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Fix MarkDependenceInst.simplify()

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Do not eliminate a mark_dependence on a begin_apply scope even though the token
has a trivial type.

Ideally, token would have a non-trivial Builtin type to avoid special cases.
This commit is contained in:
Andrew Trick
2025-06-22 15:56:14 -07:00
parent 7a29d9d8b6
commit a8da66a82e
2 changed files with 40 additions and 3 deletions
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6
SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyMarkDependence.swift
View File

@@ -42,9 +42,13 @@ extension MarkDependenceAddrInst : OnoneSimplifiable, SILCombineSimplifiable {
private extension MarkDependenceInstruction {
var isRedundant: Bool {
if base.type.isObject && base.type.isTrivial(in: base.parentFunction) {
if base.type.isObject && base.type.isTrivial(in: base.parentFunction)
&& !(base.definingInstruction is BeginApplyInst) {
// Sometimes due to specialization/builtins, we can get a mark_dependence whose base is a trivial
// typed object. Trivial values live forever. Therefore the mark_dependence does not have a meaning.
// begin_apply is a special case. A dependency on the token is limited to the coroutine scope (ideally, the token
// would have a non-trivial type like $Builtin.Token).
//
// Note: the mark_dependence is still needed for lifetime diagnostics. So it's important that this
// simplification does not run before the lifetime diagnostic pass.
return true

37
test/SILOptimizer/simplify_mark_dependence.sil
View File

@@ -1,6 +1,6 @@
// RUN: %target-sil-opt %s -onone-simplification -simplify-instruction=mark_dependence -enable-experimental-feature LifetimeDependence | %FileCheck %s
// RUN: %target-sil-opt %s -onone-simplification -simplify-instruction=mark_dependence -enable-experimental-feature Lifetimes | %FileCheck %s
// REQUIRES: swift_feature_LifetimeDependence
// REQUIRES: swift_feature_Lifetimes
import Swift
import Builtin
@@ -14,10 +14,20 @@ struct S {
struct NE: ~Escapable {}
struct NEHolder : ~Escapable {
var ne: NE {
@_lifetime(borrow self)
get
}
}
struct S2: ~Escapable {
var a: NE
}
sil @read_ne : $@yield_once @convention(method) (@guaranteed NEHolder) -> @lifetime(borrow 0) @yields @guaranteed NE
sil @use_ne : $@convention(thin) (@guaranteed NE) -> ()
// CHECK-LABEL: sil [ossa] @mark_dependence_trivial_base :
// CHECK: %2 = copy_value %0
// CHECK-NEXT: return %2
@@ -155,3 +165,26 @@ bb0(%0 : $*Builtin.Int64, %1 : $B):
return %5
}
// CHECK-LABEL: sil hidden [ossa] @testChainedDependence : $@convention(thin) (@guaranteed NEHolder) -> () {
// CHECK: bb0(%0 : @noImplicitCopy @guaranteed $NEHolder):
// CHECK: ([[YIELD:%[0-9]+]], [[TOKEN:%[0-9]+]]) = begin_apply %{{.*}}(%{{.*}}) : $@yield_once @convention(method) (@guaranteed NEHolder) -> @lifetime(borrow 0) @yields @guaranteed NE
// CHECK: [[MD1:%[0-9]+]] = mark_dependence [nonescaping] [[YIELD]] on [[TOKEN]]
// CHECK: mark_dependence [nonescaping] [[MD1]] on
// CHECK-LABEL: } // end sil function 'testChainedDependence'
sil hidden [ossa] @testChainedDependence : $@convention(thin) (@guaranteed NEHolder) -> () {
bb0(%0 : @noImplicitCopy @guaranteed $NEHolder):
%2 = begin_borrow %0
%3 = function_ref @read_ne : $@yield_once @convention(method) (@guaranteed NEHolder) -> @lifetime(borrow 0) @yields @guaranteed NE
(%4, %5) = begin_apply %3(%2) : $@yield_once @convention(method) (@guaranteed NEHolder) -> @lifetime(borrow 0) @yields @guaranteed NE
%6 = mark_dependence [nonescaping] %4 on %5
%7 = mark_dependence [nonescaping] %6 on %2
%8 = copy_value %7
%9 = move_value [var_decl] %8
%11 = function_ref @use_ne : $@convention(thin) (@guaranteed NE) -> ()
%12 = apply %11(%9) : $@convention(thin) (@guaranteed NE) -> ()
destroy_value %9
%14 = end_apply %5 as $()
end_borrow %2
%16 = tuple ()
return %16
}