LLVM  7.0.0svn
Macros | Functions
LiveRangeShrink.cpp File Reference

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#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <iterator>
#include <utility>
Include dependency graph for LiveRangeShrink.cpp:

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#define DEBUG_TYPE   "lrshrink"


 STATISTIC (NumInstrsHoistedToShrinkLiveRange, "Number of insructions hoisted to shrink live range.")
 INITIALIZE_PASS (LiveRangeShrink, "lrshrink", "Live Range Shrink Pass", false, false) using InstOrderMap
static MachineInstrFindDominatedInstruction (MachineInstr &New, MachineInstr *Old, const InstOrderMap &M)
 Returns New if it's dominated by Old, otherwise return Old. More...
static void BuildInstOrderMap (MachineBasicBlock::iterator Start, InstOrderMap &M)
 Builds Instruction to its dominating order number map M by traversing from instruction Start. More...

Detailed Description


This pass moves instructions close to the definition of its operands to shrink live range of the def instruction. The code motion is limited within the basic block. The moved instruction should have 1 def, and more than one uses, all of which are the only use of the def.


Definition in file LiveRangeShrink.cpp.

Macro Definition Documentation


#define DEBUG_TYPE   "lrshrink"

Definition at line 36 of file LiveRangeShrink.cpp.

Function Documentation

◆ BuildInstOrderMap()

static void BuildInstOrderMap ( MachineBasicBlock::iterator  Start,
InstOrderMap &  M 

◆ FindDominatedInstruction()

static MachineInstr* FindDominatedInstruction ( MachineInstr New,
MachineInstr Old,
const InstOrderMap &  M 

Returns New if it's dominated by Old, otherwise return Old.

M maintains a map from instruction to its dominating order that satisfies M[A] > M[B] guarantees that A is dominated by B. If New is not in M, return Old. Otherwise if Old is null, return New.

Definition at line 77 of file LiveRangeShrink.cpp.

References I.

Referenced by BuildInstOrderMap().


INITIALIZE_PASS ( LiveRangeShrink  ,
"lrshrink"  ,
"Live Range Shrink Pass ,
false  ,


STATISTIC ( NumInstrsHoistedToShrinkLiveRange  ,
"Number of insructions hoisted to shrink live range."