--- inline.h.~1.30.2.1.~ 2006-02-14 08:58:58.000000000 +1100 +++ inline.h 2006-05-20 09:48:46.000000000 +1000 @@ -248,6 +248,27 @@ int scm_is_pair (SCM x) { + /* The following "workaround_for_gcc_295" avoids bad code generated by + i386 gcc 2.95.4 (the Debian packaged 2.95.4-24 at least). + + Under the default -O2 the inlined SCM_I_CONSP test gets "optimized" so + the fetch of the tag word from x is done before confirming it's a + non-immediate (SCM_NIMP). Needless to say that bombs badly if x is a + immediate. This was seen to afflict scm_srfi1_split_at and something + deep in the bowels of ceval(). In both cases segvs resulted from + deferencing a random immediate value. srfi-1.test exposes the problem + through a short list, the immediate being SCM_EOL in that case. + Something in syntax.test exposed the ceval() problem. + + Just "volatile SCM workaround_for_gcc_295 = lst" is enough to avoid the + problem, without even using that variable. The "w=w" is just to + prevent a warning about it being unused. + */ +#if defined (__GNUC__) && __GNUC__ == 2 && __GNUC_MINOR__ == 95 + volatile SCM workaround_for_gcc_295 = x; + workaround_for_gcc_295 = workaround_for_gcc_295; +#endif + return SCM_I_CONSP (x); }