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Fix many bugs, regallocator now saves callee-save registers instead of target

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5093 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2002-12-17 02:50:10 +00:00
parent 6c6cf873f3
commit ae64043737
1 changed files with 163 additions and 52 deletions
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215
lib/CodeGen/RegAllocLocal.cpp
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@ -20,9 +20,9 @@
class PhysRegClassMap {
std::map<unsigned, const TargetRegisterClass*> PhysReg2RegClassMap;
public:
PhysRegClassMap(const MRegisterInfo *RI) {
for (MRegisterInfo::const_iterator I = RI->regclass_begin(),
E = RI->regclass_end(); I != E; ++I)
PhysRegClassMap(const MRegisterInfo &RI) {
for (MRegisterInfo::const_iterator I = RI.regclass_begin(),
E = RI.regclass_end(); I != E; ++I)
for (unsigned i=0; i < (*I)->getNumRegs(); ++i)
PhysReg2RegClassMap[(*I)->getRegister(i)] = *I;
}
@ -42,7 +42,8 @@ namespace {
class RA : public FunctionPass {
TargetMachine &TM;
MachineFunction *MF;
const MRegisterInfo *RegInfo;
const MRegisterInfo &RegInfo;
const MachineInstrInfo &MIInfo;
unsigned NumBytesAllocated;
PhysRegClassMap PhysRegClasses;
@ -88,7 +89,8 @@ namespace {
public:
RA(TargetMachine &tm)
: TM(tm), RegInfo(tm.getRegisterInfo()), PhysRegClasses(RegInfo) {
: TM(tm), RegInfo(*tm.getRegisterInfo()), MIInfo(tm.getInstrInfo()),
PhysRegClasses(RegInfo) {
cleanupAfterFunction();
}
@ -111,16 +113,23 @@ namespace {
/// in predecessor basic blocks.
void EliminatePHINodes(MachineBasicBlock &MBB);
/// EmitPrologue/EmitEpilogue - Use the register info object to add a
/// prologue/epilogue to the function and save/restore any callee saved
/// registers we are responsible for.
///
void EmitPrologue();
void EmitEpilogue(MachineBasicBlock &MBB);
/// isAllocatableRegister - A register may be used by the program if it's
/// not the stack or frame pointer.
bool isAllocatableRegister(unsigned R) const {
unsigned FP = RegInfo->getFramePointer(), SP = RegInfo->getStackPointer();
unsigned FP = RegInfo.getFramePointer(), SP = RegInfo.getStackPointer();
// Don't allocate the Frame or Stack pointers
if (R == FP || R == SP)
return false;
// Check to see if this register aliases the stack or frame pointer...
if (const unsigned *AliasSet = RegInfo->getAliasSet(R)) {
if (const unsigned *AliasSet = RegInfo.getAliasSet(R)) {
for (unsigned i = 0; AliasSet[i]; ++i)
if (AliasSet[i] == FP || AliasSet[i] == SP)
return false;
@ -151,13 +160,18 @@ namespace {
//
void spillPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
unsigned PhysReg) {
assert(PhysRegsUsed.find(PhysReg) != PhysRegsUsed.end() &&
"Physical register is not used: cannot spill it!");
spillVirtReg(MBB, I, PhysRegsUsed[PhysReg], PhysReg);
std::map<unsigned, unsigned>::iterator PI = PhysRegsUsed.find(PhysReg);
if (PI != PhysRegsUsed.end()) // Only spill it if it's used!
spillVirtReg(MBB, I, PI->second, PhysReg);
}
void AssignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg);
/// isPhysRegAvailable - Return true if the specified physical register is
/// free and available for use. This also includes checking to see if
/// aliased registers are all free...
///
bool RA::isPhysRegAvailable(unsigned PhysReg) const;
/// getFreeReg - Find a physical register to hold the specified virtual
/// register. If all compatible physical registers are used, this method
@ -176,9 +190,9 @@ namespace {
unsigned reloadVirtReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &I, unsigned VirtReg);
};
}
/// getStackSpaceFor - This allocates space for the specified virtual
/// register to be held on the stack.
unsigned RA::getStackSpaceFor(unsigned VirtReg,
@ -206,6 +220,7 @@ unsigned RA::getStackSpaceFor(unsigned VirtReg,
return NumBytesAllocated-RegSize;
}
/// spillVirtReg - This method spills the value specified by PhysReg into the
/// virtual register slot specified by VirtReg. It then updates the RA data
/// structures to indicate the fact that PhysReg is now available.
@ -218,8 +233,8 @@ void RA::spillVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
unsigned stackOffset = getStackSpaceFor(VirtReg, RegClass);
// Add move instruction(s)
I = RegInfo->storeReg2RegOffset(MBB, I, PhysReg, RegInfo->getFramePointer(),
-stackOffset, RegClass->getDataSize());
I = RegInfo.storeReg2RegOffset(MBB, I, PhysReg, RegInfo.getFramePointer(),
-stackOffset, RegClass->getDataSize());
++NumSpilled; // Update statistics
Virt2PhysRegMap.erase(VirtReg); // VirtReg no longer available
}
@ -232,6 +247,25 @@ void RA::spillVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
PhysRegsUseOrder.erase(It);
}
/// isPhysRegAvailable - Return true if the specified physical register is free
/// and available for use. This also includes checking to see if aliased
/// registers are all free...
///
bool RA::isPhysRegAvailable(unsigned PhysReg) const {
if (PhysRegsUsed.count(PhysReg)) return false;
// If the selected register aliases any other allocated registers, it is
// not free!
if (const unsigned *AliasSet = RegInfo.getAliasSet(PhysReg))
for (unsigned i = 0; AliasSet[i]; ++i)
if (PhysRegsUsed.count(AliasSet[i])) // Aliased register in use?
return false; // Can't use this reg then.
return true;
}
/// getFreeReg - Find a physical register to hold the specified virtual
/// register. If all compatible physical registers are used, this method spills
/// the last used virtual register to the stack, and uses that register.
@ -240,47 +274,72 @@ unsigned RA::getFreeReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &I,
unsigned VirtReg) {
const TargetRegisterClass *RegClass = MF->getRegClass(VirtReg);
unsigned PhysReg = 0;
// First check to see if we have a free register of the requested type...
for (TargetRegisterClass::iterator It = RegClass->begin(),E = RegClass->end();
It != E; ++It) {
unsigned R = *It;
if (PhysRegsUsed.find(R) == PhysRegsUsed.end()) // Is reg unused?
if (isAllocatableRegister(R)) {
if (isPhysRegAvailable(R)) { // Is reg unused?
if (isAllocatableRegister(R)) { // And is not a frame register?
// Found an unused register!
PhysReg = R;
break;
}
}
}
// If we didn't find an unused register, scavange one now!
// If we didn't find an unused register, scavenge one now!
if (PhysReg == 0) {
unsigned i = 0;
assert(!PhysRegsUseOrder.empty() && "No allocated registers??");
while (PhysRegClasses[PhysRegsUseOrder[i]] != RegClass) {
++i;
// Loop over all of the preallocated registers from the least recently used
// to the most recently used. When we find one that is capable of holding
// our register, use it.
for (unsigned i = 0; PhysReg == 0; ++i) {
assert(i != PhysRegsUseOrder.size() &&
"Couldn't find a register of the appropriate class!");
unsigned R = PhysRegsUseOrder[i];
// If the current register is compatible, use it.
if (isAllocatableRegister(R)) {
if (PhysRegClasses[R] == RegClass) {
PhysReg = R;
break;
} else {
// If one of the registers aliased to the current register is
// compatible, use it.
if (const unsigned *AliasSet = RegInfo.getAliasSet(R))
for (unsigned a = 0; AliasSet[a]; ++a)
if (PhysRegClasses[AliasSet[a]] == RegClass) {
PhysReg = AliasSet[a]; // Take an aliased register
break;
}
}
}
}
assert(isAllocatableRegister(PhysReg) && "Register is not allocatable!");
assert(PhysReg && "Physical register not assigned!?!?");
// At this point PhysRegsUseOrder[i] is the least recently used register of
// compatible register class. Spill it to memory and reap its remains.
PhysReg = PhysRegsUseOrder[i];
spillPhysReg(MBB, I, PhysReg);
// If the selected register aliases any other registers, we must make sure
// to spill them as well...
if (const unsigned *AliasSet = RegInfo.getAliasSet(PhysReg))
for (unsigned i = 0; AliasSet[i]; ++i)
if (PhysRegsUsed.count(AliasSet[i])) // Spill aliased register...
spillPhysReg(MBB, I, AliasSet[i]);
}
// If the selected register aliases any other registers, we must make sure to
// spill them as well...
if (const unsigned *AliasSet = RegInfo->getAliasSet(PhysReg))
for (unsigned i = 0; AliasSet[i]; ++i)
if (PhysRegsUsed.count(AliasSet[i])) // Spill aliased register...
spillPhysReg(MBB, I, AliasSet[i]);
// Now that we know which register we need to assign this to, do it now!
AssignVirtToPhysReg(VirtReg, PhysReg);
return PhysReg;
}
void RA::AssignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg) {
assert(PhysRegsUsed.find(PhysReg) == PhysRegsUsed.end() &&
"Phys reg already assigned!");
@ -312,12 +371,13 @@ unsigned RA::reloadVirtReg(MachineBasicBlock &MBB,
unsigned StackOffset = getStackSpaceFor(VirtReg, RegClass);
// Add move instruction(s)
I = RegInfo->loadRegOffset2Reg(MBB, I, PhysReg, RegInfo->getFramePointer(),
-StackOffset, RegClass->getDataSize());
I = RegInfo.loadRegOffset2Reg(MBB, I, PhysReg, RegInfo.getFramePointer(),
-StackOffset, RegClass->getDataSize());
++NumReloaded; // Update statistics
return PhysReg;
}
/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions in
/// predecessor basic blocks.
///
@ -375,12 +435,12 @@ void RA::EliminatePHINodes(MachineBasicBlock &MBB) {
// Retrieve the constant value from this op, move it to target
// register of the phi
if (opVal.isImmediate()) {
opI = RegInfo->moveImm2Reg(opBlock, opI, virtualReg,
(unsigned) opVal.getImmedValue(),
dataSize);
opI = RegInfo.moveImm2Reg(opBlock, opI, virtualReg,
(unsigned) opVal.getImmedValue(),
dataSize);
} else {
opI = RegInfo->moveReg2Reg(opBlock, opI, virtualReg,
opVal.getAllocatedRegNum(), dataSize);
opI = RegInfo.moveReg2Reg(opBlock, opI, virtualReg,
opVal.getAllocatedRegNum(), dataSize);
}
}
}
@ -390,31 +450,39 @@ void RA::EliminatePHINodes(MachineBasicBlock &MBB) {
}
}
void RA::AllocateBasicBlock(MachineBasicBlock &MBB) {
// loop over each instruction
MachineBasicBlock::iterator I = MBB.begin();
for (; I != MBB.end(); ++I) {
MachineInstr *MI = *I;
const MachineInstrDescriptor &MID = MIInfo.get(MI->getOpcode());
// Loop over all of the operands of the instruction, spilling registers that
// are defined, and marking explicit destinations in the PhysRegsUsed map.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
if (MI->getOperand(i).opIsDef() &&
MI->getOperand(i).isPhysicalRegister()) {
unsigned Reg = MI->getOperand(i).getAllocatedRegNum();
unsigned VMap = PhysRegsUsed[Reg];
if (VMap) { // Spill the value in this register...
spillVirtReg(MBB, I, VMap, Reg);
PhysRegsUsed[Reg] = 0; // It's free now, and it's reserved
}
unsigned Reg = MI->getOperand(i).getAllocatedRegNum();
spillPhysReg(MBB, I, Reg);
PhysRegsUsed[Reg] = 0; // It's free now, and it's reserved
PhysRegsUseOrder.push_back(Reg);
}
// FIXME: Loop over the implicit defs, spilling them, as above.
// Loop over the implicit defs, spilling them, as above.
if (const unsigned *ImplicitDefs = MID.ImplicitDefs)
for (unsigned i = 0; ImplicitDefs[i]; ++i) {
unsigned Reg = ImplicitDefs[i];
spillPhysReg(MBB, I, Reg);
PhysRegsUsed[Reg] = 0; // It's free now, and it's reserved
PhysRegsUseOrder.push_back(Reg);
}
// FIXME: Loop over the implicit uses, making sure that they are at the head
// of the use order list, so they don't get reallocated.
// Loop over the implicit uses, making sure that they are at the head of the
// use order list, so they don't get reallocated.
if (const unsigned *ImplicitUses = MID.ImplicitUses)
for (unsigned i = 0; ImplicitUses[i]; ++i)
MarkPhysRegRecentlyUsed(ImplicitUses[i]);
// Loop over all of the operands again, getting the used operands into
// registers. This has the potiential to spill incoming values because we
@ -479,6 +547,52 @@ void RA::AllocateBasicBlock(MachineBasicBlock &MBB) {
assert(PhysRegsUseOrder.empty() && "Physical regs still allocated?");
}
/// EmitPrologue - Use the register info object to add a prologue to the
/// function and save any callee saved registers we are responsible for.
///
void RA::EmitPrologue() {
// Get a list of the callee saved registers, so that we can save them on entry
// to the function.
//
MachineBasicBlock &MBB = MF->front(); // Prolog goes in entry BB
MachineBasicBlock::iterator I = MBB.begin();
const unsigned *CSRegs = RegInfo.getCalleeSaveRegs();
for (unsigned i = 0; CSRegs[i]; ++i) {
const TargetRegisterClass *RegClass = PhysRegClasses[CSRegs[i]];
unsigned Offset = getStackSpaceFor(CSRegs[i], RegClass);
// Insert the spill to the stack frame...
I = RegInfo.storeReg2RegOffset(MBB, I, CSRegs[i], RegInfo.getFramePointer(),
-Offset, RegClass->getDataSize());
}
// Round stack allocation up to a nice alignment to keep the stack aligned
// FIXME: This is X86 specific! Move to RegInfo.emitPrologue()!
NumBytesAllocated = (NumBytesAllocated + 3) & ~3;
// Add prologue to the function...
RegInfo.emitPrologue(*MF, NumBytesAllocated);
}
void RA::EmitEpilogue(MachineBasicBlock &MBB) {
// Insert instructions before the return.
MachineBasicBlock::iterator I = --MBB.end();
const unsigned *CSRegs = RegInfo.getCalleeSaveRegs();
for (unsigned i = 0; CSRegs[i]; ++i) {
const TargetRegisterClass *RegClass = PhysRegClasses[CSRegs[i]];
unsigned Offset = getStackSpaceFor(CSRegs[i], RegClass);
I = RegInfo.loadRegOffset2Reg(MBB, I, CSRegs[i], RegInfo.getFramePointer(),
-Offset, RegClass->getDataSize());
--I; // Insert in reverse order
}
RegInfo.emitEpilogue(MBB, NumBytesAllocated);
}
/// runOnMachineFunction - Register allocate the whole function
///
bool RA::runOnMachineFunction(MachineFunction &Fn) {
@ -497,12 +611,9 @@ bool RA::runOnMachineFunction(MachineFunction &Fn) {
MBB != MBBe; ++MBB)
AllocateBasicBlock(*MBB);
// Round stack allocation up to a nice alignment to keep the stack aligned
// FIXME: This is X86 specific! Move to frame manager
NumBytesAllocated = (NumBytesAllocated + 3) & ~3;
// Add prologue to the function...
RegInfo->emitPrologue(Fn, NumBytesAllocated);
// Emit a prologue for the function...
EmitPrologue();
const MachineInstrInfo &MII = TM.getInstrInfo();
@ -511,7 +622,7 @@ bool RA::runOnMachineFunction(MachineFunction &Fn) {
MBB != MBBe; ++MBB) {
// If last instruction is a return instruction, add an epilogue
if (MII.isReturn(MBB->back()->getOpcode()))
RegInfo->emitEpilogue(*MBB, NumBytesAllocated);
EmitEpilogue(*MBB);
}
cleanupAfterFunction();