Create a separate variable for compiler flags that enable
specific instruction set extensions, so that they can be used with
cc.compiles/cc.links.

Note that -mfpmath=sse is a code generation option but it does not
enable new instructions, therefore I did not make it part of
qemu_isa_flags.

Suggested-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 meson.build | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/meson.build b/meson.build
index 76335bb2a51..65ea45cef03 100644
--- a/meson.build
+++ b/meson.build
@@ -335,6 +335,10 @@ elif host_os == 'windows'
   endif
 endif
 
+# Choose instruction set (currently x86-only)
+
+qemu_isa_flags = []
+
 # __sync_fetch_and_and requires at least -march=i486. Many toolchains
 # use i686 as default anyway, but for those that don't, an explicit
 # specification is necessary
@@ -351,7 +355,7 @@ if host_arch == 'i386' and not cc.links('''
     sfaa(&val);
     return val;
   }''')
-  qemu_common_flags = ['-march=i486'] + qemu_common_flags
+  qemu_isa_flags += ['-march=i486']
 endif
 
 # Pick x86-64 baseline version
@@ -367,29 +371,31 @@ if host_arch in ['i386', 'x86_64']
     else
       # present on basically all processors but technically not part of
       # x86-64-v1, so only include -mneeded for x86-64 version 2 and above
-      qemu_common_flags = ['-mcx16'] + qemu_common_flags
+      qemu_isa_flags += ['-mcx16']
     endif
   endif
   if get_option('x86_version') >= '2'
-    qemu_common_flags = ['-mpopcnt'] + qemu_common_flags
-    qemu_common_flags = cc.get_supported_arguments('-mneeded') + qemu_common_flags
+    qemu_isa_flags += ['-mpopcnt']
+    qemu_isa_flags += cc.get_supported_arguments('-mneeded')
   endif
   if get_option('x86_version') >= '3'
-    qemu_common_flags = ['-mmovbe', '-mabm', '-mbmi', '-mbmi2', '-mfma', '-mf16c'] + qemu_common_flags
+    qemu_isa_flags += ['-mmovbe', '-mabm', '-mbmi', '-mbmi2', '-mfma', '-mf16c']
   endif
 
   # add required vector instruction set (each level implies those below)
   if get_option('x86_version') == '1'
-    qemu_common_flags = ['-msse2'] + qemu_common_flags
+    qemu_isa_flags += ['-msse2']
   elif get_option('x86_version') == '2'
-    qemu_common_flags = ['-msse4.2'] + qemu_common_flags
+    qemu_isa_flags += ['-msse4.2']
   elif get_option('x86_version') == '3'
-    qemu_common_flags = ['-mavx2'] + qemu_common_flags
+    qemu_isa_flags += ['-mavx2']
   elif get_option('x86_version') == '4'
-    qemu_common_flags = ['-mavx512f', '-mavx512bw', '-mavx512cd', '-mavx512dq', '-mavx512vl'] + qemu_common_flags
+    qemu_isa_flags += ['-mavx512f', '-mavx512bw', '-mavx512cd', '-mavx512dq', '-mavx512vl']
   endif
 endif
 
+qemu_common_flags = qemu_isa_flags + qemu_common_flags
+
 if get_option('prefer_static')
   qemu_ldflags += get_option('b_pie') ? '-static-pie' : '-static'
 endif
-- 
2.46.1