Function inlining

Stream: general

[Carbon]

What is the difference between always_inline, and inline in function definitions?

[Kyle Miller]

It looks like the only difference is that one day inline might be conditional on some sort of quota.

docs#Lean.Compiler.LCNF.Simp.inlineCandidate?

      if decl.alwaysInlineAttr then return true
      -- TODO: check inlining quota
      if decl.inlineAttr || decl.inlineIfReduceAttr then return true

[Eric Wieser]

That sounds quite hard to implement correctly, since mismatching inline attributes were the cause of a performance bug here

[Henrik Böving]

Kyle Miller said:

It looks like the only difference is that one day inline might be conditional on some sort of quota.

docs#Lean.Compiler.LCNF.Simp.inlineCandidate?

      if decl.alwaysInlineAttr then return true
      -- TODO: check inlining quota
      if decl.inlineAttr || decl.inlineIfReduceAttr then return true

Note that you are looking at new compiler code, this is not the logic that is currently implemented

[Kyle Miller]

Do you know what the current logic is @Henrik Böving ?

[Henrik Böving]

It's somewhere in the C++ part of the old compiler but I don't know by heart hwere