| commit | bf8c7d6edf224c083c90ab3ddac49979ac18ad39 | |
| author | Matthew Pickering <matthewtpickering@gmail.com> | |
| Tue, 28 Jan 2025 14:59:15 +0000 (28 14:59 +0000) | ||
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | |
| Wed, 29 Jan 2025 07:31:44 +0000 (29 02:31 -0500) | ||
| tree | d3f697bb65be315144fbaf6d142b120315b07c88 | treesnapshot (tar.gz zip) |
| parent | 8847125fecdccc4dcda45b1dba519c6dd88b4401 | commitdiff |
bytecode: Do not generate `SLIDE x 0` instructions
SLIDE x 0 is a no-op as it means to shift x elements of the stack by no
spaces. In the interpreter, this results in a loop which copies an array
element into the same place.
I have instrumented GHCi to count how many of these instructions are interpreted.
The workload was `ghc` compiling two simple modules.
Total no-op slides: 7793476
Total slides: 11413289
Percentage useless (slides): 68%
Percentage uselss of total instructions: 9%
SLIDE x 0 is a no-op as it means to shift x elements of the stack by no
spaces. In the interpreter, this results in a loop which copies an array
element into the same place.
I have instrumented GHCi to count how many of these instructions are interpreted.
The workload was `ghc` compiling two simple modules.
Total no-op slides: 7793476
Total slides: 11413289
Percentage useless (slides): 68%
Percentage uselss of total instructions: 9%
| compiler/GHC/StgToByteCode.hs | diffblobblamehistory |