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Properly handle kills of a physical register which has sub-registers that are read by later instructions.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37739 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-06-26 21:03:35 +00:00
parent c4f2fe0694
commit 4efe74129f
2 changed files with 83 additions and 13 deletions
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10
include/llvm/CodeGen/LiveVariables.h
View File

@ -31,6 +31,7 @@
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include <map>
@ -163,6 +164,15 @@ private: // Intermediate data structures
bool addRegisterDead(unsigned IncomingReg, MachineInstr *MI,
bool AddIfNotFound = false);
void addRegisterKills(unsigned Reg, MachineInstr *MI,
SmallSet<unsigned, 4> &SubKills);
/// HandlePhysRegKill - Add kills of Reg and its sub-registers to the
/// uses. Pay special attention to the sub-register uses which may come below
/// the last use of the whole register.
bool HandlePhysRegKill(unsigned Reg, MachineInstr *MI,
SmallSet<unsigned, 4> &SubKills);
bool HandlePhysRegKill(unsigned Reg, MachineInstr *MI);
void HandlePhysRegUse(unsigned Reg, MachineInstr *MI);
void HandlePhysRegDef(unsigned Reg, MachineInstr *MI);

86
lib/CodeGen/LiveVariables.cpp
View File

@ -286,38 +286,85 @@ void LiveVariables::HandlePhysRegUse(unsigned Reg, MachineInstr *MI) {
PhysRegPartUse[SuperReg] = MI;
}
bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *RefMI,
SmallSet<unsigned, 4> &SubKills) {
for (const unsigned *SubRegs = RegInfo->getImmediateSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
MachineInstr *LastRef = PhysRegInfo[SubReg];
if (LastRef != RefMI)
SubKills.insert(SubReg);
else if (!HandlePhysRegKill(SubReg, RefMI, SubKills))
SubKills.insert(SubReg);
}
if (*RegInfo->getImmediateSubRegisters(Reg) == 0) {
// No sub-registers, just check if reg is killed by RefMI.
if (PhysRegInfo[Reg] == RefMI)
return true;
} else if (SubKills.empty())
// None of the sub-registers are killed elsewhere...
return true;
return false;
}
void LiveVariables::addRegisterKills(unsigned Reg, MachineInstr *MI,
SmallSet<unsigned, 4> &SubKills) {
if (SubKills.count(Reg) == 0)
addRegisterKilled(Reg, MI, true);
else {
for (const unsigned *SubRegs = RegInfo->getImmediateSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs)
addRegisterKills(SubReg, MI, SubKills);
}
}
bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *RefMI) {
SmallSet<unsigned, 4> SubKills;
if (HandlePhysRegKill(Reg, RefMI, SubKills)) {
addRegisterKilled(Reg, RefMI);
return true;
} else {
// Some sub-registers are killed by another MI.
for (const unsigned *SubRegs = RegInfo->getImmediateSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs)
addRegisterKills(SubReg, RefMI, SubKills);
return false;
}
}
void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI) {
// Does this kill a previous version of this register?
if (MachineInstr *LastRef = PhysRegInfo[Reg]) {
if (PhysRegUsed[Reg])
addRegisterKilled(Reg, LastRef);
else if (PhysRegPartUse[Reg])
if (PhysRegUsed[Reg]) {
if (!HandlePhysRegKill(Reg, LastRef)) {
if (PhysRegPartUse[Reg])
addRegisterKilled(Reg, PhysRegPartUse[Reg], true);
}
} else if (PhysRegPartUse[Reg])
// Add implicit use / kill to last use of a sub-register.
addRegisterKilled(Reg, PhysRegPartUse[Reg], true);
else
addRegisterDead(Reg, LastRef);
}
PhysRegInfo[Reg] = MI;
PhysRegUsed[Reg] = false;
PhysRegPartUse[Reg] = NULL;
for (const unsigned *SubRegs = RegInfo->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
if (MachineInstr *LastRef = PhysRegInfo[SubReg]) {
if (PhysRegUsed[SubReg])
addRegisterKilled(SubReg, LastRef);
else if (PhysRegPartUse[SubReg])
if (PhysRegUsed[SubReg]) {
if (!HandlePhysRegKill(SubReg, LastRef)) {
if (PhysRegPartUse[SubReg])
addRegisterKilled(SubReg, PhysRegPartUse[SubReg], true);
}
//addRegisterKilled(SubReg, LastRef);
} else if (PhysRegPartUse[SubReg])
// Add implicit use / kill to last use of a sub-register.
addRegisterKilled(SubReg, PhysRegPartUse[SubReg], true);
else
addRegisterDead(SubReg, LastRef);
}
PhysRegInfo[SubReg] = MI;
PhysRegUsed[SubReg] = false;
PhysRegPartUse[SubReg] = NULL;
}
if (MI)
if (MI) {
for (const unsigned *SuperRegs = RegInfo->getSuperRegisters(Reg);
unsigned SuperReg = *SuperRegs; ++SuperRegs) {
if (PhysRegInfo[SuperReg]) {
@ -334,6 +381,17 @@ void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI) {
// Remember this partial def.
PhysRegPartDef[SuperReg].push_back(MI);
}
}
PhysRegInfo[Reg] = MI;
PhysRegUsed[Reg] = false;
PhysRegPartUse[Reg] = NULL;
for (const unsigned *SubRegs = RegInfo->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
PhysRegInfo[SubReg] = MI;
PhysRegUsed[SubReg] = false;
PhysRegPartUse[SubReg] = NULL;
}
}
}
@ -465,6 +523,8 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
// Clear some states between BB's. These are purely local information.
for (unsigned i = 0; i != NumRegs; ++i)
PhysRegPartDef[i].clear();
std::fill(PhysRegInfo, PhysRegInfo + NumRegs, (MachineInstr*)0);
std::fill(PhysRegUsed, PhysRegUsed + NumRegs, false);
std::fill(PhysRegPartUse, PhysRegPartUse + NumRegs, (MachineInstr*)0);
}