76 lines
3.0 KiB
Scheme
76 lines
3.0 KiB
Scheme
;;; Codegen details that are easy to get subtly wrong, and that the
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;;; walk-* unit tests cannot see: they check the intermediate form we
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;;; hand to fmt-c, not the C that fmt-c renders from it.
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;;;
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;;; Both cases below were found by writing an OpenGL example, not by
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;;; the existing suite, because both need an operand shape that no
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;;; earlier test program happened to use.
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(import (chicken port)
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(chicken string)
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srfi-13
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fmt-c-writer
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reader
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semen
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utils)
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(define (sex->c source)
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"Compile SOURCE, a string of Sex, and return the generated C."
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(let ((forms (with-input-from-string source
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(lambda ()
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(parameterize ((current-source-file "codegen.sex"))
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(parse-all (current-input-port)))))))
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(with-output-to-string
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(lambda ()
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(parameterize ((sex-line-directives 'none))
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(emit-c (semen-process forms)))))))
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(define (emits? source fragment)
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(and (string-contains (sex->c source) fragment) #t))
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(define (in-fn body)
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(string-append "(fn f ((a int) (b int)) void " body ")"))
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(test-group "codegen"
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;; c-switch handed its scrutinee straight to `cat', which only works
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;; when it is an atom. Anything else was displayed as a raw
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;; s-expression: `switch ((%. e type))'.
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(test-group "switch scrutinee"
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(test-assert "member access"
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(emits? "(struct s ((type int))) (fn f ((e (struct s))) void (switch (. e type) (case 1 (g))))"
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"switch (e.type)"))
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(test-assert "call"
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(emits? (in-fn "(switch (g a) (case 1 (h)))")
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"switch (g(a))"))
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(test-assert "arithmetic"
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(emits? (in-fn "(switch (+ a b) (case 1 (h)))")
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"switch (a + b)")))
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;; A cast binds tighter than every binary operator, so an operand
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;; that is itself a binary expression has to be parenthesised --
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;; otherwise the cast silently applies to the first operand only.
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(test-group "cast precedence"
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(test-assert "binary operand is parenthesised"
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(emits? (in-fn "(var p (* void) (cast (* 2 (sizeof int)) (* void)))")
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"(void *)(2 * sizeof(int))"))
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(test-assert "subtraction operand is parenthesised"
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(emits? (in-fn "(var f float (cast (- a b) float))")
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"(float)(a - b)"))
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;; ...but exactly once. The operand used to parenthesise itself
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;; again inside the parens the cast had just added.
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(test-assert "and not parenthesised twice"
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(not (emits? (in-fn "(var f float (cast (- a b) float))")
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"(float)((a - b))")))
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;; Unary operands are already unary-expressions and must be left
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;; alone, or every existing cast in the tree gains noise.
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(test-assert "identifier is left bare"
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(emits? (in-fn "(var f float (cast a float))")
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"(float)a"))
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(test-assert "address-of is left bare"
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(emits? (in-fn "(var p (* int) (cast (& a) (* int)))")
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"(int *)&a"))
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(test-assert "sizeof is left bare"
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(emits? (in-fn "(var n int (cast (sizeof int) int))")
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"(int)sizeof(int)"))))
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