1//===- llvm/CodeGen/GlobalISel/GIMatchTableExecutor.cpp -------------------===//
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/// This file implements the GIMatchTableExecutor class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/CodeGen/GlobalISel/GIMatchTableExecutor.h"
15#include "llvm/CodeGen/GlobalISel/Utils.h"
16#include "llvm/CodeGen/MachineInstr.h"
17#include "llvm/CodeGen/MachineOperand.h"
18#include "llvm/CodeGen/MachineRegisterInfo.h"
19
20#define DEBUG_TYPE "gi-match-table-executor"
21
22using namespace llvm;
23
24GIMatchTableExecutor::MatcherState::MatcherState(unsigned MaxRenderers)
25 : Renderers(MaxRenderers) {}
26
27GIMatchTableExecutor::GIMatchTableExecutor() = default;
28
29bool GIMatchTableExecutor::isOperandImmEqual(const MachineOperand &MO,
30 int64_t Value,
31 const MachineRegisterInfo &MRI,
32 bool Splat) const {
33 if (MO.isReg() && MO.getReg()) {
34 if (auto VRegVal = getIConstantVRegValWithLookThrough(VReg: MO.getReg(), MRI))
35 return VRegVal->Value.getSExtValue() == Value;
36
37 if (Splat) {
38 if (auto VRegVal = getIConstantSplatVal(Reg: MO.getReg(), MRI))
39 return VRegVal->getSExtValue() == Value;
40 }
41 }
42 return false;
43}
44
45bool GIMatchTableExecutor::isBaseWithConstantOffset(
46 const MachineOperand &Root, const MachineRegisterInfo &MRI) const {
47 if (!Root.isReg())
48 return false;
49
50 MachineInstr *RootI = MRI.getVRegDef(Reg: Root.getReg());
51 if (RootI->getOpcode() != TargetOpcode::G_PTR_ADD)
52 return false;
53
54 MachineOperand &RHS = RootI->getOperand(i: 2);
55 MachineInstr *RHSI = MRI.getVRegDef(Reg: RHS.getReg());
56 if (RHSI->getOpcode() != TargetOpcode::G_CONSTANT)
57 return false;
58
59 return true;
60}
61
62bool GIMatchTableExecutor::isObviouslySafeToFold(MachineInstr &MI,
63 MachineInstr &IntoMI) const {
64 auto IntoMIIter = IntoMI.getIterator();
65
66 // Immediate neighbours are already folded.
67 if (MI.getParent() == IntoMI.getParent() &&
68 std::next(x: MI.getIterator()) == IntoMIIter)
69 return true;
70
71 // Convergent instructions cannot be moved in the CFG.
72 if (MI.isConvergent() && MI.getParent() != IntoMI.getParent())
73 return false;
74
75 if (MI.isLoadFoldBarrier())
76 return false;
77
78 // If the load is simple, check instructions between MI and IntoMI
79 if (MI.mayLoad() && MI.getParent() == IntoMI.getParent()) {
80 if (MI.memoperands_empty())
81 return false;
82 auto &MMO = **(MI.memoperands_begin());
83 if (MMO.isAtomic() || MMO.isVolatile())
84 return false;
85
86 // Ensure instructions between MI and IntoMI are not affected when combined
87 unsigned Iter = 0;
88 const unsigned MaxIter = 20;
89 for (auto &CurrMI :
90 instructionsWithoutDebug(It: MI.getIterator(), End: IntoMI.getIterator())) {
91 if (CurrMI.isLoadFoldBarrier())
92 return false;
93
94 if (Iter++ == MaxIter)
95 return false;
96 }
97
98 return true;
99 }
100
101 return !MI.mayLoad();
102}
103