33 lines
1.5 KiB
TeX
33 lines
1.5 KiB
TeX
Example of a simple compiler pass for each problem, which makes that problem obvious
|
|
|
|
Big passes:
|
|
* null as default and absent
|
|
* inter-dependency between pieces of code which generate certain information
|
|
|
|
Graph manipulation:
|
|
* fail to update a reference to an updated element
|
|
* or issues with identity (e.g. Mono.Cecil bug)
|
|
* lookup of a key which does not exist anymore, because the node was deleted in the meantime.
|
|
|
|
Unit tests:
|
|
* Write a test for an instruction transformation (unary negation to binary subtraction), show that it requires a class, method, main method etc.
|
|
|
|
Graph construction:
|
|
* languages with mutation:
|
|
* purely functional language: promises have to be forced, or explicit lookups
|
|
* argue that purely functional languages make GC easy to design, parallelize more easily, type system easier to design and more flexible (monomorphism restriction), but lazy languages are harder to debug.
|
|
|
|
Generic graph algorithms
|
|
* depth-first search, aggregates information from nodes of two different types: show how you have to re-write it if your data structure changes a bit
|
|
* or SCC (has_cycles), where some links matter but some don't
|
|
|
|
Structural constraints
|
|
* compute the in-memory size of a C structure: should not have any cycles
|
|
* off-by-one when updating the number of references to an element
|
|
* PHOAS
|
|
|
|
|
|
|
|
Downsides
|
|
* $\alpha$-renaming: problematic, since there is no declaration / use of fields anymore.
|
|
=> IDE solution: keep track of which pass introduces which field. |