llvm/lib/CodeGen/FinalizeISel.cpp

   1 //===-- llvm/CodeGen/FinalizeISel.cpp ---------------------------*- 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 pass expands Pseudo-instructions produced by ISel, fixes register
  10 /// reservations and may do machine frame information adjustments.
  11 /// The pseudo instructions are used to allow the expansion to contain control
  12 /// flow, such as a conditional move implemented with a conditional branch and a
  13 /// phi, or an atomic operation implemented with a loop.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "llvm/CodeGen/MachineFunction.h"
  18 #include "llvm/CodeGen/MachineFunctionPass.h"
  19 #include "llvm/CodeGen/Passes.h"
  20 #include "llvm/CodeGen/TargetLowering.h"
  21 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  22 #include "llvm/InitializePasses.h"
  23 #include "llvm/Support/Debug.h"
  24 using namespace llvm;
  25
  26 #define DEBUG_TYPE "finalize-isel"
  27
  28 namespace {
  29   class FinalizeISel : public MachineFunctionPass {
  30   public:
  31     static char ID; // Pass identification, replacement for typeid
  32     FinalizeISel() : MachineFunctionPass(ID) {}
  33
  34   private:
  35     bool runOnMachineFunction(MachineFunction &MF) override;
  36
  37     void getAnalysisUsage(AnalysisUsage &AU) const override {
  38       MachineFunctionPass::getAnalysisUsage(AU);
  39     }
  40   };
  41 } // end anonymous namespace
  42
  43 char FinalizeISel::ID = 0;
  44 char &llvm::FinalizeISelID = FinalizeISel::ID;
  45 INITIALIZE_PASS(FinalizeISel, DEBUG_TYPE,
  46                 "Finalize ISel and expand pseudo-instructions", false, false)
  47
  48 bool FinalizeISel::runOnMachineFunction(MachineFunction &MF) {
  49   bool Changed = false;
  50   const TargetLowering *TLI = MF.getSubtarget().getTargetLowering();
  51
  52   // Iterate through each instruction in the function, looking for pseudos.
  53   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
  54     MachineBasicBlock *MBB = &*I;
  55     for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
  56          MBBI != MBBE; ) {
  57       MachineInstr &MI = *MBBI++;
  58
  59       // If MI is a pseudo, expand it.
  60       if (MI.usesCustomInsertionHook()) {
  61         Changed = true;
  62         MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(MI, MBB);
  63         // The expansion may involve new basic blocks.
  64         if (NewMBB != MBB) {
  65           MBB = NewMBB;
  66           I = NewMBB->getIterator();
  67           MBBI = NewMBB->begin();
  68           MBBE = NewMBB->end();
  69         }
  70       }
  71     }
  72   }
  73
  74   TLI->finalizeLowering(MF);
  75
  76   return Changed;
  77 }