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This should fix the bug seen with some registers not being allocated

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correctly: skipping instructions by incorrectly incrementing the pointer.

Also adds support for building a reg-to-regclass map, and splits the function
for saving register to stack into two, one suitable for virtual registers
(which also assigns it a physical register) and one for simply storing back
physical registers.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4898 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Misha Brukman 2002-12-03 23:15:19 +00:00
parent 03c6fafd05
commit dc2ec004f1
1 changed files with 45 additions and 6 deletions
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51
lib/CodeGen/RegAllocSimple.cpp
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@ -29,10 +29,13 @@ namespace {
unsigned NumBytesAllocated, ByteAlignment;
// Maps SSA Regs => offsets on the stack where these values are stored
std::map<unsigned, unsigned> RegMap; // FIXME: change name to OffsetMap
std::map<unsigned, unsigned> RegMap; // FIXME: change name to VirtReg2OffsetMap
// Maps SSA Regs => physical regs
std::map<unsigned, unsigned> SSA2PhysRegMap;
// Maps physical register to their register classes
std::map<unsigned, const TargetRegisterClass*> PhysReg2RegClassMap;
// 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
@ -44,6 +47,9 @@ namespace {
RegInfo(tm.getRegisterInfo()),
NumBytesAllocated(0), ByteAlignment(4)
{
// build reverse mapping for physReg -> register class
RegInfo->buildReg2RegClassMap(PhysReg2RegClassMap);
RegsUsed[RegInfo->getFramePointer()] = 1;
RegsUsed[RegInfo->getStackPointer()] = 1;
}
@ -73,8 +79,11 @@ namespace {
/// Saves reg value on the stack (maps virtual register to stack value)
MachineBasicBlock::iterator
saveRegToStack (MachineBasicBlock::iterator I, unsigned VirtReg,
unsigned PhysReg);
saveVirtRegToStack (MachineBasicBlock::iterator I, unsigned VirtReg,
unsigned PhysReg);
MachineBasicBlock::iterator
savePhysRegToStack (MachineBasicBlock::iterator I, unsigned PhysReg);
/// runOnFunction - Top level implementation of instruction selection for
/// the entire function.
@ -144,8 +153,8 @@ RegAllocSimple::moveUseToReg (MachineBasicBlock::iterator I,
}
MachineBasicBlock::iterator
RegAllocSimple::saveRegToStack (MachineBasicBlock::iterator I,
unsigned VirtReg, unsigned PhysReg)
RegAllocSimple::saveVirtRegToStack (MachineBasicBlock::iterator I,
unsigned VirtReg, unsigned PhysReg)
{
const TargetRegisterClass* regClass = MF->getRegClass(VirtReg);
assert(regClass);
@ -158,12 +167,38 @@ RegAllocSimple::saveRegToStack (MachineBasicBlock::iterator I,
offset, regClass->getDataSize());
}
MachineBasicBlock::iterator
RegAllocSimple::savePhysRegToStack (MachineBasicBlock::iterator I,
unsigned PhysReg)
{
const TargetRegisterClass* regClass = MF->getRegClass(PhysReg);
assert(regClass);
unsigned offset = allocateStackSpaceFor(PhysReg, regClass);
// Add move instruction(s)
return RegInfo->storeReg2RegOffset(CurrMBB, I, PhysReg,
RegInfo->getFramePointer(),
offset, regClass->getDataSize());
}
bool RegAllocSimple::runOnMachineFunction(MachineFunction &Fn) {
RegMap.clear();
unsigned virtualReg, physReg;
DEBUG(std::cerr << "Machine Function " << "\n");
MF = &Fn;
#if 0
// FIXME: add prolog. we should preserve callee-save registers...
MachineFunction::iterator Fi = Fn.begin();
MachineBasicBlock &MBB = *Fi;
MachineBasicBlock::iterator MBBi = MBB.begin()
const unsigned* calleeSaveRegs = tm.getCalleeSaveRegs();
while (*calleeSaveRegs) {
//MBBi = saveRegToStack(MBBi, *calleeSaveRegs,
++calleeSaveRegs;
}
#endif
for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
MBB != MBBe; ++MBB)
@ -178,6 +213,10 @@ bool RegAllocSimple::runOnMachineFunction(MachineFunction &Fn) {
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
for (int i = MI->getNumOperands() - 1; i >= 0; --i) {
@ -196,7 +235,7 @@ bool RegAllocSimple::runOnMachineFunction(MachineFunction &Fn) {
if (op.opIsDef()) {
physReg = getFreeReg(virtualReg);
MachineBasicBlock::iterator J = I;
I = saveRegToStack(++J, virtualReg, physReg);
I = saveVirtRegToStack(J, virtualReg, physReg);
} else {
I = moveUseToReg(I, virtualReg, physReg);
}