[PATCH] D103096: [analyzer] Implement cast for ranges of symbolic integers

[Denys Petrov via Phabricator via cfe-commits]

ASDenysPetrov marked 10 inline comments as done.
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@martong Thank you for your patience. I started moving to a bit another direction that we can improving it iteratively.
Just spoiling, in my latest solution a single symbol will be associated to many classes. Here are also tricky cases:

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Consider equalities

  a32 == (int8)b32
  b32 == c32

Class-Symbol map is:

  class1 { a32 , (int8)b32 }
  class2 { b32 , c32 }

Symbol-Class map is:

  a32 { 32 : class1 }
  b32 {  8 : class1, 32 : class2  }
  c32 { 32 : class2 }

If we know:

  (int8)c32 == -1

then what is:

  (int8)a32 - ?

Should we traverse like `a ->  32 -> class1 -> (int8)b32 -> b32 ->  class2 -> c32 -> (int8)c32 ` ?

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The `x8 == y32` we can treat as a range of `int8` ( {-128, 127} or  {0, 255} ).

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For `(int8)x32 == (int16)x32` we can eliminate one of the symbols in the class a s a redundant one.

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If `x32 == 0` then we can simplify(merge) such classes `(int16)x32 == y` and `(int8)x32 == z` into a single class. I beleive there are more cases.


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