Joseph Ferano
e4db079c57
The guard reserves 9 bytes but the comment explained 5, which is the longest escape alone -- it did not account for the three writes after the loop (the ellipsis and the closing quote), so the next person to touch the escape table would have preserved the wrong invariant. Swept every length to 1300 against \x01, a quote, a backslash and 'a' under ASan with a red zone past the buffer: no write past 1024, worst output 1021. Correct, but by three bytes, which is exactly why the reserve is now written down as the four things it is spent on. Nothing exercised truncation -- the longest nested string in the fixture was 18 bytes -- so println.flan now prints a struct with an 1100-byte string field, and the expected output spells the surviving count out as a number so a change to the buffer shows up as one.
125 lines
4.9 KiB
Plaintext
125 lines
4.9 KiB
Plaintext
;;;; println, one row per arm of the structural printer.
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;;;;
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;;;; The walk in render.ml is shared with the REPL, but until now its only
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;;;; coverage was the REPL tests -- and those run a dev build, where the pieces
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;;;; go to flan_dev_emit. println is the same walk with the other emitter, in
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;;;; an ordinary build, so every arm needs saying again here: the two emitters
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;;;; are the one thing the shared module does *not* make identical.
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;;;;
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;;;; Run at -O0 as well as -O2. The slice arm emits a loop over slots taken
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;;;; from the enclosing function's frame, and mem2reg is exactly the pass that
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;;;; would launder a slot mistake into working code.
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(defstruct V [x f32 y f32])
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(defstruct Blob [id i32 name string pos V tags [3 i32]])
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(defenum Colour [red 0 green 1 blue 2])
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;; Five deep, so the walk hits max_depth (4) and prints "..." rather than
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;; descending forever. A self-containing struct is the case this cap exists
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;; for; five nested ones are the same shape without needing a pointer.
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(defstruct D5 [n i32])
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(defstruct D4 [d D5])
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(defstruct D3 [d D4])
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(defstruct D2 [d D3])
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(defstruct D1 [d D2])
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(defvar b Blob)
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(defvar col Colour)
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(defvar big u64)
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(defvar small u64)
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(defvar arr [4 i32])
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(defvar wide [10 i32])
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(defvar deep D1)
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(defvar n i32)
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(defstruct Long [s string])
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(defvar long-one Long)
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(defn nothing [] )
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(defn find-it [s [i32] k i32] (Option i32)
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(dotimes [i (len s)]
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(when (= (at s i) k) (return (Some i))))
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None)
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(defn main [] i32
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;; A string at top level prints raw. Anywhere else it is quoted, which the
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;; Blob row below shows -- the two are the same value printed two ways on
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;; purpose, and that difference is the thing most likely to be "fixed".
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(println "plain string")
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(println (bytes "plain bytes"))
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(println 42)
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(println -7)
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(set small 5)
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(println small)
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;; The u64 row. Through the signed printer this reads -1, which is the one
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;; way println could disagree with the REPL about a value both can hold.
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(set big 0xFFFFFFFFFFFFFFFF)
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(println big)
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(println 3.5)
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(println -0.25)
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(println true)
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(println false)
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;; Unit is evaluated and *then* reported: a Unit expression is a call made
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;; for its effect, so emitting () without running it would be a lie.
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(println (nothing))
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(set col :green)
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(println col)
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;; red is 0, which is also the zero value, so this row says the chain of
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;; comparisons reaches the *first* member and does not fall through to the
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;; number it is erased to.
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(set col :red)
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(println col)
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;; A pointer is its shape and is never followed -- the only thing that could
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;; make this walk cycle.
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(set n 3)
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(println (addr n))
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(println (find-it (slice wide 0 10) 0))
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(println (find-it (slice wide 0 10) 99))
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(set (.id b) 7)
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(set (.name b) "sandy \"quoted\"")
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(set (.x (.pos b)) 1.5)
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(set (.y (.pos b)) -2.0)
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(set (at (.tags b) 1) 42)
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(println b)
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(set (at arr 2) 9)
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(println arr)
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;; Ten elements against a span cap of eight: eight, then "...".
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(set (at wide 9) 1)
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(println wide)
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;; A slice's length is not known until it runs, so this is the arm that
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;; emits a loop rather than unrolling.
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(println (slice arr 1 4))
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(set (.n (.d (.d (.d (.d deep))))) 5)
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(println deep)
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;; Two slice printlns in one function, and one inside a loop: the slots the
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;; loop needs are allocated per *call site* at check time, not per iteration.
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(dotimes [i 2]
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(println (slice arr 0 2)))
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(println (slice arr 2 4))
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;; A nested string longer than the escape buffer. Escaping is the one
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;; conversion whose output is not a bounded handful of characters, so it
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;; truncates -- with an ellipsis inside the quotes, because a value that
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;; prints as a shorter value is the failure nobody notices.
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(set (.s long-one) "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx")
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(println long-one)
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;; print is println without the newline.
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(print "a")
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(print "b")
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(println "c")
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0)
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