mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-09-28 22:55:52 +00:00
Simplify code by using the more powerful BuildMI forms.
Implement a small optimization. In test/Regression/CodeGen/X86/select.ll,
we now generate this for foldSel3:
foldSel3:
mov %AL, BYTE PTR [%ESP + 4]
fld DWORD PTR [%ESP + 8]
fld DWORD PTR [%ESP + 12]
mov %EAX, DWORD PTR [%ESP + 16]
mov %ECX, DWORD PTR [%ESP + 20]
cmp %EAX, %ECX
fxch %ST(1)
fcmovae %ST(0), %ST(1)
*** fstp %ST(1)
ret
Instead of:
foldSel3:
mov %AL, BYTE PTR [%ESP + 4]
fld DWORD PTR [%ESP + 8]
fld DWORD PTR [%ESP + 12]
mov %EAX, DWORD PTR [%ESP + 16]
mov %ECX, DWORD PTR [%ESP + 20]
cmp %EAX, %ECX
fxch %ST(1)
fcmovae %ST(0), %ST(1)
*** fxch %ST(1)
*** fstp %ST(0)
ret
In practice, this only effects code size: performance should be basically
unaffected.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12588 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
parent
f1ac50ec53
commit
0526f01fec
@ -118,25 +118,29 @@ namespace {
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std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
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// Emit an fxch to update the runtime processors version of the state
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MachineInstr *MI = BuildMI(X86::FXCH, 1).addReg(STReg);
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MBB->insert(I, MI);
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BuildMI(*MBB, I, X86::FXCH, 1).addReg(STReg);
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NumFXCH++;
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}
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}
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void duplicateToTop(unsigned RegNo, unsigned AsReg,
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MachineBasicBlock::iterator &I) {
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void duplicateToTop(unsigned RegNo, unsigned AsReg, MachineInstr *I) {
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unsigned STReg = getSTReg(RegNo);
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pushReg(AsReg); // New register on top of stack
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MachineInstr *MI = BuildMI(X86::FLDrr, 1).addReg(STReg);
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MBB->insert(I, MI);
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BuildMI(*MBB, I, X86::FLDrr, 1).addReg(STReg);
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}
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// popStackAfter - Pop the current value off of the top of the FP stack
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// after the specified instruction.
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void popStackAfter(MachineBasicBlock::iterator &I);
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// freeStackSlotAfter - Free the specified register from the register stack,
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// so that it is no longer in a register. If the register is currently at
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// the top of the stack, we just pop the current instruction, otherwise we
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// store the current top-of-stack into the specified slot, then pop the top
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// of stack.
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void freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned Reg);
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bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB);
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void handleZeroArgFP(MachineBasicBlock::iterator &I);
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@ -250,7 +254,7 @@ bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
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DEBUG(
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MachineBasicBlock::iterator PrevI(PrevMI);
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if (I == PrevI) {
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std::cerr<< "Just deleted pseudo instruction\n";
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std::cerr << "Just deleted pseudo instruction\n";
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} else {
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MachineBasicBlock::iterator Start = I;
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// Rewind to first instruction newly inserted.
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@ -358,11 +362,34 @@ void FPS::popStackAfter(MachineBasicBlock::iterator &I) {
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I->RemoveOperand(0);
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} else { // Insert an explicit pop
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MachineInstr *MI = BuildMI(X86::FSTPrr, 1).addReg(X86::ST0);
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I = MBB->insert(++I, MI);
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I = BuildMI(*MBB, ++I, X86::FSTPrr, 1).addReg(X86::ST0);
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}
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}
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/// freeStackSlotAfter - Free the specified register from the register stack, so
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/// that it is no longer in a register. If the register is currently at the top
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/// of the stack, we just pop the current instruction, otherwise we store the
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/// current top-of-stack into the specified slot, then pop the top of stack.
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void FPS::freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned FPRegNo) {
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if (getStackEntry(0) == FPRegNo) { // already at the top of stack? easy.
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popStackAfter(I);
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return;
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}
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// Otherwise, store the top of stack into the dead slot, killing the operand
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// without having to add in an explicit xchg then pop.
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//
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unsigned STReg = getSTReg(FPRegNo);
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unsigned OldSlot = getSlot(FPRegNo);
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unsigned TopReg = Stack[StackTop-1];
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Stack[OldSlot] = TopReg;
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RegMap[TopReg] = OldSlot;
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RegMap[FPRegNo] = ~0;
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Stack[--StackTop] = ~0;
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I = BuildMI(*MBB, ++I, X86::FSTPrr, 1).addReg(STReg);
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}
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static unsigned getFPReg(const MachineOperand &MO) {
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assert(MO.isRegister() && "Expected an FP register!");
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unsigned Reg = MO.getReg();
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@ -596,8 +623,7 @@ void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) {
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// Replace the old instruction with a new instruction
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MBB->remove(I++);
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BuildMI(*MBB, I, Opcode, 1).addReg(getSTReg(NotTOS));
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--I;
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I = BuildMI(*MBB, I, Opcode, 1).addReg(getSTReg(NotTOS));
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// If both operands are killed, pop one off of the stack in addition to
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// overwriting the other one.
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@ -610,25 +636,8 @@ void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) {
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if (MI->getOpcode() == X86::FpUCOM) {
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if (KillsOp0 && !KillsOp1)
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popStackAfter(I); // If we kill the first operand, pop it!
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else if (KillsOp1 && Op0 != Op1) {
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if (getStackEntry(0) == Op1) {
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popStackAfter(I); // If it's right at the top of stack, just pop it
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} else {
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// Otherwise, move the top of stack into the dead slot, killing the
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// operand without having to add in an explicit xchg then pop.
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//
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unsigned STReg = getSTReg(Op1);
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unsigned OldSlot = getSlot(Op1);
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unsigned TopReg = Stack[StackTop-1];
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Stack[OldSlot] = TopReg;
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RegMap[TopReg] = OldSlot;
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RegMap[Op1] = ~0;
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Stack[--StackTop] = ~0;
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MachineInstr *MI = BuildMI(X86::FSTPrr, 1).addReg(STReg);
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I = MBB->insert(++I, MI);
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}
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}
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else if (KillsOp1 && Op0 != Op1)
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freeStackSlotAfter(I, Op1);
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}
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// Update stack information so that we know the destination register is now on
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@ -663,10 +672,8 @@ void FPS::handleCondMovFP(MachineBasicBlock::iterator &I) {
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for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
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E = LV->killed_end(MI); KI != E; ++KI)
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if (KI->second == X86::FP0+Op1) {
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++I;
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moveToTop(Op1, I); // Insert fxch if necessary
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--I;
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popStackAfter(I); // Pop the top of the stack, killing value
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// Get this value off of the register stack.
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freeStackSlotAfter(I, Op1);
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break;
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}
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}
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@ -118,25 +118,29 @@ namespace {
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std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
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// Emit an fxch to update the runtime processors version of the state
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MachineInstr *MI = BuildMI(X86::FXCH, 1).addReg(STReg);
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MBB->insert(I, MI);
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BuildMI(*MBB, I, X86::FXCH, 1).addReg(STReg);
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NumFXCH++;
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}
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}
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void duplicateToTop(unsigned RegNo, unsigned AsReg,
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MachineBasicBlock::iterator &I) {
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void duplicateToTop(unsigned RegNo, unsigned AsReg, MachineInstr *I) {
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unsigned STReg = getSTReg(RegNo);
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pushReg(AsReg); // New register on top of stack
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MachineInstr *MI = BuildMI(X86::FLDrr, 1).addReg(STReg);
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MBB->insert(I, MI);
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BuildMI(*MBB, I, X86::FLDrr, 1).addReg(STReg);
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}
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// popStackAfter - Pop the current value off of the top of the FP stack
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// after the specified instruction.
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void popStackAfter(MachineBasicBlock::iterator &I);
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// freeStackSlotAfter - Free the specified register from the register stack,
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// so that it is no longer in a register. If the register is currently at
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// the top of the stack, we just pop the current instruction, otherwise we
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// store the current top-of-stack into the specified slot, then pop the top
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// of stack.
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void freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned Reg);
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bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB);
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void handleZeroArgFP(MachineBasicBlock::iterator &I);
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@ -250,7 +254,7 @@ bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
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DEBUG(
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MachineBasicBlock::iterator PrevI(PrevMI);
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if (I == PrevI) {
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std::cerr<< "Just deleted pseudo instruction\n";
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std::cerr << "Just deleted pseudo instruction\n";
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} else {
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MachineBasicBlock::iterator Start = I;
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// Rewind to first instruction newly inserted.
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@ -358,11 +362,34 @@ void FPS::popStackAfter(MachineBasicBlock::iterator &I) {
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I->RemoveOperand(0);
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} else { // Insert an explicit pop
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MachineInstr *MI = BuildMI(X86::FSTPrr, 1).addReg(X86::ST0);
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I = MBB->insert(++I, MI);
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I = BuildMI(*MBB, ++I, X86::FSTPrr, 1).addReg(X86::ST0);
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}
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}
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/// freeStackSlotAfter - Free the specified register from the register stack, so
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/// that it is no longer in a register. If the register is currently at the top
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/// of the stack, we just pop the current instruction, otherwise we store the
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/// current top-of-stack into the specified slot, then pop the top of stack.
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void FPS::freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned FPRegNo) {
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if (getStackEntry(0) == FPRegNo) { // already at the top of stack? easy.
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popStackAfter(I);
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return;
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}
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// Otherwise, store the top of stack into the dead slot, killing the operand
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// without having to add in an explicit xchg then pop.
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//
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unsigned STReg = getSTReg(FPRegNo);
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unsigned OldSlot = getSlot(FPRegNo);
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unsigned TopReg = Stack[StackTop-1];
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Stack[OldSlot] = TopReg;
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RegMap[TopReg] = OldSlot;
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RegMap[FPRegNo] = ~0;
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Stack[--StackTop] = ~0;
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I = BuildMI(*MBB, ++I, X86::FSTPrr, 1).addReg(STReg);
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}
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static unsigned getFPReg(const MachineOperand &MO) {
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assert(MO.isRegister() && "Expected an FP register!");
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unsigned Reg = MO.getReg();
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@ -596,8 +623,7 @@ void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) {
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// Replace the old instruction with a new instruction
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MBB->remove(I++);
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BuildMI(*MBB, I, Opcode, 1).addReg(getSTReg(NotTOS));
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--I;
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I = BuildMI(*MBB, I, Opcode, 1).addReg(getSTReg(NotTOS));
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// If both operands are killed, pop one off of the stack in addition to
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// overwriting the other one.
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@ -610,25 +636,8 @@ void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) {
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if (MI->getOpcode() == X86::FpUCOM) {
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if (KillsOp0 && !KillsOp1)
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popStackAfter(I); // If we kill the first operand, pop it!
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else if (KillsOp1 && Op0 != Op1) {
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if (getStackEntry(0) == Op1) {
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popStackAfter(I); // If it's right at the top of stack, just pop it
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} else {
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// Otherwise, move the top of stack into the dead slot, killing the
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// operand without having to add in an explicit xchg then pop.
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//
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unsigned STReg = getSTReg(Op1);
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unsigned OldSlot = getSlot(Op1);
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unsigned TopReg = Stack[StackTop-1];
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Stack[OldSlot] = TopReg;
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RegMap[TopReg] = OldSlot;
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RegMap[Op1] = ~0;
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Stack[--StackTop] = ~0;
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MachineInstr *MI = BuildMI(X86::FSTPrr, 1).addReg(STReg);
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I = MBB->insert(++I, MI);
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}
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}
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else if (KillsOp1 && Op0 != Op1)
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freeStackSlotAfter(I, Op1);
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}
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// Update stack information so that we know the destination register is now on
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@ -663,10 +672,8 @@ void FPS::handleCondMovFP(MachineBasicBlock::iterator &I) {
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for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
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E = LV->killed_end(MI); KI != E; ++KI)
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if (KI->second == X86::FP0+Op1) {
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++I;
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moveToTop(Op1, I); // Insert fxch if necessary
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--I;
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popStackAfter(I); // Pop the top of the stack, killing value
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// Get this value off of the register stack.
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freeStackSlotAfter(I, Op1);
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break;
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}
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}
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