LLVM  16.0.0git
Macros | Functions
DetectDeadLanes.cpp File Reference
#include "llvm/ADT/BitVector.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <deque>
Include dependency graph for DetectDeadLanes.cpp:

Go to the source code of this file.


#define DEBUG_TYPE   "detect-dead-lanes"


static bool lowersToCopies (const MachineInstr &MI)
 Returns true if MI will get lowered to a series of COPY instructions. More...
static bool isCrossCopy (const MachineRegisterInfo &MRI, const MachineInstr &MI, const TargetRegisterClass *DstRC, const MachineOperand &MO)

Detailed Description

Analysis that tracks defined/used subregister lanes across COPY instructions and instructions that get lowered to a COPY (PHI, REG_SEQUENCE, INSERT_SUBREG, EXTRACT_SUBREG). The information is used to detect dead definitions and the usage of (completely) undefined values and mark the operands as such. This pass is necessary because the dead/undef status is not obvious anymore when subregisters are involved.

Example: %0 = some definition %1 = IMPLICIT_DEF %2 = REG_SEQUENCE %0, sub0, %1, sub1 %3 = EXTRACT_SUBREG %2, sub1 = use %3 The %0 definition is dead and %3 contains an undefined value.

Definition in file DetectDeadLanes.cpp.

Macro Definition Documentation


#define DEBUG_TYPE   "detect-dead-lanes"

Definition at line 40 of file DetectDeadLanes.cpp.

Function Documentation

◆ isCrossCopy()

static bool isCrossCopy ( const MachineRegisterInfo MRI,
const MachineInstr MI,
const TargetRegisterClass DstRC,
const MachineOperand MO 

◆ lowersToCopies()

static bool lowersToCopies ( const MachineInstr MI)

Returns true if MI will get lowered to a series of COPY instructions.

We call this a COPY-like instruction.

Definition at line 131 of file DetectDeadLanes.cpp.

References MI, and PHI.

Referenced by isCrossCopy().