lib/Target/ARM/Thumb2HazardRecognizer.cpp

   1 //===-- Thumb2HazardRecognizer.cpp - Thumb2 postra hazard recognizer ------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "ARM.h"
  11 #include "Thumb2HazardRecognizer.h"
  12 #include "llvm/CodeGen/MachineInstr.h"
  13 #include "llvm/CodeGen/ScheduleDAG.h"
  14 using namespace llvm;
  15
  16 ScheduleHazardRecognizer::HazardType
  17 Thumb2HazardRecognizer::getHazardType(SUnit *SU) {
  18   if (ITBlockSize) {
  19     MachineInstr *MI = SU->getInstr();
  20     if (!MI->isDebugValue() && MI != ITBlockMIs[ITBlockSize-1])
  21       return Hazard;
  22   }
  23
  24   return PostRAHazardRecognizer::getHazardType(SU);
  25 }
  26
  27 void Thumb2HazardRecognizer::Reset() {
  28   ITBlockSize = 0;
  29   PostRAHazardRecognizer::Reset();
  30 }
  31
  32 void Thumb2HazardRecognizer::EmitInstruction(SUnit *SU) {
  33   MachineInstr *MI = SU->getInstr();
  34   unsigned Opcode = MI->getOpcode();
  35   if (ITBlockSize) {
  36     --ITBlockSize;
  37   } else if (Opcode == ARM::t2IT) {
  38     unsigned Mask = MI->getOperand(1).getImm();
  39     unsigned NumTZ = CountTrailingZeros_32(Mask);
  40     assert(NumTZ <= 3 && "Invalid IT mask!");
  41     ITBlockSize = 4 - NumTZ;
  42     MachineBasicBlock::iterator I = MI;
  43     for (unsigned i = 0; i < ITBlockSize; ++i) {
  44       // Advance to the next instruction, skipping any dbg_value instructions.
  45       do {
  46         ++I;
  47       } while (I->isDebugValue());
  48       ITBlockMIs[ITBlockSize-1-i] = &*I;
  49     }
  50   }
  51
  52   PostRAHazardRecognizer::EmitInstruction(SU);
  53 }