add configure check for broken gcc 4.9.0 and possibly other versions this is gcc bug #61144. the broken compiler is detected, but the user must manually work around it. this is partly to avoid complex logic for adding workaround CFLAGS and attempting to recheck with them, and partly for the sake of letting the user know the compiler is broken (since the workaround will result in less-efficient code production). some refactoring was also needed to move the check for gcc outside of the check for whether to build the compiler wrapper.
diff --git a/configure b/configure index 5d95672..30f409f 100755 --- a/configure +++ b/configure
@@ -125,6 +125,7 @@ warnings=no shared=yes static=yes +wrapper=auto for arg ; do case "$arg" in @@ -199,23 +200,33 @@ fi # -# Only build musl-gcc wrapper if toolchain does not already target musl +# Need to know if the compiler is gcc to decide whether to build the +# musl-gcc wrapper, and for critical bug detection in some gcc versions. # -if test -z "$wrapper" ; then printf "checking whether compiler is gcc... " if fnmatch '*gcc\ version*' "$($CC -v 2>&1)" ; then -echo yes +cc_is_gcc=yes +else +cc_is_gcc=no +fi +echo "$cc_is_gcc" + +# +# Only build musl-gcc wrapper if toolchain does not already target musl +# +if test "$wrapper" = auto ; then printf "checking whether to build musl-gcc wrapper... " +if test "$cc_is_gcc" = yes ; then wrapper=yes while read line ; do case "$line" in */ld-musl-*) wrapper=no ;; esac done <<EOF $($CC -dumpspecs) EOF -echo $wrapper else -echo no +wrapper=no fi +echo "$wrapper" fi @@ -484,6 +495,27 @@ fail "$0: error: unsupported long double type" fi +# +# Check for known bug in GCC 4.9.0 that results in a broken libc. +# +if test "$cc_is_gcc" = yes ; then +printf "checking for gcc constant folding bug with weak aliases... " +echo 'static int x = 0;' > "$tmpc" +echo 'extern int y __attribute__((__weak__, __alias__("x")));' >> "$tmpc" +echo 'extern int should_appear;' >> "$tmpc" +echo 'int foo() { return y ? should_appear : 0; }' >> "$tmpc" +case "$($CC $CFLAGS_C99FSE -I./arch/$ARCH -I./include \ + $CPPFLAGS $CFLAGS_AUTO $CFLAGS -S -o - "$tmpc" 2>/dev/null)" in +*should_appear*) +printf "no\n" +;; +*) +printf "yes\n" +fail "$0: error: broken compiler; try CFLAGS=-fno-toplevel-reorder" +;; +esac +fi + printf "creating config.mak... " cmdline=$(quote "$0") 