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Model function calls as initializing expressions (#3089)

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Start treating function calls as initializing expressions instead of as
value expressions.

This required adding support for expression categories. Value bindings
and temporary materialization conversions are created where necessary to
transition between expression categories. For a function call with a
return slot, we speculatively create a materialized temporary before the
call and either commit to it or replace it with something else later,
once we see how the function call expression is actually used.

This change follows the direction suggested in #3133 for initializing
expressions: depending on the return type of a function, the return
value will either be initialized in-place or returned directly. This is
visible in the semantics IR, which is a little unfortunate but is
probably necessary as this is part of the semantics of the program.

---------

Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
This commit is contained in:
Richard Smith
2023-08-24 19:35:07 +00:00
committed by GitHub
co-authored by Chandler Carruth
parent f790a27ace
commit 1013d1773c
101 changed files with 1802 additions and 777 deletions
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toolchain/semantics/semantics_handle_operator.cpp
+12 -8
View File
@@ -16,8 +16,9 @@ auto HandleInfixOperator(Context& context, ParseTree::Node parse_node) -> bool {
case TokenKind::Plus:
// TODO: This should search for a compatible interface. For now, it's a
// very trivial check of validity on the operation.
lhs_id = context.ImplicitAsRequired(
lhs_id = context.ConvertToValueOfType(
parse_node, lhs_id, context.semantics_ir().GetNode(rhs_id).type_id());
rhs_id = context.ConvertToValueExpression(rhs_id);
context.AddNodeAndPush(
parse_node,
@@ -31,7 +32,7 @@ auto HandleInfixOperator(Context& context, ParseTree::Node parse_node) -> bool {
// The first operand is wrapped in a ShortCircuitOperand, which we
// already handled by creating a RHS block and a resumption block, which
// are the current block and its enclosing block.
rhs_id = context.ImplicitAsBool(parse_node, rhs_id);
rhs_id = context.ConvertToBoolValue(parse_node, rhs_id);
// When the second operand is evaluated, the result of `and` and `or` is
// its value.
@@ -58,10 +59,12 @@ auto HandleInfixOperator(Context& context, ParseTree::Node parse_node) -> bool {
"Expression is not assignable.");
context.emitter().Emit(lhs_node, AssignmentToNonAssignable);
}
context.ImplicitAsRequired(
parse_node, rhs_id, context.semantics_ir().GetNode(lhs_id).type_id());
context.AddNodeAndPush(
parse_node, SemIR::Node::Assign::Make(parse_node, lhs_id, rhs_id));
context.Initialize(parse_node, lhs_id, rhs_id);
// We model assignment as an expression, so we need to push a value for
// it, even though it doesn't produce a value.
// TODO: Consider changing our parse tree to model assignment as a
// different kind of statement than an expression statement.
context.node_stack().Push(parse_node, lhs_id);
return true;
}
default:
@@ -143,7 +146,7 @@ auto HandlePrefixOperator(Context& context, ParseTree::Node parse_node)
}
case TokenKind::Not:
value_id = context.ImplicitAsBool(parse_node, value_id);
value_id = context.ConvertToBoolValue(parse_node, value_id);
context.AddNodeAndPush(
parse_node,
SemIR::Node::UnaryOperatorNot::Make(
@@ -176,6 +179,7 @@ auto HandlePrefixOperator(Context& context, ParseTree::Node parse_node)
}
builder.Emit();
}
value_id = context.ConvertToValueExpression(value_id);
context.AddNodeAndPush(
parse_node,
SemIR::Node::Dereference::Make(parse_node, result_type_id, value_id));
@@ -191,7 +195,7 @@ auto HandleShortCircuitOperand(Context& context, ParseTree::Node parse_node)
-> bool {
// Convert the condition to `bool`.
auto cond_value_id = context.node_stack().PopExpression();
cond_value_id = context.ImplicitAsBool(parse_node, cond_value_id);
cond_value_id = context.ConvertToBoolValue(parse_node, cond_value_id);
auto bool_type_id = context.semantics_ir().GetNode(cond_value_id).type_id();
// Compute the branch value: the condition for `and`, inverted for `or`.