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https://github.com/carbon-language/carbon-lang.git
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Richard Smith
35c2142392
Per the design, field access into a class value expression is a value expression, even though we could produce an ephemeral reference expression instead and avoid performing a value binding. This slightly pessimizes class member access in some cases, but we should be able to restore the old generated code by deferring actually performing the value binding until a value expression is needed.
40 lines
1.9 KiB
Plaintext
40 lines
1.9 KiB
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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class C {
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var a: (i32, i32, i32);
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}
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fn F(c: C) -> i32 {
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// TODO: `c.a` is a value expression here, which forces a value binding as
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// part of the member access, creating a tuple value temporary. We could
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// defer performing the value binding to avoid creating this temporary.
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return c.a[1];
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}
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// CHECK:STDOUT: ; ModuleID = 'value_access.carbon'
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// CHECK:STDOUT: source_filename = "value_access.carbon"
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// CHECK:STDOUT:
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// CHECK:STDOUT: define i32 @F(ptr %c) {
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// CHECK:STDOUT: %a = getelementptr inbounds { { i32, i32, i32 } }, ptr %c, i32 0, i32 0
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// CHECK:STDOUT: %tuple.elem = getelementptr inbounds { i32, i32, i32 }, ptr %a, i32 0, i32 0
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// CHECK:STDOUT: %1 = load i32, ptr %tuple.elem, align 4
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// CHECK:STDOUT: %tuple.elem1 = getelementptr inbounds { i32, i32, i32 }, ptr %a, i32 0, i32 1
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// CHECK:STDOUT: %2 = load i32, ptr %tuple.elem1, align 4
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// CHECK:STDOUT: %tuple.elem2 = getelementptr inbounds { i32, i32, i32 }, ptr %a, i32 0, i32 2
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// CHECK:STDOUT: %3 = load i32, ptr %tuple.elem2, align 4
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// CHECK:STDOUT: %tuple = alloca { i32, i32, i32 }, align 8
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// CHECK:STDOUT: %4 = getelementptr inbounds { i32, i32, i32 }, ptr %tuple, i32 0, i32 0
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// CHECK:STDOUT: store i32 %1, ptr %4, align 4
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// CHECK:STDOUT: %5 = getelementptr inbounds { i32, i32, i32 }, ptr %tuple, i32 0, i32 1
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// CHECK:STDOUT: store i32 %2, ptr %5, align 4
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// CHECK:STDOUT: %6 = getelementptr inbounds { i32, i32, i32 }, ptr %tuple, i32 0, i32 2
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// CHECK:STDOUT: store i32 %3, ptr %6, align 4
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// CHECK:STDOUT: %tuple.index = getelementptr inbounds { i32, i32, i32 }, ptr %tuple, i32 0, i32 1
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// CHECK:STDOUT: %tuple.index.load = load i32, ptr %tuple.index, align 4
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// CHECK:STDOUT: ret i32 %tuple.index.load
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// CHECK:STDOUT: }
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