This patch permits the user to supply additional specs for functions
whose bodies were not imported (DONT_TRANSLATE or not present in parsed
C source). Those specs are exported by SimplExport.
The existing apparatus can import builtin functions like ctzl/clzl in C
sources by admitting them without bodies (DONT_TRANSLATE) and giving
them axiomatic Hoare triples (FNSPEC).
Translation validation then requires export of useful semantics. The user
can supply a made-up body, and show that it is a refinement of the body
that the parser created (derived from the FNSPEC and MODIFIES clauses).
The body must export out the graph language correctly. For ctzl/clzl etc
this is easy.
This creates an issue because "unat x < 1" is reduced to "unat x = 0"
by the simplifier, meaning the unat_mono tactic doesn't get to operate on
it. The fix is pretty easy. Also includes some extra investigation material.
New testfile for graph-refine export with new handling code. Also
some slight tweaks to some CRefine proofs that will be needed to
remove DONT_TRANSLATE markers from certain key places in the seL4
code. These proofs are also compatible with previous seL4.
The C-parser contains a full parser for __asm__ syntax but
up until now hasn't done anything with it. Instead we export
some semantics. It's unspecified exactly what these semantics
are but they are parametrised with the __asm__ semantics that
went in to them, so the translation validation has something
to reason about.
Tweak modifies proofs as a result, and add some more test files.
The existing code only captured a single Guard in the body of a while.
Replace it with some ML for capturing the intersection of all guards.
(Thomas typing on Xin's keyboard.)
Sometimes it's simpler to access an unknown field of a const
global by just computing the offset from its symbol in memory
and assuming the relevant words are in the .rodata section. But
for known fields, it's easier to just figure out what the
constant value is. This complicates the proof slightly, since
it has to guess which case it is in.
Matthew Brecknell
Thomas Sewell
Alejandro Gomez-Londono
Rafal Kolanski
Thomas Sewell
Japheth Lim
Joel Beeren
Gerwin Klein
Matthew Brecknell
Gao Xin
Ramana Kumar