Joseph Ferano
dad725afe4
swap!, reverse!, sort!, sort-by!, index-of, min-of, max-of, map!, reduce and filter, each written once over $t. Every call site in the corpus moves with them. min-of and max-of are not min and max because min and max are builtins over two or more numbers and nothing shadows a builtin. These reduce a slice, which is a different operation at a different arity. sort-bytes! did not collapse into sort!, and the reason is the point of the predicates: a [u8] is not ordered? and cannot be, because < is an instruction and comparing two slices lexicographically is a loop. It is sort-by! with bytes<? written in, one line, keeping its name and its stability note. sum-i32/sum-f32 and append-i64!/append-f64! stay for the reasons the spike gave. Not what the notes predicted: none of the ten collapses on a signature change alone. filter and reduce need copyable? because the checker demands it - reduce's accumulator at (Vec i32) is a double move - and the rest declare it because a slice of owning elements would have them duplicating headers.
54 lines
1.9 KiB
Plaintext
54 lines
1.9 KiB
Plaintext
;;;; Three edges of Reach's walk, each the only route to one function.
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;;;;
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;;;; A release build is pruned: a function nothing reachable from main or from
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;;;; a global initialiser calls is not emitted at all. So an edge the walk
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;;;; forgets does not produce a wrong answer — it produces a program that does
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;;;; not link, with a message about a symbol nobody wrote. Each of the three
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;;;; functions below is called from exactly one place, and that place is an
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;;;; edge no other program in the corpus exercises:
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;;;;
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;;;; index-expr the index expression of a place, (set (at a (f)) v)
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;;;; through a place under (addr ...), here a (deref ...) so that it is
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;;;; the addr edge and not the index one again
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;;;; placeholder a restart-case clause body, which is reached by a transfer
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;;;; and never by a call the walk can see from the body
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;;;;
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;;;; Nothing here is about the values; the values are how the test notices that
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;;;; the program was built and ran at all.
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(defvar cells [4 i32])
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(defvar slot i32)
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(defstruct Nope [id i32])
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(defn index-expr [] i32 2)
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(defn through [] (Ptr i32) (addr slot))
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(defn placeholder [] i32 42)
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;;; Signals with nothing to return, so the clause body is the only way past.
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(defn missing [] i32
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(error (Nope {.id 1})))
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(defn pick [] i32
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(restart-case (missing)
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(use-placeholder [] (placeholder))))
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(defn main [] i32
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;; The index of a place is an expression, and it can call.
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(set (at cells (index-expr)) 10)
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(print (at cells 2)) (println "")
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;; (addr (deref p)) is p, so this is the addr edge over a place whose own
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;; walk is Pderef rather than Pindex — the index case above cannot stand in
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;; for it.
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(let [q (addr (deref (through)))]
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(set (deref q) 20))
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(print slot) (println "")
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;; The clause body, reached only because the handler transfers into it.
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(handler-bind [(Nope [c] (invoke-restart 'use-placeholder))]
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(print (pick)) (println ""))
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0)
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