1 files changed, 198 insertions, 0 deletions
diff --git a/build/autoconf/compiler-opts.m4 b/build/autoconf/compiler-opts.m4
new file mode 100644
index 0000000000..68960acbc1
--- /dev/null
+++ b/build/autoconf/compiler-opts.m4
@@ -0,0 +1,198 @@
+dnl This Source Code Form is subject to the terms of the Mozilla Public
+dnl License, v. 2.0. If a copy of the MPL was not distributed with this
+dnl file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+dnl Add compiler specific options
+
+dnl ============================================================================
+dnl C++ rtti
+dnl We don't use it in the code, but it can be usefull for debugging, so give
+dnl the user the option of enabling it.
+dnl ============================================================================
+AC_DEFUN([MOZ_RTTI],
+[
+if test -z "$_MOZ_USE_RTTI"; then
+    if test "$GNU_CC"; then
+        CXXFLAGS="$CXXFLAGS -fno-rtti"
+    else
+        case "$target" in
+        *-mingw*)
+            CXXFLAGS="$CXXFLAGS -GR-"
+        esac
+    fi
+fi
+])
+
+dnl ========================================================
+dnl =
+dnl = Debugging Options
+dnl =
+dnl ========================================================
+AC_DEFUN([MOZ_DEBUGGING_OPTS],
+[
+
+if test -z "$MOZ_DEBUG" -o -n "$MOZ_ASAN"; then
+    MOZ_NO_DEBUG_RTL=1
+fi
+
+AC_SUBST(MOZ_NO_DEBUG_RTL)
+
+if test -n "$MOZ_DEBUG"; then
+    if test -n "$COMPILE_ENVIRONMENT"; then
+        AC_MSG_CHECKING([for valid debug flags])
+        _SAVE_CFLAGS=$CFLAGS
+        CFLAGS="$CFLAGS $MOZ_DEBUG_FLAGS"
+        AC_TRY_COMPILE([#include <stdio.h>],
+            [printf("Hello World\n");],
+            _results=yes,
+            _results=no)
+        AC_MSG_RESULT([$_results])
+        if test "$_results" = "no"; then
+            AC_MSG_ERROR([These compiler flags are invalid: $MOZ_DEBUG_FLAGS])
+        fi
+        CFLAGS=$_SAVE_CFLAGS
+    fi
+fi
+])
+
+dnl A high level macro for selecting compiler options.
+AC_DEFUN([MOZ_COMPILER_OPTS],
+[
+  MOZ_DEBUGGING_OPTS
+  MOZ_RTTI
+
+if test "$GNU_CC"; then
+    if test -z "$DEVELOPER_OPTIONS"; then
+        CFLAGS="$CFLAGS -ffunction-sections -fdata-sections"
+        CXXFLAGS="$CXXFLAGS -ffunction-sections -fdata-sections"
+    fi
+
+    CFLAGS="$CFLAGS -fno-math-errno"
+    CXXFLAGS="$CXXFLAGS -fno-exceptions -fno-math-errno"
+fi
+
+dnl ========================================================
+dnl = Identical Code Folding
+dnl ========================================================
+
+if test "$GNU_CC" -a "$GCC_USE_GNU_LD" -a -z "$MOZ_DISABLE_ICF" -a -z "$DEVELOPER_OPTIONS"; then
+    AC_CACHE_CHECK([whether the linker supports Identical Code Folding],
+        moz_cv_opt_ld_supports_icf,
+        [echo 'int foo() {return 42;}' \
+              'int bar() {return 42;}' \
+              'int main() {return foo() - bar();}' > conftest.${ac_ext}
+        # If the linker supports ICF, foo and bar symbols will have
+        # the same address
+        if AC_TRY_COMMAND([${CC-cc} -o conftest${ac_exeext} $LDFLAGS -Wl,--icf=safe -ffunction-sections conftest.${ac_ext} $LIBS 1>&2]) &&
+           test -s conftest${ac_exeext} &&
+           $LLVM_OBJDUMP -t conftest${ac_exeext} | awk changequote(<<, >>)'{a[<<$>>6] = <<$>>1} END {if (a["foo"] && (a["foo"] != a["bar"])) { exit 1 }}'changequote([, ]); then
+            moz_cv_opt_ld_supports_icf=yes
+        else
+            moz_cv_opt_ld_supports_icf=no
+        fi
+        rm -rf conftest*])
+    if test "$moz_cv_opt_ld_supports_icf" = yes; then
+        _SAVE_LDFLAGS="$LDFLAGS -Wl,--icf=safe"
+        LDFLAGS="$LDFLAGS -Wl,--icf=safe -Wl,--print-icf-sections"
+        AC_TRY_LINK([], [],
+                    [LD_PRINT_ICF_SECTIONS=-Wl,--print-icf-sections],
+                    [LD_PRINT_ICF_SECTIONS=])
+        AC_SUBST([LD_PRINT_ICF_SECTIONS])
+        LDFLAGS="$_SAVE_LDFLAGS"
+    fi
+fi
+
+dnl ========================================================
+dnl = Detect static linkage of libstdc++
+dnl ========================================================
+
+if test "$OS_TARGET" = Linux; then
+
+AC_CACHE_CHECK([whether we're trying to statically link with libstdc++],
+    moz_cv_opt_static_libstdcxx,
+    [moz_cv_opt_static_libstdcxx=no
+     AC_LANG_SAVE
+     AC_LANG_CPLUSPLUS
+     cat > conftest.$ac_ext <<EOF
+#include <iostream>
+int main() { std::cout << 1; }
+EOF
+     dnl This test is quite conservative: it assumes dynamic linkage if the compilation step fails or if
+     dnl the binary format is not supported. But it still detects basic issues.
+     if AC_TRY_EVAL([ac_link]) && test -s conftest${ac_exeext} && $LLVM_OBJDUMP --private-headers conftest${ac_exeext} 2> conftest.err 1> conftest.out
+     then
+         if test -s conftest.err
+         then :
+         elif grep -q -E 'NEEDED.*lib(std)?c\+\+' conftest.out
+         then :
+         else moz_cv_opt_static_libstdcxx=yes
+         fi
+     fi
+     AC_LANG_RESTORE
+     rm -f conftest*
+])
+if test "$moz_cv_opt_static_libstdcxx" = "yes"; then
+    AC_MSG_ERROR([Firefox does not support linking statically with libstdc++])
+fi
+
+fi
+
+dnl ========================================================
+dnl = Automatically remove dead symbols
+dnl ========================================================
+
+SANCOV=
+if test -n "$LIBFUZZER"; then
+    case "$LIBFUZZER_FLAGS" in
+    *-fsanitize-coverage*|*-fsanitize=fuzzer*)
+        SANCOV=1
+        ;;
+    esac
+fi
+
+if test "$GNU_CC" -a "$GCC_USE_GNU_LD" -a -z "$DEVELOPER_OPTIONS" -a -z "$MOZ_PROFILE_GENERATE" -a -z "$SANCOV"; then
+    if test -n "$MOZ_DEBUG_FLAGS"; then
+        dnl See bug 670659
+        AC_CACHE_CHECK([whether removing dead symbols breaks debugging],
+            moz_cv_opt_gc_sections_breaks_debug_ranges,
+            [echo 'int foo() {return 42;}' \
+                  'int bar() {return 1;}' \
+                  'int main() {return foo();}' > conftest.${ac_ext}
+            if AC_TRY_COMMAND([${CC-cc} -o conftest.${ac_objext} $CFLAGS $MOZ_DEBUG_FLAGS -c conftest.${ac_ext} 1>&2]) &&
+                AC_TRY_COMMAND([${CC-cc} -o conftest${ac_exeext} $LDFLAGS $MOZ_DEBUG_FLAGS -Wl,--gc-sections conftest.${ac_objext} $LIBS 1>&2]) &&
+                test -s conftest${ac_exeext} -a -s conftest.${ac_objext}; then
+                 if test "`$PYTHON3 -m mozbuild.configure.check_debug_ranges conftest.${ac_objext} conftest.${ac_ext}`" = \
+                         "`$PYTHON3 -m mozbuild.configure.check_debug_ranges conftest${ac_exeext} conftest.${ac_ext}`"; then
+                     moz_cv_opt_gc_sections_breaks_debug_ranges=no
+                 else
+                     moz_cv_opt_gc_sections_breaks_debug_ranges=yes
+                 fi
+             else
+                  dnl We really don't expect to get here, but just in case
+                  moz_cv_opt_gc_sections_breaks_debug_ranges="no, but it's broken in some other way"
+             fi
+             rm -rf conftest*])
+         if test "$moz_cv_opt_gc_sections_breaks_debug_ranges" = no; then
+             DSO_LDOPTS="$DSO_LDOPTS -Wl,--gc-sections"
+         fi
+    else
+        DSO_LDOPTS="$DSO_LDOPTS -Wl,--gc-sections"
+    fi
+fi
+
+if test "$GNU_CC$CLANG_CC"; then
+    case "${OS_TARGET}" in
+    Darwin|WASI)
+        # It's the default on those targets, and clang complains about -pie
+        # being unused if passed.
+        ;;
+    *)
+        MOZ_PROGRAM_LDFLAGS="$MOZ_PROGRAM_LDFLAGS -pie"
+        ;;
+    esac
+fi
+
+AC_SUBST(MOZ_PROGRAM_LDFLAGS)
+
+
+])