util: Introduce include/qemu/cpuid.h

Clang 3.9 passes the CONFIG_AVX2_OPT configure test.  However, the
supplied <cpuid.h> does not contain the bit_AVX2 define that we use
when detecting whether the routine can be enabled.

Introduce a qemu-specific header that uses the compiler's definition
of __cpuid et al, but supplies any missing bit_* definitions needed.
This avoids introducing any extra ifdefs to util/bufferiszero.c, and
allows quite a few to be removed from tcg/i386/tcg-target.inc.c.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20170719044018.18063-1-rth@twiddle.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 24 insertions, 19 deletions

diff --git a/configure b/configure
index 6b52e19ee3..987f59ba88 100755
--- a/configure
+++ b/configure
@@ -358,6 +358,7 @@ libusb=""
 usb_redir=""
 opengl=""
 opengl_dmabuf="no"
+cpuid_h="no"
 avx2_opt="no"
 zlib="yes"
 lzo=""
@@ -1931,24 +1932,6 @@ EOF
   fi
 fi
 
-##########################################
-# avx2 optimization requirement check
-
-cat > $TMPC << EOF
-#pragma GCC push_options
-#pragma GCC target("avx2")
-#include <cpuid.h>
-#include <immintrin.h>
-static int bar(void *a) {
-    __m256i x = *(__m256i *)a;
-    return _mm256_testz_si256(x, x);
-}
-int main(int argc, char *argv[]) { return bar(argv[0]); }
-EOF
-if compile_object "" ; then
-  avx2_opt="yes"
-fi
-
 #########################################
 # zlib check
 
@@ -4646,7 +4629,6 @@ fi
 ########################################
 # check if cpuid.h is usable.
 
-cpuid_h=no
 cat > $TMPC << EOF
 #include <cpuid.h>
 int main(void) {
@@ -4668,6 +4650,29 @@ if compile_prog "" "" ; then
     cpuid_h=yes
 fi
 
+##########################################
+# avx2 optimization requirement check
+#
+# There is no point enabling this if cpuid.h is not usable,
+# since we won't be able to select the new routines.
+
+if test $cpuid_h = yes; then
+  cat > $TMPC << EOF
+#pragma GCC push_options
+#pragma GCC target("avx2")
+#include <cpuid.h>
+#include <immintrin.h>
+static int bar(void *a) {
+    __m256i x = *(__m256i *)a;
+    return _mm256_testz_si256(x, x);
+}
+int main(int argc, char *argv[]) { return bar(argv[0]); }
+EOF
+  if compile_object "" ; then
+    avx2_opt="yes"
+  fi
+fi
+
 ########################################
 # check if __[u]int128_t is usable.