1//===-- ParallelSnippetGenerator.h ------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8///
9/// \file
10/// A SnippetGenerator implementation to create parallel instruction snippets.
11///
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_TOOLS_LLVM_EXEGESIS_PARALLELSNIPPETGENERATOR_H
15#define LLVM_TOOLS_LLVM_EXEGESIS_PARALLELSNIPPETGENERATOR_H
16
17#include "SnippetGenerator.h"
18
19namespace llvm {
20namespace exegesis {
21
22class ParallelSnippetGenerator : public SnippetGenerator {
23public:
24 using SnippetGenerator::SnippetGenerator;
25 ~ParallelSnippetGenerator() override;
26
27 Expected<std::vector<CodeTemplate>>
28 generateCodeTemplates(InstructionTemplate Variant,
29 const BitVector &ForbiddenRegisters) const override;
30
31 static constexpr const size_t kMinNumDifferentAddresses = 6;
32
33private:
34 // Instantiates memory operands within a snippet.
35 // To make computations as parallel as possible, we generate independant
36 // memory locations for instructions that load and store. If there are less
37 // than kMinNumDifferentAddresses in the original snippet, we duplicate
38 // instructions until there are this number of instructions.
39 // For example, assuming kMinNumDifferentAddresses=5 and
40 // getMaxMemoryAccessSize()=64, if the original snippet is:
41 // mov eax, [memory]
42 // we might generate:
43 // mov eax, [rdi]
44 // mov eax, [rdi + 64]
45 // mov eax, [rdi + 128]
46 // mov eax, [rdi + 192]
47 // mov eax, [rdi + 256]
48 // If the original snippet is:
49 // mov eax, [memory]
50 // add eax, [memory]
51 // we might generate:
52 // mov eax, [rdi]
53 // add eax, [rdi + 64]
54 // mov eax, [rdi + 128]
55 // add eax, [rdi + 192]
56 // mov eax, [rdi + 256]
57 void instantiateMemoryOperands(
58 MCRegister ScratchSpaceReg,
59 std::vector<InstructionTemplate> &SnippetTemplate) const;
60};
61
62} // namespace exegesis
63} // namespace llvm
64
65#endif // LLVM_TOOLS_LLVM_EXEGESIS_PARALLELSNIPPETGENERATOR_H
66