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Constant evaluation support for initializing expressions. (#3624)

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The constant value we associate with an initializing representation is
the object representation that the initializing expression will store to
its destination.

Also include the type in the profile of an instruction. This is now
necessary for array values, which are represented as tuple_value
instructions with array type, to avoid instructions with different types
being merged by constant canonicalization.
This commit is contained in:
Richard Smith
2024-01-19 23:28:53 +00:00
committed by GitHub
parent a1d03b1f56
commit 87ecb34f6b
54 changed files with 588 additions and 398 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/eval.cpp
+50 -17
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@@ -138,6 +138,22 @@ static auto RebuildIfFieldsAreConstant(Context& context, SemIR::Inst inst,
: SemIR::ConstantId::NotConstant;
}
// Rebuilds the given aggregate initialization instruction as a corresponding
// constant aggregate value, if its elements are all constants.
static auto RebuildInitAsValue(Context& context, SemIR::Inst inst,
SemIR::InstKind value_kind)
-> SemIR::ConstantId {
auto init_inst = inst.As<SemIR::AnyAggregateInit>();
Phase phase = Phase::Template;
auto elements_id = GetConstantValue(context, init_inst.elements_id, &phase);
return MakeConstantResult(
context,
SemIR::AnyAggregateValue{.kind = value_kind,
.type_id = init_inst.type_id,
.elements_id = elements_id},
phase);
}
auto TryEvalInst(Context& context, SemIR::InstId inst_id, SemIR::Inst inst)
-> SemIR::ConstantId {
// TODO: Ensure we have test coverage for each of these cases that can result
@@ -163,13 +179,24 @@ auto TryEvalInst(Context& context, SemIR::InstId inst_id, SemIR::Inst inst)
case SemIR::StructValue::Kind:
return RebuildIfFieldsAreConstant(context, inst,
&SemIR::StructValue::elements_id);
case SemIR::Temporary::Kind:
return RebuildIfFieldsAreConstant(context, inst,
&SemIR::Temporary::init_id);
case SemIR::TupleValue::Kind:
return RebuildIfFieldsAreConstant(context, inst,
&SemIR::TupleValue::elements_id);
// Initializers evaluate to a value of the object representation.
case SemIR::ArrayInit::Kind:
// TODO: Add an `ArrayValue` to represent a constant array object
// representation instead of using a `TupleValue`.
return RebuildInitAsValue(context, inst, SemIR::TupleValue::Kind);
case SemIR::ClassInit::Kind:
// TODO: Add a `ClassValue` to represent a constant class object
// representation instead of using a `StructValue`.
return RebuildInitAsValue(context, inst, SemIR::StructValue::Kind);
case SemIR::StructInit::Kind:
return RebuildInitAsValue(context, inst, SemIR::StructValue::Kind);
case SemIR::TupleInit::Kind:
return RebuildInitAsValue(context, inst, SemIR::TupleValue::Kind);
// These cases are always constants.
case SemIR::Builtin::Kind:
case SemIR::ClassType::Kind:
@@ -200,25 +227,22 @@ auto TryEvalInst(Context& context, SemIR::InstId inst_id, SemIR::Inst inst)
// by `APInt`s with different bit widths.
return MakeConstantResult(context, inst, Phase::Template);
// TODO: These need special handling.
// TODO: Support subobject access.
case SemIR::ArrayIndex::Kind:
case SemIR::ArrayInit::Kind:
case SemIR::BindValue::Kind:
case SemIR::Call::Kind:
case SemIR::ClassElementAccess::Kind:
case SemIR::ClassInit::Kind:
case SemIR::CrossRef::Kind:
case SemIR::Deref::Kind:
case SemIR::InitializeFrom::Kind:
case SemIR::SpliceBlock::Kind:
case SemIR::StructAccess::Kind:
case SemIR::StructInit::Kind:
case SemIR::TemporaryStorage::Kind:
case SemIR::TupleAccess::Kind:
case SemIR::TupleIndex::Kind:
case SemIR::TupleInit::Kind:
break;
// TODO: These need special handling.
case SemIR::BindValue::Kind:
case SemIR::Call::Kind:
case SemIR::CrossRef::Kind:
case SemIR::Deref::Kind:
case SemIR::Temporary::Kind:
case SemIR::TemporaryStorage::Kind:
case SemIR::ValueAsRef::Kind:
case SemIR::ValueOfInitializer::Kind:
break;
case SemIR::BindSymbolicName::Kind:
@@ -233,12 +257,21 @@ auto TryEvalInst(Context& context, SemIR::InstId inst_id, SemIR::Inst inst)
// creating a `BindName` in that case?
return context.constant_values().Get(inst.As<SemIR::BindName>().value_id);
// These semnatic wrappers don't change the constant value.
case SemIR::NameRef::Kind:
return context.constant_values().Get(inst.As<SemIR::NameRef>().value_id);
case SemIR::Converted::Kind:
return context.constant_values().Get(
inst.As<SemIR::Converted>().result_id);
case SemIR::InitializeFrom::Kind:
return context.constant_values().Get(
inst.As<SemIR::InitializeFrom>().src_id);
case SemIR::SpliceBlock::Kind:
return context.constant_values().Get(
inst.As<SemIR::SpliceBlock>().result_id);
case SemIR::ValueOfInitializer::Kind:
return context.constant_values().Get(
inst.As<SemIR::ValueOfInitializer>().init_id);
// `not true` -> `false`, `not false` -> `true`.
// All other uses of unary `not` are non-constant.