[llvm-commits] CVS: llvm/lib/CodeGen/RegAllocSimple.cpp
Misha Brukman
brukman at cs.uiuc.edu
Fri Dec 13 03:55:04 PST 2002
Changes in directory llvm/lib/CodeGen:
RegAllocSimple.cpp updated: 1.7 -> 1.8
---
Log message:
This should handle register allocating PHI nodes.
---
Diffs of the changes:
Index: llvm/lib/CodeGen/RegAllocSimple.cpp
diff -u llvm/lib/CodeGen/RegAllocSimple.cpp:1.7 llvm/lib/CodeGen/RegAllocSimple.cpp:1.8
--- llvm/lib/CodeGen/RegAllocSimple.cpp:1.7 Thu Dec 12 22:34:02 2002
+++ llvm/lib/CodeGen/RegAllocSimple.cpp Fri Dec 13 03:54:36 2002
@@ -20,7 +20,7 @@
#include "Support/Statistic.h"
#include <map>
-namespace {
+//namespace {
struct RegAllocSimple : public FunctionPass {
TargetMachine &TM;
MachineBasicBlock *CurrMBB;
@@ -82,21 +82,24 @@
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 @@
}
};
-}
+//}
unsigned RegAllocSimple::allocateStackSpaceFor(unsigned VirtReg,
const TargetRegisterClass *regClass)
@@ -126,7 +129,7 @@
#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 @@
}
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 @@
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 @@
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 @@
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 @@
{
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 @@
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;
}
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