diff options
Diffstat (limited to 'gcc/configure.ac')
| -rw-r--r-- | gcc/configure.ac | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/gcc/configure.ac b/gcc/configure.ac index a192ad9..767e288 100644 --- a/gcc/configure.ac +++ b/gcc/configure.ac @@ -416,6 +416,32 @@ struct X<long long> { typedef long long t; }; ]], [[X<int64_t>::t x;]])],[],[AC_MSG_ERROR([error verifying int64_t uses long long])]) fi +# Check whether compiler is affected by placement new aliasing bug (PR 29286). +# If the host compiler is affected by the bug, and we build with optimization +# enabled (which happens e.g. when cross-compiling), the pool allocator may +# get miscompiled. Use -fno-strict-aliasing to work around this problem. +# Since there is no reliable feature check for the presence of this bug, +# we simply use a GCC version number check. (This should never trigger for +# stages 2 or 3 of a native bootstrap.) +aliasing_flags= +if test "$GCC" = yes; then + saved_CXXFLAGS="$CXXFLAGS" + + # The following test compilation will succeed if and only if $CXX accepts + # -fno-strict-aliasing *and* is older than GCC 4.3. + CXXFLAGS="$CXXFLAGS -fno-strict-aliasing" + AC_MSG_CHECKING([whether $CXX is affected by placement new aliasing bug]) + AC_COMPILE_IFELSE([ +#if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3) +#error compiler not affected by placement new aliasing bug +#endif +], + [AC_MSG_RESULT([yes]); aliasing_flags='-fno-strict-aliasing'], + [AC_MSG_RESULT([no])]) + + CXXFLAGS="$saved_CXXFLAGS" +fi +AC_SUBST(aliasing_flags) |