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This should handle register allocating PHI nodes.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5002 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Misha Brukman 2002-12-13 09:54:36 +00:00
parent 2b46e8eccc
commit 203b769b20
1 changed files with 97 additions and 23 deletions
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120
lib/CodeGen/RegAllocSimple.cpp
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@ -20,7 +20,7 @@
#include "Support/Statistic.h"
#include <map>
namespace {
//namespace {
struct RegAllocSimple : public FunctionPass {
TargetMachine &TM;
MachineBasicBlock *CurrMBB;
@ -82,21 +82,24 @@ namespace {
void cleanupAfterFunction() {
RegMap.clear();
SSA2PhysRegMap.clear();
NumBytesAllocated = 4;
NumBytesAllocated = ByteAlignment;
}
/// Moves value from memory into that register
MachineBasicBlock::iterator
moveUseToReg (MachineBasicBlock::iterator I, unsigned VirtReg,
moveUseToReg (MachineBasicBlock *MBB,
MachineBasicBlock::iterator I, unsigned VirtReg,
unsigned &PhysReg);
/// Saves reg value on the stack (maps virtual register to stack value)
MachineBasicBlock::iterator
saveVirtRegToStack (MachineBasicBlock::iterator I, unsigned VirtReg,
saveVirtRegToStack (MachineBasicBlock *MBB,
MachineBasicBlock::iterator I, unsigned VirtReg,
unsigned PhysReg);
MachineBasicBlock::iterator
savePhysRegToStack (MachineBasicBlock::iterator I, unsigned PhysReg);
savePhysRegToStack (MachineBasicBlock *MBB,
MachineBasicBlock::iterator I, unsigned PhysReg);
/// runOnFunction - Top level implementation of instruction selection for
/// the entire function.
@ -108,7 +111,7 @@ namespace {
}
};
}
//}
unsigned RegAllocSimple::allocateStackSpaceFor(unsigned VirtReg,
const TargetRegisterClass *regClass)
@ -126,7 +129,7 @@ unsigned RegAllocSimple::allocateStackSpaceFor(unsigned VirtReg,
#endif
// FIXME: forcing each arg to take 4 bytes on the stack
RegMap[VirtReg] = NumBytesAllocated;
NumBytesAllocated += 4;
NumBytesAllocated += ByteAlignment;
}
return RegMap[VirtReg];
}
@ -153,7 +156,8 @@ unsigned RegAllocSimple::getFreeReg(unsigned virtualReg) {
}
MachineBasicBlock::iterator
RegAllocSimple::moveUseToReg (MachineBasicBlock::iterator I,
RegAllocSimple::moveUseToReg (MachineBasicBlock *MBB,
MachineBasicBlock::iterator I,
unsigned VirtReg, unsigned &PhysReg)
{
const TargetRegisterClass* regClass = MF->getRegClass(VirtReg);
@ -162,16 +166,15 @@ RegAllocSimple::moveUseToReg (MachineBasicBlock::iterator I,
unsigned stackOffset = allocateStackSpaceFor(VirtReg, regClass);
PhysReg = getFreeReg(VirtReg);
// FIXME: increment the frame pointer
// Add move instruction(s)
return RegInfo->loadRegOffset2Reg(CurrMBB, I, PhysReg,
return RegInfo->loadRegOffset2Reg(MBB, I, PhysReg,
RegInfo->getFramePointer(),
-stackOffset, regClass->getDataSize());
}
MachineBasicBlock::iterator
RegAllocSimple::saveVirtRegToStack (MachineBasicBlock::iterator I,
RegAllocSimple::saveVirtRegToStack (MachineBasicBlock *MBB,
MachineBasicBlock::iterator I,
unsigned VirtReg, unsigned PhysReg)
{
const TargetRegisterClass* regClass = MF->getRegClass(VirtReg);
@ -180,13 +183,14 @@ RegAllocSimple::saveVirtRegToStack (MachineBasicBlock::iterator I,
unsigned stackOffset = allocateStackSpaceFor(VirtReg, regClass);
// Add move instruction(s)
return RegInfo->storeReg2RegOffset(CurrMBB, I, PhysReg,
return RegInfo->storeReg2RegOffset(MBB, I, PhysReg,
RegInfo->getFramePointer(),
-stackOffset, regClass->getDataSize());
}
MachineBasicBlock::iterator
RegAllocSimple::savePhysRegToStack (MachineBasicBlock::iterator I,
RegAllocSimple::savePhysRegToStack (MachineBasicBlock *MBB,
MachineBasicBlock::iterator I,
unsigned PhysReg)
{
const TargetRegisterClass* regClass = MF->getRegClass(PhysReg);
@ -195,7 +199,7 @@ RegAllocSimple::savePhysRegToStack (MachineBasicBlock::iterator I,
unsigned offset = allocateStackSpaceFor(PhysReg, regClass);
// Add move instruction(s)
return RegInfo->storeReg2RegOffset(CurrMBB, I, PhysReg,
return RegInfo->storeReg2RegOffset(MBB, I, PhysReg,
RegInfo->getFramePointer(),
offset, regClass->getDataSize());
}
@ -212,20 +216,90 @@ bool RegAllocSimple::runOnMachineFunction(MachineFunction &Fn) {
{
CurrMBB = &(*MBB);
// Handle PHI instructions specially: add moves to each pred block
while (MBB->front()->getOpcode() == 0) {
MachineInstr *MI = MBB->front();
// get rid of the phi
MBB->erase(MBB->begin());
DEBUG(std::cerr << "num ops: " << MI->getNumOperands() << "\n");
MachineOperand &targetReg = MI->getOperand(0);
// If it's a virtual register, allocate a physical one
// otherwise, just use whatever register is there now
// note: it MUST be a register -- we're assigning to it
virtualReg = (unsigned) targetReg.getAllocatedRegNum();
if (targetReg.isVirtualRegister()) {
physReg = getFreeReg(virtualReg);
} else {
physReg = targetReg.getAllocatedRegNum();
}
// Find the register class of the target register: should be the
// same as the values we're trying to store there
const TargetRegisterClass* regClass = PhysReg2RegClassMap[physReg];
assert(regClass && "Target register class not found!");
unsigned dataSize = regClass->getDataSize();
for (int i = MI->getNumOperands() - 1; i >= 2; i-=2) {
MachineOperand &opVal = MI->getOperand(i-1);
// Get the MachineBasicBlock equivalent of the BasicBlock that is the
// source path the phi
BasicBlock *opBB =
cast<BasicBlock>(MI->getOperand(i).getVRegValue());
MachineBasicBlock *opBlock = NULL;
for (MachineFunction::iterator opFi = Fn.begin(), opFe = Fn.end();
opFi != opFe; ++opFi)
{
if (opFi->getBasicBlock() == opBB) {
opBlock = opFi; break;
}
}
assert(opBlock && "MachineBasicBlock object not found for specified block!");
MachineBasicBlock::iterator opI = opBlock->end();
MachineInstr *opMI = *(--opI);
const MachineInstrInfo &MII = TM.getInstrInfo();
// insert the move just before the return/branch
if (MII.isReturn(opMI->getOpcode()) || MII.isBranch(opMI->getOpcode()))
{
// Retrieve the constant value from this op, move it to target
// register of the phi
if (opVal.getType() == MachineOperand::MO_SignExtendedImmed ||
opVal.getType() == MachineOperand::MO_UnextendedImmed)
{
opI = RegInfo->moveImm2Reg(opBlock, opI, physReg,
(unsigned) opVal.getImmedValue(),
dataSize);
saveVirtRegToStack(opBlock, opI, virtualReg, physReg);
} else {
// Allocate a physical register and add a move in the BB
unsigned opVirtualReg = (unsigned) opVal.getAllocatedRegNum();
unsigned opPhysReg; // = getFreeReg(opVirtualReg);
opI = moveUseToReg(opBlock, opI, opVirtualReg, opPhysReg);
opI = RegInfo->moveReg2Reg(opBlock, opI, physReg, opPhysReg,
dataSize);
// Save that register value to the stack of the TARGET REG
saveVirtRegToStack(opBlock, opI, virtualReg, opPhysReg);
}
}
}
// really delete the instruction
delete MI;
}
//loop over each basic block
for (MachineBasicBlock::iterator I = MBB->begin(); I != MBB->end(); ++I)
{
MachineInstr *MI = *I;
DEBUG(std::cerr << "instr: ";
MI->print(std::cerr, TM));
// FIXME: add a preliminary pass that will invalidate any registers that
// are used by the instruction (including implicit uses)
// Loop over each instruction:
// uses, move from memory into registers
// Loop over uses, move from memory into registers
for (int i = MI->getNumOperands() - 1; i >= 0; --i) {
MachineOperand &op = MI->getOperand(i);
@ -253,10 +327,10 @@ bool RegAllocSimple::runOnMachineFunction(MachineFunction &Fn) {
physReg = getFreeReg(virtualReg);
}
MachineBasicBlock::iterator J = I;
J = saveVirtRegToStack(++J, virtualReg, physReg);
J = saveVirtRegToStack(CurrMBB, ++J, virtualReg, physReg);
I = --J;
} else {
I = moveUseToReg(I, virtualReg, physReg);
I = moveUseToReg(CurrMBB, I, virtualReg, physReg);
}
VirtReg2PhysRegMap[virtualReg] = physReg;
}