host/i386: assume presence of SSE2

QEMU now requires an x86-64-v2 host, which has SSE2.
Use it freely in buffer_is_zero.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

host/include/i386/host/cpuinfo.h

@@ -14,7 +14,6 @@
 #define CPUINFO_POPCNT          (1u << 4)
 #define CPUINFO_BMI1            (1u << 5)
 #define CPUINFO_BMI2            (1u << 6)
-#define CPUINFO_SSE2            (1u << 7)
 #define CPUINFO_AVX1            (1u << 9)
 #define CPUINFO_AVX2            (1u << 10)
 #define CPUINFO_AVX512F         (1u << 11)

util/bufferiszero.c

@@ -188,14 +188,14 @@ static biz_accel_fn const accel_table[] = {
 
 static unsigned best_accel(void)
 {
+#ifdef CONFIG_AVX2_OPT
     unsigned info = cpuinfo_init();
 
-#ifdef CONFIG_AVX2_OPT
     if (info & CPUINFO_AVX2) {
         return 2;
     }
 #endif
-    return info & CPUINFO_SSE2 ? 1 : 0;
+    return 1;
 }
 
 #elif defined(__aarch64__) && defined(__ARM_NEON)

util/cpuinfo-i386.c

@@ -34,7 +34,6 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
     if (max >= 1) {
         __cpuid(1, a, b, c, d);
 
-        info |= (d & bit_SSE2 ? CPUINFO_SSE2 : 0);
         info |= (c & bit_MOVBE ? CPUINFO_MOVBE : 0);
         info |= (c & bit_POPCNT ? CPUINFO_POPCNT : 0);
         info |= (c & bit_PCLMUL ? CPUINFO_PCLMUL : 0);