From a988b4c56143d90f98034daf176e416b08dddf36 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 20 Oct 2022 14:20:30 +0200
Subject: [PATCH] build: move remaining compiler flag tests to meson
MIME-Version: 1.0
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Remove the only remaining uses of QEMU_CFLAGS.  Now that no
feature tests are done in configure, it is possible to remove
CONFIGURE_CFLAGS and CONFIGURE_LDFLAGS as well.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 configure   | 79 ++++++++---------------------------------------------
 meson.build | 52 ++++++++++++++++++++++++++++++++++-
 2 files changed, 62 insertions(+), 69 deletions(-)

diff --git a/configure b/configure
index cb42749d25..86883f1bbe 100755
--- a/configure
+++ b/configure
@@ -163,14 +163,14 @@ do_cc() {
 
 compile_object() {
   local_cflags="$1"
-  do_cc $CFLAGS $EXTRA_CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -c -o $TMPO $TMPC
+  do_cc $CFLAGS $EXTRA_CFLAGS $local_cflags -c -o $TMPO $TMPC
 }
 
 compile_prog() {
   local_cflags="$1"
   local_ldflags="$2"
-  do_cc $CFLAGS $EXTRA_CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC \
-      $LDFLAGS $EXTRA_LDFLAGS $CONFIGURE_LDFLAGS $local_ldflags
+  do_cc $CFLAGS $EXTRA_CFLAGS $local_cflags -o $TMPE $TMPC \
+      $LDFLAGS $EXTRA_LDFLAGS $local_ldflags
 }
 
 # symbolically link $1 to $2.  Portable version of "ln -sf".
@@ -375,19 +375,6 @@ windmc="${WINDMC-${cross_prefix}windmc}"
 pkg_config="${PKG_CONFIG-${cross_prefix}pkg-config}"
 sdl2_config="${SDL2_CONFIG-${cross_prefix}sdl2-config}"
 
-# default flags for all hosts
-# We use -fwrapv to tell the compiler that we require a C dialect where
-# left shift of signed integers is well defined and has the expected
-# 2s-complement style results. (Both clang and gcc agree that it
-# provides these semantics.)
-QEMU_CFLAGS="-fno-strict-aliasing -fno-common -fwrapv"
-QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS"
-
-# Flags that are needed during configure but later taken care of by Meson
-CONFIGURE_CFLAGS="-std=gnu11 -Wall"
-CONFIGURE_LDFLAGS=
-
-
 check_define() {
 cat > $TMPC <<EOF
 #if !defined($1)
@@ -466,21 +453,13 @@ openbsd)
 darwin)
   bsd="yes"
   darwin="yes"
-  # Disable attempts to use ObjectiveC features in os/object.h since they
-  # won't work when we're compiling with gcc as a C compiler.
-  QEMU_CFLAGS="-DOS_OBJECT_USE_OBJC=0 $QEMU_CFLAGS"
 ;;
 sunos)
   solaris="yes"
   make="${MAKE-gmake}"
-# needed for CMSG_ macros in sys/socket.h
-  QEMU_CFLAGS="-D_XOPEN_SOURCE=600 $QEMU_CFLAGS"
-# needed for TIOCWIN* defines in termios.h
-  QEMU_CFLAGS="-D__EXTENSIONS__ $QEMU_CFLAGS"
 ;;
 haiku)
   pie="no"
-  QEMU_CFLAGS="-DB_USE_POSITIVE_POSIX_ERRORS -D_BSD_SOURCE -fPIC $QEMU_CFLAGS"
 ;;
 linux)
   linux="yes"
@@ -633,8 +612,6 @@ done
 
 if test "$mingw32" = "yes" ; then
   EXESUF=".exe"
-  # MinGW needs -mthreads for TLS and macro _MT.
-  CONFIGURE_CFLAGS="-mthreads $CONFIGURE_CFLAGS"
   prefix="/qemu"
   bindir=""
   qemu_suffix=""
@@ -1196,59 +1173,26 @@ static THREAD int tls_var;
 int main(void) { return tls_var; }
 EOF
 
-# Meson currently only handles pie as a boolean for now so if we have
-# explicitly disabled PIE we need to extend our cflags because it wont.
 if test "$static" = "yes"; then
   if test "$pie" != "no" && compile_prog "-Werror -fPIE -DPIE" "-static-pie"; then
-    CONFIGURE_CFLAGS="-fPIE -DPIE $CONFIGURE_CFLAGS"
     pie="yes"
   elif test "$pie" = "yes"; then
     error_exit "-static-pie not available due to missing toolchain support"
   else
     pie="no"
-    QEMU_CFLAGS="-fno-pie $QEMU_CFLAGS"
   fi
-elif test "$pie" = "no"; then
-  if compile_prog "-Werror -fno-pie" "-no-pie"; then
-    CONFIGURE_CFLAGS="-fno-pie $CONFIGURE_CFLAGS"
-    CONFIGURE_LDFLAGS="-no-pie $CONFIGURE_LDFLAGS"
-    QEMU_CFLAGS="-fno-pie -no-pie $QEMU_CFLAGS"
+elif test "$pie" != "no"; then
+  if compile_prog "-Werror -fPIE -DPIE" "-pie"; then
+    pie="yes"
+  elif test "$pie" = "yes"; then
+    error_exit "PIE not available due to missing toolchain support"
+  else
+    echo "Disabling PIE due to missing toolchain support"
+    pie="no"
   fi
-elif compile_prog "-Werror -fPIE -DPIE" "-pie"; then
-  CONFIGURE_CFLAGS="-fPIE -DPIE $CONFIGURE_CFLAGS"
-  CONFIGURE_LDFLAGS="-pie $CONFIGURE_LDFLAGS"
-  pie="yes"
-elif test "$pie" = "yes"; then
-  error_exit "PIE not available due to missing toolchain support"
-else
-  echo "Disabling PIE due to missing toolchain support"
-  pie="no"
 fi
 
 ##########################################
-# __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
-
-if test "$cpu" = "i386"; then
-  cat > $TMPC << EOF
-static int sfaa(int *ptr)
-{
-  return __sync_fetch_and_and(ptr, 0);
-}
-
-int main(void)
-{
-  int val = 42;
-  val = __sync_val_compare_and_swap(&val, 0, 1);
-  sfaa(&val);
-  return val;
-}
-EOF
-  if ! compile_prog "" "" ; then
-    QEMU_CFLAGS="-march=i486 $QEMU_CFLAGS"
-  fi
-fi
 
 if test -z "${target_list+xxx}" ; then
     default_targets=yes
@@ -1931,7 +1875,6 @@ echo "MESON=$meson" >> $config_host_mak
 echo "NINJA=$ninja" >> $config_host_mak
 echo "PKG_CONFIG=${pkg_config}" >> $config_host_mak
 echo "CC=$cc" >> $config_host_mak
-echo "QEMU_CFLAGS=$QEMU_CFLAGS" >> $config_host_mak
 echo "EXESUF=$EXESUF" >> $config_host_mak
 
 # use included Linux headers
diff --git a/meson.build b/meson.build
index 515e31973a..2d3e468730 100644
--- a/meson.build
+++ b/meson.build
@@ -190,10 +190,50 @@ endif
 # Compiler flags #
 ##################
 
-qemu_common_flags = config_host['QEMU_CFLAGS'].split()
+# default flags for all hosts
+# We use -fwrapv to tell the compiler that we require a C dialect where
+# left shift of signed integers is well defined and has the expected
+# 2s-complement style results. (Both clang and gcc agree that it
+# provides these semantics.)
+
+qemu_common_flags = [
+  '-D_GNU_SOURCE', '-D_FILE_OFFSET_BITS=64', '-D_LARGEFILE_SOURCE',
+  '-fno-strict-aliasing', '-fno-common', '-fwrapv' ]
 qemu_cflags = []
 qemu_ldflags = []
 
+if targetos == 'darwin'
+  # Disable attempts to use ObjectiveC features in os/object.h since they
+  # won't work when we're compiling with gcc as a C compiler.
+  qemu_common_flags += '-DOS_OBJECT_USE_OBJC=0'
+elif targetos == 'solaris'
+  # needed for CMSG_ macros in sys/socket.h
+  qemu_common_flags += '-D_XOPEN_SOURCE=600'
+  # needed for TIOCWIN* defines in termios.h
+  qemu_common_flags += '-D__EXTENSIONS__'
+elif targetos == 'haiku'
+  qemu_common_flags += ['-DB_USE_POSITIVE_POSIX_ERRORS', '-D_BSD_SOURCE', '-fPIC']
+endif
+
+# __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
+if host_arch == 'i386' and not cc.links('''
+  static int sfaa(int *ptr)
+  {
+    return __sync_fetch_and_and(ptr, 0);
+  }
+
+  int main(void)
+  {
+    int val = 42;
+    val = __sync_val_compare_and_swap(&val, 0, 1);
+    sfaa(&val);
+    return val;
+  }''')
+  qemu_common_flags = ['-march=i486'] + qemu_common_flags
+endif
+
 if get_option('gprof')
   qemu_common_flags += ['-p']
   qemu_ldflags += ['-p']
@@ -203,6 +243,16 @@ if get_option('prefer_static')
   qemu_ldflags += get_option('b_pie') ? '-static-pie' : '-static'
 endif
 
+# Meson currently only handles pie as a boolean for now, so if the user
+# has explicitly disabled PIE we need to extend our cflags.
+if not get_option('b_pie')
+  qemu_common_flags += cc.get_supported_arguments('-fno-pie')
+  if not get_option('prefer_static')
+    # No PIE is implied by -static which we added above.
+    qemu_ldflags += cc.get_supported_link_arguments('-no-pie')
+  endif
+endif
+
 if not get_option('stack_protector').disabled()
   stack_protector_probe = '''
     int main(int argc, char *argv[])