/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/lib/CodeGen/AntiDepBreaker.h
Line | Count | Source (jump to first uncovered line) |
1 | | //===- llvm/CodeGen/AntiDepBreaker.h - Anti-Dependence Breaking -*- 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 | | // This file implements the AntiDepBreaker class, which implements |
10 | | // anti-dependence breaking heuristics for post-register-allocation scheduling. |
11 | | // |
12 | | //===----------------------------------------------------------------------===// |
13 | | |
14 | | #ifndef LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H |
15 | | #define LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H |
16 | | |
17 | | #include "llvm/ADT/iterator_range.h" |
18 | | #include "llvm/CodeGen/MachineBasicBlock.h" |
19 | | #include "llvm/CodeGen/MachineInstr.h" |
20 | | #include "llvm/CodeGen/MachineOperand.h" |
21 | | #include "llvm/CodeGen/ScheduleDAG.h" |
22 | | #include "llvm/Support/Compiler.h" |
23 | | #include <cassert> |
24 | | #include <utility> |
25 | | #include <vector> |
26 | | |
27 | | namespace llvm { |
28 | | |
29 | | /// This class works in conjunction with the post-RA scheduler to rename |
30 | | /// registers to break register anti-dependencies (WAR hazards). |
31 | | class LLVM_LIBRARY_VISIBILITY AntiDepBreaker { |
32 | | public: |
33 | | using DbgValueVector = |
34 | | std::vector<std::pair<MachineInstr *, MachineInstr *>>; |
35 | | |
36 | | virtual ~AntiDepBreaker(); |
37 | | |
38 | | /// Initialize anti-dep breaking for a new basic block. |
39 | | virtual void StartBlock(MachineBasicBlock *BB) = 0; |
40 | | |
41 | | /// Identifiy anti-dependencies within a basic-block region and break them by |
42 | | /// renaming registers. Return the number of anti-dependencies broken. |
43 | | virtual unsigned BreakAntiDependencies(const std::vector<SUnit> &SUnits, |
44 | | MachineBasicBlock::iterator Begin, |
45 | | MachineBasicBlock::iterator End, |
46 | | unsigned InsertPosIndex, |
47 | | DbgValueVector &DbgValues) = 0; |
48 | | |
49 | | /// Update liveness information to account for the current |
50 | | /// instruction, which will not be scheduled. |
51 | | virtual void Observe(MachineInstr &MI, unsigned Count, |
52 | | unsigned InsertPosIndex) = 0; |
53 | | |
54 | | /// Finish anti-dep breaking for a basic block. |
55 | | virtual void FinishBlock() = 0; |
56 | | |
57 | | /// Update DBG_VALUE if dependency breaker is updating |
58 | | /// other machine instruction to use NewReg. |
59 | 3 | void UpdateDbgValue(MachineInstr &MI, unsigned OldReg, unsigned NewReg) { |
60 | 3 | assert(MI.isDebugValue() && "MI is not DBG_VALUE!"); |
61 | 3 | if (MI.getOperand(0).isReg() && MI.getOperand(0).getReg() == OldReg) |
62 | 2 | MI.getOperand(0).setReg(NewReg); |
63 | 3 | } |
64 | | |
65 | | /// Update all DBG_VALUE instructions that may be affected by the dependency |
66 | | /// breaker's update of ParentMI to use NewReg. |
67 | | void UpdateDbgValues(const DbgValueVector &DbgValues, MachineInstr *ParentMI, |
68 | 1.90k | unsigned OldReg, unsigned NewReg) { |
69 | 1.90k | // The following code is dependent on the order in which the DbgValues are |
70 | 1.90k | // constructed in ScheduleDAGInstrs::buildSchedGraph. |
71 | 1.90k | MachineInstr *PrevDbgMI = nullptr; |
72 | 1.90k | for (const auto &DV : make_range(DbgValues.crbegin(), DbgValues.crend())) { |
73 | 85 | MachineInstr *PrevMI = DV.second; |
74 | 85 | if ((PrevMI == ParentMI) || (PrevMI == PrevDbgMI)84 ) { |
75 | 3 | MachineInstr *DbgMI = DV.first; |
76 | 3 | UpdateDbgValue(*DbgMI, OldReg, NewReg); |
77 | 3 | PrevDbgMI = DbgMI; |
78 | 82 | } else if (PrevDbgMI) { |
79 | 0 | break; // If no match and already found a DBG_VALUE, we're done. |
80 | 0 | } |
81 | 85 | } |
82 | 1.90k | } |
83 | | }; |
84 | | |
85 | | } // end namespace llvm |
86 | | |
87 | | #endif // LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H |