87 lines
2.6 KiB
C++
87 lines
2.6 KiB
C++
//===-- MipsDirectObjLower.cpp - Mips LLVM direct object lowering -----===//
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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 contains code to lower Mips MCInst records that are normally
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// left to the assembler to lower such as large shifts.
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//
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//===----------------------------------------------------------------------===//
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#include "MipsDirectObjLower.h"
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#include "MipsInstrInfo.h"
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#include "llvm/MC/MCInst.h"
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#include "llvm/MC/MCStreamer.h"
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using namespace llvm;
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// If the D<shift> instruction has a shift amount that is greater
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// than 31 (checked in calling routine), lower it to a D<shift>32 instruction
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void Mips::LowerLargeShift(MCInst& Inst) {
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assert(Inst.getNumOperands() == 3 && "Invalid no. of operands for shift!");
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assert(Inst.getOperand(2).isImm());
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bool isLarge = false;
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int64_t Shift;
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Shift = Inst.getOperand(2).getImm();
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if (Shift > 31) {
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Shift -= 32;
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isLarge = true;
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}
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// saminus32
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(Inst.getOperand(2)).setImm(Shift);
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if (isLarge)
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switch (Inst.getOpcode()) {
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default:
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// Calling function is not synchronized
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llvm_unreachable("Unexpected shift instruction");
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case Mips::DSLL:
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Inst.setOpcode(Mips::DSLL32);
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return;
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case Mips::DSRL:
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Inst.setOpcode(Mips::DSRL32);
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return;
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case Mips::DSRA:
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Inst.setOpcode(Mips::DSRA32);
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return;
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}
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}
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// Pick a DEXT or DINS instruction variant based on the pos and size operands
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void Mips::LowerDextDins(MCInst& InstIn) {
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int Opcode = InstIn.getOpcode();
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if (Opcode == Mips::DEXT)
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assert(InstIn.getNumOperands() == 4 &&
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"Invalid no. of machine operands for DEXT!");
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else // Only DEXT and DINS are possible
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assert(InstIn.getNumOperands() == 5 &&
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"Invalid no. of machine operands for DINS!");
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assert(InstIn.getOperand(2).isImm());
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int64_t pos = InstIn.getOperand(2).getImm();
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assert(InstIn.getOperand(3).isImm());
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int64_t size = InstIn.getOperand(3).getImm();
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if (size <= 32) {
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if ((pos < 32)) { // DEXT/DINS, do nothing
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return;
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} else { // DEXTU/DINSU
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InstIn.getOperand(2).setImm(pos - 32);
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InstIn.setOpcode((Opcode == Mips::DEXT) ? Mips::DEXTU : Mips::DINSU);
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return;
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}
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} else { // DEXTM/DINSM
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assert(pos < 32 && "DEXT/DINS cannot have both size and pos > 32");
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InstIn.getOperand(3).setImm(size - 32);
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InstIn.setOpcode((Opcode == Mips::DEXT) ? Mips::DEXTM : Mips::DINSM);
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return;
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}
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}
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