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SideEffectAnalysis: don't assume that arguments with trivial type can not be pointers. #34289

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Merged
merged 1 commit into from
Oct 13, 2020
Merged

SideEffectAnalysis: don't assume that arguments with trivial type can not be pointers. #34289

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8 changes: 2 additions & 6 deletions lib/SILOptimizer/Analysis/MemoryBehavior.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -215,11 +215,7 @@ class MemoryBehaviorVisitor
SIMPLE_MEMBEHAVIOR_INST(CondFailInst, None)
#undef SIMPLE_MEMBEHAVIOR_INST

// If we are asked to treat ref count increments as being inert, return None
// for these.
//
// FIXME: Once we separate the notion of ref counts from reading/writing
// memory this will be unnecessary.
// Incrementing reference counts doesn't have an observable memory effect.
#define REFCOUNTINC_MEMBEHAVIOR_INST(Name) \
MemBehavior visit##Name(Name *I) { \
return MemBehavior::None; \
Expand Down Expand Up @@ -455,7 +451,7 @@ MemBehavior MemoryBehaviorVisitor::getApplyBehavior(FullApplySite AS) {
behavior = MemBehavior::MayRead;

// Ask escape analysis.
if (!nonEscapingAddress && !EA->canEscapeTo(V, AS))
if (!EA->canEscapeTo(V, AS))
behavior = MemBehavior::None;
}
LLVM_DEBUG(llvm::dbgs() << " Found apply, returning " << behavior << '\n');
Expand Down
5 changes: 0 additions & 5 deletions lib/SILOptimizer/Analysis/SideEffectAnalysis.cpp
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Expand Up @@ -222,11 +222,6 @@ FunctionSideEffects::getMemBehavior(RetainObserveKind ScanKind) const {
MemoryBehavior
FunctionSideEffects::getArgumentBehavior(FullApplySite applySite,
unsigned argIdx) {
// Rule out trivial non-address argument types.
SILType argType = applySite.getArgument(argIdx)->getType();
if (!argType.isAddress() && argType.isTrivial(*applySite.getFunction()))
return MemoryBehavior::None;

// The overall argument effect is the combination of the argument and the
// global effects.
MemoryBehavior behavior =
Expand Down
22 changes: 22 additions & 0 deletions test/SILOptimizer/dead_store_elim.sil
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Expand Up @@ -469,6 +469,28 @@ bb3:
return %9999 : $()
}

sil @read_from_raw_pointer : $@convention(thin) (Builtin.RawPointer) -> UInt8 {
bb0(%0 : $Builtin.RawPointer):
%1 = pointer_to_address %0 : $Builtin.RawPointer to [strict] $*UInt8
%2 = load %1 : $*UInt8
return %2 : $UInt8
}

// CHECK-LABEL: sil @dont_remove_store_to_escaping_allocstack_to_known_function : $@convention(thin) (UInt8) -> UInt8
// CHECK: alloc_stack
// CHECK-NEXT: store
// CHECK: } // end sil function 'dont_remove_store_to_escaping_allocstack_to_known_function'
sil @dont_remove_store_to_escaping_allocstack_to_known_function : $@convention(thin) (UInt8) -> UInt8 {
bb0(%0 : $UInt8):
%1 = alloc_stack $UInt8
store %0 to %1 : $*UInt8
%3 = address_to_pointer %1 : $*UInt8 to $Builtin.RawPointer
%4 = function_ref @read_from_raw_pointer : $@convention(thin) (Builtin.RawPointer) -> UInt8
%5 = apply %4(%3) : $@convention(thin) (Builtin.RawPointer) -> UInt8
dealloc_stack %1 : $*UInt8
return %5 : $UInt8
}

sil @unknown : $@convention(thin) () -> ()

// CHECK-LABEL: sil @inout_is_not_aliasing : $@convention(thin) (@inout Builtin.Int32) -> () {
Expand Down
22 changes: 22 additions & 0 deletions test/SILOptimizer/mem-behavior.sil
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Expand Up @@ -35,6 +35,13 @@ bb0(%0 : $X):
return %r : $()
}

sil @read_from_raw_pointer : $@convention(thin) (Builtin.RawPointer) -> UInt8 {
bb0(%0 : $Builtin.RawPointer):
%1 = pointer_to_address %0 : $Builtin.RawPointer to [strict] $*UInt8
%2 = load %1 : $*UInt8
return %2 : $UInt8
}

// CHECK-LABEL: @call_unknown_func
// CHECK: PAIR #1.
// CHECK-NEXT: %4 = apply %3(%0, %1) : $@convention(thin) (Int32, @in Int32) -> ()
Expand Down Expand Up @@ -224,6 +231,21 @@ bb0(%0 : $*Int32):
return %5 : $Int32
}

// CHECK-LABEL: @escaping_allocstack_to_known_function
// CHECK: PAIR #1.
// CHECK-NEXT: %5 = apply %4(%3) : $@convention(thin) (Builtin.RawPointer) -> UInt8 // user: %7
// CHECK-NEXT: %1 = alloc_stack $UInt8 // users: %6, %3, %2
// CHECK-NEXT: r=1,w=0
sil @escaping_allocstack_to_known_function : $@convention(thin) (UInt8) -> UInt8 {
bb0(%0 : $UInt8):
%1 = alloc_stack $UInt8
store %0 to %1 : $*UInt8
%3 = address_to_pointer %1 : $*UInt8 to $Builtin.RawPointer
%4 = function_ref @read_from_raw_pointer : $@convention(thin) (Builtin.RawPointer) -> UInt8
%5 = apply %4(%3) : $@convention(thin) (Builtin.RawPointer) -> UInt8
dealloc_stack %1 : $*UInt8
return %5 : $UInt8
}

// CHECK-LABEL: @tryapply_allocstack_and_copyaddr
// CHECK: PAIR #0.
Expand Down