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Add MachineBasicBlock::addLiveIn().

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This function adds a live-in physical register to an MBB and ensures
that it is copied to a virtual register immediately.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185594 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2013-07-03 23:56:20 +00:00
parent 62da588a2e
commit f647652445
2 changed files with 38 additions and 0 deletions
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5
include/llvm/CodeGen/MachineBasicBlock.h
View File

@ -296,6 +296,11 @@ public:
/// is an error to add the same register to the same set more than once.
void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); }
/// Add PhysReg as live in to this block, and ensure that there is a copy of
/// PhysReg to a virtual register of class RC. Return the virtual register
/// that is a copy of the live in PhysReg.
unsigned addLiveIn(unsigned PhysReg, const TargetRegisterClass *RC);
/// removeLiveIn - Remove the specified register from the live in set.
///
void removeLiveIn(unsigned Reg);

33
lib/CodeGen/MachineBasicBlock.cpp
View File

@ -19,6 +19,7 @@
#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/SlotIndexes.h"
@ -341,6 +342,38 @@ bool MachineBasicBlock::isLiveIn(unsigned Reg) const {
return I != livein_end();
}
unsigned
MachineBasicBlock::addLiveIn(unsigned PhysReg, const TargetRegisterClass *RC) {
assert(getParent() && "MBB must be inserted in function");
assert(TargetRegisterInfo::isPhysicalRegister(PhysReg) && "Expected physreg");
assert(RC && "Register class is required");
assert((isLandingPad() || this == &getParent()->front()) &&
"Only the entry block and landing pads can have physreg live ins");
bool LiveIn = isLiveIn(PhysReg);
iterator I = getFirstNonPHI(), E = end();
MachineRegisterInfo &MRI = getParent()->getRegInfo();
const TargetInstrInfo &TII = *getParent()->getTarget().getInstrInfo();
// Look for an existing copy.
if (LiveIn)
for (;I != E && I->isCopy(); ++I)
if (I->getOperand(1).getReg() == PhysReg) {
unsigned VirtReg = I->getOperand(0).getReg();
if (!MRI.constrainRegClass(VirtReg, RC))
llvm_unreachable("Incompatible live-in register class.");
return VirtReg;
}
// No luck, create a virtual register.
unsigned VirtReg = MRI.createVirtualRegister(RC);
BuildMI(*this, I, DebugLoc(), TII.get(TargetOpcode::COPY), VirtReg)
.addReg(PhysReg, RegState::Kill);
if (!LiveIn)
addLiveIn(PhysReg);
return VirtReg;
}
void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) {
getParent()->splice(NewAfter, this);
}