1 //===-- SIFixVGPRCopies.cpp - Fix VGPR Copies after regalloc --------------===//
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 /// Add implicit use of exec to vector register copies.
11 ///
12 //===----------------------------------------------------------------------===//
13 
14 #include "AMDGPU.h"
15 #include "AMDGPUSubtarget.h"
16 #include "SIInstrInfo.h"
17 #include "MCTargetDesc/AMDGPUMCTargetDesc.h"
18 #include "llvm/CodeGen/MachineFunctionPass.h"
19 
20 using namespace llvm;
21 
22 #define DEBUG_TYPE "si-fix-vgpr-copies"
23 
24 namespace {
25 
26 class SIFixVGPRCopies : public MachineFunctionPass {
27 public:
28   static char ID;
29 
30 public:
31   SIFixVGPRCopies() : MachineFunctionPass(ID) {
32     initializeSIFixVGPRCopiesPass(*PassRegistry::getPassRegistry());
33   }
34 
35   bool runOnMachineFunction(MachineFunction &MF) override;
36 
37   StringRef getPassName() const override { return "SI Fix VGPR copies"; }
38 };
39 
40 } // End anonymous namespace.
41 
42 INITIALIZE_PASS(SIFixVGPRCopies, DEBUG_TYPE, "SI Fix VGPR copies", false, false)
43 
44 char SIFixVGPRCopies::ID = 0;
45 
46 char &llvm::SIFixVGPRCopiesID = SIFixVGPRCopies::ID;
47 
48 bool SIFixVGPRCopies::runOnMachineFunction(MachineFunction &MF) {
49   const GCNSubtarget &ST = MF.getSubtarget<GCNSubtarget>();
50   const SIRegisterInfo *TRI = ST.getRegisterInfo();
51   const SIInstrInfo *TII = ST.getInstrInfo();
52   bool Changed = false;
53 
54   for (MachineBasicBlock &MBB : MF) {
55     for (MachineInstr &MI : MBB) {
56       switch (MI.getOpcode()) {
57       case AMDGPU::COPY:
58         if (TII->isVGPRCopy(MI) && !MI.readsRegister(AMDGPU::EXEC, TRI)) {
59           MI.addOperand(MF,
60                         MachineOperand::CreateReg(AMDGPU::EXEC, false, true));
61           LLVM_DEBUG(dbgs() << "Add exec use to " << MI);
62           Changed = true;
63         }
64         break;
65       default:
66         break;
67       }
68     }
69   }
70 
71   return Changed;
72 }
73