Address review comments

Check for SIMD -m flags before checking for header issues. Clarify
comment.

Author: jmroot

configure

@@ -7849,15 +7849,15 @@ if test "$ac_sys_system" != "Linux-android" -a "$ac_sys_system" != "WASI" || tes
   dnl This can be extended here to detect e.g. Power8, which HACL* should also support.
   # Older versions of the mmintrin headers shipped with clang may error if they are
   # included without using the corresponding -msse* option. See GH issue #130213.
-  AC_MSG_CHECKING([if __m128i can be used without -msse*])
-  AC_COMPILE_IFELSE(
-    [AC_LANG_PROGRAM([#include <emmintrin.h>
-                      #include <tmmintrin.h>
-                      #include <smmintrin.h>],
-        [__m128i testvar;])],
-    [AC_MSG_RESULT([yes])
-     AX_CHECK_COMPILE_FLAG([-msse -msse2 -msse3 -msse4.1 -msse4.2],[
-        [LIBHACL_SIMD128_FLAGS="-msse -msse2 -msse3 -msse4.1 -msse4.2"]
+  AX_CHECK_COMPILE_FLAG([-msse -msse2 -msse3 -msse4.1 -msse4.2],[
+    [LIBHACL_SIMD128_FLAGS="-msse -msse2 -msse3 -msse4.1 -msse4.2"]
+    AC_MSG_CHECKING([if __m128i can be used without -msse*])
+      AC_COMPILE_IFELSE(
+        [AC_LANG_PROGRAM([#include <emmintrin.h>
+                          #include <tmmintrin.h>
+                          #include <smmintrin.h>],
+            [__m128i testvar;])],
+        [AC_MSG_RESULT([yes])
 
         AC_DEFINE([HACL_CAN_COMPILE_SIMD128], [1], [HACL* library can compile SIMD128 implementations])
 
@@ -7873,8 +7873,8 @@ if test "$ac_sys_system" != "Linux-android" -a "$ac_sys_system" != "WASI" || tes
           AC_MSG_RESULT([standard])
         fi
 
-      ], [], [-Werror])
-  ], [AC_MSG_RESULT([no])])
+      ], [AC_MSG_RESULT([no])])
+  ], [], [-Werror])
 fi
 AC_SUBST([LIBHACL_SIMD128_FLAGS])
 AC_SUBST([LIBHACL_SIMD128_OBJS])
@@ -7887,16 +7887,17 @@ AC_SUBST([LIBHACL_SIMD128_OBJS])
 # (https://developer.android.com/ndk/guides/abis#86-64), this is safe because we do a
 # runtime CPUID check.
 if test "$ac_sys_system" != "Linux-android" -a "$ac_sys_system" != "WASI" || test "$ANDROID_API_LEVEL" -ge 28; then
-  # Some versions of immintrin.h may not provide the __m256i type if no -mavx*
-  # option is used. See GH issue #130213.
-  AC_MSG_CHECKING([if __m256i can be used without -mavx2])
-  AC_COMPILE_IFELSE(
-    [AC_LANG_PROGRAM([#include <immintrin.h>],
-        [__m256i testvar;])],
-    [AC_MSG_RESULT([yes])
-     AX_CHECK_COMPILE_FLAG([-mavx2],[
-        [LIBHACL_SIMD256_FLAGS="-mavx2"]
-        AC_DEFINE([HACL_CAN_COMPILE_SIMD256], [1], [HACL* library can compile SIMD256 implementations])
+  # Some versions of immintrin.h require -mavx* to provide the __m256i type
+  # but blake2module.c must not be compiled with those options and may
+  # include libintvector.h which contains __m256i. See GH issue #130213.
+  AX_CHECK_COMPILE_FLAG([-mavx2],[
+     [LIBHACL_SIMD256_FLAGS="-mavx2"]
+     AC_MSG_CHECKING([if __m256i can be used without -mavx2])
+     AC_COMPILE_IFELSE(
+        [AC_LANG_PROGRAM([#include <immintrin.h>],
+            [__m256i testvar;])],
+        [AC_MSG_RESULT([yes])
+         AC_DEFINE([HACL_CAN_COMPILE_SIMD256], [1], [HACL* library can compile SIMD256 implementations])
 
         # macOS universal2 builds *support* the -mavx2 compiler flag because it's
         # available on x86_64; but the HACL SIMD256 build then fails because the
@@ -7910,8 +7911,8 @@ if test "$ac_sys_system" != "Linux-android" -a "$ac_sys_system" != "WASI" || tes
           [LIBHACL_SIMD256_OBJS="Modules/_hacl/Hacl_Hash_Blake2b_Simd256.o"]
           AC_MSG_RESULT([standard])
         fi
-      ], [], [-Werror])
-    ], [AC_MSG_RESULT([no])])
+      ], [AC_MSG_RESULT([no])])
+    ], [], [-Werror])
 fi
 AC_SUBST([LIBHACL_SIMD256_FLAGS])
 AC_SUBST([LIBHACL_SIMD256_OBJS])