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Aidan Hallaidan-hall
Aidan Hall
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ComputeSideEffects: Compute for functions with effect attributes
After computing side effects, we also remove any global or argument effects that are computed to happen, but are defined not to, based on the effect attribute. This allows us to compute the deinit_barrier effect for such functions, fixing the test case here: rdar://155870190 This supercedes swiftlang#38324.
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3 files changed

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‎SwiftCompilerSources/Sources/Optimizer/FunctionPasses/ComputeSideEffects.swift‎

Lines changed: 82 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -37,43 +37,109 @@ let computeSideEffects = FunctionPass(name: "compute-side-effects") {
3737
return
3838
}
3939

40-
if function.effectAttribute != .none {
41-
// Don't try to infer side effects if there are defined effect attributes.
42-
return
43-
}
44-
4540
var collectedEffects = CollectedEffects(function: function, context)
4641

47-
// First step: collect effects from all instructions.
48-
//
42+
// Collect effects from all instructions.
4943
for block in function.blocks {
5044
for inst in block.instructions {
5145
collectedEffects.addInstructionEffects(inst)
5246
}
5347
}
54-
55-
// Second step: If an argument has unknown uses, we must add all previously collected
56-
// global effects to the argument, because we don't know to which "global" side-effect
57-
// instruction the argument might have escaped.
48+
// If an argument has unknown uses, we must add all previously collected
49+
// global effects to the argument, because we don't know to which "global"
50+
// side-effect instruction the argument might have escaped.
5851
for argument in function.arguments {
5952
collectedEffects.addEffectsForEscapingArgument(argument: argument)
6053
collectedEffects.addEffectsForConsumingArgument(argument: argument)
6154
}
6255

56+
let globalEffects: SideEffects.GlobalEffects
57+
do {
58+
let computed = collectedEffects.globalEffects
59+
60+
// Combine computed global effects with effects defined by the function's effect attribute, if it has one.
61+
62+
// The defined and computed global effects of a function with an effect attribute should be treated as
63+
// worst case global effects of the function.
64+
// This means a global effect should only occur iff it is computed AND defined to occur.
65+
66+
let defined = function.definedGlobalEffects
67+
68+
globalEffects = SideEffects.GlobalEffects(
69+
memory: SideEffects.Memory(read: defined.memory.read && computed.memory.read,
70+
write: defined.memory.write && computed.memory.write),
71+
ownership: SideEffects.Ownership(copy: defined.ownership.copy && computed.ownership.copy,
72+
destroy: defined.ownership.destroy && computed.ownership.destroy),
73+
allocates: defined.allocates && computed.allocates,
74+
isDeinitBarrier: defined.isDeinitBarrier && computed.isDeinitBarrier
75+
)
76+
}
77+
78+
// Obtain the argument effects of the function.
79+
var argumentEffects = collectedEffects.argumentEffects
80+
81+
// `[readnone]` and `[readonly]` functions can still access the value fields
82+
// of their indirect arguments, permitting v** read and write effects. If
83+
// additional read or write effects are computed, we can replace.
84+
switch function.effectAttribute {
85+
case .readNone:
86+
for i in (0..<argumentEffects.count) {
87+
// Even a `[readnone]` function can read from indirect arguments.
88+
if !function.argumentConventions[i].isIndirectIn {
89+
argumentEffects[i].read = nil
90+
} else if argumentEffects[i].read?.mayHaveClassProjection ?? false {
91+
argumentEffects[i].read = SmallProjectionPath(.anyValueFields)
92+
}
93+
94+
// Even a `[readnone]` function can write to indirect results.
95+
if !function.argument(at: i).isIndirectResult {
96+
argumentEffects[i].write = nil
97+
} else if argumentEffects[i].write?.mayHaveClassProjection ?? false {
98+
argumentEffects[i].write = SmallProjectionPath(.anyValueFields)
99+
}
100+
101+
argumentEffects[i].copy = nil
102+
argumentEffects[i].destroy = nil
103+
}
104+
105+
case .readOnly:
106+
for i in (0..<argumentEffects.count) {
107+
// Even a `[readonly]` function can write to indirect results.
108+
if !function.argument(at: i).isIndirectResult {
109+
argumentEffects[i].write = nil
110+
} else if argumentEffects[i].write?.mayHaveClassProjection ?? false {
111+
argumentEffects[i].write = SmallProjectionPath(.anyValueFields)
112+
}
113+
114+
argumentEffects[i].destroy = nil
115+
}
116+
117+
case .releaseNone:
118+
for i in (0..<argumentEffects.count) {
119+
// A `[releasenone]` function can do anything except destroy an argument.
120+
argumentEffects[i].destroy = nil
121+
}
122+
123+
case .none:
124+
// The user makes no additional guarantees about the effects of the function.
125+
break
126+
}
127+
128+
63129
// Don't modify the effects if they didn't change. This avoids sending a change notification
64130
// which can trigger unnecessary other invalidations.
65131
if let existingEffects = function.effects.sideEffects,
66-
existingEffects.arguments == collectedEffects.argumentEffects,
67-
existingEffects.global == collectedEffects.globalEffects {
132+
existingEffects.arguments == argumentEffects,
133+
existingEffects.global == globalEffects {
68134
return
69135
}
70136

71137
// Finally replace the function's side effects.
72138
function.modifyEffects(context) { (effects: inout FunctionEffects) in
73139
let globalEffects = function.isProgramTerminationPoint ?
74-
collectedEffects.globalEffects.forProgramTerminationPoints
75-
: collectedEffects.globalEffects
76-
effects.sideEffects = SideEffects(arguments: collectedEffects.argumentEffects, global: globalEffects)
140+
globalEffects.forProgramTerminationPoints
141+
: globalEffects
142+
effects.sideEffects = SideEffects(arguments: argumentEffects, global: globalEffects)
77143
}
78144
}
79145

‎test/SILOptimizer/side_effects.sil‎

Lines changed: 116 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1281,3 +1281,119 @@ bb0(%0: $any Error):
12811281
%r = tuple ()
12821282
return %r : $()
12831283
}
1284+
1285+
// Base case: @destroy_not_escaped_closure_test. It has every global and argument effect, so we can see which are removed.
1286+
// CHECK-LABEL: sil [readnone] @test_effect_attribute_readnone
1287+
// CHECK-NEXT: [global: copy,deinit_barrier]
1288+
// CHECK-NEXT: {{^[^[]}}
1289+
// CHECK-LABEL: } // end sil function 'test_effect_attribute_readnone'
1290+
sil [readnone] @test_effect_attribute_readnone : $@convention(thin)(@owned @callee_guaranteed () -> ()) -> Builtin.Int1 {
1291+
bb0(%0 : $@callee_guaranteed () -> ()):
1292+
%1 = destroy_not_escaped_closure %0: $@callee_guaranteed () -> ()
1293+
return %1 : $Builtin.Int1
1294+
}
1295+
1296+
// CHECK-LABEL: sil [readonly] @test_effect_attribute_readonly
1297+
// CHECK-NEXT: [%0: read v**.c*.v**, copy v**.c*.v**]
1298+
// CHECK-NEXT: [global: read,copy,deinit_barrier]
1299+
// CHECK-NEXT: {{^[^[]}}
1300+
// CHECK-LABEL: } // end sil function 'test_effect_attribute_readonly'
1301+
sil [readonly] @test_effect_attribute_readonly : $@convention(thin)(@owned @callee_guaranteed () -> ()) -> Builtin.Int1 {
1302+
bb0(%0 : $@callee_guaranteed () -> ()):
1303+
%1 = destroy_not_escaped_closure %0: $@callee_guaranteed () -> ()
1304+
return %1 : $Builtin.Int1
1305+
}
1306+
1307+
// CHECK-LABEL: sil [releasenone] @test_effect_attribute_releasenone
1308+
// CHECK-NEXT: [%0: read v**.c*.v**, write v**.c*.v**, copy v**.c*.v**]
1309+
// CHECK-NEXT: [global: read,write,copy,allocate,deinit_barrier]
1310+
// CHECK-NEXT: {{^[^[]}}
1311+
// CHECK-LABEL: } // end sil function 'test_effect_attribute_releasenone'
1312+
sil [releasenone] @test_effect_attribute_releasenone : $@convention(thin)(@owned @callee_guaranteed () -> ()) -> Builtin.Int1 {
1313+
bb0(%0 : $@callee_guaranteed () -> ()):
1314+
%1 = destroy_not_escaped_closure %0: $@callee_guaranteed () -> ()
1315+
return %1 : $Builtin.Int1
1316+
}
1317+
1318+
// These tests are adapted from the test case in rdar://155870190
1319+
sil @test_effect_attribute_no_barrier : $@convention(thin) () -> () {
1320+
[global: ]
1321+
}
1322+
1323+
sil @test_effect_attribute_barrier : $@convention(thin) () -> () {
1324+
[global: deinit_barrier]
1325+
}
1326+
// CHECK-LABEL: sil [readnone] @test_effect_attribute_call_no_barrier
1327+
// CHECK-NEXT: [global: ]
1328+
// CHECK-NEXT: {{^[^[]}}
1329+
// CHECK-LABEL: } // end sil function 'test_effect_attribute_call_no_barrier'
1330+
sil [readnone] @test_effect_attribute_call_no_barrier : $@convention(thin) () -> @out Any {
1331+
bb0(%0 : $*Any):
1332+
%2 = function_ref @test_effect_attribute_no_barrier : $@convention(thin) () -> ()
1333+
apply %2() : $@convention(thin) () -> ()
1334+
%4 = tuple ()
1335+
return %4
1336+
}
1337+
1338+
// CHECK-LABEL: sil [readnone] @test_effect_attribute_call_barrier
1339+
// CHECK-NEXT: [global: deinit_barrier]
1340+
// CHECK-NEXT: {{^[^[]}}
1341+
// CHECK-LABEL: } // end sil function 'test_effect_attribute_call_barrier'
1342+
sil [readnone] @test_effect_attribute_call_barrier : $@convention(thin) () -> @out Any {
1343+
bb0(%0 : $*Any):
1344+
%2 = function_ref @test_effect_attribute_barrier : $@convention(thin) () -> ()
1345+
apply %2() : $@convention(thin) () -> ()
1346+
%4 = tuple ()
1347+
return %4
1348+
}
1349+
1350+
// The readnone attribute can not rule out reads from indirect arguments.
1351+
// CHECK-LABEL: sil [readnone] @test_effect_attribute_readnone_direct_argument
1352+
// CHECK-NEXT: [global: ]
1353+
// CHECK-NEXT: {{^[^[]}}
1354+
// CHECK-LABEL: } // end sil function 'test_effect_attribute_readnone_direct_argument'
1355+
sil [readnone] @test_effect_attribute_readnone_direct_argument : $@convention(thin) (Int) -> Int {
1356+
bb0(%0 : $Int):
1357+
return %0
1358+
}
1359+
1360+
// CHECK-LABEL: sil [readnone] @test_effect_attribute_readnone_indirect_argument
1361+
// CHECK-NEXT: [%0: read v**]
1362+
// CHECK-NEXT: [global: ]
1363+
// CHECK-NEXT: {{^[^[]}}
1364+
// CHECK-LABEL: } // end sil function 'test_effect_attribute_readnone_indirect_argument'
1365+
sil [readnone] @test_effect_attribute_readnone_indirect_argument : $@convention(thin) (@in Int) -> Int {
1366+
bb0(%0 : $*Int):
1367+
%1 = load %0
1368+
return %1
1369+
}
1370+
1371+
// Base case: @retain_and_store. The indirect result has a write effect, which readnone & readonly can't rule out.
1372+
// CHECK-LABEL: sil [readnone] @test_effect_attribute_readnone_indirect_result
1373+
// CHECK-NEXT: [%0: write v**]
1374+
// CHECK-NEXT: [global: ]
1375+
// CHECK-NEXT: {{^[^[]}}
1376+
// CHECK-LABEL: } // end sil function 'test_effect_attribute_readnone_indirect_result'
1377+
sil [readnone] @test_effect_attribute_readnone_indirect_result : $@convention(thin) (@guaranteed X) -> @out X {
1378+
bb0(%0 : $*X, %1 : $X):
1379+
strong_retain %1 : $X
1380+
store %1 to %0 : $*X
1381+
1382+
%r = tuple ()
1383+
return %r : $()
1384+
}
1385+
1386+
// CHECK-LABEL: sil [readonly] @test_effect_attribute_readonly_indirect_result
1387+
// CHECK-NEXT: [%0: write v**]
1388+
// CHECK-NEXT: [%1: copy v**]
1389+
// CHECK-NEXT: [global: ]
1390+
// CHECK-NEXT: {{^[^[]}}
1391+
// CHECK-LABEL: } // end sil function 'test_effect_attribute_readonly_indirect_result'
1392+
sil [readonly] @test_effect_attribute_readonly_indirect_result : $@convention(thin) (@guaranteed X) -> @out X {
1393+
bb0(%0 : $*X, %1 : $X):
1394+
strong_retain %1 : $X
1395+
store %1 to %0 : $*X
1396+
1397+
%r = tuple ()
1398+
return %r : $()
1399+
}

‎test/SILOptimizer/templvalueopt_ossa.sil‎

Lines changed: 33 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -336,6 +336,39 @@ bb0(%0 : @guaranteed $Any, %1 : $*Any):
336336
return %11 : $()
337337
}
338338

339+
sil [readnone] @createAny_effects : $@convention(thin) () -> @out Any
340+
sil [readnone] @createAny_no_barrier_effects : $@convention(thin) () -> @out Any {
341+
[global:]
342+
}
343+
344+
// CHECK-LABEL: sil [ossa] @test_deinit_barrier_effects :
345+
// CHECK: copy_addr [take]
346+
// CHECK-LABEL: } // end sil function 'test_deinit_barrier_effects'
347+
sil [ossa] @test_deinit_barrier_effects : $@convention(thin) (@guaranteed Any, @inout Any) -> () {
348+
bb0(%0 : @guaranteed $Any, %1 : $*Any):
349+
%2 = alloc_stack $Any
350+
%4 = function_ref @createAny_effects : $@convention(thin) () -> @out Any
351+
%5 = apply %4(%2) : $@convention(thin) () -> @out Any
352+
copy_addr [take] %2 to %1 : $*Any
353+
dealloc_stack %2 : $*Any
354+
%11 = tuple ()
355+
return %11 : $()
356+
}
357+
358+
// CHECK-LABEL: sil [ossa] @test_no_deinit_barrier_effects :
359+
// CHECK-NOT: copy_addr
360+
// CHECK-LABEL: } // end sil function 'test_no_deinit_barrier_effects'
361+
sil [ossa] @test_no_deinit_barrier_effects : $@convention(thin) (@guaranteed Any, @inout Any) -> () {
362+
bb0(%0 : @guaranteed $Any, %1 : $*Any):
363+
%2 = alloc_stack $Any
364+
%4 = function_ref @createAny_no_barrier_effects : $@convention(thin) () -> @out Any
365+
%5 = apply %4(%2) : $@convention(thin) () -> @out Any
366+
copy_addr [take] %2 to %1 : $*Any
367+
dealloc_stack %2 : $*Any
368+
%11 = tuple ()
369+
return %11 : $()
370+
}
371+
339372
struct TwoFields {
340373
var a: Child
341374
var b: Child

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