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Add shared tagged variant core #88

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66 changes: 44 additions & 22 deletions internal/backend/llvm/drop_emit.go
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Original file line number Diff line number Diff line change
Expand Up @@ -68,8 +68,8 @@ func emitDropValue(b *llvmBuilder, value llvmValue, typeID ir.TypeID) {
emitOwnedPointerFree(b, value, typ.Elem)
return
}
if typ.Kind == ir.TypeOptional {
emitOptionalDrop(b, value, typ.Elem)
if typ.Kind == ir.TypeVariant {
emitVariantDrop(b, value, typ)
return
}
if typ.Kind == ir.TypeArray && typ.Length == "" {
Expand Down Expand Up @@ -161,24 +161,34 @@ func emitInterfaceStorageRelease(b *llvmBuilder, interfaceType ir.TypeID, interf
b.call(releaseFn, []llvmValue{allocator, data})
}

func emitOptionalDrop(b *llvmBuilder, value llvmValue, inner ir.TypeID) {
if !typeNeedsDrop(b.emitter.mod.Types, inner) {
func emitVariantDrop(b *llvmBuilder, value llvmValue, variant ir.Type) {
dropCases := make([]int, 0, len(variant.Cases))
for caseIndex, variantCase := range variant.Cases {
if variantCase.Payload != ir.InvalidType && typeNeedsDrop(b.emitter.mod.Types, variantCase.Payload) {
dropCases = append(dropCases, caseIndex)
}
}
if len(dropCases) == 0 {
return
}
present := b.extractField(value, llvmFieldPresent)
payload := b.extractField(value, llvmFieldValue)
emitConditionalDrop(b, present, payload, inner)
}

func emitConditionalDrop(b *llvmBuilder, condition, value llvmValue, typeID ir.TypeID) {
id := b.nextID
b.nextID++
dropLabel := fmt.Sprintf("drop_some_%d", id)
doneLabel := fmt.Sprintf("drop_done_%d", id)
b.condBranch(condition, dropLabel, doneLabel)
b.namedLabel(dropLabel)
emitDropValue(b, value, typeID)
b.branch(doneLabel)
tag := b.variantTag(value)
doneLabel := fmt.Sprintf("drop_variant_done_%d", id)
switchCases := make([]llvmSwitchCase, len(dropCases))
for i, caseIndex := range dropCases {
switchCases[i] = llvmSwitchCase{
Value: b.variantCaseTag(caseIndex, tag.Layout),
Label: fmt.Sprintf("drop_variant_%d_case_%d", id, caseIndex),
}
}
b.switchBranch(tag, doneLabel, switchCases)
for i, caseIndex := range dropCases {
b.namedLabel(switchCases[i].Label)
variantCase := variant.Cases[caseIndex]
emitDropValue(b, b.variantPayload(value, caseIndex), variantCase.Payload)
b.branch(doneLabel)
}
b.namedLabel(doneLabel)
}

Expand Down Expand Up @@ -249,8 +259,12 @@ func typeNeedsDrop(types *ir.TypeTable, id ir.TypeID) bool {
switch typ.Kind {
case ir.TypeOwnedPtr, ir.TypeString:
return true
case ir.TypeOptional:
return typeNeedsDrop(types, typ.Elem)
case ir.TypeVariant:
for _, variantCase := range typ.Cases {
if variantCase.Payload != ir.InvalidType && typeNeedsDrop(types, variantCase.Payload) {
return true
}
}
case ir.TypeArray:
return typ.Length == "" || typeNeedsDrop(types, typ.Elem)
case ir.TypeStruct:
Expand All @@ -273,8 +287,12 @@ func typeCarriesAllocatorID(types *ir.TypeTable, id ir.TypeID) bool {
return true
case ir.TypeOwnedPtr:
return !isInterfaceType(types, typ.Elem)
case ir.TypeOptional:
return typeCarriesAllocatorID(types, typ.Elem)
case ir.TypeVariant:
for _, variantCase := range typ.Cases {
if variantCase.Payload != ir.InvalidType && typeCarriesAllocatorID(types, variantCase.Payload) {
return true
}
}
case ir.TypeArray:
return typ.Length == "" || typeCarriesAllocatorID(types, typ.Elem)
case ir.TypeStruct:
Expand All @@ -295,8 +313,12 @@ func typeNeedsRawFreeID(types *ir.TypeTable, id ir.TypeID) bool {
switch typ.Kind {
case ir.TypeOwnedPtr:
return !isInterfaceType(types, typ.Elem) && typeNeedsRawFreeID(types, typ.Elem)
case ir.TypeOptional:
return typeNeedsRawFreeID(types, typ.Elem)
case ir.TypeVariant:
for _, variantCase := range typ.Cases {
if variantCase.Payload != ir.InvalidType && typeNeedsRawFreeID(types, variantCase.Payload) {
return true
}
}
case ir.TypeArray:
return typ.Length == "" || typeNeedsRawFreeID(types, typ.Elem)
case ir.TypeStruct:
Expand Down
44 changes: 44 additions & 0 deletions internal/backend/llvm/emitter.go
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Original file line number Diff line number Diff line change
Expand Up @@ -316,6 +316,8 @@ func GenerateLLVMIR(mod *mir.Module, diag *diagnostics.DiagnosticBag, targetInfo
case *mir.Branch:
cond := emitCondRef(lb, term.Cond)
lb.condBranch(cond, fmt.Sprintf("b%d", term.ThenID), fmt.Sprintf("b%d", term.ElseID))
case *mir.SwitchVariant:
emitVariantSwitch(lb, term)
case *mir.Ret:
if term.Value == nil || isVoidType(mod.Types, fn.ReturnType) {
if returnLayout.Kind != llvmLayoutVoid {
Expand All @@ -336,6 +338,48 @@ func GenerateLLVMIR(mod *mir.Module, diag *diagnostics.DiagnosticBag, targetInfo
return finalLLVMText(&b, emitter)
}

func emitVariantSwitch(b *llvmBuilder, term *mir.SwitchVariant) {
if b == nil || term == nil || term.Value == nil || len(term.Targets) == 0 {
if b != nil {
b.emitter.markInvalid("variant switch requires subject and targets")
}
return
}
variant, ok := b.emitter.mod.Types.Type(mirRefType(term.Value))
if !ok || variant.Kind != ir.TypeVariant {
b.emitter.markInvalid("variant switch requires variant subject")
return
}
if len(term.Targets) != len(variant.Cases) {
b.emitter.markInvalid("variant switch must cover every case")
return
}
value := emitRef(b, term.Value)
tag := b.variantTag(value)
cases := make([]llvmSwitchCase, len(term.Targets))
seen := make(map[int]struct{}, len(term.Targets))
for i, target := range term.Targets {
if _, caseOK := variant.VariantCase(target.Case); !caseOK {
b.emitter.markInvalid(fmt.Sprintf("variant switch has invalid case %d", target.Case))
return
}
if _, duplicate := seen[target.Case]; duplicate {
b.emitter.markInvalid(fmt.Sprintf("variant switch repeats case %d", target.Case))
return
}
seen[target.Case] = struct{}{}
cases[i] = llvmSwitchCase{
Value: b.variantCaseTag(target.Case, tag.Layout),
Label: fmt.Sprintf("b%d", target.TargetID),
}
}
invalidLabel := fmt.Sprintf("invalid_variant_%d", b.nextID)
b.nextID++
b.switchBranch(tag, invalidLabel, cases)
b.namedLabel(invalidLabel)
b.trap()
}

// ValidateRuntimeSymbols checks runtime ABI reservations after ownership and
// lowering have made actual print, allocation, and destruction use explicit.
func ValidateRuntimeSymbols(modules []*mir.Module, diag *diagnostics.DiagnosticBag) bool {
Expand Down
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