remove useless loop in a function body
Bug #554190 reported by
Roman Marynchak
This bug affects 1 person
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| SBCL |
Confirmed
|
Wishlist
|
Unassigned | ||
Bug Description
I cannot imagine the simpler example than this one:
(defun completely-useless ()
(loop for i from 1 to 10000000000 do (= 1 1)))
However, it does iterates in that loop... Is there some misunderstanding from my side, or SBCL just gives up any loop optimizations? I will not even try more complex examples from the famous book "Optimizing Compilers for Modern Architectures: A Dependence-based Approach", since they require more advanced loop analysis logic in the compiler than SBCL seems to have these days.
Regards,
Roman
Revision history for this message
| Nathan Froyd (froydnj) wrote | #1 |
| Changed in sbcl: | |
| importance: | Undecided → Wishlist |
| tags: | added: optimization |
| Changed in sbcl: | |
| status: | New → Confirmed |
Revision history for this message
| Nikodemus Siivola (nikodemus) wrote | #2 |
| summary: |
- SBCL fails to remove the simplest useless loop in a function body + remove useless loop in a function body |
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SBCL does not do any classic loop optimizations (e.g. unrolling), let alone any of the higher-level transforms described in Allen and Kennedy.