1 //===-- FloatingPoint.cpp - Floating point Reg -> Stack converter ---------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the pass which converts floating point instructions from
11 // virtual registers into register stack instructions. This pass uses live
12 // variable information to indicate where the FPn registers are used and their
15 // This pass is hampered by the lack of decent CFG manipulation routines for
16 // machine code. In particular, this wants to be able to split critical edges
17 // as necessary, traverse the machine basic block CFG in depth-first order, and
18 // allow there to be multiple machine basic blocks for each LLVM basicblock
19 // (needed for critical edge splitting).
21 // In particular, this pass currently barfs on critical edges. Because of this,
22 // it requires the instruction selector to insert FP_REG_KILL instructions on
23 // the exits of any basic block that has critical edges going from it, or which
24 // branch to a critical basic block.
26 // FIXME: this is not implemented yet. The stackifier pass only works on local
29 //===----------------------------------------------------------------------===//
31 #define DEBUG_TYPE "fp"
33 #include "X86InstrInfo.h"
34 #include "llvm/CodeGen/MachineFunctionPass.h"
35 #include "llvm/CodeGen/MachineInstrBuilder.h"
36 #include "llvm/CodeGen/LiveVariables.h"
37 #include "llvm/CodeGen/Passes.h"
38 #include "llvm/Target/TargetInstrInfo.h"
39 #include "llvm/Target/TargetMachine.h"
40 #include "Support/Debug.h"
41 #include "Support/DepthFirstIterator.h"
42 #include "Support/Statistic.h"
43 #include "Support/STLExtras.h"
49 Statistic<> NumFXCH("x86-codegen", "Number of fxch instructions inserted");
50 Statistic<> NumFP ("x86-codegen", "Number of floating point instructions");
52 struct FPS : public MachineFunctionPass {
53 virtual bool runOnMachineFunction(MachineFunction &MF);
55 virtual const char *getPassName() const { return "X86 FP Stackifier"; }
57 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
58 AU.addRequired<LiveVariables>();
59 MachineFunctionPass::getAnalysisUsage(AU);
62 LiveVariables *LV; // Live variable info for current function...
63 MachineBasicBlock *MBB; // Current basic block
64 unsigned Stack[8]; // FP<n> Registers in each stack slot...
65 unsigned RegMap[8]; // Track which stack slot contains each register
66 unsigned StackTop; // The current top of the FP stack.
68 void dumpStack() const {
69 std::cerr << "Stack contents:";
70 for (unsigned i = 0; i != StackTop; ++i) {
71 std::cerr << " FP" << Stack[i];
72 assert(RegMap[Stack[i]] == i && "Stack[] doesn't match RegMap[]!");
77 // getSlot - Return the stack slot number a particular register number is
79 unsigned getSlot(unsigned RegNo) const {
80 assert(RegNo < 8 && "Regno out of range!");
84 // getStackEntry - Return the X86::FP<n> register in register ST(i)
85 unsigned getStackEntry(unsigned STi) const {
86 assert(STi < StackTop && "Access past stack top!");
87 return Stack[StackTop-1-STi];
90 // getSTReg - Return the X86::ST(i) register which contains the specified
92 unsigned getSTReg(unsigned RegNo) const {
93 return StackTop - 1 - getSlot(RegNo) + llvm::X86::ST0;
96 // pushReg - Push the specified FP<n> register onto the stack
97 void pushReg(unsigned Reg) {
98 assert(Reg < 8 && "Register number out of range!");
99 assert(StackTop < 8 && "Stack overflow!");
100 Stack[StackTop] = Reg;
101 RegMap[Reg] = StackTop++;
104 bool isAtTop(unsigned RegNo) const { return getSlot(RegNo) == StackTop-1; }
105 void moveToTop(unsigned RegNo, MachineBasicBlock::iterator &I) {
106 if (!isAtTop(RegNo)) {
107 unsigned Slot = getSlot(RegNo);
108 unsigned STReg = getSTReg(RegNo);
109 unsigned RegOnTop = getStackEntry(0);
111 // Swap the slots the regs are in
112 std::swap(RegMap[RegNo], RegMap[RegOnTop]);
114 // Swap stack slot contents
115 assert(RegMap[RegOnTop] < StackTop);
116 std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
118 // Emit an fxch to update the runtime processors version of the state
119 BuildMI(*MBB, I, X86::FXCH, 1).addReg(STReg);
124 void duplicateToTop(unsigned RegNo, unsigned AsReg, MachineInstr *I) {
125 unsigned STReg = getSTReg(RegNo);
126 pushReg(AsReg); // New register on top of stack
128 BuildMI(*MBB, I, X86::FLDrr, 1).addReg(STReg);
131 // popStackAfter - Pop the current value off of the top of the FP stack
132 // after the specified instruction.
133 void popStackAfter(MachineBasicBlock::iterator &I);
135 // freeStackSlotAfter - Free the specified register from the register stack,
136 // so that it is no longer in a register. If the register is currently at
137 // the top of the stack, we just pop the current instruction, otherwise we
138 // store the current top-of-stack into the specified slot, then pop the top
140 void freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned Reg);
142 bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB);
144 void handleZeroArgFP(MachineBasicBlock::iterator &I);
145 void handleOneArgFP(MachineBasicBlock::iterator &I);
146 void handleOneArgFPRW(MachineBasicBlock::iterator &I);
147 void handleTwoArgFP(MachineBasicBlock::iterator &I);
148 void handleCondMovFP(MachineBasicBlock::iterator &I);
149 void handleSpecialFP(MachineBasicBlock::iterator &I);
153 FunctionPass *llvm::createX86FloatingPointStackifierPass() { return new FPS(); }
155 /// runOnMachineFunction - Loop over all of the basic blocks, transforming FP
156 /// register references into FP stack references.
158 bool FPS::runOnMachineFunction(MachineFunction &MF) {
159 LV = &getAnalysis<LiveVariables>();
162 // Process the function in depth first order so that we process at least one
163 // of the predecessors for every reachable block in the function.
164 std::set<MachineBasicBlock*> Processed;
165 MachineBasicBlock *Entry = MF.begin();
167 bool Changed = false;
168 for (df_ext_iterator<MachineBasicBlock*, std::set<MachineBasicBlock*> >
169 I = df_ext_begin(Entry, Processed), E = df_ext_end(Entry, Processed);
171 Changed |= processBasicBlock(MF, **I);
176 /// processBasicBlock - Loop over all of the instructions in the basic block,
177 /// transforming FP instructions into their stack form.
179 bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
180 const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
181 bool Changed = false;
184 for (MachineBasicBlock::iterator I = BB.begin(); I != BB.end(); ++I) {
185 MachineInstr *MI = I;
186 unsigned Flags = TII.get(MI->getOpcode()).TSFlags;
187 if ((Flags & X86II::FPTypeMask) == X86II::NotFP)
188 continue; // Efficiently ignore non-fp insts!
190 MachineInstr *PrevMI = 0;
194 ++NumFP; // Keep track of # of pseudo instrs
195 DEBUG(std::cerr << "\nFPInst:\t";
196 MI->print(std::cerr, MF.getTarget()));
198 // Get dead variables list now because the MI pointer may be deleted as part
200 LiveVariables::killed_iterator IB = LV->dead_begin(MI);
201 LiveVariables::killed_iterator IE = LV->dead_end(MI);
203 DEBUG(const MRegisterInfo *MRI = MF.getTarget().getRegisterInfo();
204 LiveVariables::killed_iterator I = LV->killed_begin(MI);
205 LiveVariables::killed_iterator E = LV->killed_end(MI);
207 std::cerr << "Killed Operands:";
209 std::cerr << " %" << MRI->getName(I->second);
213 switch (Flags & X86II::FPTypeMask) {
214 case X86II::ZeroArgFP: handleZeroArgFP(I); break;
215 case X86II::OneArgFP: handleOneArgFP(I); break; // fstp ST(0)
216 case X86II::OneArgFPRW: handleOneArgFPRW(I); break; // ST(0) = fsqrt(ST(0))
217 case X86II::TwoArgFP: handleTwoArgFP(I); break;
218 case X86II::CondMovFP: handleCondMovFP(I); break;
219 case X86II::SpecialFP: handleSpecialFP(I); break;
220 default: assert(0 && "Unknown FP Type!");
223 // Check to see if any of the values defined by this instruction are dead
224 // after definition. If so, pop them.
225 for (; IB != IE; ++IB) {
226 unsigned Reg = IB->second;
227 if (Reg >= X86::FP0 && Reg <= X86::FP6) {
228 DEBUG(std::cerr << "Register FP#" << Reg-X86::FP0 << " is dead!\n");
229 ++I; // Insert fxch AFTER the instruction
230 moveToTop(Reg-X86::FP0, I); // Insert fxch if necessary
231 --I; // Move to fxch or old instruction
232 popStackAfter(I); // Pop the top of the stack, killing value
236 // Print out all of the instructions expanded to if -debug
238 MachineBasicBlock::iterator PrevI(PrevMI);
240 std::cerr << "Just deleted pseudo instruction\n";
242 MachineBasicBlock::iterator Start = I;
243 // Rewind to first instruction newly inserted.
244 while (Start != BB.begin() && prior(Start) != PrevI) --Start;
245 std::cerr << "Inserted instructions:\n\t";
246 Start->print(std::cerr, MF.getTarget());
247 while (++Start != next(I));
255 assert(StackTop == 0 && "Stack not empty at end of basic block?");
259 //===----------------------------------------------------------------------===//
260 // Efficient Lookup Table Support
261 //===----------------------------------------------------------------------===//
267 bool operator<(const TableEntry &TE) const { return from < TE.from; }
268 bool operator<(unsigned V) const { return from < V; }
272 static bool TableIsSorted(const TableEntry *Table, unsigned NumEntries) {
273 for (unsigned i = 0; i != NumEntries-1; ++i)
274 if (!(Table[i] < Table[i+1])) return false;
278 static int Lookup(const TableEntry *Table, unsigned N, unsigned Opcode) {
279 const TableEntry *I = std::lower_bound(Table, Table+N, Opcode);
280 if (I != Table+N && I->from == Opcode)
285 #define ARRAY_SIZE(TABLE) \
286 (sizeof(TABLE)/sizeof(TABLE[0]))
289 #define ASSERT_SORTED(TABLE)
291 #define ASSERT_SORTED(TABLE) \
292 { static bool TABLE##Checked = false; \
293 if (!TABLE##Checked) \
294 assert(TableIsSorted(TABLE, ARRAY_SIZE(TABLE)) && \
295 "All lookup tables must be sorted for efficient access!"); \
300 //===----------------------------------------------------------------------===//
302 //===----------------------------------------------------------------------===//
304 // PopTable - Sorted map of instructions to their popping version. The first
305 // element is an instruction, the second is the version which pops.
307 static const TableEntry PopTable[] = {
308 { X86::FADDrST0 , X86::FADDPrST0 },
310 { X86::FDIVRrST0, X86::FDIVRPrST0 },
311 { X86::FDIVrST0 , X86::FDIVPrST0 },
313 { X86::FIST16m , X86::FISTP16m },
314 { X86::FIST32m , X86::FISTP32m },
316 { X86::FMULrST0 , X86::FMULPrST0 },
318 { X86::FST32m , X86::FSTP32m },
319 { X86::FST64m , X86::FSTP64m },
320 { X86::FSTrr , X86::FSTPrr },
322 { X86::FSUBRrST0, X86::FSUBRPrST0 },
323 { X86::FSUBrST0 , X86::FSUBPrST0 },
325 { X86::FUCOMIr , X86::FUCOMIPr },
327 { X86::FUCOMPr , X86::FUCOMPPr },
328 { X86::FUCOMr , X86::FUCOMPr },
331 /// popStackAfter - Pop the current value off of the top of the FP stack after
332 /// the specified instruction. This attempts to be sneaky and combine the pop
333 /// into the instruction itself if possible. The iterator is left pointing to
334 /// the last instruction, be it a new pop instruction inserted, or the old
335 /// instruction if it was modified in place.
337 void FPS::popStackAfter(MachineBasicBlock::iterator &I) {
338 ASSERT_SORTED(PopTable);
339 assert(StackTop > 0 && "Cannot pop empty stack!");
340 RegMap[Stack[--StackTop]] = ~0; // Update state
342 // Check to see if there is a popping version of this instruction...
343 int Opcode = Lookup(PopTable, ARRAY_SIZE(PopTable), I->getOpcode());
345 I->setOpcode(Opcode);
346 if (Opcode == X86::FUCOMPPr)
349 } else { // Insert an explicit pop
350 I = BuildMI(*MBB, ++I, X86::FSTPrr, 1).addReg(X86::ST0);
354 /// freeStackSlotAfter - Free the specified register from the register stack, so
355 /// that it is no longer in a register. If the register is currently at the top
356 /// of the stack, we just pop the current instruction, otherwise we store the
357 /// current top-of-stack into the specified slot, then pop the top of stack.
358 void FPS::freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned FPRegNo) {
359 if (getStackEntry(0) == FPRegNo) { // already at the top of stack? easy.
364 // Otherwise, store the top of stack into the dead slot, killing the operand
365 // without having to add in an explicit xchg then pop.
367 unsigned STReg = getSTReg(FPRegNo);
368 unsigned OldSlot = getSlot(FPRegNo);
369 unsigned TopReg = Stack[StackTop-1];
370 Stack[OldSlot] = TopReg;
371 RegMap[TopReg] = OldSlot;
372 RegMap[FPRegNo] = ~0;
373 Stack[--StackTop] = ~0;
374 I = BuildMI(*MBB, ++I, X86::FSTPrr, 1).addReg(STReg);
378 static unsigned getFPReg(const MachineOperand &MO) {
379 assert(MO.isRegister() && "Expected an FP register!");
380 unsigned Reg = MO.getReg();
381 assert(Reg >= X86::FP0 && Reg <= X86::FP6 && "Expected FP register!");
382 return Reg - X86::FP0;
386 //===----------------------------------------------------------------------===//
387 // Instruction transformation implementation
388 //===----------------------------------------------------------------------===//
390 /// handleZeroArgFP - ST(0) = fld0 ST(0) = flds <mem>
392 void FPS::handleZeroArgFP(MachineBasicBlock::iterator &I) {
393 MachineInstr *MI = I;
394 unsigned DestReg = getFPReg(MI->getOperand(0));
395 MI->RemoveOperand(0); // Remove the explicit ST(0) operand
397 // Result gets pushed on the stack...
401 /// handleOneArgFP - fst <mem>, ST(0)
403 void FPS::handleOneArgFP(MachineBasicBlock::iterator &I) {
404 MachineInstr *MI = I;
405 assert((MI->getNumOperands() == 5 || MI->getNumOperands() == 1) &&
406 "Can only handle fst* & ftst instructions!");
408 // Is this the last use of the source register?
409 unsigned Reg = getFPReg(MI->getOperand(MI->getNumOperands()-1));
410 bool KillsSrc = false;
411 for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
412 E = LV->killed_end(MI); KI != E; ++KI)
413 KillsSrc |= KI->second == X86::FP0+Reg;
415 // FSTP80r and FISTP64r are strange because there are no non-popping versions.
416 // If we have one _and_ we don't want to pop the operand, duplicate the value
417 // on the stack instead of moving it. This ensure that popping the value is
420 if ((MI->getOpcode() == X86::FSTP80m ||
421 MI->getOpcode() == X86::FISTP64m) && !KillsSrc) {
422 duplicateToTop(Reg, 7 /*temp register*/, I);
424 moveToTop(Reg, I); // Move to the top of the stack...
426 MI->RemoveOperand(MI->getNumOperands()-1); // Remove explicit ST(0) operand
428 if (MI->getOpcode() == X86::FSTP80m || MI->getOpcode() == X86::FISTP64m) {
429 assert(StackTop > 0 && "Stack empty??");
431 } else if (KillsSrc) { // Last use of operand?
437 /// handleOneArgFPRW: Handle instructions that read from the top of stack and
438 /// replace the value with a newly computed value. These instructions may have
439 /// non-fp operands after their FP operands.
443 /// R1 = fadd R2, [mem]
445 void FPS::handleOneArgFPRW(MachineBasicBlock::iterator &I) {
446 MachineInstr *MI = I;
447 assert(MI->getNumOperands() >= 2 && "FPRW instructions must have 2 ops!!");
449 // Is this the last use of the source register?
450 unsigned Reg = getFPReg(MI->getOperand(1));
451 bool KillsSrc = false;
452 for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
453 E = LV->killed_end(MI); KI != E; ++KI)
454 KillsSrc |= KI->second == X86::FP0+Reg;
457 // If this is the last use of the source register, just make sure it's on
458 // the top of the stack.
460 assert(StackTop > 0 && "Stack cannot be empty!");
462 pushReg(getFPReg(MI->getOperand(0)));
464 // If this is not the last use of the source register, _copy_ it to the top
466 duplicateToTop(Reg, getFPReg(MI->getOperand(0)), I);
469 MI->RemoveOperand(1); // Drop the source operand.
470 MI->RemoveOperand(0); // Drop the destination operand.
474 //===----------------------------------------------------------------------===//
475 // Define tables of various ways to map pseudo instructions
478 // ForwardST0Table - Map: A = B op C into: ST(0) = ST(0) op ST(i)
479 static const TableEntry ForwardST0Table[] = {
480 { X86::FpADD , X86::FADDST0r },
481 { X86::FpDIV , X86::FDIVST0r },
482 { X86::FpMUL , X86::FMULST0r },
483 { X86::FpSUB , X86::FSUBST0r },
484 { X86::FpUCOM , X86::FUCOMr },
485 { X86::FpUCOMI, X86::FUCOMIr },
488 // ReverseST0Table - Map: A = B op C into: ST(0) = ST(i) op ST(0)
489 static const TableEntry ReverseST0Table[] = {
490 { X86::FpADD , X86::FADDST0r }, // commutative
491 { X86::FpDIV , X86::FDIVRST0r },
492 { X86::FpMUL , X86::FMULST0r }, // commutative
493 { X86::FpSUB , X86::FSUBRST0r },
494 { X86::FpUCOM , ~0 },
495 { X86::FpUCOMI, ~0 },
498 // ForwardSTiTable - Map: A = B op C into: ST(i) = ST(0) op ST(i)
499 static const TableEntry ForwardSTiTable[] = {
500 { X86::FpADD , X86::FADDrST0 }, // commutative
501 { X86::FpDIV , X86::FDIVRrST0 },
502 { X86::FpMUL , X86::FMULrST0 }, // commutative
503 { X86::FpSUB , X86::FSUBRrST0 },
504 { X86::FpUCOM , X86::FUCOMr },
505 { X86::FpUCOMI, X86::FUCOMIr },
508 // ReverseSTiTable - Map: A = B op C into: ST(i) = ST(i) op ST(0)
509 static const TableEntry ReverseSTiTable[] = {
510 { X86::FpADD , X86::FADDrST0 },
511 { X86::FpDIV , X86::FDIVrST0 },
512 { X86::FpMUL , X86::FMULrST0 },
513 { X86::FpSUB , X86::FSUBrST0 },
514 { X86::FpUCOM , ~0 },
515 { X86::FpUCOMI, ~0 },
519 /// handleTwoArgFP - Handle instructions like FADD and friends which are virtual
520 /// instructions which need to be simplified and possibly transformed.
522 /// Result: ST(0) = fsub ST(0), ST(i)
523 /// ST(i) = fsub ST(0), ST(i)
524 /// ST(0) = fsubr ST(0), ST(i)
525 /// ST(i) = fsubr ST(0), ST(i)
527 /// In addition to three address instructions, this also handles the FpUCOM
528 /// instruction which only has two operands, but no destination. This
529 /// instruction is also annoying because there is no "reverse" form of it
532 void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) {
533 ASSERT_SORTED(ForwardST0Table); ASSERT_SORTED(ReverseST0Table);
534 ASSERT_SORTED(ForwardSTiTable); ASSERT_SORTED(ReverseSTiTable);
535 MachineInstr *MI = I;
537 unsigned NumOperands = MI->getNumOperands();
538 bool isCompare = MI->getOpcode() == X86::FpUCOM ||
539 MI->getOpcode() == X86::FpUCOMI;
540 assert((NumOperands == 3 || (NumOperands == 2 && isCompare)) &&
541 "Illegal TwoArgFP instruction!");
542 unsigned Dest = getFPReg(MI->getOperand(0));
543 unsigned Op0 = getFPReg(MI->getOperand(NumOperands-2));
544 unsigned Op1 = getFPReg(MI->getOperand(NumOperands-1));
545 bool KillsOp0 = false, KillsOp1 = false;
547 for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
548 E = LV->killed_end(MI); KI != E; ++KI) {
549 KillsOp0 |= (KI->second == X86::FP0+Op0);
550 KillsOp1 |= (KI->second == X86::FP0+Op1);
553 // If this is an FpUCOM instruction, we must make sure the first operand is on
554 // the top of stack, the other one can be anywhere...
558 unsigned TOS = getStackEntry(0);
560 // One of our operands must be on the top of the stack. If neither is yet, we
562 if (Op0 != TOS && Op1 != TOS) { // No operand at TOS?
563 // We can choose to move either operand to the top of the stack. If one of
564 // the operands is killed by this instruction, we want that one so that we
565 // can update right on top of the old version.
567 moveToTop(Op0, I); // Move dead operand to TOS.
569 } else if (KillsOp1) {
573 // All of the operands are live after this instruction executes, so we
574 // cannot update on top of any operand. Because of this, we must
575 // duplicate one of the stack elements to the top. It doesn't matter
576 // which one we pick.
578 duplicateToTop(Op0, Dest, I);
582 } else if (!KillsOp0 && !KillsOp1 && !isCompare) {
583 // If we DO have one of our operands at the top of the stack, but we don't
584 // have a dead operand, we must duplicate one of the operands to a new slot
586 duplicateToTop(Op0, Dest, I);
591 // Now we know that one of our operands is on the top of the stack, and at
592 // least one of our operands is killed by this instruction.
593 assert((TOS == Op0 || TOS == Op1) &&
594 (KillsOp0 || KillsOp1 || isCompare) &&
595 "Stack conditions not set up right!");
597 // We decide which form to use based on what is on the top of the stack, and
598 // which operand is killed by this instruction.
599 const TableEntry *InstTable;
600 bool isForward = TOS == Op0;
601 bool updateST0 = (TOS == Op0 && !KillsOp1) || (TOS == Op1 && !KillsOp0);
604 InstTable = ForwardST0Table;
606 InstTable = ReverseST0Table;
609 InstTable = ForwardSTiTable;
611 InstTable = ReverseSTiTable;
614 int Opcode = Lookup(InstTable, ARRAY_SIZE(ForwardST0Table), MI->getOpcode());
615 assert(Opcode != -1 && "Unknown TwoArgFP pseudo instruction!");
617 // NotTOS - The register which is not on the top of stack...
618 unsigned NotTOS = (TOS == Op0) ? Op1 : Op0;
620 // Replace the old instruction with a new instruction
622 I = BuildMI(*MBB, I, Opcode, 1).addReg(getSTReg(NotTOS));
624 // If both operands are killed, pop one off of the stack in addition to
625 // overwriting the other one.
626 if (KillsOp0 && KillsOp1 && Op0 != Op1) {
627 assert(!updateST0 && "Should have updated other operand!");
628 popStackAfter(I); // Pop the top of stack
631 // Insert an explicit pop of the "updated" operand for FUCOM
633 if (KillsOp0 && !KillsOp1)
634 popStackAfter(I); // If we kill the first operand, pop it!
635 else if (KillsOp1 && Op0 != Op1)
636 freeStackSlotAfter(I, Op1);
639 // Update stack information so that we know the destination register is now on
642 unsigned UpdatedSlot = getSlot(updateST0 ? TOS : NotTOS);
643 assert(UpdatedSlot < StackTop && Dest < 7);
644 Stack[UpdatedSlot] = Dest;
645 RegMap[Dest] = UpdatedSlot;
647 delete MI; // Remove the old instruction
650 /// handleCondMovFP - Handle two address conditional move instructions. These
651 /// instructions move a st(i) register to st(0) iff a condition is true. These
652 /// instructions require that the first operand is at the top of the stack, but
653 /// otherwise don't modify the stack at all.
654 void FPS::handleCondMovFP(MachineBasicBlock::iterator &I) {
655 MachineInstr *MI = I;
657 unsigned Op0 = getFPReg(MI->getOperand(0));
658 unsigned Op1 = getFPReg(MI->getOperand(1));
660 // The first operand *must* be on the top of the stack.
663 // Change the second operand to the stack register that the operand is in.
664 MI->RemoveOperand(0);
665 MI->getOperand(0).setReg(getSTReg(Op1));
667 // If we kill the second operand, make sure to pop it from the stack.
669 for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
670 E = LV->killed_end(MI); KI != E; ++KI)
671 if (KI->second == X86::FP0+Op1) {
672 // Get this value off of the register stack.
673 freeStackSlotAfter(I, Op1);
679 /// handleSpecialFP - Handle special instructions which behave unlike other
680 /// floating point instructions. This is primarily intended for use by pseudo
683 void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
684 MachineInstr *MI = I;
685 switch (MI->getOpcode()) {
686 default: assert(0 && "Unknown SpecialFP instruction!");
687 case X86::FpGETRESULT: // Appears immediately after a call returning FP type!
688 assert(StackTop == 0 && "Stack should be empty after a call!");
689 pushReg(getFPReg(MI->getOperand(0)));
691 case X86::FpSETRESULT:
692 assert(StackTop == 1 && "Stack should have one element on it to return!");
693 --StackTop; // "Forget" we have something on the top of stack!
696 unsigned SrcReg = getFPReg(MI->getOperand(1));
697 unsigned DestReg = getFPReg(MI->getOperand(0));
698 bool KillsSrc = false;
699 for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
700 E = LV->killed_end(MI); KI != E; ++KI)
701 KillsSrc |= KI->second == X86::FP0+SrcReg;
704 // If the input operand is killed, we can just change the owner of the
705 // incoming stack slot into the result.
706 unsigned Slot = getSlot(SrcReg);
707 assert(Slot < 7 && DestReg < 7 && "FpMOV operands invalid!");
708 Stack[Slot] = DestReg;
709 RegMap[DestReg] = Slot;
712 // For FMOV we just duplicate the specified value to a new stack slot.
713 // This could be made better, but would require substantial changes.
714 duplicateToTop(SrcReg, DestReg, I);
720 I = MBB->erase(I); // Remove the pseudo instruction