wanted: document %SAP-ALIEN runtime allocation compiler notes
Bug #495044 reported by
Tobias C. Rittweiler
This bug affects 2 people
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| SBCL |
Confirmed
|
Wishlist
|
Unassigned | ||
Bug Description
(defun open-directory-1 (directory)
(declare (optimize (speed 0)))
(sb-posix:opendir directory)) ; => NO note
(defun open-directory-2 (directory)
(declare (optimize (speed 1)))
(sb-posix:opendir directory)) ; => note
I found it a tad bit surprising to see that note being emitted even for
normal SPEED settings.
However the DEFTRANSFORM for %SAP-ALIEN in src/compiler/
specifies :IMPORTANT T -- so I guess this is done on purpose.
So this probably is not a bug, but I'd hope that someone adds an explanation
in a comment, and mark this report as "Invalid" -- so we can later point other
people to it.
Revision history for this message
| Nikodemus Siivola (nikodemus) wrote Re: [Bug 495044] [NEW] "could not optimize away %SAP-ALIEN: forced to do runtime allocation" note even with (SPEED 1) | #1 |
| summary: |
- "could not optimize away %SAP-ALIEN: forced to do runtime allocation" - note even with (SPEED 1) + wanted: document %SAP-ALIEN runtime allocation compiler notes |
| Changed in sbcl: | |
| importance: | Undecided → Wishlist |
| status: | New → Confirmed |
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status confirmed
tag alien compiler documentation
importance wishlist
summary "wanted: document %SAP-ALIEN runtime allocation compiler notes"
:IMPORTANT transforms complain if they cannot be applied unless SPEED is 0.
This particular ones is :IMPORTANT because if it fails alien code
becomes approximately 100 times slower. Not just "you don't get
optimum performance", but _really_ slow compared to what one would
normally expect.
Instead of pointing people at replies like this we should rather
update documentation -- including how to fix these notes when they
slow your code down to crawl.