* module/language/cps/cse.scm (compute-available-expressions): Compute a
bailout set -- or at least, set things up so that we can do so.
(compute-idoms): Don't add predecessors that bail out.
(apply-cse, cse, compute-equivalent-subexpressions): Thread the
bailout set through the computations.
* module/language/cps/cse.scm (compute-available-expressions): Prepare
for being able to prune joins from bailouts. Always loop after the
first iteration.
* module/language/cps/effects-analysis.scm: Remove &possible-bailout.
Rename &definite-bailout to &bailout, and rename
&all-effects-but-bailout to &unknown-effects.
* module/language/cps/cse.scm: New file.
* module/language/cps/compile-bytecode.scm: Wire up CSE, on by default.
Currently using the #:cps-cse? keyword.
* module/Makefile.am: Add new file.
