SAWScript.Prover.Rewrite.rewriteEqs is very slow

[brianhuffman]

The problem is that it rebuilds the simpset from scratch (using function basic_ss) every time it is called, which is quite expensive.

saw-script/src/SAWScript/Prover/Rewrite.hs

Lines 20 to 28 in 47aa9f3

	rewriteEqs :: SharedContext -> Term -> IO Term
	rewriteEqs sc t =
	do let eqs = map (mkIdent preludeName)
	[ "eq_Bool", "eq_Nat", "eq_bitvector", "eq_VecBool"
	, "eq_VecVec" ]
	rs <- scEqsRewriteRules sc eqs
	ss <- addRules rs <$> basic_ss sc
	t' <- rewriteSharedTerm sc ss t
	return t'

Profiling on my use-case shows that basic_ss makes up around 30% of both the total runtime and total allocation.
Interestingly, one of the most expensive parts of building the simpset is scTypeOfGlobal, so we should probably optimize that one too.

[brianhuffman]

Function basic_ss is also called from function resolveSAWTerm, which I think is actually the source of the performance issue I'm seeing.

saw-script/src/SAWScript/Crucible/LLVM/ResolveSetupValue.hs

Line 372 in 47aa9f3

ss <- basic_ss sc

We should cache the simpset somewhere, instead of recomputing it every single time.