Re: [PULL 06/61] util: add util function buffer_zero_avx512()

[Paolo Bonzini]

This breaks if AVX2 and AVX512 are both disabled but SSE2 isn't, because
it calls buffer_is_zero_sse2 even with length < 64.  Fix:

diff --git a/util/bufferiszero.c b/util/bufferiszero.c
index b6eab0c..6639035 100644
--- a/util/bufferiszero.c
+++ b/util/bufferiszero.c
@@ -247,23 +247,20 @@ buffer_zero_avx512(const void *buf, size_t len)

 static unsigned cpuid_cache = INIT_CACHE;
 static bool (*buffer_accel)(const void *, size_t) = INIT_ACCEL;
-static int length_to_accel;
+static int length_to_accel = 64;

 static void init_accel(unsigned cache)
 {
     bool (*fn)(const void *, size_t) = buffer_zero_int;
     if (cache & CACHE_SSE2) {
         fn = buffer_zero_sse2;
-        length_to_accel = 64;
     }
 #ifdef CONFIG_AVX2_OPT
     if (cache & CACHE_SSE4) {
         fn = buffer_zero_sse4;
-        length_to_accel = 64;
     }
     if (cache & CACHE_AVX2) {
         fn = buffer_zero_avx2;
-        length_to_accel = 64;
     }
 #endif
 #ifdef CONFIG_AVX512F_OPT

Paolo