#8279: bad alignment in code gen yields substantial perf issue --------------------------------------------+------------------------------ Reporter: carter | Owner: Type: bug | Status: new Priority: highest | Milestone: Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime performance bug | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: #8082 --------------------------------------------+------------------------------ Comment (by simonmar): So the problem with 16-byte aligning branch targets is that many of our code blocks have a 3-word info table. We would have to pad these info tables by one word in addition to aligning to 16 bytes. That might not be too bad, but someone needs to do the measurements to see what the code size / speed tradeoff is. Also we don't necessarily want to align all our labels, because many of them are just heap-check failure targets and wouldn't benefit from aligning at all. I tend to optimise for small binary sizes because I was brought up on computers with 32K of memory and I think you should never waste a byte :-) If you think binary size can be won elsewhere, please do it :-P -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8279#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler