eeffaf110e
Refactor the stateless (hash-based) token calculation logic out of the `AllocToken` pass and into `llvm/Support/AllocToken.h`. This helps with making the token calculation logic available to other parts of the codebase, which will be necessary for frontend implementation of `__builtin_infer_alloc_token` to perform constexpr evaluation. The `AllocTokenMode` enum and a new `AllocTokenMetadata` struct are moved into a shared header. The `getAllocTokenHash()` function now provides the source of truth for calculating token IDs for `TypeHash` and `TypeHashPointerSplit` modes.
51 lines
1.6 KiB
C++
51 lines
1.6 KiB
C++
//===- AllocToken.cpp - Allocation Token Calculation ----------------------===//
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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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//
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// Definition of AllocToken modes and shared calculation of stateless token IDs.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/AllocToken.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/SipHash.h"
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using namespace llvm;
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static uint64_t getStableHash(const AllocTokenMetadata &Metadata,
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uint64_t MaxTokens) {
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return getStableSipHash(Metadata.TypeName) % MaxTokens;
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}
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std::optional<uint64_t> llvm::getAllocToken(AllocTokenMode Mode,
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const AllocTokenMetadata &Metadata,
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uint64_t MaxTokens) {
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assert(MaxTokens && "Must provide non-zero max tokens");
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switch (Mode) {
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case AllocTokenMode::Increment:
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case AllocTokenMode::Random:
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// Stateful modes cannot be implemented as a pure function.
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return std::nullopt;
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case AllocTokenMode::TypeHash:
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return getStableHash(Metadata, MaxTokens);
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case AllocTokenMode::TypeHashPointerSplit: {
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if (MaxTokens == 1)
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return 0;
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const uint64_t HalfTokens = MaxTokens / 2;
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uint64_t Hash = getStableHash(Metadata, HalfTokens);
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if (Metadata.ContainsPointer)
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Hash += HalfTokens;
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return Hash;
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}
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}
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llvm_unreachable("");
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}
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