aliases

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Simple alias analysis for the HLO and the code generators.

Imports

ast, astalgo, types, trees

Types

TAnalysisResult = enum
  arNo, arMaybe, arYes

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Procs

proc isPartOf(a, b: PNode): TAnalysisResult {.
    ...raises: [KeyError, Exception, ERecoverableError], tags: [RootEffect],
    forbids: [].}

checks if location a can be part of location b. We treat seqs and strings as pointers because the code gen often just passes them as such.

Note: a can only be part of b, if a's type can be part of b's type. Since however type analysis is more expensive, we perform it only if necessary.

cases:

YES-cases:

x    <| x   # for general trees
x[]  <| x
x[i] <| x
x.f  <| x

NO-cases:

x           !<| y    # depending on type and symbol kind
x[constA]   !<| x[constB]
x.f         !<| x.g
x.f         !<| y.f  iff x !<= y

MAYBE-cases:

x[] ?<| y[]   iff compatible type


x[]  ?<| y  depending on type

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