forked from OSchip/llvm-project
86 lines
2.5 KiB
C++
86 lines
2.5 KiB
C++
//===-- MipsConstantIslandPass.cpp - Emit Pc Relative loads----------------===//
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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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//
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// This pass is used to make Pc relative loads of constants.
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// For now, only Mips16 will use this. While it has the same name and
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// uses many ideas from the LLVM ARM Constant Island Pass, it's not intended
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// to reuse any of the code from the ARM version.
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//
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// Loading constants inline is expensive on Mips16 and it's in general better
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// to place the constant nearby in code space and then it can be loaded with a
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// simple 16 bit load instruction.
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//
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// The constants can be not just numbers but addresses of functions and labels.
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// This can be particularly helpful in static relocation mode for embedded
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// non linux targets.
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//
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//
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#define DEBUG_TYPE "mips-constant-islands"
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#include "Mips.h"
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#include "MCTargetDesc/MipsBaseInfo.h"
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#include "MipsTargetMachine.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/IR/Function.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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using namespace llvm;
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namespace {
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typedef MachineBasicBlock::iterator Iter;
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typedef MachineBasicBlock::reverse_iterator ReverseIter;
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class MipsConstantIslands : public MachineFunctionPass {
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public:
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static char ID;
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MipsConstantIslands(TargetMachine &tm)
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: MachineFunctionPass(ID), TM(tm),
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TII(static_cast<const MipsInstrInfo*>(tm.getInstrInfo())),
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IsPIC(TM.getRelocationModel() == Reloc::PIC_),
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ABI(TM.getSubtarget<MipsSubtarget>().getTargetABI()) {}
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virtual const char *getPassName() const {
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return "Mips Constant Islands";
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}
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bool runOnMachineFunction(MachineFunction &F);
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private:
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const TargetMachine &TM;
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const MipsInstrInfo *TII;
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bool IsPIC;
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unsigned ABI;
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};
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char MipsConstantIslands::ID = 0;
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} // end of anonymous namespace
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/// createMipsLongBranchPass - Returns a pass that converts branches to long
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/// branches.
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FunctionPass *llvm::createMipsConstantIslandPass(MipsTargetMachine &tm) {
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return new MipsConstantIslands(tm);
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}
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bool MipsConstantIslands::runOnMachineFunction(MachineFunction &F) {
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return true;
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}
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