* module/language/tree-il/peval.scm (<operand>): Instead of having a
`residualize?' field, have it be a use count.
(peval): Adapt to <operand> change. Add function to kill uses of an
operand. Use it in the <prompt> inliner. Add another kind of
degenerate prompt to elide. We should really switch to CPS though, as
that will allow us to contify more aggressively.
* test-suite/tests/peval.test ("partial evaluation"): Adapt (while #t
#t) test, which was sensitive to how far the recursive inlining got.
Add a test for the degenerate prompt elision.
* module/language/tree-il/peval.scm (peval): Inline applications where
we know the contents of the tail.
* test-suite/tests/peval.test ("partial evaluation"): Add tests.
* module/language/tree-il/peval.scm (peval): If we can lift one common
test, see if we can lift others as well.
* test-suite/tests/peval.test: Add a test.
* module/language/tree-il/peval.scm (peval): Optimize common tests in
chains of "if" expressions, like those generated by matchers.
* test-suite/tests/peval.test ("partial evaluation"): Add a test.
* module/language/tree-il/peval.scm (<operand>, make-operand)
(make-bound-operands, peval): Avoid emitting needless aliases in
degenerate cases of let.
(visit-operand): If we visit an operand with a fresh counter and have
to abort, record that fact.
* test-suite/tests/peval.test ("partial evaluation"): Add a test.
