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GenericSpecializer: Allow simple function specialization cycles. #17885

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Merged
merged 2 commits into from
Jul 12, 2018
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GenericSpecializer: Allow simple function specialization cycles. #17885

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0cde468
tests: Fix test for detecting generic specialization explosions.
eeckstein Jul 11, 2018
1ebe33e
GenericSpecializer: Allow simple function specialization cycles.
eeckstein Jul 11, 2018
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9 changes: 8 additions & 1 deletion lib/SILOptimizer/Utils/Generics.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -288,6 +288,7 @@ static bool createsInfiniteSpecializationLoop(ApplySite Apply) {
auto *Callee = Apply.getCalleeFunction();
SILFunction *Caller = nullptr;
Caller = Apply.getFunction();
int numAcceptedCycles = 1;

// Name of the function to be specialized.
auto GenericFunc = Callee;
Expand Down Expand Up @@ -327,7 +328,13 @@ static bool createsInfiniteSpecializationLoop(ApplySite Apply) {
if (growingSubstitutions(CurSpecializationInfo->getSubstitutions(),
Apply.getSubstitutionMap())) {
DEBUG(llvm::dbgs() << "Found a generic specialization loop!\n");
return true;

// Accept a cycles up to a limit. This is necessary to generate
// efficient code for some library functions, like compactMap, which
// contain small specialization cycles.
if (numAcceptedCycles == 0)
return true;
numAcceptedCycles--;
}
}

Expand Down
6 changes: 3 additions & 3 deletions test/SILOptimizer/generic_specialization_loops_detection_with_loops.swift
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Expand Up @@ -21,16 +21,16 @@

// Check that the compiler has produced a specialization information for a call-site that
// was inlined from a specialized generic function.
// CHECK-LABEL: // Generic specialization information for call-site $S044generic_specialization_loops_detection_with_C04foo4yyx_q_tr0_lF <Array<Int>, Array<Double>>
// CHECK-LABEL: // Generic specialization information for call-site $S044generic_specialization_loops_detection_with_C04foo4yyx_q_tr0_lFSaySays5UInt8VGG_SaySaySiGGTg5:
// CHECK-NEXT: // Caller: $S044generic_specialization_loops_detection_with_C04foo4yyx_q_tr0_lFSi_SdTg5
// CHECK-NEXT: // Parent: $S044generic_specialization_loops_detection_with_C04bar4yyx_q_tr0_lF
// CHECK-NEXT: // Substitutions: <Int, Double>
// CHECK-NEXT: // Substitutions: <Array<UInt8>, Array<Int>>
// CHECK-NEXT: //
// CHECK-NEXT: // Caller: $S044generic_specialization_loops_detection_with_C011testFooBar4yyF
// CHECK-NEXT: // Parent: $S044generic_specialization_loops_detection_with_C04foo4yyx_q_tr0_lF
// CHECK-NEXT: // Substitutions: <Int, Double>
// CHECK-NEXT: //
// CHECK-NEXT: apply %{{[0-9]+}}<Array<Int>, Array<Double>>
// CHECK-NEXT: apply %{{.*}}Array<Array<UInt8>>

// Check specializations of mutually recursive functions which
// may result in an infinite specialization loop.
Expand Down
16 changes: 8 additions & 8 deletions test/SILOptimizer/generic_specialization_loops_detection_without_loops.swift
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Expand Up @@ -137,13 +137,13 @@ func flood2<T>(_ x: T) {
@inline(never)
public func run_TypeFlood(_ N: Int) {
for _ in 1...N {
flood3(Some1<Some1<Some1<Int>>>())
flood3(Some1<Some1<Some0<Int>>>())
flood3(Some1<Some0<Some1<Int>>>())
flood3(Some1<Some0<Some0<Int>>>())
flood3(Some0<Some1<Some1<Int>>>())
flood3(Some0<Some1<Some0<Int>>>())
flood3(Some0<Some0<Some1<Int>>>())
flood3(Some0<Some0<Some0<Int>>>())
flood2(Some1<Some1<Some1<Int>>>())
flood2(Some1<Some1<Some0<Int>>>())
flood2(Some1<Some0<Some1<Int>>>())
flood2(Some1<Some0<Some0<Int>>>())
flood2(Some0<Some1<Some1<Int>>>())
flood2(Some0<Some1<Some0<Int>>>())
flood2(Some0<Some0<Some1<Int>>>())
flood2(Some0<Some0<Some0<Int>>>())
}
}