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0115643a5b
We shifted the MachineBasicBlocks to the end of the MachineFunction in DFS order. This will not ensure that MachineBasicBlocks which fell through to one another will remain contiguous. Instead, implement a stable sort algorithm for iplist. This partially reverts commit r214150. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@247978 91177308-0d34-0410-b5e6-96231b3b80d8
94 lines
2.9 KiB
C++
94 lines
2.9 KiB
C++
//===-- FuncletLayout.cpp - Contiguously lay out funclets -----------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements basic block placement transformations which result in
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// funclets being contiguous.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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using namespace llvm;
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#define DEBUG_TYPE "funclet-layout"
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namespace {
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class FuncletLayout : public MachineFunctionPass {
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public:
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static char ID; // Pass identification, replacement for typeid
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FuncletLayout() : MachineFunctionPass(ID) {
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initializeFuncletLayoutPass(*PassRegistry::getPassRegistry());
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}
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bool runOnMachineFunction(MachineFunction &F) override;
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};
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}
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static void
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collectFuncletMembers(DenseMap<MachineBasicBlock *, int> &FuncletMembership,
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int Funclet, MachineBasicBlock *MBB) {
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// Don't revisit blocks.
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if (FuncletMembership.count(MBB) > 0)
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return;
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// Add this MBB to our funclet.
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FuncletMembership[MBB] = Funclet;
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bool IsReturn = false;
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int NumTerminators = 0;
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for (MachineInstr &MI : MBB->terminators()) {
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IsReturn |= MI.isReturn();
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++NumTerminators;
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}
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assert((!IsReturn || NumTerminators == 1) &&
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"Expected only one terminator when a return is present!");
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// Returns are boundaries where funclet transfer can occur, don't follow
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// successors.
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if (IsReturn)
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return;
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for (MachineBasicBlock *SMBB : MBB->successors())
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if (!SMBB->isEHPad())
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collectFuncletMembers(FuncletMembership, Funclet, SMBB);
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}
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char FuncletLayout::ID = 0;
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char &llvm::FuncletLayoutID = FuncletLayout::ID;
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INITIALIZE_PASS(FuncletLayout, "funclet-layout",
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"Contiguously Lay Out Funclets", false, false)
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bool FuncletLayout::runOnMachineFunction(MachineFunction &F) {
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// We don't have anything to do if there aren't any EH pads.
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if (!F.getMMI().hasEHFunclets())
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return false;
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SmallVector<MachineBasicBlock *, 16> FuncletBlocks;
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for (MachineBasicBlock &MBB : F)
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if (MBB.isEHFuncletEntry())
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FuncletBlocks.push_back(&MBB);
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// We don't have anything to do if there aren't any EH pads.
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if (FuncletBlocks.empty())
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return false;
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DenseMap<MachineBasicBlock *, int> FuncletMembership;
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for (MachineBasicBlock *MBB : FuncletBlocks)
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collectFuncletMembers(FuncletMembership, MBB->getNumber(), MBB);
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F.sort([&](MachineBasicBlock &x, MachineBasicBlock &y) {
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return FuncletMembership[&x] < FuncletMembership[&y];
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});
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// Conservatively assume we changed something.
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return true;
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}
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