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[AST] Increase size of type variable id field to 20 bits #25666

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Merged
merged 4 commits into from
Jun 24, 2019
Merged

[AST] Increase size of type variable id field to 20 bits #25666

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dae1971
[ConstraintSystem] NFC: Remove duplicate code from LinkedExprAnalyzer
xedin Jun 21, 2019
1a26b3c
[AST] Increase size of type variable id field to 20 bits
xedin Jun 21, 2019
ba3972f
[AST] Abort the process when type variable id overflows
xedin Jun 21, 2019
00f426d
[AST] Explicitly specify number of extra bits type variable type is u…
xedin Jun 21, 2019
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17 changes: 11 additions & 6 deletions include/swift/AST/Types.h
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Original file line number Diff line number Diff line change
Expand Up @@ -336,16 +336,16 @@ class alignas(1 << TypeAlignInBits) TypeBase {
NumProtocols : 16
);

SWIFT_INLINE_BITFIELD_FULL(TypeVariableType, TypeBase, 64-NumTypeBaseBits,
SWIFT_INLINE_BITFIELD_FULL(TypeVariableType, TypeBase, 20+4+20,
/// The unique number assigned to this type variable.
ID : 32 - NumTypeBaseBits,
ID : 20,

/// Type variable options.
Options : 4,

/// Index into the list of type variables, as used by the
/// constraint graph.
GraphIndex : 28
GraphIndex : 20
);

SWIFT_INLINE_BITFIELD(SILFunctionType, TypeBase, NumSILExtInfoBits+3+1+2,
Expand Down Expand Up @@ -5224,8 +5224,11 @@ TypeVariableType : public TypeBase {
TypeVariableType(const ASTContext &C, unsigned ID)
: TypeBase(TypeKind::TypeVariable, &C,
RecursiveTypeProperties::HasTypeVariable) {
// Note: the ID may overflow, but its only used for printing.
// Note: the ID may overflow (current limit is 2^20 - 1).
Bits.TypeVariableType.ID = ID;
if (Bits.TypeVariableType.ID != ID) {
llvm::report_fatal_error("Type variable id overflow");
}
}

class Implementation;
Expand Down Expand Up @@ -5261,8 +5264,10 @@ TypeVariableType : public TypeBase {
return reinterpret_cast<Implementation *>(this + 1);
}

/// Type variable IDs are not globally unique and are only meant as a visual
/// aid when dumping AST.
/// Type variable IDs are not globally unique and are
/// used in equivalence class merging (so representative
/// is always a type variable with smaller id), as well
/// as a visual aid when dumping AST.
unsigned getID() const { return Bits.TypeVariableType.ID; }

// Implement isa/cast/dyncast/etc.
Expand Down
42 changes: 11 additions & 31 deletions lib/Sema/CSGen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -360,7 +360,7 @@ namespace {
/// expression, attempt to derive a favored type for it.
bool computeFavoredTypeForExpr(Expr *expr, ConstraintSystem &CS) {
LinkedTypeInfo lti;

expr->walk(LinkedExprAnalyzer(lti, CS));

// Link anonymous closure params of the same index.
Expand All @@ -381,41 +381,21 @@ namespace {
}
}

// Link integer literal tyvars.
if (lti.intLiteralTyvars.size() > 1) {
auto rep1 = CS.getRepresentative(lti.intLiteralTyvars[0]);

for (size_t i = 1; i < lti.intLiteralTyvars.size(); i++) {
auto rep2 = CS.getRepresentative(lti.intLiteralTyvars[i]);
auto mergeTypeVariables = [&](ArrayRef<TypeVariableType *> typeVars) {
if (typeVars.size() < 2)
return;

auto rep1 = CS.getRepresentative(typeVars.front());
for (unsigned i = 1, n = typeVars.size(); i != n; ++i) {
auto rep2 = CS.getRepresentative(typeVars[i]);
if (rep1 != rep2)
CS.mergeEquivalenceClasses(rep1, rep2, /*updateWorkList*/ false);
}
}

// Link float literal tyvars.
if (lti.floatLiteralTyvars.size() > 1) {
auto rep1 = CS.getRepresentative(lti.floatLiteralTyvars[0]);

for (size_t i = 1; i < lti.floatLiteralTyvars.size(); i++) {
auto rep2 = CS.getRepresentative(lti.floatLiteralTyvars[i]);

if (rep1 != rep2)
CS.mergeEquivalenceClasses(rep1, rep2, /*updateWorkList*/ false);
}
}

// Link string literal tyvars.
if (lti.stringLiteralTyvars.size() > 1) {
auto rep1 = CS.getRepresentative(lti.stringLiteralTyvars[0]);

for (size_t i = 1; i < lti.stringLiteralTyvars.size(); i++) {
auto rep2 = CS.getRepresentative(lti.stringLiteralTyvars[i]);
};

if (rep1 != rep2)
CS.mergeEquivalenceClasses(rep1, rep2, /*updateWorkList*/ false);
}
}
mergeTypeVariables(lti.intLiteralTyvars);
mergeTypeVariables(lti.floatLiteralTyvars);
mergeTypeVariables(lti.stringLiteralTyvars);

if (lti.collectedTypes.size() == 1) {
// TODO: Compute the BCT.
Expand Down
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