mirror of
https://github.com/apple/swift.git
synced 2025-12-14 20:36:38 +01:00
f9b524b1cb
The main changes are: *) Rewrite everything in swift. So far, parts of memory-behavior analysis were already implemented in swift. Now everything is done in swift and lives in `AliasAnalysis.swift`. This is a big code simplification. *) Support many more instructions in the memory-behavior analysis - especially OSSA instructions, like `begin_borrow`, `end_borrow`, `store_borrow`, `load_borrow`. The computation of end_borrow effects is now much more precise. Also, partial_apply is now handled more precisely. *) Simplify and reduce type-based alias analysis (TBAA). The complexity of the old TBAA comes from old days where the language and SIL didn't have strict aliasing and exclusivity rules (e.g. for inout arguments). Now TBAA is only needed for code using unsafe pointers. The new TBAA handles this - and not more. Note that TBAA for classes is already done in `AccessBase.isDistinct`. *) Handle aliasing in `begin_access [modify]` scopes. We already supported truly immutable scopes like `begin_access [read]` or `ref_element_addr [immutable]`. For `begin_access [modify]` we know that there are no other reads or writes to the access-address within the scope. *) Don't cache memory-behavior results. It turned out that the hit-miss rate was pretty bad (~ 1:7). The overhead of the cache lookup took as long as recomputing the memory behavior.
61 lines
1.8 KiB
Swift
61 lines
1.8 KiB
Swift
//===--- AliasInfoDumper.swift --------------------------------------------===//
|
|
//
|
|
// This source file is part of the Swift.org open source project
|
|
//
|
|
// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
|
|
// Licensed under Apache License v2.0 with Runtime Library Exception
|
|
//
|
|
// See https://swift.org/LICENSE.txt for license information
|
|
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
import SIL
|
|
|
|
/// Prints the memory behavior of relevant instructions in relation to address values of the function.
|
|
let aliasInfoDumper = FunctionPass(name: "dump-alias-info") {
|
|
(function: Function, context: FunctionPassContext) in
|
|
|
|
let aliasAnalysis = context.aliasAnalysis
|
|
|
|
print("@\(function.name)")
|
|
|
|
let values = function.allValues
|
|
|
|
var pair = 0
|
|
for (index1, value1) in values.enumerated() {
|
|
for (index2, value2) in values.enumerated() {
|
|
if index2 >= index1 {
|
|
let result = aliasAnalysis.mayAlias(value1, value2)
|
|
precondition(result == aliasAnalysis.mayAlias(value2, value1), "alias analysis not symmetric")
|
|
|
|
print("PAIR #\(pair).")
|
|
print(" \(value1)")
|
|
print(" \(value2)")
|
|
if result {
|
|
print(" MayAlias")
|
|
} else if !value1.uses.isEmpty && !value2.uses.isEmpty {
|
|
print(" NoAlias")
|
|
} else {
|
|
print(" noalias?")
|
|
}
|
|
|
|
pair += 1
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
private extension Function {
|
|
var allValues: [Value] {
|
|
var values: [Value] = []
|
|
for block in blocks {
|
|
values.append(contentsOf: block.arguments.map { $0 })
|
|
for inst in block.instructions {
|
|
values.append(contentsOf: inst.results)
|
|
}
|
|
}
|
|
return values
|
|
}
|
|
}
|