#include "X86.h"
#include "X86InstrInfo.h"
#include "llvm/ADT/DepthFirstIterator.h"
-#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/EdgeBundles.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/InlineAsm.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
namespace {
struct FPS : public MachineFunctionPass {
static char ID;
- FPS() : MachineFunctionPass(&ID) {
+ FPS() : MachineFunctionPass(ID) {
+ initializeEdgeBundlesPass(*PassRegistry::getPassRegistry());
// This is really only to keep valgrind quiet.
// The logic in isLive() is too much for it.
memset(Stack, 0, sizeof(Stack));
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
+ AU.addRequired<EdgeBundles>();
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
// FixStack[i] == getStackEntry(i) for all i < FixCount.
unsigned char FixStack[8];
- LiveBundle(unsigned m = 0) : Mask(m), FixCount(0) {}
+ LiveBundle() : Mask(0), FixCount(0) {}
// Have the live registers been assigned a stack order yet?
bool isFixed() const { return !Mask || FixCount; }
// with no live FP registers.
SmallVector<LiveBundle, 8> LiveBundles;
- // Map each MBB in the current function to an (ingoing, outgoing) index into
- // LiveBundles. Blocks with no FP registers live in or out map to (0, 0)
- // and are not actually stored in the map.
- DenseMap<MachineBasicBlock*, std::pair<unsigned, unsigned> > BlockBundle;
+ // The edge bundle analysis provides indices into the LiveBundles vector.
+ EdgeBundles *Bundles;
// Return a bitmask of FP registers in block's live-in list.
- unsigned calcLiveInMask(MachineBasicBlock *MBB) {
+ static unsigned calcLiveInMask(MachineBasicBlock *MBB) {
unsigned Mask = 0;
for (MachineBasicBlock::livein_iterator I = MBB->livein_begin(),
E = MBB->livein_end(); I != E; ++I) {
void bundleCFG(MachineFunction &MF);
MachineBasicBlock *MBB; // Current basic block
+
+ // The hardware keeps track of how many FP registers are live, so we have
+ // to model that exactly. Usually, each live register corresponds to an
+ // FP<n> register, but when dealing with calls, returns, and inline
+ // assembly, it is sometimes necessary to have live scratch registers.
unsigned Stack[8]; // FP<n> Registers in each stack slot...
- unsigned RegMap[8]; // Track which stack slot contains each register
unsigned StackTop; // The current top of the FP stack.
+ enum {
+ NumFPRegs = 16 // Including scratch pseudo-registers.
+ };
+
+ // For each live FP<n> register, point to its Stack[] entry.
+ // The first entries correspond to FP0-FP6, the rest are scratch registers
+ // used when we need slightly different live registers than what the
+ // register allocator thinks.
+ unsigned RegMap[NumFPRegs];
+
+ // Pending fixed registers - Inline assembly needs FP registers to appear
+ // in fixed stack slot positions. This is handled by copying FP registers
+ // to ST registers before the instruction, and copying back after the
+ // instruction.
+ //
+ // This is modeled with pending ST registers. NumPendingSTs is the number
+ // of ST registers (ST0-STn) we are tracking. PendingST[n] points to an FP
+ // register that holds the ST value. The ST registers are not moved into
+ // place until immediately before the instruction that needs them.
+ //
+ // It can happen that we need an ST register to be live when no FP register
+ // holds the value:
+ //
+ // %ST0 = COPY %FP4<kill>
+ //
+ // When that happens, we allocate a scratch FP register to hold the ST
+ // value. That means every register in PendingST must be live.
+
+ unsigned NumPendingSTs;
+ unsigned char PendingST[8];
+
// Set up our stack model to match the incoming registers to MBB.
void setupBlockStack();
// Shuffle live registers to match the expectations of successor blocks.
void finishBlockStack();
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void dumpStack() const {
dbgs() << "Stack contents:";
for (unsigned i = 0; i != StackTop; ++i) {
dbgs() << " FP" << Stack[i];
assert(RegMap[Stack[i]] == i && "Stack[] doesn't match RegMap[]!");
}
+ for (unsigned i = 0; i != NumPendingSTs; ++i)
+ dbgs() << ", ST" << i << " in FP" << unsigned(PendingST[i]);
dbgs() << "\n";
}
+#endif
- /// isStackEmpty - Return true if the FP stack is empty.
- bool isStackEmpty() const {
- return StackTop == 0;
- }
-
- // getSlot - Return the stack slot number a particular register number is
- // in.
+ /// getSlot - Return the stack slot number a particular register number is
+ /// in.
unsigned getSlot(unsigned RegNo) const {
- assert(RegNo < 8 && "Regno out of range!");
+ assert(RegNo < NumFPRegs && "Regno out of range!");
return RegMap[RegNo];
}
- // isLive - Is RegNo currently live in the stack?
+ /// isLive - Is RegNo currently live in the stack?
bool isLive(unsigned RegNo) const {
unsigned Slot = getSlot(RegNo);
return Slot < StackTop && Stack[Slot] == RegNo;
}
- // getScratchReg - Return an FP register that is not currently in use.
- unsigned getScratchReg() {
- for (int i = 7; i >= 0; --i)
+ /// getScratchReg - Return an FP register that is not currently in use.
+ unsigned getScratchReg() const {
+ for (int i = NumFPRegs - 1; i >= 8; --i)
if (!isLive(i))
return i;
llvm_unreachable("Ran out of scratch FP registers");
}
- // getStackEntry - Return the X86::FP<n> register in register ST(i).
+ /// isScratchReg - Returns trus if RegNo is a scratch FP register.
+ static bool isScratchReg(unsigned RegNo) {
+ return RegNo > 8 && RegNo < NumFPRegs;
+ }
+
+ /// getStackEntry - Return the X86::FP<n> register in register ST(i).
unsigned getStackEntry(unsigned STi) const {
- assert(STi < StackTop && "Access past stack top!");
+ if (STi >= StackTop)
+ report_fatal_error("Access past stack top!");
return Stack[StackTop-1-STi];
}
- // getSTReg - Return the X86::ST(i) register which contains the specified
- // FP<RegNo> register.
+ /// getSTReg - Return the X86::ST(i) register which contains the specified
+ /// FP<RegNo> register.
unsigned getSTReg(unsigned RegNo) const {
- return StackTop - 1 - getSlot(RegNo) + llvm::X86::ST0;
+ return StackTop - 1 - getSlot(RegNo) + X86::ST0;
}
// pushReg - Push the specified FP<n> register onto the stack.
void pushReg(unsigned Reg) {
- assert(Reg < 8 && "Register number out of range!");
- assert(StackTop < 8 && "Stack overflow!");
+ assert(Reg < NumFPRegs && "Register number out of range!");
+ if (StackTop >= 8)
+ report_fatal_error("Stack overflow!");
Stack[StackTop] = Reg;
RegMap[Reg] = StackTop++;
}
std::swap(RegMap[RegNo], RegMap[RegOnTop]);
// Swap stack slot contents.
- assert(RegMap[RegOnTop] < StackTop);
+ if (RegMap[RegOnTop] >= StackTop)
+ report_fatal_error("Access past stack top!");
std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
// Emit an fxch to update the runtime processors version of the state.
BuildMI(*MBB, I, dl, TII->get(X86::LD_Frr)).addReg(STReg);
}
- // popStackAfter - Pop the current value off of the top of the FP stack
- // after the specified instruction.
+ /// duplicatePendingSTBeforeKill - The instruction at I is about to kill
+ /// RegNo. If any PendingST registers still need the RegNo value, duplicate
+ /// them to new scratch registers.
+ void duplicatePendingSTBeforeKill(unsigned RegNo, MachineInstr *I) {
+ for (unsigned i = 0; i != NumPendingSTs; ++i) {
+ if (PendingST[i] != RegNo)
+ continue;
+ unsigned SR = getScratchReg();
+ DEBUG(dbgs() << "Duplicating pending ST" << i
+ << " in FP" << RegNo << " to FP" << SR << '\n');
+ duplicateToTop(RegNo, SR, I);
+ PendingST[i] = SR;
+ }
+ }
+
+ /// popStackAfter - Pop the current value off of the top of the FP stack
+ /// after the specified instruction.
void popStackAfter(MachineBasicBlock::iterator &I);
- // freeStackSlotAfter - Free the specified register from the register stack,
- // so that it is no longer in a register. If the register is currently at
- // the top of the stack, we just pop the current instruction, otherwise we
- // store the current top-of-stack into the specified slot, then pop the top
- // of stack.
+ /// freeStackSlotAfter - Free the specified register from the register
+ /// stack, so that it is no longer in a register. If the register is
+ /// currently at the top of the stack, we just pop the current instruction,
+ /// otherwise we store the current top-of-stack into the specified slot,
+ /// then pop the top of stack.
void freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned Reg);
- // freeStackSlotBefore - Just the pop, no folding. Return the inserted
- // instruction.
+ /// freeStackSlotBefore - Just the pop, no folding. Return the inserted
+ /// instruction.
MachineBasicBlock::iterator
freeStackSlotBefore(MachineBasicBlock::iterator I, unsigned FPRegNo);
- // Adjust the live registers to be the set in Mask.
+ /// Adjust the live registers to be the set in Mask.
void adjustLiveRegs(unsigned Mask, MachineBasicBlock::iterator I);
- // Shuffle the top FixCount stack entries susch that FP reg FixStack[0] is
- //st(0), FP reg FixStack[1] is st(1) etc.
+ /// Shuffle the top FixCount stack entries such that FP reg FixStack[0] is
+ /// st(0), FP reg FixStack[1] is st(1) etc.
void shuffleStackTop(const unsigned char *FixStack, unsigned FixCount,
MachineBasicBlock::iterator I);
void handleCondMovFP(MachineBasicBlock::iterator &I);
void handleSpecialFP(MachineBasicBlock::iterator &I);
- bool translateCopy(MachineInstr*);
+ // Check if a COPY instruction is using FP registers.
+ static bool isFPCopy(MachineInstr *MI) {
+ unsigned DstReg = MI->getOperand(0).getReg();
+ unsigned SrcReg = MI->getOperand(1).getReg();
+
+ return X86::RFP80RegClass.contains(DstReg) ||
+ X86::RFP80RegClass.contains(SrcReg);
+ }
};
char FPS::ID = 0;
}
// Early exit.
if (!FPIsUsed) return false;
+ Bundles = &getAnalysis<EdgeBundles>();
TII = MF.getTarget().getInstrInfo();
// Prepare cross-MBB liveness.
if (Processed.insert(BB))
Changed |= processBasicBlock(MF, *BB);
- BlockBundle.clear();
LiveBundles.clear();
return Changed;
/// registers may be implicitly defined, or not used by all successors.
void FPS::bundleCFG(MachineFunction &MF) {
assert(LiveBundles.empty() && "Stale data in LiveBundles");
- assert(BlockBundle.empty() && "Stale data in BlockBundle");
- SmallPtrSet<MachineBasicBlock*, 8> PropDown, PropUp;
-
- // LiveBundle[0] is the empty live-in set.
- LiveBundles.resize(1);
+ LiveBundles.resize(Bundles->getNumBundles());
- // First gather the actual live-in masks for all MBBs.
+ // Gather the actual live-in masks for all MBBs.
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *MBB = I;
const unsigned Mask = calcLiveInMask(MBB);
if (!Mask)
continue;
- // Ingoing bundle index.
- unsigned &Idx = BlockBundle[MBB].first;
- // Already assigned an ingoing bundle?
- if (Idx)
- continue;
- // Allocate a new LiveBundle struct for this block's live-ins.
- const unsigned BundleIdx = Idx = LiveBundles.size();
- DEBUG(dbgs() << "Creating LB#" << BundleIdx << ": in:BB#"
- << MBB->getNumber());
- LiveBundles.push_back(Mask);
- LiveBundle &Bundle = LiveBundles.back();
-
- // Make sure all predecessors have the same live-out set.
- PropUp.insert(MBB);
-
- // Keep pushing liveness up and down the CFG until convergence.
- // Only critical edges cause iteration here, but when they do, multiple
- // blocks can be assigned to the same LiveBundle index.
- do {
- // Assign BundleIdx as liveout from predecessors in PropUp.
- for (SmallPtrSet<MachineBasicBlock*, 16>::iterator I = PropUp.begin(),
- E = PropUp.end(); I != E; ++I) {
- MachineBasicBlock *MBB = *I;
- for (MachineBasicBlock::const_pred_iterator LinkI = MBB->pred_begin(),
- LinkE = MBB->pred_end(); LinkI != LinkE; ++LinkI) {
- MachineBasicBlock *PredMBB = *LinkI;
- // PredMBB's liveout bundle should be set to LIIdx.
- unsigned &Idx = BlockBundle[PredMBB].second;
- if (Idx) {
- assert(Idx == BundleIdx && "Inconsistent CFG");
- continue;
- }
- Idx = BundleIdx;
- DEBUG(dbgs() << " out:BB#" << PredMBB->getNumber());
- // Propagate to siblings.
- if (PredMBB->succ_size() > 1)
- PropDown.insert(PredMBB);
- }
- }
- PropUp.clear();
-
- // Assign BundleIdx as livein to successors in PropDown.
- for (SmallPtrSet<MachineBasicBlock*, 16>::iterator I = PropDown.begin(),
- E = PropDown.end(); I != E; ++I) {
- MachineBasicBlock *MBB = *I;
- for (MachineBasicBlock::const_succ_iterator LinkI = MBB->succ_begin(),
- LinkE = MBB->succ_end(); LinkI != LinkE; ++LinkI) {
- MachineBasicBlock *SuccMBB = *LinkI;
- // LinkMBB's livein bundle should be set to BundleIdx.
- unsigned &Idx = BlockBundle[SuccMBB].first;
- if (Idx) {
- assert(Idx == BundleIdx && "Inconsistent CFG");
- continue;
- }
- Idx = BundleIdx;
- DEBUG(dbgs() << " in:BB#" << SuccMBB->getNumber());
- // Propagate to siblings.
- if (SuccMBB->pred_size() > 1)
- PropUp.insert(SuccMBB);
- // Also accumulate the bundle liveness mask from the liveins here.
- Bundle.Mask |= calcLiveInMask(SuccMBB);
- }
- }
- PropDown.clear();
- } while (!PropUp.empty());
- DEBUG({
- dbgs() << " live:";
- for (unsigned i = 0; i < 8; ++i)
- if (Bundle.Mask & (1<<i))
- dbgs() << " %FP" << i;
- dbgs() << '\n';
- });
+ // Update MBB ingoing bundle mask.
+ LiveBundles[Bundles->getBundle(MBB->getNumber(), false)].Mask |= Mask;
}
}
bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
bool Changed = false;
MBB = &BB;
+ NumPendingSTs = 0;
setupBlockStack();
if (MI->isInlineAsm())
FPInstClass = X86II::SpecialFP;
- if (MI->isCopy() && translateCopy(MI))
+ if (MI->isCopy() && isFPCopy(MI))
+ FPInstClass = X86II::SpecialFP;
+
+ if (MI->isImplicitDef() &&
+ X86::RFP80RegClass.contains(MI->getOperand(0).getReg()))
FPInstClass = X86II::SpecialFP;
if (FPInstClass == X86II::NotFP)
}
dumpStack();
);
+ (void)PrevMI;
Changed = true;
}
return Changed;
}
-/// setupBlockStack - Use the BlockBundle map to set up our model of the stack
+/// setupBlockStack - Use the live bundles to set up our model of the stack
/// to match predecessors' live out stack.
void FPS::setupBlockStack() {
DEBUG(dbgs() << "\nSetting up live-ins for BB#" << MBB->getNumber()
<< " derived from " << MBB->getName() << ".\n");
StackTop = 0;
- const LiveBundle &Bundle = LiveBundles[BlockBundle.lookup(MBB).first];
+ // Get the live-in bundle for MBB.
+ const LiveBundle &Bundle =
+ LiveBundles[Bundles->getBundle(MBB->getNumber(), false)];
if (!Bundle.Mask) {
DEBUG(dbgs() << "Block has no FP live-ins.\n");
DEBUG(dbgs() << "Setting up live-outs for BB#" << MBB->getNumber()
<< " derived from " << MBB->getName() << ".\n");
- unsigned BundleIdx = BlockBundle.lookup(MBB).second;
+ // Get MBB's live-out bundle.
+ unsigned BundleIdx = Bundles->getBundle(MBB->getNumber(), true);
LiveBundle &Bundle = LiveBundles[BundleIdx];
// We may need to kill and define some registers to match successors.
namespace {
struct TableEntry {
- unsigned from;
- unsigned to;
+ uint16_t from;
+ uint16_t to;
bool operator<(const TableEntry &TE) const { return from < TE.from; }
friend bool operator<(const TableEntry &TE, unsigned V) {
return TE.from < V;
}
- friend bool operator<(unsigned V, const TableEntry &TE) {
+ friend bool LLVM_ATTRIBUTE_UNUSED operator<(unsigned V,
+ const TableEntry &TE) {
return V < TE.from;
}
};
MachineInstr* MI = I;
DebugLoc dl = MI->getDebugLoc();
ASSERT_SORTED(PopTable);
- assert(StackTop > 0 && "Cannot pop empty stack!");
+ if (StackTop == 0)
+ report_fatal_error("Cannot pop empty stack!");
RegMap[Stack[--StackTop]] = ~0; // Update state
// Check to see if there is a popping version of this instruction...
// Kill registers by popping.
if (Kills && I != MBB->begin()) {
MachineBasicBlock::iterator I2 = llvm::prior(I);
- for (;;) {
+ while (StackTop) {
unsigned KReg = getStackEntry(0);
if (!(Kills & (1 << KReg)))
break;
continue;
// (Reg st0) (OldReg st0) = (Reg OldReg st0)
moveToTop(Reg, I);
- moveToTop(OldReg, I);
+ if (FixCount > 0)
+ moveToTop(OldReg, I);
}
DEBUG(dumpStack());
}
// Change from the pseudo instruction to the concrete instruction.
MI->RemoveOperand(0); // Remove the explicit ST(0) operand
MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
-
+
// Result gets pushed on the stack.
pushReg(DestReg);
}
unsigned Reg = getFPReg(MI->getOperand(NumOps-1));
bool KillsSrc = MI->killsRegister(X86::FP0+Reg);
+ if (KillsSrc)
+ duplicatePendingSTBeforeKill(Reg, I);
+
// FISTP64m is strange because there isn't a non-popping versions.
// If we have one _and_ we don't want to pop the operand, duplicate the value
// on the stack instead of moving it. This ensure that popping the value is
} else {
moveToTop(Reg, I); // Move to the top of the stack...
}
-
+
// Convert from the pseudo instruction to the concrete instruction.
MI->RemoveOperand(NumOps-1); // Remove explicit ST(0) operand
MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
MI->getOpcode() == X86::ISTT_FP32m ||
MI->getOpcode() == X86::ISTT_FP64m ||
MI->getOpcode() == X86::ST_FP80m) {
- assert(StackTop > 0 && "Stack empty??");
+ if (StackTop == 0)
+ report_fatal_error("Stack empty??");
--StackTop;
} else if (KillsSrc) { // Last use of operand?
popStackAfter(I);
bool KillsSrc = MI->killsRegister(X86::FP0+Reg);
if (KillsSrc) {
+ duplicatePendingSTBeforeKill(Reg, I);
// If this is the last use of the source register, just make sure it's on
// the top of the stack.
moveToTop(Reg, I);
- assert(StackTop > 0 && "Stack cannot be empty!");
+ if (StackTop == 0)
+ report_fatal_error("Stack cannot be empty!");
--StackTop;
pushReg(getFPReg(MI->getOperand(0)));
} else {
MI->RemoveOperand(1);
MI->getOperand(0).setReg(getSTReg(Op1));
MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
-
+
// If we kill the second operand, make sure to pop it from the stack.
if (Op0 != Op1 && KillsOp1) {
// Get this value off of the register stack.
///
void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
MachineInstr *MI = I;
- DebugLoc dl = MI->getDebugLoc();
switch (MI->getOpcode()) {
default: llvm_unreachable("Unknown SpecialFP instruction!");
- case X86::FpGET_ST0_32:// Appears immediately after a call returning FP type!
- case X86::FpGET_ST0_64:// Appears immediately after a call returning FP type!
- case X86::FpGET_ST0_80:// Appears immediately after a call returning FP type!
- assert(StackTop == 0 && "Stack should be empty after a call!");
- pushReg(getFPReg(MI->getOperand(0)));
- break;
- case X86::FpGET_ST1_32:// Appears immediately after a call returning FP type!
- case X86::FpGET_ST1_64:// Appears immediately after a call returning FP type!
- case X86::FpGET_ST1_80:{// Appears immediately after a call returning FP type!
- // FpGET_ST1 should occur right after a FpGET_ST0 for a call or inline asm.
- // The pattern we expect is:
- // CALL
- // FP1 = FpGET_ST0
- // FP4 = FpGET_ST1
- //
- // At this point, we've pushed FP1 on the top of stack, so it should be
- // present if it isn't dead. If it was dead, we already emitted a pop to
- // remove it from the stack and StackTop = 0.
-
- // Push FP4 as top of stack next.
- pushReg(getFPReg(MI->getOperand(0)));
+ case TargetOpcode::COPY: {
+ // We handle three kinds of copies: FP <- FP, FP <- ST, and ST <- FP.
+ const MachineOperand &MO1 = MI->getOperand(1);
+ const MachineOperand &MO0 = MI->getOperand(0);
+ unsigned DstST = MO0.getReg() - X86::ST0;
+ unsigned SrcST = MO1.getReg() - X86::ST0;
+ bool KillsSrc = MI->killsRegister(MO1.getReg());
+
+ // ST = COPY FP. Set up a pending ST register.
+ if (DstST < 8) {
+ unsigned SrcFP = getFPReg(MO1);
+ assert(isLive(SrcFP) && "Cannot copy dead register");
+ assert(!MO0.isDead() && "Cannot copy to dead ST register");
+
+ // Unallocated STs are marked as the nonexistent FP255.
+ while (NumPendingSTs <= DstST)
+ PendingST[NumPendingSTs++] = NumFPRegs;
+
+ // STi could still be live from a previous inline asm.
+ if (isScratchReg(PendingST[DstST])) {
+ DEBUG(dbgs() << "Clobbering old ST in FP" << unsigned(PendingST[DstST])
+ << '\n');
+ freeStackSlotBefore(MI, PendingST[DstST]);
+ }
- // If StackTop was 0 before we pushed our operand, then ST(0) must have been
- // dead. In this case, the ST(1) value is the only thing that is live, so
- // it should be on the TOS (after the pop that was emitted) and is. Just
- // continue in this case.
- if (StackTop == 1)
+ // When the source is killed, allocate a scratch FP register.
+ if (KillsSrc) {
+ duplicatePendingSTBeforeKill(SrcFP, I);
+ unsigned Slot = getSlot(SrcFP);
+ unsigned SR = getScratchReg();
+ PendingST[DstST] = SR;
+ Stack[Slot] = SR;
+ RegMap[SR] = Slot;
+ } else
+ PendingST[DstST] = SrcFP;
break;
-
- // Because pushReg just pushed ST(1) as TOS, we now have to swap the two top
- // elements so that our accounting is correct.
- unsigned RegOnTop = getStackEntry(0);
- unsigned RegNo = getStackEntry(1);
-
- // Swap the slots the regs are in.
- std::swap(RegMap[RegNo], RegMap[RegOnTop]);
-
- // Swap stack slot contents.
- assert(RegMap[RegOnTop] < StackTop);
- std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
- break;
- }
- case X86::FpSET_ST0_32:
- case X86::FpSET_ST0_64:
- case X86::FpSET_ST0_80: {
- // FpSET_ST0_80 is generated by copyRegToReg for setting up inline asm
- // arguments that use an st constraint. We expect a sequence of
- // instructions: Fp_SET_ST0 Fp_SET_ST1? INLINEASM
- unsigned Op0 = getFPReg(MI->getOperand(0));
-
- if (!MI->killsRegister(X86::FP0 + Op0)) {
- // Duplicate Op0 into a temporary on the stack top.
- duplicateToTop(Op0, getScratchReg(), I);
- } else {
- // Op0 is killed, so just swap it into position.
- moveToTop(Op0, I);
}
- --StackTop; // "Forget" we have something on the top of stack!
- break;
- }
- case X86::FpSET_ST1_32:
- case X86::FpSET_ST1_64:
- case X86::FpSET_ST1_80: {
- // Set up st(1) for inline asm. We are assuming that st(0) has already been
- // set up by FpSET_ST0, and our StackTop is off by one because of it.
- unsigned Op0 = getFPReg(MI->getOperand(0));
- // Restore the actual StackTop from before Fp_SET_ST0.
- // Note we can't handle Fp_SET_ST1 without a preceeding Fp_SET_ST0, and we
- // are not enforcing the constraint.
- ++StackTop;
- unsigned RegOnTop = getStackEntry(0); // This reg must remain in st(0).
- if (!MI->killsRegister(X86::FP0 + Op0)) {
- duplicateToTop(Op0, getScratchReg(), I);
- moveToTop(RegOnTop, I);
- } else if (getSTReg(Op0) != X86::ST1) {
- // We have the wrong value at st(1). Shuffle! Untested!
- moveToTop(getStackEntry(1), I);
- moveToTop(Op0, I);
- moveToTop(RegOnTop, I);
+
+ // FP = COPY ST. Extract fixed stack value.
+ // Any instruction defining ST registers must have assigned them to a
+ // scratch register.
+ if (SrcST < 8) {
+ unsigned DstFP = getFPReg(MO0);
+ assert(!isLive(DstFP) && "Cannot copy ST to live FP register");
+ assert(NumPendingSTs > SrcST && "Cannot copy from dead ST register");
+ unsigned SrcFP = PendingST[SrcST];
+ assert(isScratchReg(SrcFP) && "Expected ST in a scratch register");
+ assert(isLive(SrcFP) && "Scratch holding ST is dead");
+
+ // DstFP steals the stack slot from SrcFP.
+ unsigned Slot = getSlot(SrcFP);
+ Stack[Slot] = DstFP;
+ RegMap[DstFP] = Slot;
+
+ // Always treat the ST as killed.
+ PendingST[SrcST] = NumFPRegs;
+ while (NumPendingSTs && PendingST[NumPendingSTs - 1] == NumFPRegs)
+ --NumPendingSTs;
+ break;
}
- assert(StackTop >= 2 && "Too few live registers");
- StackTop -= 2; // "Forget" both st(0) and st(1).
- break;
- }
- case X86::MOV_Fp3232:
- case X86::MOV_Fp3264:
- case X86::MOV_Fp6432:
- case X86::MOV_Fp6464:
- case X86::MOV_Fp3280:
- case X86::MOV_Fp6480:
- case X86::MOV_Fp8032:
- case X86::MOV_Fp8064:
- case X86::MOV_Fp8080: {
- const MachineOperand &MO1 = MI->getOperand(1);
- unsigned SrcReg = getFPReg(MO1);
- const MachineOperand &MO0 = MI->getOperand(0);
- unsigned DestReg = getFPReg(MO0);
- if (MI->killsRegister(X86::FP0+SrcReg)) {
+ // FP <- FP copy.
+ unsigned DstFP = getFPReg(MO0);
+ unsigned SrcFP = getFPReg(MO1);
+ assert(isLive(SrcFP) && "Cannot copy dead register");
+ if (KillsSrc) {
// If the input operand is killed, we can just change the owner of the
// incoming stack slot into the result.
- unsigned Slot = getSlot(SrcReg);
- assert(Slot < 7 && DestReg < 7 && "FpMOV operands invalid!");
- Stack[Slot] = DestReg;
- RegMap[DestReg] = Slot;
-
+ unsigned Slot = getSlot(SrcFP);
+ Stack[Slot] = DstFP;
+ RegMap[DstFP] = Slot;
} else {
- // For FMOV we just duplicate the specified value to a new stack slot.
+ // For COPY we just duplicate the specified value to a new stack slot.
// This could be made better, but would require substantial changes.
- duplicateToTop(SrcReg, DestReg, I);
+ duplicateToTop(SrcFP, DstFP, I);
}
+ break;
+ }
+
+ case TargetOpcode::IMPLICIT_DEF: {
+ // All FP registers must be explicitly defined, so load a 0 instead.
+ unsigned Reg = MI->getOperand(0).getReg() - X86::FP0;
+ DEBUG(dbgs() << "Emitting LD_F0 for implicit FP" << Reg << '\n');
+ BuildMI(*MBB, I, MI->getDebugLoc(), TII->get(X86::LD_F0));
+ pushReg(Reg);
+ break;
+ }
+
+ case X86::FpPOP_RETVAL: {
+ // The FpPOP_RETVAL instruction is used after calls that return a value on
+ // the floating point stack. We cannot model this with ST defs since CALL
+ // instructions have fixed clobber lists. This instruction is interpreted
+ // to mean that there is one more live register on the stack than we
+ // thought.
+ //
+ // This means that StackTop does not match the hardware stack between a
+ // call and the FpPOP_RETVAL instructions. We do tolerate FP instructions
+ // between CALL and FpPOP_RETVAL as long as they don't overflow the
+ // hardware stack.
+ unsigned DstFP = getFPReg(MI->getOperand(0));
+
+ // Move existing stack elements up to reflect reality.
+ assert(StackTop < 8 && "Stack overflowed before FpPOP_RETVAL");
+ if (StackTop) {
+ std::copy_backward(Stack, Stack + StackTop, Stack + StackTop + 1);
+ for (unsigned i = 0; i != NumFPRegs; ++i)
+ ++RegMap[i];
}
+ ++StackTop;
+
+ // DstFP is the new bottom of the stack.
+ Stack[0] = DstFP;
+ RegMap[DstFP] = 0;
+
+ // DstFP will be killed by processBasicBlock if this was a dead def.
break;
+ }
+
case TargetOpcode::INLINEASM: {
// The inline asm MachineInstr currently only *uses* FP registers for the
// 'f' constraint. These should be turned into the current ST(x) register
- // in the machine instr. Also, any kills should be explicitly popped after
- // the inline asm.
- unsigned Kills = 0;
+ // in the machine instr.
+ //
+ // There are special rules for x87 inline assembly. The compiler must know
+ // exactly how many registers are popped and pushed implicitly by the asm.
+ // Otherwise it is not possible to restore the stack state after the inline
+ // asm.
+ //
+ // There are 3 kinds of input operands:
+ //
+ // 1. Popped inputs. These must appear at the stack top in ST0-STn. A
+ // popped input operand must be in a fixed stack slot, and it is either
+ // tied to an output operand, or in the clobber list. The MI has ST use
+ // and def operands for these inputs.
+ //
+ // 2. Fixed inputs. These inputs appear in fixed stack slots, but are
+ // preserved by the inline asm. The fixed stack slots must be STn-STm
+ // following the popped inputs. A fixed input operand cannot be tied to
+ // an output or appear in the clobber list. The MI has ST use operands
+ // and no defs for these inputs.
+ //
+ // 3. Preserved inputs. These inputs use the "f" constraint which is
+ // represented as an FP register. The inline asm won't change these
+ // stack slots.
+ //
+ // Outputs must be in ST registers, FP outputs are not allowed. Clobbered
+ // registers do not count as output operands. The inline asm changes the
+ // stack as if it popped all the popped inputs and then pushed all the
+ // output operands.
+
+ // Scan the assembly for ST registers used, defined and clobbered. We can
+ // only tell clobbers from defs by looking at the asm descriptor.
+ unsigned STUses = 0, STDefs = 0, STClobbers = 0, STDeadDefs = 0;
+ unsigned NumOps = 0;
+ for (unsigned i = InlineAsm::MIOp_FirstOperand, e = MI->getNumOperands();
+ i != e && MI->getOperand(i).isImm(); i += 1 + NumOps) {
+ unsigned Flags = MI->getOperand(i).getImm();
+ NumOps = InlineAsm::getNumOperandRegisters(Flags);
+ if (NumOps != 1)
+ continue;
+ const MachineOperand &MO = MI->getOperand(i + 1);
+ if (!MO.isReg())
+ continue;
+ unsigned STReg = MO.getReg() - X86::ST0;
+ if (STReg >= 8)
+ continue;
+
+ switch (InlineAsm::getKind(Flags)) {
+ case InlineAsm::Kind_RegUse:
+ STUses |= (1u << STReg);
+ break;
+ case InlineAsm::Kind_RegDef:
+ case InlineAsm::Kind_RegDefEarlyClobber:
+ STDefs |= (1u << STReg);
+ if (MO.isDead())
+ STDeadDefs |= (1u << STReg);
+ break;
+ case InlineAsm::Kind_Clobber:
+ STClobbers |= (1u << STReg);
+ break;
+ default:
+ break;
+ }
+ }
+
+ if (STUses && !isMask_32(STUses))
+ MI->emitError("fixed input regs must be last on the x87 stack");
+ unsigned NumSTUses = CountTrailingOnes_32(STUses);
+
+ // Defs must be contiguous from the stack top. ST0-STn.
+ if (STDefs && !isMask_32(STDefs)) {
+ MI->emitError("output regs must be last on the x87 stack");
+ STDefs = NextPowerOf2(STDefs) - 1;
+ }
+ unsigned NumSTDefs = CountTrailingOnes_32(STDefs);
+
+ // So must the clobbered stack slots. ST0-STm, m >= n.
+ if (STClobbers && !isMask_32(STDefs | STClobbers))
+ MI->emitError("clobbers must be last on the x87 stack");
+
+ // Popped inputs are the ones that are also clobbered or defined.
+ unsigned STPopped = STUses & (STDefs | STClobbers);
+ if (STPopped && !isMask_32(STPopped))
+ MI->emitError("implicitly popped regs must be last on the x87 stack");
+ unsigned NumSTPopped = CountTrailingOnes_32(STPopped);
+
+ DEBUG(dbgs() << "Asm uses " << NumSTUses << " fixed regs, pops "
+ << NumSTPopped << ", and defines " << NumSTDefs << " regs.\n");
+
+ // Scan the instruction for FP uses corresponding to "f" constraints.
+ // Collect FP registers to kill afer the instruction.
+ // Always kill all the scratch regs.
+ unsigned FPKills = ((1u << NumFPRegs) - 1) & ~0xff;
+ unsigned FPUsed = 0;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &Op = MI->getOperand(i);
if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
continue;
- assert(Op.isUse() && "Only handle inline asm uses right now");
-
+ if (!Op.isUse())
+ MI->emitError("illegal \"f\" output constraint");
unsigned FPReg = getFPReg(Op);
- Op.setReg(getSTReg(FPReg));
-
+ FPUsed |= 1U << FPReg;
+
// If we kill this operand, make sure to pop it from the stack after the
// asm. We just remember it for now, and pop them all off at the end in
// a batch.
if (Op.isKill())
- Kills |= 1U << FPReg;
+ FPKills |= 1U << FPReg;
}
+ // The popped inputs will be killed by the instruction, so duplicate them
+ // if the FP register needs to be live after the instruction, or if it is
+ // used in the instruction itself. We effectively treat the popped inputs
+ // as early clobbers.
+ for (unsigned i = 0; i < NumSTPopped; ++i) {
+ if ((FPKills & ~FPUsed) & (1u << PendingST[i]))
+ continue;
+ unsigned SR = getScratchReg();
+ duplicateToTop(PendingST[i], SR, I);
+ DEBUG(dbgs() << "Duplicating ST" << i << " in FP"
+ << unsigned(PendingST[i]) << " to avoid clobbering it.\n");
+ PendingST[i] = SR;
+ }
+
+ // Make sure we have a unique live register for every fixed use. Some of
+ // them could be undef uses, and we need to emit LD_F0 instructions.
+ for (unsigned i = 0; i < NumSTUses; ++i) {
+ if (i < NumPendingSTs && PendingST[i] < NumFPRegs) {
+ // Check for shared assignments.
+ for (unsigned j = 0; j < i; ++j) {
+ if (PendingST[j] != PendingST[i])
+ continue;
+ // STi and STj are inn the same register, create a copy.
+ unsigned SR = getScratchReg();
+ duplicateToTop(PendingST[i], SR, I);
+ DEBUG(dbgs() << "Duplicating ST" << i << " in FP"
+ << unsigned(PendingST[i])
+ << " to avoid collision with ST" << j << '\n');
+ PendingST[i] = SR;
+ }
+ continue;
+ }
+ unsigned SR = getScratchReg();
+ DEBUG(dbgs() << "Emitting LD_F0 for ST" << i << " in FP" << SR << '\n');
+ BuildMI(*MBB, I, MI->getDebugLoc(), TII->get(X86::LD_F0));
+ pushReg(SR);
+ PendingST[i] = SR;
+ if (NumPendingSTs == i)
+ ++NumPendingSTs;
+ }
+ assert(NumPendingSTs >= NumSTUses && "Fixed registers should be assigned");
+
+ // Now we can rearrange the live registers to match what was requested.
+ shuffleStackTop(PendingST, NumPendingSTs, I);
+ DEBUG({dbgs() << "Before asm: "; dumpStack();});
+
+ // With the stack layout fixed, rewrite the FP registers.
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &Op = MI->getOperand(i);
+ if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
+ continue;
+ unsigned FPReg = getFPReg(Op);
+ Op.setReg(getSTReg(FPReg));
+ }
+
+ // Simulate the inline asm popping its inputs and pushing its outputs.
+ StackTop -= NumSTPopped;
+
+ // Hold the fixed output registers in scratch FP registers. They will be
+ // transferred to real FP registers by copies.
+ NumPendingSTs = 0;
+ for (unsigned i = 0; i < NumSTDefs; ++i) {
+ unsigned SR = getScratchReg();
+ pushReg(SR);
+ FPKills &= ~(1u << SR);
+ }
+ for (unsigned i = 0; i < NumSTDefs; ++i)
+ PendingST[NumPendingSTs++] = getStackEntry(i);
+ DEBUG({dbgs() << "After asm: "; dumpStack();});
+
+ // If any of the ST defs were dead, pop them immediately. Our caller only
+ // handles dead FP defs.
+ MachineBasicBlock::iterator InsertPt = MI;
+ for (unsigned i = 0; STDefs & (1u << i); ++i) {
+ if (!(STDeadDefs & (1u << i)))
+ continue;
+ freeStackSlotAfter(InsertPt, PendingST[i]);
+ PendingST[i] = NumFPRegs;
+ }
+ while (NumPendingSTs && PendingST[NumPendingSTs - 1] == NumFPRegs)
+ --NumPendingSTs;
+
// If this asm kills any FP registers (is the last use of them) we must
// explicitly emit pop instructions for them. Do this now after the asm has
// executed so that the ST(x) numbers are not off (which would happen if we
//
// Note: this might be a non-optimal pop sequence. We might be able to do
// better by trying to pop in stack order or something.
- MachineBasicBlock::iterator InsertPt = MI;
- while (Kills) {
- unsigned FPReg = CountTrailingZeros_32(Kills);
- freeStackSlotAfter(InsertPt, FPReg);
- Kills &= ~(1U << FPReg);
+ while (FPKills) {
+ unsigned FPReg = CountTrailingZeros_32(FPKills);
+ if (isLive(FPReg))
+ freeStackSlotAfter(InsertPt, FPReg);
+ FPKills &= ~(1U << FPReg);
}
// Don't delete the inline asm!
return;
}
-
+
+ case X86::WIN_FTOL_32:
+ case X86::WIN_FTOL_64: {
+ // Push the operand into ST0.
+ MachineOperand &Op = MI->getOperand(0);
+ assert(Op.isUse() && Op.isReg() &&
+ Op.getReg() >= X86::FP0 && Op.getReg() <= X86::FP6);
+ unsigned FPReg = getFPReg(Op);
+ if (Op.isKill())
+ moveToTop(FPReg, I);
+ else
+ duplicateToTop(FPReg, FPReg, I);
+
+ // Emit the call. This will pop the operand.
+ BuildMI(*MBB, I, MI->getDebugLoc(), TII->get(X86::CALLpcrel32))
+ .addExternalSymbol("_ftol2")
+ .addReg(X86::ST0, RegState::ImplicitKill)
+ .addReg(X86::EAX, RegState::Define | RegState::Implicit)
+ .addReg(X86::EDX, RegState::Define | RegState::Implicit)
+ .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit);
+ --StackTop;
+
+ break;
+ }
+
case X86::RET:
case X86::RETI:
// If RET has an FP register use operand, pass the first one in ST(0) and
// Assert that the top of stack contains the right FP register.
assert(StackTop == 1 && FirstFPRegOp == getStackEntry(0) &&
"Top of stack not the right register for RET!");
-
+
// Ok, everything is good, mark the value as not being on the stack
// anymore so that our assertion about the stack being empty at end of
// block doesn't fire.
StackTop = 0;
return;
}
-
+
// Otherwise, we are returning two values:
// 2) If returning the same value for both, we only have one thing in the FP
// stack. Consider: RET FP1, FP1
if (StackTop == 1) {
assert(FirstFPRegOp == SecondFPRegOp && FirstFPRegOp == getStackEntry(0)&&
"Stack misconfiguration for RET!");
-
+
// Duplicate the TOS so that we return it twice. Just pick some other FPx
// register to hold it.
unsigned NewReg = getScratchReg();
duplicateToTop(FirstFPRegOp, NewReg, MI);
FirstFPRegOp = NewReg;
}
-
+
/// Okay we know we have two different FPx operands now:
assert(StackTop == 2 && "Must have two values live!");
-
+
/// 3) If SecondFPRegOp is currently in ST(0) and FirstFPRegOp is currently
/// in ST(1). In this case, emit an fxch.
if (getStackEntry(0) == SecondFPRegOp) {
assert(getStackEntry(1) == FirstFPRegOp && "Unknown regs live");
moveToTop(FirstFPRegOp, MI);
}
-
+
/// 4) Finally, FirstFPRegOp must be in ST(0) and SecondFPRegOp must be in
/// ST(1). Just remove both from our understanding of the stack and return.
assert(getStackEntry(0) == FirstFPRegOp && "Unknown regs live");
} else
--I;
}
-
-// Translate a COPY instruction to a pseudo-op that handleSpecialFP understands.
-bool FPS::translateCopy(MachineInstr *MI) {
- unsigned DstReg = MI->getOperand(0).getReg();
- unsigned SrcReg = MI->getOperand(1).getReg();
-
- if (DstReg == X86::ST0) {
- MI->setDesc(TII->get(X86::FpSET_ST0_80));
- MI->RemoveOperand(0);
- return true;
- }
- if (DstReg == X86::ST1) {
- MI->setDesc(TII->get(X86::FpSET_ST1_80));
- MI->RemoveOperand(0);
- return true;
- }
- if (SrcReg == X86::ST0) {
- MI->setDesc(TII->get(X86::FpGET_ST0_80));
- return true;
- }
- if (SrcReg == X86::ST1) {
- MI->setDesc(TII->get(X86::FpGET_ST1_80));
- return true;
- }
- if (X86::RFP80RegClass.contains(DstReg, SrcReg)) {
- MI->setDesc(TII->get(X86::MOV_Fp8080));
- return true;
- }
- return false;
-}
projects / oota-llvm.git / blobdiff