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IRGen: Outline some of the relative protocol witness table code generation to save on code size #64000

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merged 1 commit into from
Mar 1, 2023
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IRGen: Outline some of the relative protocol witness table code generation to save on code size #64000

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105 changes: 84 additions & 21 deletions lib/IRGen/GenProto.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2660,7 +2660,19 @@ llvm::Value *irgen::loadParentProtocolWitnessTable(IRGenFunction &IGF,
index);
return baseWTable;
}
auto &Builder = IGF.Builder;

llvm::SmallString<40> fnName;
llvm::raw_svector_ostream(fnName)
<< "__swift_relative_protocol_witness_table_parent_"
<< index.getValue();

auto helperFn = cast<llvm::Function>(IGM.getOrCreateHelperFunction(
fnName, IGM.WitnessTablePtrTy, {IGM.WitnessTablePtrTy},
[&](IRGenFunction &subIGF) {

auto it = subIGF.CurFn->arg_begin();
llvm::Value *wtable = &*it;
auto &Builder = subIGF.Builder;
auto *ptrVal = Builder.CreatePtrToInt(wtable, IGM.IntPtrTy);
auto *one = llvm::ConstantInt::get(IGM.IntPtrTy, 1);
auto *isCond = Builder.CreateAnd(ptrVal, one);
Expand All @@ -2674,30 +2686,30 @@ llvm::Value *irgen::loadParentProtocolWitnessTable(IRGenFunction &IGF,
auto *mask = Builder.CreateNot(one);
auto *wtableAddr = Builder.CreateAnd(ptrVal, mask);
wtableAddr = Builder.CreateIntToPtr(wtableAddr, IGM.WitnessTablePtrTy);
auto addr = slotForLoadOfOpaqueWitness(IGF, wtableAddr, index,
auto addr = slotForLoadOfOpaqueWitness(subIGF, wtableAddr, index,
false /*isRelative*/);
llvm::Value *baseWTable = Builder.CreateLoad(addr);
baseWTable = IGF.Builder.CreateBitCast(baseWTable, IGF.IGM.WitnessTablePtrTy);
baseWTable = subIGF.Builder.CreateBitCast(baseWTable, IGM.WitnessTablePtrTy);
Builder.CreateBr(endBB);

Builder.emitBlock(isNotCondBB);
if (auto &schema = IGF.getOptions().PointerAuth.RelativeProtocolWitnessTable) {
auto info = PointerAuthInfo::emit(IGF, schema, nullptr,
if (auto &schema = subIGF.getOptions().PointerAuth.RelativeProtocolWitnessTable) {
auto info = PointerAuthInfo::emit(subIGF, schema, nullptr,
PointerAuthEntity());
wtable = emitPointerAuthAuth(IGF, wtable, info);
wtable = emitPointerAuthAuth(subIGF, wtable, info);
}
auto baseWTable2 =
emitInvariantLoadOfOpaqueWitness(IGF,/*isProtocolWitness*/true, wtable,
emitInvariantLoadOfOpaqueWitness(subIGF,/*isProtocolWitness*/true, wtable,
index);
baseWTable2 = IGF.Builder.CreateBitCast(baseWTable2,
IGF.IGM.WitnessTablePtrTy);
if (auto &schema = IGF.getOptions().PointerAuth.RelativeProtocolWitnessTable) {
auto info = PointerAuthInfo::emit(IGF, schema, nullptr,
baseWTable2 = subIGF.Builder.CreateBitCast(baseWTable2,
subIGF.IGM.WitnessTablePtrTy);
if (auto &schema = subIGF.getOptions().PointerAuth.RelativeProtocolWitnessTable) {
auto info = PointerAuthInfo::emit(subIGF, schema, nullptr,
PointerAuthEntity());
baseWTable2 = emitPointerAuthSign(IGF, baseWTable2, info);
baseWTable2 = emitPointerAuthSign(subIGF, baseWTable2, info);

baseWTable2 = IGF.Builder.CreateBitCast(baseWTable2,
IGF.IGM.WitnessTablePtrTy);
baseWTable2 = subIGF.Builder.CreateBitCast(baseWTable2,
IGM.WitnessTablePtrTy);
}

Builder.CreateBr(endBB);
Expand All @@ -2706,7 +2718,15 @@ llvm::Value *irgen::loadParentProtocolWitnessTable(IRGenFunction &IGF,
auto *phi = Builder.CreatePHI(wtable->getType(), 2);
phi->addIncoming(baseWTable, isCondBB);
phi->addIncoming(baseWTable2, isNotCondBB);
return phi;
Builder.CreateRet(phi);

}, true /*noinline*/));

auto *call = IGF.Builder.CreateCallWithoutDbgLoc(
helperFn->getFunctionType(), helperFn, {wtable});
call->setCallingConv(IGF.IGM.DefaultCC);
call->setDoesNotThrow();
return call;
}

llvm::Value *irgen::loadConditionalConformance(IRGenFunction &IGF,
Expand Down Expand Up @@ -3827,6 +3847,49 @@ static llvm::Value *emitWTableSlotLoad(IRGenFunction &IGF, llvm::Value *wtable,
return IGF.emitInvariantLoad(slot);
}

static FunctionPointer emitRelativeProtocolWitnessTableAccess(IRGenFunction &IGF,
WitnessIndex index,
llvm::Value *wtable,
SILDeclRef member) {
auto witnessTableTy = wtable->getType();
auto &IGM = IGF.IGM;
llvm::SmallString<40> fnName;
auto entity = LinkEntity::forMethodDescriptor(member);
auto mangled = entity.mangleAsString();
llvm::raw_svector_ostream(fnName)
<< "__swift_relative_protocol_witness_table_access_"
<< index.forProtocolWitnessTable().getValue()
<< "_" << mangled;

auto fnType = IGF.IGM.getSILTypes().getConstantFunctionType(
IGF.IGM.getMaximalTypeExpansionContext(), member);
Signature signature = IGF.IGM.getSignature(fnType);

auto helperFn = cast<llvm::Function>(IGM.getOrCreateHelperFunction(
fnName, IGM.Int8PtrTy, {witnessTableTy},
[&](IRGenFunction &subIGF) {

auto it = subIGF.CurFn->arg_begin();
llvm::Value *wtable = &*it;
wtable = subIGF.optionallyLoadFromConditionalProtocolWitnessTable(wtable);
auto slot = slotForLoadOfOpaqueWitness(subIGF, wtable,
index.forProtocolWitnessTable(),
true);
llvm::Value *witnessFnPtr = emitWTableSlotLoad(subIGF, wtable, member, slot,
true);

subIGF.Builder.CreateRet(witnessFnPtr);

}, true /*noinline*/));

auto *call = IGF.Builder.CreateCallWithoutDbgLoc(
helperFn->getFunctionType(), helperFn, {wtable});
call->setCallingConv(IGF.IGM.DefaultCC);
call->setDoesNotThrow();
auto fn = IGF.Builder.CreateBitCast(call, signature.getType()->getPointerTo());
return FunctionPointer::createUnsigned(fnType, fn, signature, true);
}

FunctionPointer irgen::emitWitnessMethodValue(IRGenFunction &IGF,
llvm::Value *wtable,
SILDeclRef member) {
Expand All @@ -3839,22 +3902,22 @@ FunctionPointer irgen::emitWitnessMethodValue(IRGenFunction &IGF,
auto &fnProtoInfo = IGF.IGM.getProtocolInfo(proto, ProtocolInfoKind::Full);
auto index = fnProtoInfo.getFunctionIndex(member);
auto isRelativeTable = IGF.IGM.IRGen.Opts.UseRelativeProtocolWitnessTables;
if (isRelativeTable) {
return emitRelativeProtocolWitnessTableAccess(IGF, index, wtable, member);
}

wtable = IGF.optionallyLoadFromConditionalProtocolWitnessTable(wtable);
auto slot =
slotForLoadOfOpaqueWitness(IGF, wtable, index.forProtocolWitnessTable(),
isRelativeTable);
false/*isRelativeTable*/);
llvm::Value *witnessFnPtr = emitWTableSlotLoad(IGF, wtable, member, slot,
isRelativeTable);
false/*isRelativeTable*/);

auto fnType = IGF.IGM.getSILTypes().getConstantFunctionType(
IGF.IGM.getMaximalTypeExpansionContext(), member);
Signature signature = IGF.IGM.getSignature(fnType);
witnessFnPtr = IGF.Builder.CreateBitCast(witnessFnPtr,
signature.getType()->getPointerTo());
if (isRelativeTable) {
return FunctionPointer::createUnsigned(fnType, witnessFnPtr, signature,
true);
}

auto &schema = fnType->isAsync()
? IGF.getOptions().PointerAuth.AsyncProtocolWitnesses
Expand Down
47 changes: 11 additions & 36 deletions test/IRGen/relative_protocol_witness_table.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -204,6 +204,11 @@ func instantiate_conditional_conformance_2nd<T>(_ t : T) where T: Sub, T.S == T

// CHECK: define{{.*}} swiftcc void @"$s1A14requireWitnessyyxAA8FuncOnlyRzlF"(%swift.opaque* noalias nocapture {{%.*}}, %swift.type* {{%.*}}, i8** [[PWT:%.*]])
// CHECK:[[ENTRY:.*]]:
// CHECK: [[T4:%.*]] = call i8* @"__swift_relative_protocol_witness_table_access_1_$s1A8FuncOnlyP1ayyFTq"(i8** [[PWT]])
// CHECK: [[T5:%.*]] = bitcast i8* [[T4]] to void (%swift.opaque*, %swift.type*, i8**)*
// CHECK: call{{.*}} swiftcc void [[T5]]

// CHECK: define{{.*}} hidden i8* @"__swift_relative_protocol_witness_table_access_1_$s1A8FuncOnlyP1ayyFTq"(i8** [[PWT:%.*]])
// CHECK: [[T0:%.*]] = ptrtoint i8** [[PWT]] to i64
// CHECK: [[T1:%.*]] = and i64 [[T0]], 1
// CHECK: [[C:%.*]] = icmp eq i64 [[T1]], 1
Expand All @@ -229,12 +234,15 @@ func instantiate_conditional_conformance_2nd<T>(_ t : T) where T: Sub, T.S == T
// CHECK: [[T2:%.*]] = ptrtoint i32* [[SLOT]] to i64
// CHECK: [[T3:%.*]] = add i64 [[T2]], [[T1]]
// CHECK: [[T4:%.*]] = inttoptr i64 [[T3]] to i8*
// CHECK: [[T5:%.*]] = bitcast i8* [[T4]] to void (%swift.opaque*, %swift.type*, i8**)*
// CHECK: call{{.*}} swiftcc void [[T5]]
// CHECK: ret i8* [[T4]]

// Parent witness entry access.

// CHECK: define hidden swiftcc void @"$s1A15requireWitness2yyxAA9InheritedRzlF"(%swift.opaque* noalias nocapture {{%.*}}, %swift.type* {{%.*}}, i8** [[T_INHERITED:%.*]])
// CHECK: [[T_FUNCONLY:%.*]] = call i8** @__swift_relative_protocol_witness_table_parent_1(i8** [[T_INHERITED]])
// CHECK: call i8* @"__swift_relative_protocol_witness_table_access_1_$s1A8FuncOnlyP1ayyFTq"(i8** [[T_FUNCONLY]])

// CHECK: define{{.*}} hidden i8** @__swift_relative_protocol_witness_table_parent_1(i8** [[T_INHERITED:%.*]])
// CHECK: [[T0:%.*]] = ptrtoint i8** [[T_INHERITED]] to i64
// CHECK: [[T1:%.*]] = and i64 [[T0]], 1
// CHECK: [[T2:%.*]] = icmp eq i64 [[T1]], 1
Expand Down Expand Up @@ -323,40 +331,7 @@ func instantiate_conditional_conformance_2nd<T>(_ t : T) where T: Sub, T.S == T
// CHECK: [[T2:%.*]] = bitcast i8** [[C1]] to i8***
// CHECK: [[T3:%.*]] = getelementptr inbounds i8**, i8*** [[T2]], i32 0
// CHECK: [[T4:%.*]] = load i8**, i8*** [[T3]]
// CHECK: [[T5:%.*]] = ptrtoint i8** [[T4]] to i64
// CHECK: [[T6:%.*]] = and i64 [[T5]], 1
// CHECK: [[T7:%.*]] = icmp eq i64 [[T6]], 1
// CHECK: br i1 [[T7]], label %[[T8:.*]], label %[[T14:.*]]

// CHECK: [[T8]]:
// CHECK: [[T9:%.*]] = and i64 [[T5]], -2
// CHECK: [[T10:%.*]] = inttoptr i64 [[T9]] to i8**
// CHECK: [[T11:%.*]] = getelementptr inbounds i8*, i8** [[T10]], i32 1
// CHECK: [[T12:%.*]] = load i8*, i8** [[T11]]
// CHECK: [[T13:%.*]] = bitcast i8* [[T12]] to i8**
// CHECK: br label %[[T23:.*]]

// CHECK: [[T14]]:
// CHECK-arm64e: [[P0:%.*]] = ptrtoint i8** [[T4]] to i64
// CHECK-arm64e: [[P1:%.*]] = call i64 @llvm.ptrauth.auth(i64 [[P0]], i32 2, i64 47152)
// CHECK-arm64e: [[P2:%.*]] = inttoptr i64 [[P1]] to i8**
// CHECK-arm64e: [[T15:%.*]] = bitcast i8** [[P2]] to i32*
// CHECK-x86_64: [[T15:%.*]] = bitcast i8** [[T4]] to i32*
// CHECK-arm64: [[T15:%.*]] = bitcast i8** [[T4]] to i32*
// CHECK: [[T16:%.*]] = getelementptr inbounds i32, i32* [[T15]], i32 1
// CHECK: [[T17:%.*]] = load i32, i32* [[T16]]
// CHECK: [[T18:%.*]] = sext i32 [[T17]] to i64
// CHECK: [[T19:%.*]] = ptrtoint i32* [[T16]] to i64
// CHECK: [[T20:%.*]] = add i64 [[T19]], [[T18]]
// CHECK: [[T21:%.*]] = inttoptr i64 [[T20]] to i8*
// CHECK: [[T22:%.*]] = bitcast i8* [[T21]] to i8**
// CHECK-arm64e: [[P0:%.*]] = ptrtoint i8** [[T22]] to i64
// CHECK-arm64e: [[P1:%.*]] = call i64 @llvm.ptrauth.sign(i64 [[P0]], i32 2, i64 47152)
// CHECK-arm64e: [[T22:%.*]] = inttoptr i64 [[P1]] to i8**
// CHECK: br label %[[T23]]

// CHECK: [[T23]]:
// CHECK: [[TBASE:%.*]] = phi i8** [ [[T13]], %[[T8]] ], [ [[T22]], %[[T14]] ]
// CHECK: [[TBASE:%.*]] = call i8** @__swift_relative_protocol_witness_table_parent_1(i8** [[T4]])
// CHECK: [[T24:%.*]] = getelementptr inbounds [1 x i8**], [1 x i8**]* [[C2]], i32 0, i32 0
// CHECK: [[T25:%.*]] = getelementptr inbounds i8**, i8*** [[T24]], i32 0
// CHECK: store i8** [[TBASE]], i8*** [[T25]]
Expand Down