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ClosureSpecializer: extend the benefit-analysis so that specialization is also done in case a closure is passed through multiple call-levels. #18077

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Merged
merged 1 commit into from
Jul 19, 2018
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ClosureSpecializer: extend the benefit-analysis so that specialization is also done in case a closure is passed through multiple call-levels. #18077

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8 changes: 7 additions & 1 deletion include/swift/SIL/SILInstruction.h
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Original file line number Diff line number Diff line change
Expand Up @@ -7683,11 +7683,17 @@ class ApplySite {
}
}

/// Returns true if \p oper is an argument operand and not the callee
/// operand.
bool isArgumentOperand(const Operand &oper) {
return oper.getOperandNumber() >= getOperandIndexOfFirstArgument();
}

// Translate the index of the argument to the full apply or partial_apply into
// to the corresponding index into the arguments of the called function.
unsigned getCalleeArgIndex(const Operand &oper) {
assert(oper.getUser() == Inst);
assert(oper.getOperandNumber() >= getOperandIndexOfFirstArgument());
assert(isArgumentOperand(oper));

unsigned appliedArgIdx =
oper.getOperandNumber() - getOperandIndexOfFirstArgument();
Expand Down
75 changes: 43 additions & 32 deletions lib/SILOptimizer/IPO/ClosureSpecializer.cpp
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Expand Up @@ -908,6 +908,37 @@ static void markReabstractionPartialApplyAsUsed(
llvm_unreachable("Unexpect instruction");
}

/// Returns true if the \p closureArgIdx argument of \p callee is called in
/// \p callee or any function called by callee.
static bool isClosureAppliedIn(SILFunction *Callee, unsigned closureArgIdx,
SmallPtrSetImpl<SILFunction *> &HandledFuncs) {
// Limit the number of recursive calls to not go into exponential behavior in
// corner cases.
const int RecursionBudget = 8;

SILValue Arg = Callee->getArgument(closureArgIdx);
for (Operand *ArgUse : Arg->getUses()) {
if (auto UserAI = FullApplySite::isa(ArgUse->getUser())) {
if (UserAI.getCallee() == Arg)
return true;

assert(UserAI.isArgumentOperand(*ArgUse) &&
"any other non-argument operands than the callee?");

SILFunction *ApplyCallee = UserAI.getReferencedFunction();
if (ApplyCallee && !ApplyCallee->isExternalDeclaration() &&
HandledFuncs.count(ApplyCallee) == 0 &&
HandledFuncs.size() < RecursionBudget) {
HandledFuncs.insert(ApplyCallee);
if (isClosureAppliedIn(UserAI.getReferencedFunction(),
UserAI.getCalleeArgIndex(*ArgUse), HandledFuncs))
return true;
}
}
}
return false;
}

bool SILClosureSpecializerTransform::gatherCallSites(
SILFunction *Caller,
llvm::SmallVectorImpl<ClosureInfo*> &ClosureCandidates,
Expand Down Expand Up @@ -1018,43 +1049,23 @@ bool SILClosureSpecializerTransform::gatherCallSites(
if (mayBindDynamicSelf(ApplyCallee))
return CFGChanged;

// Ok, we know that we can perform the optimization but not whether or
// not the optimization is profitable. Find the index of the argument
// corresponding to our partial apply.
Optional<unsigned> ClosureIndex;
for (unsigned i = 0, e = AI.getNumArguments(); i != e; ++i) {
if (AI.getArgument(i) != Use->get())
continue;
ClosureIndex = i;
DEBUG(llvm::dbgs() << " Found callsite with closure argument at "
<< i << ": " << *AI.getInstruction());
break;
}

// If we did not find an index, there is nothing further to do,
// continue.
if (!ClosureIndex.hasValue())
// Check if the closure is passed as an argument (and not called).
if (!AI.isArgumentOperand(*Use))
continue;

// Make sure that the Closure is invoked in the Apply's callee. We only
// want to perform closure specialization if we know that we will be
// able to change a partial_apply into an apply.
//
// TODO: Maybe just call the function directly instead of moving the
// partial apply?
SILValue Arg = ApplyCallee->getArgument(ClosureIndex.getValue());
if (std::none_of(Arg->use_begin(), Arg->use_end(),
[&Arg](Operand *Op) -> bool {
auto UserAI = FullApplySite::isa(Op->getUser());
return UserAI && UserAI.getCallee() == Arg;
})) {
unsigned ClosureIndex = AI.getCalleeArgIndex(*Use);

// Ok, we know that we can perform the optimization but not whether or
// not the optimization is profitable. Check if the closure is actually
// called in the callee (or in a function called by the callee).
SmallPtrSet<SILFunction *, 8> HandledFuncs;
if (!isClosureAppliedIn(ApplyCallee, ClosureIndex, HandledFuncs))
continue;
}

unsigned firstParamArgIdx =
AI.getSubstCalleeConv().getSILArgIndexOfFirstParam();
assert(ClosureIndex.getValue() >= firstParamArgIdx);
auto ClosureParamIndex = ClosureIndex.getValue() - firstParamArgIdx;
assert(ClosureIndex >= firstParamArgIdx);
auto ClosureParamIndex = ClosureIndex - firstParamArgIdx;

auto ParamInfo = AI.getSubstCalleeType()->getParameters();
SILParameterInfo ClosureParamInfo = ParamInfo[ClosureParamIndex];
Expand Down Expand Up @@ -1097,7 +1108,7 @@ bool SILClosureSpecializerTransform::gatherCallSites(
// Now we know that CSDesc is profitable to specialize. Add it to our
// call site list.
CInfo->CallSites.push_back(
CallSiteDescriptor(CInfo, AI, ClosureIndex.getValue(),
CallSiteDescriptor(CInfo, AI, ClosureIndex,
ClosureParamInfo, std::move(NonFailureExitBBs)));
}
if (CInfo) {
Expand Down
24 changes: 23 additions & 1 deletion test/SILOptimizer/closure_specialize_simple.sil
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,23 @@ bb2:
return %2 : $Builtin.Int1
}

// CHECK-LABEL: sil shared @$S37simple_partial_apply_2nd_level_caller0a1_b1_C4_funBi1_Tf1c_n : $@convention(thin) (Builtin.Int1) -> Builtin.Int1 {
// CHECK: bb0([[CAPTURED_ARG:%.*]] : $Builtin.Int1):
// CHECK: [[SPECIALIZED_CALLEE:%.*]] = function_ref @$S27simple_partial_apply_caller0a1_b1_C4_funBi1_Tf1c_n :
// CHECK: [[RET:%.*]]= apply [[SPECIALIZED_CALLEE]]([[CAPTURED_ARG]])
// CHECK: return [[RET]]
sil @simple_partial_apply_2nd_level_caller : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1 {
bb0(%0 : $@callee_owned (Builtin.Int1) -> Builtin.Int1):
br bb1

bb1:
%1 = function_ref @simple_partial_apply_caller : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1
%2 = apply %1(%0) : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1
cond_br undef, bb1, bb2

bb2:
return %2 : $Builtin.Int1
}
sil @simple_partial_apply_caller_decl : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1

sil @simple_multiple_partial_apply_caller : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1, @owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1 {
Expand Down Expand Up @@ -177,8 +194,10 @@ bb2:
}

// CHECK-LABEL: sil @loop_driver : $@convention(thin) (Builtin.Int1, Builtin.Int1) -> () {
// CHECK: [[SPECIALIZED_FUN:%.*]] = function_ref @$S27simple_partial_apply_caller0a1_b1_C4_funBi1_Tf1c_n : $@convention(thin) (Builtin.Int1) -> Builtin.Int1
// CHECK-DAG: [[SPECIALIZED_FUN:%.*]] = function_ref @$S27simple_partial_apply_caller0a1_b1_C4_funBi1_Tf1c_n : $@convention(thin) (Builtin.Int1) -> Builtin.Int1
// CHECK-DAG: [[SPECIALIZED_FUN2:%.*]] = function_ref @$S37simple_partial_apply_2nd_level_caller0a1_b1_C4_funBi1_Tf1c_n : $@convention(thin) (Builtin.Int1) -> Builtin.Int1
// CHECK: apply [[SPECIALIZED_FUN]]
// CHECK: apply [[SPECIALIZED_FUN2]]

// We can't call this one b/c it is just a declaration.
// CHECK: [[UNSPECIALIZED_FUN_DECL:%.*]] = function_ref @simple_partial_apply_caller_decl : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1
Expand Down Expand Up @@ -218,6 +237,9 @@ bb0(%0 : $Builtin.Int1, %1 : $Builtin.Int1):
%4 = function_ref @simple_partial_apply_caller : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1
%5 = apply %4(%3) : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1

%51 = function_ref @simple_partial_apply_2nd_level_caller : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1
%52 = apply %51(%3) : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1

%6 = partial_apply %2(%0) : $@convention(thin) (Builtin.Int1, Builtin.Int1) -> Builtin.Int1
%7 = function_ref @simple_partial_apply_caller_decl : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1
%8 = apply %7(%6) : $@convention(thin) (@owned @callee_owned (Builtin.Int1) -> Builtin.Int1) -> Builtin.Int1
Expand Down