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//===--- GenericSpecializer.cpp - Specialization of generic functions -----===//
// This source file is part of the open source project
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
// See for license information
// See for the list of Swift project authors
// Specialize calls to generic functions by substituting static type
// information.
#define DEBUG_TYPE "sil-generic-specializer"
#include "swift/SIL/OptimizationRemark.h"
#include "swift/SIL/SILFunction.h"
#include "swift/SIL/SILInstruction.h"
#include "swift/SILOptimizer/PassManager/Transforms.h"
#include "swift/SILOptimizer/Utils/Generics.h"
#include "swift/SILOptimizer/Utils/InstOptUtils.h"
#include "swift/SILOptimizer/Utils/SILOptFunctionBuilder.h"
#include "llvm/ADT/SmallVector.h"
using namespace swift;
namespace {
class GenericSpecializer : public SILFunctionTransform {
bool specializeAppliesInFunction(SILFunction &F);
/// The entry point to the transformation.
void run() override {
SILFunction &F = *getFunction();
LLVM_DEBUG(llvm::dbgs() << "***** GenericSpecializer on function:"
<< F.getName() << " *****\n");
if (specializeAppliesInFunction(F))
} // end anonymous namespace
bool GenericSpecializer::specializeAppliesInFunction(SILFunction &F) {
SILOptFunctionBuilder FunctionBuilder(*this);
DeadInstructionSet DeadApplies;
llvm::SmallSetVector<SILInstruction *, 8> Applies;
OptRemark::Emitter ORE(DEBUG_TYPE, F);
bool Changed = false;
for (auto &BB : F) {
// Collect the applies for this block in reverse order so that we
// can pop them off the end of our vector and process them in
// forward order.
for (auto &I : llvm::reverse(BB)) {
// Skip non-apply instructions, apply instructions with no
// substitutions, apply instructions where we do not statically
// know the called function, and apply instructions where we do
// not have the body of the called function.
ApplySite Apply = ApplySite::isa(&I);
if (!Apply || !Apply.hasSubstitutions())
auto *Callee = Apply.getReferencedFunctionOrNull();
if (!Callee)
if (!Callee->isDefinition() && !Callee->hasPrespecialization()) {
ORE.emit([&]() {
using namespace OptRemark;
return RemarkMissed("NoDef", I)
<< "Unable to specialize generic function "
<< NV("Callee", Callee) << " since definition is not visible";
// Attempt to specialize each apply we collected, deleting any
// that we do specialize (along with other instructions we clone
// in the process of doing so). We pop from the end of the list to
// avoid tricky iterator invalidation issues.
while (!Applies.empty()) {
auto *I = Applies.pop_back_val();
auto Apply = ApplySite::isa(I);
assert(Apply && "Expected an apply!");
SILFunction *Callee = Apply.getReferencedFunctionOrNull();
assert(Callee && "Expected to have a known callee");
if (!Apply.canOptimize() || !Callee->shouldOptimize())
// We have a call that can potentially be specialized, so
// attempt to do so.
llvm::SmallVector<SILFunction *, 2> NewFunctions;
trySpecializeApplyOfGeneric(FunctionBuilder, Apply, DeadApplies,
NewFunctions, ORE);
// Remove all the now-dead applies. We must do this immediately
// rather than defer it in order to avoid problems with cloning
// dead instructions when doing recursive specialization.
while (!DeadApplies.empty()) {
auto *AI = DeadApplies.pop_back_val();
// Remove any applies we are deleting so that we don't attempt
// to specialize them.
recursivelyDeleteTriviallyDeadInstructions(AI, true);
Changed = true;
// If calling the specialization utility resulted in new functions
// (as opposed to returning a previous specialization), we need to notify
// the pass manager so that the new functions get optimized.
for (SILFunction *NewF : reverse(NewFunctions)) {
addFunctionToPassManagerWorklist(NewF, Callee);
return Changed;
SILTransform *swift::createGenericSpecializer() {
return new GenericSpecializer();