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https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 21:30:12 +01:00
Adrien Leravat
19c74ead49
Add partial support for initializing expressions for variable declaration. This is based on https://github.com/carbon-language/carbon-lang/pull/2006, which introduces expression categories, and how it is possible to convert to/from those different categories. ## Functional changes * Initializing expressions initialize directly the provided storage when used to initialize a variable. * Allows initializing expressions to avoid a copy when using `[var|let] name: type = call_expression(...)` by initializing `name` in-place. * Support `returned var: ...` and `return <expr>` * Support nested initializing expressions ## Main implementation changes * Updated PatternMatch logic to handle expression categories * Updated `VariableDefinition` interpreter statement to allocate and pass a location to initializing expressions * Update statement actions to allow passing an allocation, used by return expr or returned var * Modified the RuntimeScope API to be one step closer to the memory model we want to have * Remove `GetAllocationId` and older `Bind` which don't apply * New set of tests to highlight those different situations * Added a new intrinsic to print the allocation stack (and make sure we behave correctly, beyond visible side effects) ## Next work * Dedicated `Action` to retrieve expression category information in the interpreter (https://github.com/carbon-language/carbon-lang/pull/2927) * Avoid copies when initializing value expression from reference expression and prevent mutations for the duration of the "pinning" (https://github.com/carbon-language/carbon-lang/pull/2927) * Avoid unnecessary copies from value expression to value expression, after ensuring that even value expression temporaries are registered for destruction. * Avoid unnecessary copies when binding function arguments
39 lines
997 B
Plaintext
39 lines
997 B
Plaintext
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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// AUTOUPDATE
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// CHECK:STDOUT: Initialize c from initializing expression (return <expr>)
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// CHECK:STDOUT: 0: Heap{}, 1: !Uninit<class C>, 2: C{}
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// CHECK:STDOUT: Object created, returning
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// CHECK:STDOUT: c destroyed
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// CHECK:STDOUT: 0: Heap{}, 1: C{}, 2: !!C{}
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// CHECK:STDOUT: c destroyed
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// CHECK:STDOUT: result: 0
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package ExplorerTest api;
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class C {
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destructor[self: Self] {
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Print("c destroyed");
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}
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}
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fn CallWithReturnExpression() -> C {
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var c: C = {};
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heap.PrintAllocs();
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Print("Object created, returning");
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return c;
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}
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fn FromInitializingExpression_ReturnExpr() {
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Print("Initialize c from initializing expression (return <expr>)");
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let c: C = CallWithReturnExpression();
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heap.PrintAllocs();
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}
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fn Main() -> i32 {
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FromInitializingExpression_ReturnExpr();
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return 0;
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}
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