Bug 1879776 - Move -Wa,--noexecstack check to python configure r=glandium

Provide the minimal support from moz.configure to do so.

The only observable change of this patch is to permute -fPIC and
-Wa,--noexecstack in ASFLAGS.

Differential Revision: https://phabricator.services.mozilla.com/D201349

build/moz.configure/compile-checks.configure

@@ -204,7 +204,7 @@ def check_symbol(symbol, language="C", flags=None, when=None, onerror=lambda: No
 #   when the warning flag is wanted.
 # - `check`, when not set, skips checking whether the flag is supported and
 #   adds it to the list of flags unconditionally.
-# - `link`, when set, also perform a linking step.
+# - `mode`, can be "compile", "link" or "assemble"
 @template
 def check_and_add_flags(
     flag,
@@ -213,11 +213,13 @@ def check_and_add_flags(
     compiler=None,
     when=None,
     check=True,
-    link=False,
+    mode="compile",
 ):
+    assert mode in ("compile", "link", "assemble")
+
     if compiler is not None:
         compilers = (compiler,)
-    elif link:
+    elif mode in ("link", "assemble"):
         compilers = (c_compiler,)
     else:
         compilers = (c_compiler, cxx_compiler)
@@ -234,20 +236,25 @@ def check_and_add_flags(
 
     for c in compilers:
         assert c in {c_compiler, cxx_compiler, host_c_compiler, host_cxx_compiler}
-        if link:
-            lang, list_of_flags = {
-                c_compiler: ("C", flags_collection.ldflags),
-                cxx_compiler: ("C++", flags_collection.ldflags),
-                host_c_compiler: ("host C", flags_collection.host_ldflags),
-                host_cxx_compiler: ("host C++", flags_collection.host_ldflags),
-            }[c]
-        else:
+        if mode == "compile":
             lang, list_of_flags = {
                 c_compiler: ("C", flags_collection.cflags),
                 cxx_compiler: ("C++", flags_collection.cxxflags),
                 host_c_compiler: ("host C", flags_collection.host_cflags),
                 host_cxx_compiler: ("host C++", flags_collection.host_cxxflags),
             }[c]
+        elif mode == "assemble":
+            lang, list_of_flags = {
+                c_compiler: ("C", flags_collection.asflags),
+                host_c_compiler: ("host C", flags_collection.host_asflags),
+            }[c]
+        elif mode == "link":
+            lang, list_of_flags = {
+                c_compiler: ("C", flags_collection.ldflags),
+                cxx_compiler: ("C++", flags_collection.ldflags),
+                host_c_compiler: ("host C", flags_collection.host_ldflags),
+                host_cxx_compiler: ("host C++", flags_collection.host_ldflags),
+            }[c]
 
         result = when
 
@@ -261,7 +268,7 @@ def check_and_add_flags(
 
                 return flags
 
-            if link:
+            if mode == "link":
 
                 def runner(*args, **kwargs):
                     if c in (c_compiler, cxx_compiler):
@@ -377,6 +384,27 @@ def add_flag(warning, compiler=None, when=None):
     check_and_add_flag(warning, compiler, when, check=False)
 
 
+# Like the compilation checks above, but for asm flags.
+@dependable
+def asm_flags():
+    return namespace(asflags=[], host_asflags=[])
+
+
+# Tests the given assembler flag is supported; if the flag
+# is supported, add it to the list of compilation flags for the build.
+# - `flag` is the flag to test
+# - `when` (optional) is a @depends function or option name conditioning
+#   when the warning flag is wanted.
+# - `check`, when not set, skips checking whether the flag is supported and
+#   adds it to the list of flags unconditionally. This is only meant for
+#   add_flag().
+@template
+def check_and_add_asm_flag(flag, when=None, check=True):
+    return check_and_add_flags(
+        flag, asm_flags, [flag], when=when, check=check, mode="assemble",
+    )
+
+
 # Like the compilation checks above, but for linker flags.
 @dependable
 def linker_flags():
@@ -394,7 +422,7 @@ def linker_flags():
 @template
 def check_and_add_linker_flag(flag, compiler=None, when=None, check=True):
     return check_and_add_flags(
-        flag, linker_flags, [flag], when=when, check=check, link=True
+        flag, linker_flags, [flag], when=when, check=check, mode="link",
     )
 
 

build/moz.configure/flags.configure

@@ -163,6 +163,7 @@ def check_build_id_sha1(developer_options):
 check_and_add_linker_flag("-Wl,--build-id=uuid", when=check_build_id_uuid)
 check_and_add_linker_flag("-Wl,--build-id=sha1", when=check_build_id_sha1)
 
+check_and_add_asm_flag("-Wa,--noexecstack", when=is_gnu_cc)
 check_and_add_linker_flag("-Wl,-z,noexecstack", when=is_gnu_cc)
 check_and_add_linker_flag("-Wl,-z,text", when=is_gnu_cc)
 check_and_add_linker_flag("-Wl,-z,relro", when=is_gnu_cc)
@@ -184,5 +185,7 @@ def check_Bsymbolic(enable_asan, is_gnu_cc):
 check_and_add_linker_flag("-Wl,-Bsymbolic", when=check_Bsymbolic)
 
 # Please keep these last in this file.
+add_old_configure_assignment("_COMPILATION_ASFLAGS", asm_flags.asflags)
+add_old_configure_assignment("_COMPILATION_HOST_ASFLAGS", asm_flags.host_asflags)
 add_old_configure_assignment("_COMPILATION_LDFLAGS", linker_flags.ldflags)
 add_old_configure_assignment("_COMPILATION_HOST_LDFLAGS", linker_flags.host_ldflags)

js/src/old-configure.in

@@ -194,14 +194,6 @@ if test "$GNU_CC"; then
         ASFLAGS="$ASFLAGS -fPIC"
     fi
 
-    AC_MSG_CHECKING([for --noexecstack option to as])
-    _SAVE_CFLAGS=$CFLAGS
-    CFLAGS="$CFLAGS -Wa,--noexecstack"
-    AC_TRY_COMPILE(,,AC_MSG_RESULT([yes])
-                     [ASFLAGS="$ASFLAGS -Wa,--noexecstack"],
-                     AC_MSG_RESULT([no]))
-    CFLAGS=$_SAVE_CFLAGS
-
     _DEFINES_CFLAGS="-include $jsconfdefs -DMOZILLA_CLIENT"
 fi
 
@@ -913,6 +905,10 @@ CXXFLAGS=`echo \
 	$_COMPILATION_CXXFLAGS \
 	$CXXFLAGS`
 
+ASFLAGS=`echo \
+    $_COMPILATION_ASFLAGS \
+    $ASFLAGS`
+
 COMPILE_CFLAGS=`echo \
     $_DEFINES_CFLAGS \
     $COMPILE_CFLAGS`

old-configure.in

@@ -193,14 +193,6 @@ if test "$GNU_CC"; then
         ASFLAGS="$ASFLAGS -fPIC"
     fi
 
-    AC_MSG_CHECKING([for --noexecstack option to as])
-    _SAVE_CFLAGS=$CFLAGS
-    CFLAGS="$CFLAGS -Wa,--noexecstack"
-    AC_TRY_COMPILE(,,AC_MSG_RESULT([yes])
-                     [ASFLAGS="$ASFLAGS -Wa,--noexecstack"],
-                     AC_MSG_RESULT([no]))
-    CFLAGS=$_SAVE_CFLAGS
-
     AC_MSG_CHECKING([for --ignore-unresolved-symbol option to ld])
     HAVE_LINKER_SUPPORT_IGNORE_UNRESOLVED=
     _SAVE_LDFLAGS=$LDFLAGS
@@ -1212,6 +1204,10 @@ CXXFLAGS=`echo \
     $_COMPILATION_CXXFLAGS \
     $CXXFLAGS`
 
+ASFLAGS=`echo \
+    $_COMPILATION_ASFLAGS \
+    $ASFLAGS`
+
 COMPILE_CFLAGS=`echo \
     $_DEFINES_CFLAGS \
     $COMPILE_CFLAGS`