LLVM  10.0.0svn
Macros | Enumerations | Functions | Variables
X86FlagsCopyLowering.cpp File Reference

Lowers COPY nodes of EFLAGS by directly extracting and preserving individual flag bits. More...

#include "X86.h"
#include "X86InstrBuilder.h"
#include "X86InstrInfo.h"
#include "X86Subtarget.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/SparseBitVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/MachineSSAUpdater.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSchedule.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/MC/MCSchedule.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <iterator>
#include <utility>
Include dependency graph for X86FlagsCopyLowering.cpp:

Go to the source code of this file.

Macros

#define PASS_KEY   "x86-flags-copy-lowering"
 
#define DEBUG_TYPE   PASS_KEY
 
#define LLVM_EXPAND_INSTR_SIZES(MNEMONIC, SUFFIX)
 
#define LLVM_EXPAND_ADC_SBB_INSTR(MNEMONIC)
 

Enumerations

enum  FlagArithMnemonic
 An enumeration of the arithmetic instruction mnemonics which have interesting flag semantics. More...
 

Functions

 STATISTIC (NumCopiesEliminated, "Number of copies of EFLAGS eliminated")
 
 STATISTIC (NumSetCCsInserted, "Number of setCC instructions inserted")
 
 STATISTIC (NumTestsInserted, "Number of test instructions inserted")
 
 STATISTIC (NumAddsInserted, "Number of adds instructions inserted")
 
 INITIALIZE_PASS_BEGIN (X86FlagsCopyLoweringPass, DEBUG_TYPE, "X86 EFLAGS copy lowering", false, false) INITIALIZE_PASS_END(X86FlagsCopyLoweringPass
 
static FlagArithMnemonic getMnemonicFromOpcode (unsigned Opcode)
 
static MachineBasicBlocksplitBlock (MachineBasicBlock &MBB, MachineInstr &SplitI, const X86InstrInfo &TII)
 

Variables

 DEBUG_TYPE
 
X86 EFLAGS copy lowering
 
X86 EFLAGS copy false
 

Detailed Description

Lowers COPY nodes of EFLAGS by directly extracting and preserving individual flag bits.

We have to do this by carefully analyzing and rewriting the usage of the copied EFLAGS register because there is no general way to rematerialize the entire EFLAGS register safely and efficiently. Using popf both forces dynamic stack adjustment and can create correctness issues due to IF, TF, and other non-status flags being overwritten. Using sequences involving SAHF don't work on all x86 processors and are often quite slow compared to directly testing a single status preserved in its own GPR.

Definition in file X86FlagsCopyLowering.cpp.

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE   PASS_KEY

Definition at line 66 of file X86FlagsCopyLowering.cpp.

◆ LLVM_EXPAND_ADC_SBB_INSTR

#define LLVM_EXPAND_ADC_SBB_INSTR (   MNEMONIC)
Value:
LLVM_EXPAND_INSTR_SIZES(MNEMONIC, rr) \
LLVM_EXPAND_INSTR_SIZES(MNEMONIC, rr_REV) \
LLVM_EXPAND_INSTR_SIZES(MNEMONIC, rm) \
LLVM_EXPAND_INSTR_SIZES(MNEMONIC, mr) \
case X86::MNEMONIC##8ri: \
case X86::MNEMONIC##16ri8: \
case X86::MNEMONIC##32ri8: \
case X86::MNEMONIC##64ri8: \
case X86::MNEMONIC##16ri: \
case X86::MNEMONIC##32ri: \
case X86::MNEMONIC##64ri32: \
case X86::MNEMONIC##8mi: \
case X86::MNEMONIC##16mi8: \
case X86::MNEMONIC##32mi8: \
case X86::MNEMONIC##64mi8: \
case X86::MNEMONIC##16mi: \
case X86::MNEMONIC##32mi: \
case X86::MNEMONIC##64mi32: \
case X86::MNEMONIC##8i8: \
case X86::MNEMONIC##16i16: \
case X86::MNEMONIC##32i32: \
case X86::MNEMONIC##64i32:
#define LLVM_EXPAND_INSTR_SIZES(MNEMONIC, SUFFIX)

Referenced by getMnemonicFromOpcode().

◆ LLVM_EXPAND_INSTR_SIZES

#define LLVM_EXPAND_INSTR_SIZES (   MNEMONIC,
  SUFFIX 
)
Value:
case X86::MNEMONIC##8##SUFFIX: \
case X86::MNEMONIC##16##SUFFIX: \
case X86::MNEMONIC##32##SUFFIX: \
case X86::MNEMONIC##64##SUFFIX:

Referenced by getMnemonicFromOpcode().

◆ PASS_KEY

#define PASS_KEY   "x86-flags-copy-lowering"

Definition at line 65 of file X86FlagsCopyLowering.cpp.

Enumeration Type Documentation

◆ FlagArithMnemonic

enum FlagArithMnemonic
strong

An enumeration of the arithmetic instruction mnemonics which have interesting flag semantics.

We can map instruction opcodes into these mnemonics to make it easy to dispatch with specific functionality.

Definition at line 157 of file X86FlagsCopyLowering.cpp.

Function Documentation

◆ getMnemonicFromOpcode()

static FlagArithMnemonic getMnemonicFromOpcode ( unsigned  Opcode)
static

◆ INITIALIZE_PASS_BEGIN()

INITIALIZE_PASS_BEGIN ( X86FlagsCopyLoweringPass  ,
DEBUG_TYPE  ,
"X86 EFLAGS copy lowering ,
false  ,
false   
)

◆ splitBlock()

static MachineBasicBlock& splitBlock ( MachineBasicBlock MBB,
MachineInstr SplitI,
const X86InstrInfo TII 
)
static

◆ STATISTIC() [1/4]

STATISTIC ( NumCopiesEliminated  ,
"Number of copies of EFLAGS eliminated"   
)

◆ STATISTIC() [2/4]

STATISTIC ( NumSetCCsInserted  ,
"Number of setCC instructions inserted"   
)

◆ STATISTIC() [3/4]

STATISTIC ( NumTestsInserted  ,
"Number of test instructions inserted"   
)

◆ STATISTIC() [4/4]

STATISTIC ( NumAddsInserted  ,
"Number of adds instructions inserted"   
)

Variable Documentation

◆ DEBUG_TYPE

DEBUG_TYPE

Definition at line 137 of file X86FlagsCopyLowering.cpp.

◆ false

X86 EFLAGS copy false

Definition at line 137 of file X86FlagsCopyLowering.cpp.

◆ lowering

X86 EFLAGS copy lowering

Definition at line 137 of file X86FlagsCopyLowering.cpp.