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Grab bag of minor cleanups. Export some statistics about the number of

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spills and reloads emitted


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5054 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2002-12-15 20:36:09 +00:00
parent 2109f502d6
commit da7e453aac
1 changed files with 56 additions and 46 deletions
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102
lib/CodeGen/RegAllocSimple.cpp
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@ -10,6 +10,7 @@
#include "llvm/Target/TargetMachine.h"
#include "Support/Statistic.h"
#include <iostream>
#include <set>
/// PhysRegClassMap - Construct a mapping of physical register numbers to their
/// register classes.
@ -36,7 +37,10 @@ public:
namespace {
struct RegAllocSimple : public FunctionPass {
Statistic<> NumSpilled ("ra-simple", "Number of registers spilled");
Statistic<> NumReloaded("ra-simple", "Number of registers reloaded");
class RegAllocSimple : public FunctionPass {
TargetMachine &TM;
MachineFunction *MF;
const MRegisterInfo *RegInfo;
@ -54,20 +58,40 @@ namespace {
// Made to combat the incorrect allocation of r2 = add r1, r1
std::map<unsigned, unsigned> VirtReg2PhysRegMap;
// Maps RegClass => which index we can take a register from. Since this is a
// simple register allocator, when we need a register of a certain class, we
// just take the next available one.
std::map<unsigned, unsigned> RegsUsed;
// RegsUsed - Keep track of what registers are currently in use.
std::set<unsigned> RegsUsed;
// RegClassIdx - Maps RegClass => which index we can take a register
// from. Since this is a simple register allocator, when we need a register
// of a certain class, we just take the next available one.
std::map<const TargetRegisterClass*, unsigned> RegClassIdx;
public:
RegAllocSimple(TargetMachine &tm)
: TM(tm), RegInfo(tm.getRegisterInfo()), PhysRegClasses(RegInfo) {
RegsUsed[RegInfo->getFramePointer()] = 1;
RegsUsed[RegInfo->getStackPointer()] = 1;
RegsUsed.insert(RegInfo->getFramePointer());
RegsUsed.insert(RegInfo->getStackPointer());
cleanupAfterFunction();
}
bool runOnFunction(Function &Fn) {
return runOnMachineFunction(MachineFunction::get(&Fn));
}
private:
/// runOnMachineFunction - Register allocate the whole function
bool runOnMachineFunction(MachineFunction &Fn);
/// AllocateBasicBlock - Register allocate the specified basic block.
void AllocateBasicBlock(MachineBasicBlock &MBB);
/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions
/// in predecessor basic blocks.
void EliminatePHINodes(MachineBasicBlock &MBB);
bool isAvailableReg(unsigned Reg) {
// assert(Reg < MRegisterInfo::FirstVirtualReg && "...");
return RegsUsed.find(Reg) == RegsUsed.end();
@ -78,8 +102,11 @@ namespace {
unsigned allocateStackSpaceFor(unsigned VirtReg,
const TargetRegisterClass *regClass);
/// Given size (in bytes), returns a register that is currently unused
/// Given a virtual register, returns a physical register that is currently
/// unused.
///
/// Side effect: marks that register as being used until manually cleared
///
unsigned getFreeReg(unsigned virtualReg);
/// Returns all `borrowed' registers back to the free pool
@ -91,15 +118,14 @@ namespace {
///
void invalidatePhysRegs(const MachineInstr *MI) {
unsigned Opcode = MI->getOpcode();
const MachineInstrInfo &MII = TM.getInstrInfo();
const MachineInstrDescriptor &Desc = MII.get(Opcode);
const MachineInstrDescriptor &Desc = TM.getInstrInfo().get(Opcode);
const unsigned *regs = Desc.ImplicitUses;
while (*regs)
RegsUsed[*regs++] = 1;
RegsUsed.insert(*regs++);
regs = Desc.ImplicitDefs;
while (*regs)
RegsUsed[*regs++] = 1;
RegsUsed.insert(*regs++);
}
void cleanupAfterFunction() {
@ -123,22 +149,6 @@ namespace {
MachineBasicBlock::iterator
savePhysRegToStack (MachineBasicBlock &MBB,
MachineBasicBlock::iterator I, unsigned PhysReg);
/// runOnFunction - Top level implementation of instruction selection for
/// the entire function.
///
bool runOnMachineFunction(MachineFunction &Fn);
/// AllocateBasicBlock - Register allocate the specified basic block.
void AllocateBasicBlock(MachineBasicBlock &MBB);
/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions
/// in predecessor basic blocks.
void EliminatePHINodes(MachineBasicBlock &MBB);
bool runOnFunction(Function &Fn) {
return runOnMachineFunction(MachineFunction::get(&Fn));
}
};
}
@ -182,9 +192,8 @@ unsigned RegAllocSimple::getFreeReg(unsigned virtualReg) {
if (isAvailableReg(physReg))
return physReg;
else {
else
return getFreeReg(virtualReg);
}
}
MachineBasicBlock::iterator
@ -199,6 +208,7 @@ RegAllocSimple::moveUseToReg (MachineBasicBlock &MBB,
PhysReg = getFreeReg(VirtReg);
// Add move instruction(s)
++NumReloaded;
return RegInfo->loadRegOffset2Reg(MBB, I, PhysReg,
RegInfo->getFramePointer(),
-stackOffset, regClass->getDataSize());
@ -215,6 +225,7 @@ RegAllocSimple::saveVirtRegToStack (MachineBasicBlock &MBB,
unsigned stackOffset = allocateStackSpaceFor(VirtReg, regClass);
// Add move instruction(s)
++NumSpilled;
return RegInfo->storeReg2RegOffset(MBB, I, PhysReg,
RegInfo->getFramePointer(),
-stackOffset, regClass->getDataSize());
@ -231,6 +242,7 @@ RegAllocSimple::savePhysRegToStack (MachineBasicBlock &MBB,
unsigned offset = allocateStackSpaceFor(PhysReg, regClass);
// Add move instruction(s)
++NumSpilled;
return RegInfo->storeReg2RegOffset(MBB, I, PhysReg,
RegInfo->getFramePointer(),
offset, regClass->getDataSize());
@ -239,9 +251,11 @@ RegAllocSimple::savePhysRegToStack (MachineBasicBlock &MBB,
/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions in
/// predecessor basic blocks.
void RegAllocSimple::EliminatePHINodes(MachineBasicBlock &MBB) {
const MachineInstrInfo &MII = TM.getInstrInfo();
while (MBB.front()->getOpcode() == 0) {
MachineInstr *MI = MBB.front();
// get rid of the phi
// Unlink the PHI node from the basic block... but don't delete the PHI
MBB.erase(MBB.begin());
// a preliminary pass that will invalidate any registers that
@ -249,13 +263,13 @@ void RegAllocSimple::EliminatePHINodes(MachineBasicBlock &MBB) {
invalidatePhysRegs(MI);
DEBUG(std::cerr << "num invalid regs: " << RegsUsed.size() << "\n");
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
// 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!
//
unsigned virtualReg = (unsigned) targetReg.getAllocatedRegNum();
unsigned physReg;
if (targetReg.isVirtualRegister()) {
@ -278,7 +292,6 @@ void RegAllocSimple::EliminatePHINodes(MachineBasicBlock &MBB) {
MachineBasicBlock &opBlock = *MI->getOperand(i).getMachineBasicBlock();
MachineBasicBlock::iterator opI = opBlock.end();
MachineInstr *opMI = *--opI;
const MachineInstrInfo &MII = TM.getInstrInfo();
// must backtrack over ALL the branches in the previous block, until no
// more
@ -300,10 +313,9 @@ void RegAllocSimple::EliminatePHINodes(MachineBasicBlock &MBB) {
} else {
// Allocate a physical register and add a move in the BB
unsigned opVirtualReg = (unsigned) opVal.getAllocatedRegNum();
unsigned opPhysReg; // = getFreeReg(opVirtualReg);
unsigned opPhysReg;
opI = moveUseToReg(opBlock, opI, opVirtualReg, physReg);
//opI = RegInfo->moveReg2Reg(opBlock, opI, physReg, opPhysReg,
// dataSize);
// Save that register value to the stack of the TARGET REG
saveVirtRegToStack(opBlock, opI, virtualReg, physReg);
}
@ -334,9 +346,7 @@ void RegAllocSimple::AllocateBasicBlock(MachineBasicBlock &MBB) {
for (int i = MI->getNumOperands() - 1; i >= 0; --i) {
MachineOperand &op = MI->getOperand(i);
if (op.isImmediate()) {
DEBUG(std::cerr << "const\n");
} else if (op.isVirtualRegister()) {
if (op.isVirtualRegister()) {
unsigned virtualReg = (unsigned) op.getAllocatedRegNum();
DEBUG(std::cerr << "op: " << op << "\n");
DEBUG(std::cerr << "\t inst[" << i << "]: ";
@ -352,7 +362,7 @@ void RegAllocSimple::AllocateBasicBlock(MachineBasicBlock &MBB) {
if (TM.getInstrInfo().isTwoAddrInstr(MI->getOpcode()) && i == 0) {
// must be same register number as the first operand
// This maps a = b + c into b += c, and saves b into a's spot
physReg = (unsigned) MI->getOperand(1).getAllocatedRegNum();
physReg = MI->getOperand(1).getAllocatedRegNum();
} else {
physReg = getFreeReg(virtualReg);
}
@ -375,6 +385,8 @@ void RegAllocSimple::AllocateBasicBlock(MachineBasicBlock &MBB) {
}
}
/// runOnMachineFunction - Register allocate the whole function
///
bool RegAllocSimple::runOnMachineFunction(MachineFunction &Fn) {
DEBUG(std::cerr << "Machine Function " << "\n");
MF = &Fn;
@ -393,9 +405,7 @@ bool RegAllocSimple::runOnMachineFunction(MachineFunction &Fn) {
for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
MBB != MBBe; ++MBB) {
// check if last instruction is a RET
MachineBasicBlock::iterator I = MBB->end();
MachineInstr *MI = *--I;
if (MII.isReturn(MI->getOpcode())) {
if (MII.isReturn(MBB->back()->getOpcode())) {
// this block has a return instruction, add epilogue
RegInfo->emitEpilogue(*MBB, NumBytesAllocated);
}