcmp) {
     __builtin_cpu_init();
-    if (cpu_supports(SSE4_1)) RETURN_FUNC(wmemcmp_func, wmemcmp_sse4);
-    if (cpu_is(ATOM)) RETURN_FUNC(wmemcmp_func, wmemcmp_atom);
+    if (__builtin_cpu_supports("sse4.1")) RETURN_FUNC(wmemcmp_func, wmemcmp_sse4);
+    if (__builtin_cpu_is("atom")) RETURN_FUNC(wmemcmp_func, wmemcmp_atom);
     RETURN_FUNC(wmemcmp_func, wmemcmp_freebsd);
 }
 
 typedef int strcmp_func(const char* __lhs, const char* __rhs);
 DEFINE_IFUNC_FOR(strcmp) {
     __builtin_cpu_init();
-    if (cpu_supports(SSSE3)) RETURN_FUNC(strcmp_func, strcmp_ssse3);
+    if (__builtin_cpu_supports("ssse3")) RETURN_FUNC(strcmp_func, strcmp_ssse3);
     RETURN_FUNC(strcmp_func, strcmp_generic);
 }
 
 typedef int strncmp_func(const char* __lhs, const char* __rhs, size_t __n);
 DEFINE_IFUNC_FOR(strncmp) {
     __builtin_cpu_init();
-    if (cpu_supports(SSSE3)) RETURN_FUNC(strncmp_func, strncmp_ssse3);
+    if (__builtin_cpu_supports("ssse3")) RETURN_FUNC(strncmp_func, strncmp_ssse3);
     RETURN_FUNC(strncmp_func, strncmp_generic);
 }
 
 typedef char* strcat_func(char* __dst, const char* __src);
 DEFINE_IFUNC_FOR(strcat) {
     __builtin_cpu_init();
-    if (cpu_supports(SSSE3)) RETURN_FUNC(strcat_func, strcat_ssse3);
+    if (__builtin_cpu_supports("ssse3")) RETURN_FUNC(strcat_func, strcat_ssse3);
     RETURN_FUNC(strcat_func, strcat_generic);
 }
 
 typedef char* strncat_func(char* __dst, const char* __src, size_t __n);
 DEFINE_IFUNC_FOR(strncat) {
     __builtin_cpu_init();
-    if (cpu_supports(SSSE3)) RETURN_FUNC(strncat_func, strncat_ssse3);
+    if (__builtin_cpu_supports("ssse3")) RETURN_FUNC(strncat_func, strncat_ssse3);
     RETURN_FUNC(strncat_func, strncat_openbsd);
 }
 
 typedef size_t strlcat_func(char *dst, const char *src, size_t dsize);
 DEFINE_IFUNC_FOR(strlcat) {
     __builtin_cpu_init();
-    if (cpu_supports(SSSE3)) RETURN_FUNC(strlcat_func, strlcat_ssse3);
+    if (__builtin_cpu_supports("ssse3")) RETURN_FUNC(strlcat_func, strlcat_ssse3);
     RETURN_FUNC(strlcat_func, strlcat_openbsd);
 }
 
 typedef size_t strlcpy_func(char *dst, const char *src, size_t dsize);
 DEFINE_IFUNC_FOR(strlcpy) {
     __builtin_cpu_init();
-    if (cpu_supports(SSSE3)) RETURN_FUNC(strlcpy_func, strlcpy_ssse3);
+    if (__builtin_cpu_supports("ssse3")) RETURN_FUNC(strlcpy_func, strlcpy_ssse3);
     RETURN_FUNC(strlcpy_func, strlcpy_openbsd);
 }
 
 typedef wchar_t* wcscat_func(wchar_t *s1, const wchar_t *s2);
 DEFINE_IFUNC_FOR(wcscat) {
     __builtin_cpu_init();
-    if (cpu_supports(SSSE3)) RETURN_FUNC(wcscat_func, wcscat_ssse3);
+    if (__builtin_cpu_supports("ssse3")) RETURN_FUNC(wcscat_func, wcscat_ssse3);
     RETURN_FUNC(wcscat_func, wcscat_freebsd);
 }
 
 typedef wchar_t* wcscpy_func(wchar_t *s1, const wchar_t *s2);
 DEFINE_IFUNC_FOR(wcscpy) {
     __builtin_cpu_init();
-    if (cpu_supports(SSSE3)) RETURN_FUNC(wcscpy_func, wcscpy_ssse3);
+    if (__builtin_cpu_supports("ssse3")) RETURN_FUNC(wcscpy_func, wcscpy_ssse3);
     RETURN_FUNC(wcscpy_func, wcscpy_freebsd);
 }