Move the EvalConstantInst overloads out of eval.cpp into their own file. (#5040)

For now they're all in the same file; we might consider splitting them
further if that file gets too large.
This commit is contained in:
Richard Smith
2025-02-28 00:50:43 +00:00
committed by GitHub
parent 536bfd9cbf
commit f30fa2d3db
6 changed files with 597 additions and 509 deletions
+29 -509
View File
@@ -6,6 +6,7 @@
#include "toolchain/base/kind_switch.h"
#include "toolchain/check/diagnostic_helpers.h"
#include "toolchain/check/eval_inst.h"
#include "toolchain/check/facet_type.h"
#include "toolchain/check/generic.h"
#include "toolchain/check/import_ref.h"
@@ -694,39 +695,6 @@ static auto PerformArrayIndex(EvalContext& eval_context, SemIR::ArrayIndex inst)
return eval_context.GetConstantValue(elements[index_val.getZExtValue()]);
}
// Enforces that an integer type has a valid bit width.
static auto ValidateIntType(Context& context, SemIRLoc loc,
SemIR::IntType result) -> bool {
auto bit_width =
context.insts().TryGetAs<SemIR::IntValue>(result.bit_width_id);
if (!bit_width) {
// Symbolic bit width.
return true;
}
const auto& bit_width_val = context.ints().Get(bit_width->int_id);
if (bit_width_val.isZero() ||
(context.types().IsSignedInt(bit_width->type_id) &&
bit_width_val.isNegative())) {
CARBON_DIAGNOSTIC(IntWidthNotPositive, Error,
"integer type width of {0} is not positive", TypedInt);
context.emitter().Emit(
loc, IntWidthNotPositive,
{.type = bit_width->type_id, .value = bit_width_val});
return false;
}
if (bit_width_val.ugt(IntStore::MaxIntWidth)) {
CARBON_DIAGNOSTIC(IntWidthTooLarge, Error,
"integer type width of {0} is greater than the "
"maximum supported width of {1}",
TypedInt, int);
context.emitter().Emit(loc, IntWidthTooLarge,
{.type = bit_width->type_id, .value = bit_width_val},
IntStore::MaxIntWidth);
return false;
}
return true;
}
// Forms a constant int type as an evaluation result. Requires that width_id is
// constant.
static auto MakeIntTypeResult(Context& context, SemIRLoc loc,
@@ -742,31 +710,6 @@ static auto MakeIntTypeResult(Context& context, SemIRLoc loc,
return MakeConstantResult(context, result, phase);
}
// Enforces that the bit width is 64 for a float.
static auto ValidateFloatBitWidth(Context& context, SemIRLoc loc,
SemIR::InstId inst_id) -> bool {
auto inst = context.insts().GetAs<SemIR::IntValue>(inst_id);
if (context.ints().Get(inst.int_id) == 64) {
return true;
}
CARBON_DIAGNOSTIC(CompileTimeFloatBitWidth, Error, "bit width must be 64");
context.emitter().Emit(loc, CompileTimeFloatBitWidth);
return false;
}
// Enforces that a float type has a valid bit width.
static auto ValidateFloatType(Context& context, SemIRLoc loc,
SemIR::FloatType result) -> bool {
auto bit_width =
context.insts().TryGetAs<SemIR::IntValue>(result.bit_width_id);
if (!bit_width) {
// Symbolic bit width.
return true;
}
return ValidateFloatBitWidth(context, loc, result.bit_width_id);
}
// Performs a conversion between integer types, truncating if the value doesn't
// fit in the destination type.
static auto PerformIntConvert(Context& context, SemIR::InstId arg_id,
@@ -1585,454 +1528,33 @@ static auto MakeConstantForCall(EvalContext& eval_context, SemIRLoc loc,
return SemIR::ConstantId::NotConstant;
}
// The result of constant evaluation of an instruction.
class ConstantEvalResult {
public:
// Produce a new constant as the result of an evaluation. The phase of the
// produced constant must be the same as the greatest phase of the operands in
// the evaluation. This will typically be the case if the evaluation uses all
// of its operands.
static auto New(SemIR::Inst inst) -> ConstantEvalResult {
return ConstantEvalResult(inst);
}
// Produce an existing constant as the result of an evaluation.
static constexpr auto Existing(SemIR::ConstantId existing_id)
-> ConstantEvalResult {
CARBON_CHECK(existing_id.is_constant());
return ConstantEvalResult(existing_id);
}
// Indicates that an error was produced by evaluation.
static const ConstantEvalResult Error;
// Indicates that we encountered an instruction whose evaluation is
// non-constant despite having constant operands. This should be rare;
// usually we want to produce an error in this case.
static const ConstantEvalResult NotConstant;
// Indicates that we encountered an instruction for which we've not
// implemented constant evaluation yet. Instruction is treated as not
// constant.
static const ConstantEvalResult TODO;
// Returns whether the result of evaluation is that we should produce a new
// constant described by `new_inst()` rather than an existing `ConstantId`
// described by `existing()`.
auto is_new() const -> bool { return !result_id_.has_value(); }
// Returns the existing constant that this the instruction evaluates to, or
// `None` if this is evaluation produces a new constant.
auto existing() const -> SemIR::ConstantId { return result_id_; }
// Returns the new constant instruction that is the result of evaluation.
auto new_inst() const -> SemIR::Inst {
CARBON_CHECK(is_new());
return new_inst_;
}
private:
constexpr explicit ConstantEvalResult(SemIR::ConstantId raw_id)
: result_id_(raw_id) {}
explicit ConstantEvalResult(SemIR::Inst inst)
: result_id_(SemIR::ConstantId::None), new_inst_(inst) {}
SemIR::ConstantId result_id_;
union {
SemIR::Inst new_inst_;
};
};
constexpr ConstantEvalResult ConstantEvalResult::Error =
Existing(SemIR::ErrorInst::SingletonConstantId);
constexpr ConstantEvalResult ConstantEvalResult::NotConstant =
ConstantEvalResult(SemIR::ConstantId::NotConstant);
constexpr ConstantEvalResult ConstantEvalResult::TODO = NotConstant;
// `EvalConstantInst` evaluates an instruction whose operands are all constant,
// in a context unrelated to the enclosing evaluation. The function is given the
// instruction after its operands, including its type, are replaced by their
// evaluated value, and returns a `ConstantEvalResult` describing the result of
// evaluating the instruction.
//
// An overload is provided for each type whose constant kind is one of the
// following:
//
// - InstConstantKind::Indirect
// - InstConstantKind::SymbolicOnly
// - InstConstantKind::Conditional
//
// ... except for cases where the result of evaluation depends on the evaluation
// context itself. Those cases are handled by explicit specialization of
// `TryEvalTypedInst`.
static auto EvalConstantInst(Context& context, SemIRLoc loc,
SemIR::ArrayType inst) -> ConstantEvalResult {
auto bound_inst = context.insts().Get(inst.bound_id);
auto int_bound = bound_inst.TryAs<SemIR::IntValue>();
if (!int_bound) {
CARBON_CHECK(context.constant_values().Get(inst.bound_id).is_symbolic(),
"Unexpected inst {0} for template constant int", bound_inst);
return ConstantEvalResult::New(inst);
}
// TODO: We should check that the size of the resulting array type
// fits in 64 bits, not just that the bound does. Should we use a
// 32-bit limit for 32-bit targets?
const auto& bound_val = context.ints().Get(int_bound->int_id);
if (context.types().IsSignedInt(int_bound->type_id) &&
bound_val.isNegative()) {
CARBON_DIAGNOSTIC(ArrayBoundNegative, Error,
"array bound of {0} is negative", TypedInt);
context.emitter().Emit(loc, ArrayBoundNegative,
{.type = int_bound->type_id, .value = bound_val});
return ConstantEvalResult::Error;
}
if (bound_val.getActiveBits() > 64) {
CARBON_DIAGNOSTIC(ArrayBoundTooLarge, Error,
"array bound of {0} is too large", TypedInt);
context.emitter().Emit(loc, ArrayBoundTooLarge,
{.type = int_bound->type_id, .value = bound_val});
return ConstantEvalResult::Error;
}
return ConstantEvalResult::New(inst);
}
static auto EvalConstantInst(Context& context, SemIRLoc loc,
SemIR::IntType inst) -> ConstantEvalResult {
return ValidateIntType(context, loc, inst) ? ConstantEvalResult::New(inst)
: ConstantEvalResult::Error;
}
static auto EvalConstantInst(Context& context, SemIRLoc loc,
SemIR::FloatType inst) -> ConstantEvalResult {
return ValidateFloatType(context, loc, inst) ? ConstantEvalResult::New(inst)
: ConstantEvalResult::Error;
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::ArrayInit init) -> ConstantEvalResult {
// TODO: Add an `ArrayValue` to represent a constant array object
// representation instead of using a `TupleValue`.
return ConstantEvalResult::New(
SemIR::TupleValue{.type_id = init.type_id, .elements_id = init.inits_id});
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::ClassInit init) -> ConstantEvalResult {
// TODO: Add a `ClassValue` to represent a constant class object
// representation instead of using a `StructValue`.
return ConstantEvalResult::New(SemIR::StructValue{
.type_id = init.type_id, .elements_id = init.elements_id});
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::StructInit init) -> ConstantEvalResult {
return ConstantEvalResult::New(SemIR::StructValue{
.type_id = init.type_id, .elements_id = init.elements_id});
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::TupleInit init) -> ConstantEvalResult {
return ConstantEvalResult::New(SemIR::TupleValue{
.type_id = init.type_id, .elements_id = init.elements_id});
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::FunctionDecl inst) -> ConstantEvalResult {
return ConstantEvalResult::New(SemIR::StructValue{
.type_id = inst.type_id, .elements_id = SemIR::InstBlockId::Empty});
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::ClassDecl inst) -> ConstantEvalResult {
// If the class has generic parameters, we don't produce a class type, but a
// callable whose return value is a class type.
if (context.classes().Get(inst.class_id).has_parameters()) {
return ConstantEvalResult::New(SemIR::StructValue{
.type_id = inst.type_id, .elements_id = SemIR::InstBlockId::Empty});
}
// A non-generic class declaration evaluates to the class type.
return ConstantEvalResult::New(
SemIR::ClassType{.type_id = SemIR::TypeType::SingletonTypeId,
.class_id = inst.class_id,
.specific_id = SemIR::SpecificId::None});
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::InterfaceDecl inst) -> ConstantEvalResult {
// If the interface has generic parameters, we don't produce an interface
// type, but a callable whose return value is an interface type.
if (context.interfaces().Get(inst.interface_id).has_parameters()) {
return ConstantEvalResult::New(SemIR::StructValue{
.type_id = inst.type_id, .elements_id = SemIR::InstBlockId::Empty});
}
// A non-generic interface declaration evaluates to a facet type.
return ConstantEvalResult::New(FacetTypeFromInterface(
context, inst.interface_id, SemIR::SpecificId::None));
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::SpecificConstant inst)
-> ConstantEvalResult {
// Pull the constant value out of the specific.
return ConstantEvalResult::Existing(SemIR::GetConstantValueInSpecific(
context.sem_ir(), inst.specific_id, inst.inst_id));
}
// Performs an access into an aggregate, retrieving the specified element.
static auto PerformAggregateAccess(Context& context, SemIR::Inst inst)
-> ConstantEvalResult {
auto access_inst = inst.As<SemIR::AnyAggregateAccess>();
if (auto aggregate = context.insts().TryGetAs<SemIR::AnyAggregateValue>(
access_inst.aggregate_id)) {
auto elements = context.inst_blocks().Get(aggregate->elements_id);
auto index = static_cast<size_t>(access_inst.index.index);
CARBON_CHECK(index < elements.size(), "Access out of bounds.");
// `Phase` is not used here. If this element is a concrete constant, then
// so is the result of indexing, even if the aggregate also contains a
// symbolic context.
return ConstantEvalResult::Existing(
context.constant_values().Get(elements[index]));
}
return ConstantEvalResult::New(inst);
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::ClassElementAccess inst)
-> ConstantEvalResult {
return PerformAggregateAccess(context, inst);
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::StructAccess inst) -> ConstantEvalResult {
return PerformAggregateAccess(context, inst);
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::TupleAccess inst) -> ConstantEvalResult {
return PerformAggregateAccess(context, inst);
}
static auto EvalConstantInst(Context& context, SemIRLoc loc,
SemIR::ImplWitnessAccess inst)
-> ConstantEvalResult {
// This is PerformAggregateAccess followed by GetConstantInSpecific.
if (auto witness =
context.insts().TryGetAs<SemIR::ImplWitness>(inst.witness_id)) {
auto elements = context.inst_blocks().Get(witness->elements_id);
auto index = static_cast<size_t>(inst.index.index);
CARBON_CHECK(index < elements.size(), "Access out of bounds.");
auto element = elements[index];
if (!element.has_value()) {
// TODO: Perhaps this should be a `{}` value with incomplete type?
CARBON_DIAGNOSTIC(ImplAccessMemberBeforeComplete, Error,
"accessing member from impl before the end of "
"its definition");
// TODO: Add note pointing to the impl declaration.
context.emitter().Emit(loc, ImplAccessMemberBeforeComplete);
return ConstantEvalResult::Error;
}
LoadImportRef(context, element);
return ConstantEvalResult::Existing(GetConstantValueInSpecific(
context.sem_ir(), witness->specific_id, element));
}
return ConstantEvalResult::New(inst);
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::BindValue /*inst*/) -> ConstantEvalResult {
// TODO: Handle this once we've decided how to represent constant values of
// reference expressions.
return ConstantEvalResult::TODO;
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::Deref /*inst*/) -> ConstantEvalResult {
// TODO: Handle this.
return ConstantEvalResult::TODO;
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::Temporary /*inst*/) -> ConstantEvalResult {
// TODO: Handle this. Can we just return the value of `init_id`?
return ConstantEvalResult::TODO;
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::VtablePtr /*inst*/) -> ConstantEvalResult {
// TODO: Handle this.
return ConstantEvalResult::TODO;
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::AsCompatible inst) -> ConstantEvalResult {
// AsCompatible changes the type of the source instruction; its constant
// value, if there is one, needs to be modified to be of the same type.
auto value_id = context.constant_values().Get(inst.source_id);
CARBON_CHECK(value_id.is_constant());
auto value_inst =
context.insts().Get(context.constant_values().GetInstId(value_id));
auto phase = GetPhase(context.constant_values(),
context.types().GetConstantId(inst.type_id));
value_inst.SetType(inst.type_id);
// Finish computing the new phase by incorporating the phases of the
// arguments.
// Given an instruction, compute its phase based on its operands.
static auto ComputeInstPhase(Context& context, SemIR::Inst inst) -> Phase {
EvalContext eval_context(context, SemIR::InstId::None);
auto kinds = value_inst.ArgKinds();
GetConstantValueForArg(eval_context, kinds.first, value_inst.arg0(), &phase);
GetConstantValueForArg(eval_context, kinds.second, value_inst.arg1(), &phase);
auto phase = GetPhase(context.constant_values(),
context.types().GetConstantId(inst.type_id()));
auto kinds = inst.ArgKinds();
GetConstantValueForArg(eval_context, kinds.first, inst.arg0(), &phase);
GetConstantValueForArg(eval_context, kinds.second, inst.arg1(), &phase);
CARBON_CHECK(IsConstant(phase));
// We can't use `ConstantEvalResult::New` because it would use the wrong
// phase, so manually build a new constant.
return ConstantEvalResult::Existing(
MakeConstantResult(context, value_inst, phase));
return phase;
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::BindAlias inst) -> ConstantEvalResult {
return ConstantEvalResult::Existing(
context.constant_values().Get(inst.value_id));
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::ExportDecl inst) -> ConstantEvalResult {
return ConstantEvalResult::Existing(
context.constant_values().Get(inst.value_id));
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::NameRef inst) -> ConstantEvalResult {
return ConstantEvalResult::Existing(
context.constant_values().Get(inst.value_id));
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::ValueParamPattern inst)
-> ConstantEvalResult {
// TODO: Treat this as a non-expression (here and in GetExprCategory)
// once generic deduction doesn't need patterns to have constant values.
return ConstantEvalResult::Existing(
context.constant_values().Get(inst.subpattern_id));
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::Converted inst) -> ConstantEvalResult {
return ConstantEvalResult::Existing(
context.constant_values().Get(inst.result_id));
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::InitializeFrom inst) -> ConstantEvalResult {
return ConstantEvalResult::Existing(
context.constant_values().Get(inst.src_id));
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::SpliceBlock inst) -> ConstantEvalResult {
return ConstantEvalResult::Existing(
context.constant_values().Get(inst.result_id));
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::ValueOfInitializer inst)
-> ConstantEvalResult {
return ConstantEvalResult::Existing(
context.constant_values().Get(inst.init_id));
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::FacetAccessType inst)
-> ConstantEvalResult {
if (auto facet_value = context.insts().TryGetAs<SemIR::FacetValue>(
inst.facet_value_inst_id)) {
return ConstantEvalResult::Existing(
context.constant_values().Get(facet_value->type_inst_id));
// Convert a ConstantEvalResult to a ConstantId. Factored out of
// TryEvalTypedInst to avoid repeated instantiation of common code.
static auto ConvertEvalResultToConstantId(Context& context,
ConstantEvalResult result,
Phase orig_phase)
-> SemIR::ConstantId {
if (result.is_new()) {
return MakeConstantResult(
context, result.new_inst(),
result.same_phase_as_inst()
? orig_phase
: ComputeInstPhase(context, result.new_inst()));
}
return ConstantEvalResult::New(inst);
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::FacetAccessWitness inst)
-> ConstantEvalResult {
if (auto facet_value = context.insts().TryGetAs<SemIR::FacetValue>(
inst.facet_value_inst_id)) {
return ConstantEvalResult::Existing(
context.constant_values().Get(facet_value->witness_inst_id));
}
return ConstantEvalResult::New(inst);
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::UnaryOperatorNot inst)
-> ConstantEvalResult {
// `not true` -> `false`, `not false` -> `true`.
// All other uses of unary `not` are non-constant.
auto const_id = context.constant_values().Get(inst.operand_id);
if (const_id.is_concrete()) {
auto value = context.insts().GetAs<SemIR::BoolLiteral>(
context.constant_values().GetInstId(const_id));
value.value = SemIR::BoolValue::From(!value.value.ToBool());
return ConstantEvalResult::New(value);
}
return ConstantEvalResult::NotConstant;
}
static auto EvalConstantInst(Context& context, SemIRLoc /*loc*/,
SemIR::ConstType inst) -> ConstantEvalResult {
// `const (const T)` evaluates to `const T`.
if (context.types().Is<SemIR::ConstType>(inst.inner_id)) {
return ConstantEvalResult::Existing(
context.types().GetConstantId(inst.inner_id));
}
// Otherwise, `const T` evaluates to itself.
return ConstantEvalResult::New(inst);
}
static auto EvalConstantInst(Context& context, SemIRLoc loc,
SemIR::RequireCompleteType inst)
-> ConstantEvalResult {
auto witness_type_id =
GetSingletonType(context, SemIR::WitnessType::SingletonInstId);
// If the type is a concrete constant, require it to be complete now.
auto complete_type_id = inst.complete_type_id;
if (context.types().GetConstantId(complete_type_id).is_concrete()) {
if (!TryToCompleteType(context, complete_type_id, loc, [&] {
// TODO: It'd be nice to report the original type prior to
// evaluation here.
CARBON_DIAGNOSTIC(IncompleteTypeInMonomorphization, Error,
"type {0} is incomplete", SemIR::TypeId);
return context.emitter().Build(loc, IncompleteTypeInMonomorphization,
complete_type_id);
})) {
return ConstantEvalResult::Error;
}
return ConstantEvalResult::New(SemIR::CompleteTypeWitness{
.type_id = witness_type_id,
.object_repr_id = context.types().GetObjectRepr(complete_type_id)});
}
// If it's not a concrete constant, require it to be complete once it
// becomes one.
return ConstantEvalResult::New(inst);
}
static auto EvalConstantInst(Context& /*context*/, SemIRLoc /*loc*/,
SemIR::ImportRefUnloaded inst)
-> ConstantEvalResult {
CARBON_FATAL("ImportRefUnloaded should be loaded before TryEvalInst: {0}",
inst);
return result.existing();
}
// Evaluates an instruction of a known type in an evaluation context. The
@@ -2078,14 +1600,12 @@ static auto TryEvalTypedInst(EvalContext& eval_context, SemIR::InstId inst_id,
ConstantKind == SemIR::InstConstantKind::WheneverPossible) {
return MakeConstantResult(eval_context.context(), inst, phase);
} else {
ConstantEvalResult result = EvalConstantInst(
eval_context.context(), eval_context.GetDiagnosticLoc({inst_id}),
inst.As<InstT>());
if (result.is_new()) {
return MakeConstantResult(eval_context.context(), result.new_inst(),
phase);
}
return result.existing();
return ConvertEvalResultToConstantId(
eval_context.context(),
EvalConstantInst(eval_context.context(),
eval_context.GetDiagnosticLoc({inst_id}),
inst.As<InstT>()),
phase);
}
}
}