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Fix a miscompile in existential specialization during SILCombine. #41344

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Merged
merged 1 commit into from
Feb 12, 2022
Merged

Fix a miscompile in existential specialization during SILCombine. #41344

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5 changes: 5 additions & 0 deletions include/swift/SIL/SILInstruction.h
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Original file line number Diff line number Diff line change
Expand Up @@ -6814,6 +6814,11 @@ class OpenExistentialAddrInst
SILType SelfTy, OpenedExistentialAccess AccessKind);

public:
static bool isRead(SILInstruction *inst) {
auto *open = dyn_cast<OpenExistentialAddrInst>(inst);
return open && open->getAccessKind() == OpenedExistentialAccess::Immutable;
}

OpenedExistentialAccess getAccessKind() const { return ForAccess; }
};

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2 changes: 1 addition & 1 deletion lib/SILOptimizer/Utils/Existential.cpp
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Expand Up @@ -90,7 +90,7 @@ static SILInstruction *getStackInitInst(SILValue allocStackAddr,
DebugValueInst::hasAddrVal(User) ||
isa<DestroyAddrInst>(User) || isa<WitnessMethodInst>(User) ||
isa<DeinitExistentialAddrInst>(User) ||
isa<OpenExistentialAddrInst>(User) || User == ASIUser) {
OpenExistentialAddrInst::isRead(User) || User == ASIUser) {
continue;
}
if (auto *CAI = dyn_cast<CopyAddrInst>(User)) {
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61 changes: 61 additions & 0 deletions test/SILOptimizer/sil_combine_concrete_existential.sil
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Expand Up @@ -721,6 +721,67 @@ bb3(%20 : $Error):
throw %20 : $Error
}

// -----------------------------------------------------------------------------
// rdar://88664423 (SR-15791: Miscompile under -O with mutating protocol method)
//
// Basic outline (test case has more copies):
// %1 = alloc_stack $PPP
// %2 = init_existential %1
// %3 = open_existential_addr mutable_access %1
// apply mutatingFunc(%3)
// %5 = open_existential_addr %1
// %6 = alloc_stack $@opened P
// copy_addr %5 to [initialization] %6 : $*@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP
// apply callee3(%5)
//
// When ConcreteExistentialInfo identified the initialization of:
// %4 = alloc_stack [lexical] $PPP, var, name "mergedCommand"
//
// It checks for any mutation other than the initialization itself.
// In this case, `open_existential_addr mutable_access` must be
// considered a possible mutation of the on-stack value.

sil @mutatingFunc : $@convention(method) (@inout S) -> ()

sil @callee3 : $@convention(thin) <τ_0_0 where τ_0_0 : PPP> (@in τ_0_0) -> ()

// CHECK-LABEL: sil @testMutatingCopiedOpenExistential : $@convention(thin) (S) -> () {
// CHECK: bb0(%0 : $S):
// CHECK: [[EXISCP:%.*]] = alloc_stack [lexical] $PPP, var, name "mergedCommand"
// CHECK: apply %{{.*}} : $@convention(method) (@inout S) -> ()
// CHECK: [[OPENED:%.*]] = open_existential_addr mutable_access [[EXISCP]] : $*PPP to $*@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP
// CHECK: [[OPENEDCP:%.*]] = alloc_stack $@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP
// CHECK: copy_addr [[OPENED]] to [initialization] [[OPENEDCP]] : $*@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP
// CHECK: [[CALLEE3:%.*]] = function_ref @callee3 : $@convention(thin) <τ_0_0 where τ_0_0 : PPP> (@in τ_0_0) -> ()
// CHECK: apply [[CALLEE3]]<@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP>([[OPENEDCP]]) : $@convention(thin) <τ_0_0 where τ_0_0 : PPP> (@in τ_0_0) -> ()
// CHECK-LABEL: } // end sil function 'testMutatingCopiedOpenExistential'
sil @testMutatingCopiedOpenExistential : $@convention(thin) (S) -> () {
bb0(%0 : $S):
%1 = alloc_stack $PPP
%2 = init_existential_addr %1 : $*PPP, $S
store %0 to %2 : $*S
%4 = alloc_stack [lexical] $PPP, var, name "mergedCommand"
copy_addr %1 to [initialization] %4 : $*PPP
%6 = open_existential_addr mutable_access %4 : $*PPP to $*@opened("3818BC52-89A1-11EC-999A-D0817AD9985D") PPP
%7 = unchecked_addr_cast %6 : $*@opened("3818BC52-89A1-11EC-999A-D0817AD9985D") PPP to $*S

%8 = function_ref @mutatingFunc : $@convention(method) (@inout S) -> ()
%9 = apply %8(%7) : $@convention(method) (@inout S) -> ()
%10 = open_existential_addr mutable_access %4 : $*PPP to $*@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP
%11 = alloc_stack $@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP
copy_addr %10 to [initialization] %11 : $*@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP

%13 = function_ref @callee3 : $@convention(thin) <τ_0_0 where τ_0_0 : PPP> (@in τ_0_0) -> ()
%14 = apply %13<@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP>(%11) : $@convention(thin) <τ_0_0 where τ_0_0 : PPP> (@in τ_0_0) -> ()
dealloc_stack %11 : $*@opened("381F6B6A-89A1-11EC-999A-D0817AD9985D") PPP
destroy_addr %4 : $*PPP
dealloc_stack %4 : $*PPP
destroy_addr %1 : $*PPP
dealloc_stack %1 : $*PPP
%20 = tuple ()
return %20 : $()
}

sil_vtable SubscriptionViewControllerBuilder {}
sil_vtable SubscriptionViewController {}
sil_vtable ViewController {}
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