Not pushing conditions using permission introspection further in #853
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The
--conditionalizePermissions
command line option rewrites implications and ternary expressions to avoid branching.The general pattern is that
e1 ==> acc(e2.f, e3)
is rewritten toacc(e2.f, e1 ? e3 : none
.This rewriting is not always sound if the condition (
e1
in this case) uses permission introspection.Example:
must not be rewritten to
since the value of
perm(P1(x)) >= write
changes.This PR conservatively prevents any rewriting where the condition contains
perm
orforperm
.This fixes one issue mentioned in #851.