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The `Twine::str()` function currently always allocates heap memory via `std::string`. However, some instances of `Twine` don't need an intermediate buffer at all, and the rest can attempt to print into a stack buffer first. This is intentionally not making use of `Twine::isSingleStringLiteral()` from D157010 to skip saving the string in the bump-pointer allocator, since the `StringSaver` documentation suggests that MUST happen for every given string. Reviewed By: benlangmuir Differential Revision: https://reviews.llvm.org/D157015
39 lines
1.1 KiB
C++
39 lines
1.1 KiB
C++
//===-- StringSaver.cpp ---------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/StringSaver.h"
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#include "llvm/ADT/SmallString.h"
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using namespace llvm;
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StringRef StringSaver::save(StringRef S) {
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char *P = Alloc.Allocate<char>(S.size() + 1);
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if (!S.empty())
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memcpy(P, S.data(), S.size());
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P[S.size()] = '\0';
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return StringRef(P, S.size());
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}
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StringRef StringSaver::save(const Twine &S) {
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SmallString<128> Storage;
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return save(S.toStringRef(Storage));
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}
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StringRef UniqueStringSaver::save(StringRef S) {
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auto R = Unique.insert(S);
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if (R.second) // cache miss, need to actually save the string
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*R.first = Strings.save(S); // safe replacement with equal value
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return *R.first;
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}
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StringRef UniqueStringSaver::save(const Twine &S) {
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SmallString<128> Storage;
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return save(S.toStringRef(Storage));
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}
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