Andrew Trick 6befb10d35 Cache struct/class field offsets in SIL. ...

The field's ordinal value is used by the Projection abstraction, which is
the basis of efficiently comparing and sorting access paths in SIL. It must
be cached before it is used by any SIL passes, including the verifier, or it
causes widespread quadratic complexity.

Fixes <rdar://problem/50353228> Swift compile time regression with optimizations enabled

In production code, a file that was taking 40 minutes to compile now
takes 1 minute, with more than half of the time in LLVM.

Here's a short script that reproduces the problem. It used to take 30s
and now takes 0.06s:

// swift genlazyinit.swift > lazyinit.sil
// sil-opt ./lazyinit.sil --access-enforcement-opts

var NumProperties = 300

print("""
      sil_stage canonical

      import Builtin
      import Swift
      import SwiftShims

      public class LazyProperties {
      """)

for i in 0..<NumProperties {
  print("""
          //  public lazy var i\(i): Int { get set }
          @_hasStorage @_hasInitialValue final var __lazy_storage__i\(i): Int? { get set }
        """)
}

print("""
      }

     // LazyProperties.init()
     sil @$s4lazy14LazyPropertiesCACycfc : $@convention(method) (@owned LazyProperties) -> @owned LazyProperties {
     bb0(%0 : $LazyProperties):
       %enum = enum $Optional<Int>, #Optional.none!enumelt
     """)

for i in 0..<NumProperties {
  let adr = (i*4) + 2
  let access = adr + 1
  print("""
          %\(adr) = ref_element_addr %0 : $LazyProperties, #LazyProperties.__lazy_storage__i\(i)
          %\(access) = begin_access [modify] [dynamic] %\(adr) : $*Optional<Int>
          store %enum to %\(access) : $*Optional<Int>
          end_access %\(access) : $*Optional<Int>
        """)
}

print("""
        return %0 : $LazyProperties
      } // end sil function '$s4lazy14LazyPropertiesCACycfc'
      """)

2019-05-13 16:54:55 -07:00

101 KiB

Raw Blame History

View Raw