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Modify the two address instruction pass to remove the duplicate

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operand of the instruction and thus simplify the register allocation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11124 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alkis Evlogimenos
2004-02-04 22:17:40 +00:00
parent a33ceaa2d4
commit 14be64018f
11 changed files with 227 additions and 232 deletions
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124
lib/CodeGen/TwoAddressInstructionPass.cpp
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@@ -16,11 +16,14 @@
// to:
//
// A = B
// A = A op C
// A op= C
//
// Note that if a register allocator chooses to use this pass, that it has to
// be capable of handling the non-SSA nature of these rewritten virtual
// registers.
// Note that if a register allocator chooses to use this pass, that it
// has to be capable of handling the non-SSA nature of these rewritten
// virtual registers.
//
// It is also worth noting that the duplicate operand of the two
// address instruction is removed.
//
//===----------------------------------------------------------------------===//
@@ -98,63 +101,70 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
mi->getOperand(1).isUse() &&
"two address instruction invalid");
// we have nothing to do if the two operands are the same
// if the two operands are the same we just remove the use
// and mark the def as def&use
if (mi->getOperand(0).getAllocatedRegNum() ==
mi->getOperand(1).getAllocatedRegNum())
continue;
MadeChange = true;
// rewrite:
// a = b op c
// to:
// a = b
// a = a op c
unsigned regA = mi->getOperand(0).getAllocatedRegNum();
unsigned regB = mi->getOperand(1).getAllocatedRegNum();
assert(MRegisterInfo::isVirtualRegister(regA) &&
MRegisterInfo::isVirtualRegister(regB) &&
"cannot update physical register live information");
// first make sure we do not have a use of a in the
// instruction (a = b + a for example) because our
// transformation will not work. This should never occur
// because we are in SSA form.
for (unsigned i = 1; i != mi->getNumOperands(); ++i)
assert(!mi->getOperand(i).isRegister() ||
mi->getOperand(i).getAllocatedRegNum() != (int)regA);
const TargetRegisterClass* rc =MF.getSSARegMap()->getRegClass(regA);
unsigned Added = MRI.copyRegToReg(*mbbi, mii, regA, regB, rc);
numInstrsAdded += Added;
MachineInstr* prevMi = *(mii - 1);
DEBUG(std::cerr << "\t\tadded instruction: ";
prevMi->print(std::cerr, TM));
// update live variables for regA
assert(Added == 1 && "Cannot handle multi-instruction copies yet!");
LiveVariables::VarInfo& varInfo = LV.getVarInfo(regA);
varInfo.DefInst = prevMi;
// update live variables for regB
if (LV.removeVirtualRegisterKilled(regB, &*mbbi, mi))
LV.addVirtualRegisterKilled(regB, &*mbbi, prevMi);
if (LV.removeVirtualRegisterDead(regB, &*mbbi, mi))
LV.addVirtualRegisterDead(regB, &*mbbi, prevMi);
// replace all occurences of regB with regA
for (unsigned i = 1; i < mi->getNumOperands(); ++i) {
if (mi->getOperand(i).isRegister() &&
mi->getOperand(i).getReg() == regB)
mi->SetMachineOperandReg(i, regA);
mi->getOperand(1).getAllocatedRegNum()) {
}
else {
MadeChange = true;
// rewrite:
// a = b op c
// to:
// a = b
// a = a op c
unsigned regA = mi->getOperand(0).getAllocatedRegNum();
unsigned regB = mi->getOperand(1).getAllocatedRegNum();
assert(MRegisterInfo::isVirtualRegister(regA) &&
MRegisterInfo::isVirtualRegister(regB) &&
"cannot update physical register live information");
// first make sure we do not have a use of a in the
// instruction (a = b + a for example) because our
// transformation will not work. This should never occur
// because we are in SSA form.
for (unsigned i = 1; i != mi->getNumOperands(); ++i)
assert(!mi->getOperand(i).isRegister() ||
mi->getOperand(i).getAllocatedRegNum() != (int)regA);
const TargetRegisterClass* rc =
MF.getSSARegMap()->getRegClass(regA);
unsigned Added = MRI.copyRegToReg(*mbbi, mii, regA, regB, rc);
numInstrsAdded += Added;
MachineInstr* prevMi = *(mii - 1);
DEBUG(std::cerr << "\t\tadded instruction: ";
prevMi->print(std::cerr, TM));
// update live variables for regA
assert(Added == 1 &&
"Cannot handle multi-instruction copies yet!");
LiveVariables::VarInfo& varInfo = LV.getVarInfo(regA);
varInfo.DefInst = prevMi;
// update live variables for regB
if (LV.removeVirtualRegisterKilled(regB, &*mbbi, mi))
LV.addVirtualRegisterKilled(regB, &*mbbi, prevMi);
if (LV.removeVirtualRegisterDead(regB, &*mbbi, mi))
LV.addVirtualRegisterDead(regB, &*mbbi, prevMi);
// replace all occurences of regB with regA
for (unsigned i = 1, e = mi->getNumOperands(); i != e; ++i) {
if (mi->getOperand(i).isRegister() &&
mi->getOperand(i).getReg() == regB)
mi->SetMachineOperandReg(i, regA);
}
}
assert(mi->getOperand(0).isDef());
mi->getOperand(0).setUse();
mi->RemoveOperand(1);
DEBUG(std::cerr << "\t\tmodified original to: ";
mi->print(std::cerr, TM));
assert(mi->getOperand(0).getAllocatedRegNum() ==
mi->getOperand(1).getAllocatedRegNum());
}
}