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IRGen: Don't use relative pointers for value witness tables under relative procotol witness tables mode #63298

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Merged
merged 1 commit into from
Jan 30, 2023
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IRGen: Don't use relative pointers for value witness tables under relative procotol witness tables mode #63298

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14 changes: 12 additions & 2 deletions lib/IRGen/GenOpaque.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -334,25 +334,34 @@ Address irgen::slotForLoadOfOpaqueWitness(IRGenFunction &IGF,
/// Load a specific witness from a known table. The result is
/// always an i8*.
llvm::Value *irgen::emitInvariantLoadOfOpaqueWitness(IRGenFunction &IGF,
bool isProtocolWitness,
llvm::Value *table,
WitnessIndex index,
llvm::Value **slotPtr) {
auto isRelativeTable = IGF.IGM.IRGen.Opts.UseRelativeProtocolWitnessTables;
// Is this is a load of a relative protocol witness table entry.
auto isRelativeTable = IGF.IGM.IRGen.Opts.UseRelativeProtocolWitnessTables &&
isProtocolWitness;

auto slot = slotForLoadOfOpaqueWitness(IGF, table, index, isRelativeTable);
if (slotPtr) *slotPtr = slot.getAddress();

if (isRelativeTable) {
return IGF.emitLoadOfRelativePointer(slot, false, IGF.IGM.Int8Ty);
}

return IGF.emitInvariantLoad(slot);
}

/// Load a specific witness from a known table. The result is
/// always an i8*.
llvm::Value *irgen::emitInvariantLoadOfOpaqueWitness(IRGenFunction &IGF,
bool isProtocolWitness,
llvm::Value *table,
llvm::Value *index,
llvm::Value **slotPtr) {
assert(table->getType() == IGF.IGM.WitnessTablePtrTy);
assert(!isProtocolWitness &&
"This function does not yet support relative protocol witnesses");

// GEP to the appropriate index.
llvm::Value *slot =
Expand Down Expand Up @@ -438,7 +447,8 @@ static FunctionPointer emitLoadOfValueWitnessFunction(IRGenFunction &IGF,

llvm::Value *slot;
llvm::Value *witness =
emitInvariantLoadOfOpaqueWitness(IGF, table, windex, &slot);
emitInvariantLoadOfOpaqueWitness(IGF, /*isProtocolWitness*/false, table,
windex, &slot);
auto label = getValueWitnessLabel(index);
auto signature = IGF.IGM.getValueWitnessSignature(index);

Expand Down
2 changes: 2 additions & 0 deletions lib/IRGen/GenOpaque.h
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Expand Up @@ -52,6 +52,7 @@ namespace irgen {
/// The load is marked invariant. This should not be used in contexts where
/// the referenced witness table is still undergoing initialization.
llvm::Value *emitInvariantLoadOfOpaqueWitness(IRGenFunction &IGF,
bool isProtocolWitness,
llvm::Value *table,
WitnessIndex index,
llvm::Value **slot = nullptr);
Expand All @@ -62,6 +63,7 @@ namespace irgen {
/// The load is marked invariant. This should not be used in contexts where
/// the referenced witness table is still undergoing initialization.
llvm::Value *emitInvariantLoadOfOpaqueWitness(IRGenFunction &IGF,
bool isProtocolWitness,
llvm::Value *table,
llvm::Value *index,
llvm::Value **slot = nullptr);
Expand Down
9 changes: 6 additions & 3 deletions lib/IRGen/GenProto.cpp
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Expand Up @@ -2634,7 +2634,8 @@ llvm::Value *irgen::loadParentProtocolWitnessTable(IRGenFunction &IGF,
auto &IGM = IGF.IGM;
if (!IGM.IRGen.Opts.UseRelativeProtocolWitnessTables) {
auto baseWTable =
emitInvariantLoadOfOpaqueWitness(IGF, wtable, index);
emitInvariantLoadOfOpaqueWitness(IGF,/*isProtocolWitness*/true, wtable,
index);
return baseWTable;
}
auto &Builder = IGF.Builder;
Expand All @@ -2659,7 +2660,8 @@ llvm::Value *irgen::loadParentProtocolWitnessTable(IRGenFunction &IGF,

Builder.emitBlock(isNotCondBB);
auto baseWTable2 =
emitInvariantLoadOfOpaqueWitness(IGF, wtable, index);
emitInvariantLoadOfOpaqueWitness(IGF,/*isProtocolWitness*/true, wtable,
index);
baseWTable2 = IGF.Builder.CreateBitCast(baseWTable2,
IGF.IGM.WitnessTablePtrTy);
Builder.CreateBr(endBB);
Expand All @@ -2677,7 +2679,8 @@ llvm::Value *irgen::loadConditionalConformance(IRGenFunction &IGF,

auto &IGM = IGF.IGM;
if (!IGM.IRGen.Opts.UseRelativeProtocolWitnessTables) {
return emitInvariantLoadOfOpaqueWitness(IGF, wtable, index);
return emitInvariantLoadOfOpaqueWitness(IGF, /*isProtocolWitness*/true,
wtable, index);
}

auto &Builder = IGF.Builder;
Expand Down
16 changes: 16 additions & 0 deletions test/IRGen/relative_protocol_witness_table.swift
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Expand Up @@ -3,6 +3,10 @@
// REQUIRES: CPU=x86_64 || CPU=arm64
// UNSUPPORTED: CPU=arm64e

func testVWT<T>(_ t: T) {
var local = t
}

protocol FuncOnly {
func a()
func b()
Expand Down Expand Up @@ -185,6 +189,18 @@ func instantiate_conditional_conformance_2nd<T>(_ t : T) where T: Sub, T.S == T
// CHECK-SAME: i64 ptrtoint (i32* getelementptr inbounds ([4 x i32], [4 x i32]* @"$s1A17ConditionalStructVyxGAA20WithAssocConformanceA2A8FuncOnlyRzAA5InitPRzlWP", i32 0, i32 3) to i64)) to i32)
// CHECK-SAME: ], align 8

// Make sure value witness table lookup is done right.

// CHECK: define{{.*}} swiftcc void @"$s1A7testVWTyyxlF"(%swift.opaque* {{.*}}, %swift.type* [[T:%.*]])
// CHECK: [[T0:%.*]] = bitcast %swift.type* [[T]] to i8***
// CHECK: [[VWT_ADDR:%.*]] = getelementptr inbounds i8**, i8*** [[T0]], i64 -1
// CHECK: [[VWT_PTR:%.*]] = load i8**, i8*** [[VWT_ADDR]]
// CHECK: [[T1:%.*]] = getelementptr inbounds i8*, i8** [[VWT_PTR]], i32 2
// CHECK: [[T2:%.*]] = load i8*, i8** [[T1]]
// CHECK: [[T3:%.*]] = bitcast i8* [[T2]] to %swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
// CHECK: call %swift.opaque* [[T3]](%swift.opaque* {{.*}}, %swift.opaque* {{.*}}, %swift.type* [[T]])


// Simple witness entry access.

// CHECK: define{{.*}} swiftcc void @"$s1A14requireWitnessyyxAA8FuncOnlyRzlF"(%swift.opaque* noalias nocapture {{%.*}}, %swift.type* {{%.*}}, i8** [[PWT:%.*]])
Expand Down