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https://github.com/carbon-language/carbon-lang.git
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Chandler Carruth
f27a977d86
These only show up post-merge as we're only running ASan there. This disables the recent `[[clang::preserve_none]]` optimization when ASan is enabled as there is an LLVM bug on AArch64 that causes register corruption with that calling convention. This is factored into a common helper library so we can use it in other places as well. Assisted-by: Antigravity with Gemini
49 lines
1.5 KiB
C++
49 lines
1.5 KiB
C++
// 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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#include "common/preserve_none.h"
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#include <gtest/gtest.h>
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#include <array>
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namespace Carbon {
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namespace {
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using DispatchFn = auto(int value, int remaining) CARBON_PRESERVE_NONE->int;
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CARBON_PRESERVE_NONE static auto DispatchDone(int value, int /*remaining*/)
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-> int {
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return value;
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}
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CARBON_PRESERVE_NONE static auto DispatchStep(int value, int remaining) -> int;
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constexpr std::array<DispatchFn*, 2> DispatchTable = {
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&DispatchDone,
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&DispatchStep,
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};
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CARBON_PRESERVE_NONE static auto DispatchStep(int value, int remaining) -> int {
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// Touch enough temporaries that register allocation exercises caller-saved
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// registers under `preserve_none`.
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int next = (value * 3 + 1) ^ (remaining * 7);
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int next_remaining = remaining - 1;
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[[clang::musttail]] return DispatchTable[next_remaining != 0 ? 1 : 0](
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next, next_remaining);
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}
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TEST(PreserveNoneTest, TailCallDispatchWithAlignedCallerStack) {
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// Overalign a local buffer so sanitizer stack instrumentation exercises stack
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// realignment alongside `CARBON_PRESERVE_NONE` calls.
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alignas(64) std::array<int, 8> scratch = {1, 2, 3, 4, 5, 6, 7, 8};
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DispatchFn* entry = &DispatchStep;
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int result = entry(scratch[0], 16);
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EXPECT_EQ(scratch[7], 8);
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EXPECT_NE(result, 0);
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}
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} // namespace
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} // namespace Carbon
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