Line data    Source code

       1             : //===--- ARMComputeBlockSize.cpp - Compute machine block sizes ------------===//
       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 "ARMBaseInstrInfo.h"
      12             : #include "ARMBasicBlockInfo.h"
      13             : #include "ARMMachineFunctionInfo.h"
      14             : #include "llvm/CodeGen/MachineBasicBlock.h"
      15             : #include "llvm/CodeGen/MachineFunction.h"
      16             : #include "llvm/CodeGen/MachineInstr.h"
      17             : #include "llvm/CodeGen/TargetSubtargetInfo.h"
      18             : #include <vector>
      19             : 
      20             : using namespace llvm;
      21             : 
      22             : namespace llvm {
      23             : 
      24             : // mayOptimizeThumb2Instruction - Returns true if optimizeThumb2Instructions
      25             : // below may shrink MI.
      26             : static bool
      27      120503 : mayOptimizeThumb2Instruction(const MachineInstr *MI) {
      28      241006 :   switch(MI->getOpcode()) {
      29             :     // optimizeThumb2Instructions.
      30             :     case ARM::t2LEApcrel:
      31             :     case ARM::t2LDRpci:
      32             :     // optimizeThumb2Branches.
      33             :     case ARM::t2B:
      34             :     case ARM::t2Bcc:
      35             :     case ARM::tBcc:
      36             :     // optimizeThumb2JumpTables.
      37             :     case ARM::t2BR_JT:
      38             :     case ARM::tBR_JTr:
      39             :       return true;
      40             :   }
      41      117819 :   return false;
      42             : }
      43             : 
      44       21103 : void computeBlockSize(MachineFunction *MF, MachineBasicBlock *MBB,
      45             :                       BasicBlockInfo &BBI) {
      46             :   const ARMBaseInstrInfo *TII =
      47       21103 :     static_cast<const ARMBaseInstrInfo *>(MF->getSubtarget().getInstrInfo());
      48       21103 :   bool isThumb = MF->getInfo<ARMFunctionInfo>()->isThumbFunction();
      49       21103 :   BBI.Size = 0;
      50       21103 :   BBI.Unalign = 0;
      51       21103 :   BBI.PostAlign = 0;
      52             : 
      53      248047 :   for (MachineInstr &I : *MBB) {
      54      226944 :     BBI.Size += TII->getInstSizeInBytes(I);
      55             :     // For inline asm, getInstSizeInBytes returns a conservative estimate.
      56             :     // The actual size may be smaller, but still a multiple of the instr size.
      57      226944 :     if (I.isInlineAsm())
      58       18090 :       BBI.Unalign = isThumb ? 1 : 2;
      59             :     // Also consider instructions that may be shrunk later.
      60      209091 :     else if (isThumb && mayOptimizeThumb2Instruction(&I))
      61        2684 :       BBI.Unalign = 1;
      62             :   }
      63             : 
      64             :   // tBR_JTr contains a .align 2 directive.
      65       63097 :   if (!MBB->empty() && MBB->back().getOpcode() == ARM::tBR_JTr) {
      66          18 :     BBI.PostAlign = 2;
      67          18 :     MBB->getParent()->ensureAlignment(2);
      68             :   }
      69       21103 : }
      70             : 
      71       14600 : std::vector<BasicBlockInfo> computeAllBlockSizes(MachineFunction *MF) {
      72             :   std::vector<BasicBlockInfo> BBInfo;
      73       14600 :   BBInfo.resize(MF->getNumBlockIDs());
      74             : 
      75       35648 :   for (MachineBasicBlock &MBB : *MF)
      76       42096 :     computeBlockSize(MF, &MBB, BBInfo[MBB.getNumber()]);
      77             : 
      78       14600 :   return BBInfo;
      79             : }
      80             : 
      81             : } // end namespace llvm