summaryrefslogtreecommitdiffstats
path: root/lib/CodeGen/PrologEpilogInserter.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'lib/CodeGen/PrologEpilogInserter.cpp')
-rw-r--r--lib/CodeGen/PrologEpilogInserter.cpp362
1 files changed, 285 insertions, 77 deletions
diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
index 9e7ad67..8793df7 100644
--- a/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/lib/CodeGen/PrologEpilogInserter.cpp
@@ -31,7 +31,9 @@
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/IndexedMap.h"
#include "llvm/ADT/STLExtras.h"
#include <climits>
@@ -51,22 +53,26 @@ FunctionPass *llvm::createPrologEpilogCodeInserter() { return new PEI(); }
/// frame indexes with appropriate references.
///
bool PEI::runOnMachineFunction(MachineFunction &Fn) {
+ const Function* F = Fn.getFunction();
const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
RS = TRI->requiresRegisterScavenging(Fn) ? new RegScavenger() : NULL;
+ FrameIndexVirtualScavenging = TRI->requiresFrameIndexScavenging(Fn);
// Get MachineModuleInfo so that we can track the construction of the
// frame.
if (MachineModuleInfo *MMI = getAnalysisIfAvailable<MachineModuleInfo>())
Fn.getFrameInfo()->setMachineModuleInfo(MMI);
+ // Calculate the MaxCallFrameSize and HasCalls variables for the function's
+ // frame information. Also eliminates call frame pseudo instructions.
+ calculateCallsInformation(Fn);
+
// Allow the target machine to make some adjustments to the function
// e.g. UsedPhysRegs before calculateCalleeSavedRegisters.
TRI->processFunctionBeforeCalleeSavedScan(Fn, RS);
- // Scan the function for modified callee saved registers and insert spill
- // code for any callee saved registers that are modified. Also calculate
- // the MaxCallFrameSize and HasCalls variables for the function's frame
- // information and eliminates call frame pseudo instructions.
+ // Scan the function for modified callee saved registers and insert spill code
+ // for any callee saved registers that are modified.
calculateCalleeSavedRegisters(Fn);
// Determine placement of CSR spill/restore code:
@@ -78,7 +84,8 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
placeCSRSpillsAndRestores(Fn);
// Add the code to save and restore the callee saved registers
- insertCSRSpillsAndRestores(Fn);
+ if (!F->hasFnAttr(Attribute::Naked))
+ insertCSRSpillsAndRestores(Fn);
// Allow the target machine to make final modifications to the function
// before the frame layout is finalized.
@@ -92,13 +99,20 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
// called functions. Because of this, calculateCalleeSavedRegisters
// must be called before this function in order to set the HasCalls
// and MaxCallFrameSize variables.
- insertPrologEpilogCode(Fn);
+ if (!F->hasFnAttr(Attribute::Naked))
+ insertPrologEpilogCode(Fn);
// Replace all MO_FrameIndex operands with physical register references
// and actual offsets.
//
replaceFrameIndices(Fn);
+ // If register scavenging is needed, as we've enabled doing it as a
+ // post-pass, scavenge the virtual registers that frame index elimiation
+ // inserted.
+ if (TRI->requiresRegisterScavenging(Fn) && FrameIndexVirtualScavenging)
+ scavengeFrameVirtualRegs(Fn);
+
delete RS;
clearAllSets();
return true;
@@ -117,35 +131,24 @@ void PEI::getAnalysisUsage(AnalysisUsage &AU) const {
}
#endif
-/// calculateCalleeSavedRegisters - Scan the function for modified callee saved
-/// registers. Also calculate the MaxCallFrameSize and HasCalls variables for
-/// the function's frame information and eliminates call frame pseudo
-/// instructions.
-///
-void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) {
+/// calculateCallsInformation - Calculate the MaxCallFrameSize and HasCalls
+/// variables for the function's frame information and eliminate call frame
+/// pseudo instructions.
+void PEI::calculateCallsInformation(MachineFunction &Fn) {
const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
- const TargetFrameInfo *TFI = Fn.getTarget().getFrameInfo();
- // Get the callee saved register list...
- const unsigned *CSRegs = RegInfo->getCalleeSavedRegs(&Fn);
+ unsigned MaxCallFrameSize = 0;
+ bool HasCalls = false;
// Get the function call frame set-up and tear-down instruction opcode
int FrameSetupOpcode = RegInfo->getCallFrameSetupOpcode();
int FrameDestroyOpcode = RegInfo->getCallFrameDestroyOpcode();
- // These are used to keep track the callee-save area. Initialize them.
- MinCSFrameIndex = INT_MAX;
- MaxCSFrameIndex = 0;
-
- // Early exit for targets which have no callee saved registers and no call
- // frame setup/destroy pseudo instructions.
- if ((CSRegs == 0 || CSRegs[0] == 0) &&
- FrameSetupOpcode == -1 && FrameDestroyOpcode == -1)
+ // Early exit for targets which have no call frame setup/destroy pseudo
+ // instructions.
+ if (FrameSetupOpcode == -1 && FrameDestroyOpcode == -1)
return;
- unsigned MaxCallFrameSize = 0;
- bool HasCalls = false;
-
std::vector<MachineBasicBlock::iterator> FrameSDOps;
for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB)
for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I)
@@ -157,31 +160,57 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) {
if (Size > MaxCallFrameSize) MaxCallFrameSize = Size;
HasCalls = true;
FrameSDOps.push_back(I);
+ } else if (I->getOpcode() == TargetInstrInfo::INLINEASM) {
+ // An InlineAsm might be a call; assume it is to get the stack frame
+ // aligned correctly for calls.
+ HasCalls = true;
}
MachineFrameInfo *FFI = Fn.getFrameInfo();
FFI->setHasCalls(HasCalls);
FFI->setMaxCallFrameSize(MaxCallFrameSize);
- for (unsigned i = 0, e = FrameSDOps.size(); i != e; ++i) {
- MachineBasicBlock::iterator I = FrameSDOps[i];
- // If call frames are not being included as part of the stack frame,
- // and there is no dynamic allocation (therefore referencing frame slots
- // off sp), leave the pseudo ops alone. We'll eliminate them later.
+ for (std::vector<MachineBasicBlock::iterator>::iterator
+ i = FrameSDOps.begin(), e = FrameSDOps.end(); i != e; ++i) {
+ MachineBasicBlock::iterator I = *i;
+
+ // If call frames are not being included as part of the stack frame, and
+ // there is no dynamic allocation (therefore referencing frame slots off
+ // sp), leave the pseudo ops alone. We'll eliminate them later.
if (RegInfo->hasReservedCallFrame(Fn) || RegInfo->hasFP(Fn))
RegInfo->eliminateCallFramePseudoInstr(Fn, *I->getParent(), I);
}
+}
+
+
+/// calculateCalleeSavedRegisters - Scan the function for modified callee saved
+/// registers.
+void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) {
+ const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
+ const TargetFrameInfo *TFI = Fn.getTarget().getFrameInfo();
+ MachineFrameInfo *FFI = Fn.getFrameInfo();
+
+ // Get the callee saved register list...
+ const unsigned *CSRegs = RegInfo->getCalleeSavedRegs(&Fn);
+
+ // These are used to keep track the callee-save area. Initialize them.
+ MinCSFrameIndex = INT_MAX;
+ MaxCSFrameIndex = 0;
+
+ // Early exit for targets which have no callee saved registers.
+ if (CSRegs == 0 || CSRegs[0] == 0)
+ return;
- // Now figure out which *callee saved* registers are modified by the current
+ // Figure out which *callee saved* registers are modified by the current
// function, thus needing to be saved and restored in the prolog/epilog.
- //
- const TargetRegisterClass* const *CSRegClasses =
+ const TargetRegisterClass * const *CSRegClasses =
RegInfo->getCalleeSavedRegClasses(&Fn);
+
std::vector<CalleeSavedInfo> CSI;
for (unsigned i = 0; CSRegs[i]; ++i) {
unsigned Reg = CSRegs[i];
if (Fn.getRegInfo().isPhysRegUsed(Reg)) {
- // If the reg is modified, save it!
+ // If the reg is modified, save it!
CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i]));
} else {
for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
@@ -198,39 +227,47 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) {
return; // Early exit if no callee saved registers are modified!
unsigned NumFixedSpillSlots;
- const std::pair<unsigned,int> *FixedSpillSlots =
+ const TargetFrameInfo::SpillSlot *FixedSpillSlots =
TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots);
// Now that we know which registers need to be saved and restored, allocate
// stack slots for them.
- for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
- unsigned Reg = CSI[i].getReg();
- const TargetRegisterClass *RC = CSI[i].getRegClass();
+ for (std::vector<CalleeSavedInfo>::iterator
+ I = CSI.begin(), E = CSI.end(); I != E; ++I) {
+ unsigned Reg = I->getReg();
+ const TargetRegisterClass *RC = I->getRegClass();
+
+ int FrameIdx;
+ if (RegInfo->hasReservedSpillSlot(Fn, Reg, FrameIdx)) {
+ I->setFrameIdx(FrameIdx);
+ continue;
+ }
// Check to see if this physreg must be spilled to a particular stack slot
// on this target.
- const std::pair<unsigned,int> *FixedSlot = FixedSpillSlots;
+ const TargetFrameInfo::SpillSlot *FixedSlot = FixedSpillSlots;
while (FixedSlot != FixedSpillSlots+NumFixedSpillSlots &&
- FixedSlot->first != Reg)
+ FixedSlot->Reg != Reg)
++FixedSlot;
- int FrameIdx;
- if (FixedSlot == FixedSpillSlots+NumFixedSpillSlots) {
+ if (FixedSlot == FixedSpillSlots + NumFixedSpillSlots) {
// Nope, just spill it anywhere convenient.
unsigned Align = RC->getAlignment();
unsigned StackAlign = TFI->getStackAlignment();
- // We may not be able to sastify the desired alignment specification of
- // the TargetRegisterClass if the stack alignment is smaller.
- // Use the min.
+
+ // We may not be able to satisfy the desired alignment specification of
+ // the TargetRegisterClass if the stack alignment is smaller. Use the
+ // min.
Align = std::min(Align, StackAlign);
FrameIdx = FFI->CreateStackObject(RC->getSize(), Align);
if ((unsigned)FrameIdx < MinCSFrameIndex) MinCSFrameIndex = FrameIdx;
if ((unsigned)FrameIdx > MaxCSFrameIndex) MaxCSFrameIndex = FrameIdx;
} else {
// Spill it to the stack where we must.
- FrameIdx = FFI->CreateFixedObject(RC->getSize(), FixedSlot->second);
+ FrameIdx = FFI->CreateFixedObject(RC->getSize(), FixedSlot->Offset);
}
- CSI[i].setFrameIdx(FrameIdx);
+
+ I->setFrameIdx(FrameIdx);
}
FFI->setCalleeSavedInfo(CSI);
@@ -244,6 +281,8 @@ void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) {
MachineFrameInfo *FFI = Fn.getFrameInfo();
const std::vector<CalleeSavedInfo> &CSI = FFI->getCalleeSavedInfo();
+ FFI->setCalleeSavedInfoValid(true);
+
// Early exit if no callee saved registers are modified!
if (CSI.empty())
return;
@@ -403,8 +442,7 @@ static inline void
AdjustStackOffset(MachineFrameInfo *FFI, int FrameIdx,
bool StackGrowsDown, int64_t &Offset,
unsigned &MaxAlign) {
- // If stack grows down, we need to add size of find the lowest address of the
- // object.
+ // If the stack grows down, add the object size to find the lowest address.
if (StackGrowsDown)
Offset += FFI->getObjectSize(FrameIdx);
@@ -437,16 +475,17 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
// Loop over all of the stack objects, assigning sequential addresses...
MachineFrameInfo *FFI = Fn.getFrameInfo();
- unsigned MaxAlign = FFI->getMaxAlignment();
+ unsigned MaxAlign = 1;
// Start at the beginning of the local area.
// The Offset is the distance from the stack top in the direction
// of stack growth -- so it's always nonnegative.
- int64_t Offset = TFI.getOffsetOfLocalArea();
+ int LocalAreaOffset = TFI.getOffsetOfLocalArea();
if (StackGrowsDown)
- Offset = -Offset;
- assert(Offset >= 0
+ LocalAreaOffset = -LocalAreaOffset;
+ assert(LocalAreaOffset >= 0
&& "Local area offset should be in direction of stack growth");
+ int64_t Offset = LocalAreaOffset;
// If there are fixed sized objects that are preallocated in the local area,
// non-fixed objects can't be allocated right at the start of local area.
@@ -538,32 +577,38 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
AdjustStackOffset(FFI, SFI, StackGrowsDown, Offset, MaxAlign);
}
- // Round up the size to a multiple of the alignment, but only if there are
- // calls or alloca's in the function. This ensures that any calls to
- // subroutines have their stack frames suitable aligned.
- // Also do this if we need runtime alignment of the stack. In this case
- // offsets will be relative to SP not FP; round up the stack size so this
- // works.
- if (!RegInfo->targetHandlesStackFrameRounding() &&
- (FFI->hasCalls() || FFI->hasVarSizedObjects() ||
- (RegInfo->needsStackRealignment(Fn) &&
- FFI->getObjectIndexEnd() != 0))) {
+ if (!RegInfo->targetHandlesStackFrameRounding()) {
// If we have reserved argument space for call sites in the function
// immediately on entry to the current function, count it as part of the
// overall stack size.
- if (RegInfo->hasReservedCallFrame(Fn))
+ if (FFI->hasCalls() && RegInfo->hasReservedCallFrame(Fn))
Offset += FFI->getMaxCallFrameSize();
- unsigned AlignMask = std::max(TFI.getStackAlignment(),MaxAlign) - 1;
+ // Round up the size to a multiple of the alignment. If the function has
+ // any calls or alloca's, align to the target's StackAlignment value to
+ // ensure that the callee's frame or the alloca data is suitably aligned;
+ // otherwise, for leaf functions, align to the TransientStackAlignment
+ // value.
+ unsigned StackAlign;
+ if (FFI->hasCalls() || FFI->hasVarSizedObjects() ||
+ (RegInfo->needsStackRealignment(Fn) && FFI->getObjectIndexEnd() != 0))
+ StackAlign = TFI.getStackAlignment();
+ else
+ StackAlign = TFI.getTransientStackAlignment();
+ // If the frame pointer is eliminated, all frame offsets will be relative
+ // to SP not FP; align to MaxAlign so this works.
+ StackAlign = std::max(StackAlign, MaxAlign);
+ unsigned AlignMask = StackAlign - 1;
Offset = (Offset + AlignMask) & ~uint64_t(AlignMask);
}
// Update frame info to pretend that this is part of the stack...
- FFI->setStackSize(Offset+TFI.getOffsetOfLocalArea());
+ FFI->setStackSize(Offset - LocalAreaOffset);
// Remember the required stack alignment in case targets need it to perform
// dynamic stack alignment.
- FFI->setMaxAlignment(MaxAlign);
+ if (MaxAlign > FFI->getMaxAlignment())
+ FFI->setMaxAlignment(MaxAlign);
}
@@ -604,14 +649,9 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
for (MachineFunction::iterator BB = Fn.begin(),
E = Fn.end(); BB != E; ++BB) {
int SPAdj = 0; // SP offset due to call frame setup / destroy.
- if (RS) RS->enterBasicBlock(BB);
+ if (RS && !FrameIndexVirtualScavenging) RS->enterBasicBlock(BB);
for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
- if (I->getOpcode() == TargetInstrInfo::DECLARE) {
- // Ignore it.
- ++I;
- continue;
- }
if (I->getOpcode() == FrameSetupOpcode ||
I->getOpcode() == FrameDestroyOpcode) {
@@ -654,8 +694,16 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
// If this instruction has a FrameIndex operand, we need to
// use that target machine register info object to eliminate
// it.
-
- TRI.eliminateFrameIndex(MI, SPAdj, RS);
+ int Value;
+ unsigned VReg =
+ TRI.eliminateFrameIndex(MI, SPAdj, &Value,
+ FrameIndexVirtualScavenging ? NULL : RS);
+ if (VReg) {
+ assert (FrameIndexVirtualScavenging &&
+ "Not scavenging, but virtual returned from "
+ "eliminateFrameIndex()!");
+ FrameConstantRegMap[VReg] = FrameConstantEntry(Value, SPAdj);
+ }
// Reset the iterator if we were at the beginning of the BB.
if (AtBeginning) {
@@ -670,10 +718,170 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
if (DoIncr && I != BB->end()) ++I;
// Update register states.
- if (RS && MI) RS->forward(MI);
+ if (RS && !FrameIndexVirtualScavenging && MI) RS->forward(MI);
}
assert(SPAdj == 0 && "Unbalanced call frame setup / destroy pairs?");
}
}
+/// findLastUseReg - find the killing use of the specified register within
+/// the instruciton range. Return the operand number of the kill in Operand.
+static MachineBasicBlock::iterator
+findLastUseReg(MachineBasicBlock::iterator I, MachineBasicBlock::iterator ME,
+ unsigned Reg, unsigned *Operand) {
+ // Scan forward to find the last use of this virtual register
+ for (++I; I != ME; ++I) {
+ MachineInstr *MI = I;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
+ if (MI->getOperand(i).isReg()) {
+ unsigned OpReg = MI->getOperand(i).getReg();
+ if (OpReg == 0 || !TargetRegisterInfo::isVirtualRegister(OpReg))
+ continue;
+ assert (OpReg == Reg
+ && "overlapping use of scavenged index register!");
+ // If this is the killing use, we're done
+ if (MI->getOperand(i).isKill()) {
+ if (Operand)
+ *Operand = i;
+ return I;
+ }
+ }
+ }
+ // If we hit the end of the basic block, there was no kill of
+ // the virtual register, which is wrong.
+ assert (0 && "scavenged index register never killed!");
+ return ME;
+}
+
+/// scavengeFrameVirtualRegs - Replace all frame index virtual registers
+/// with physical registers. Use the register scavenger to find an
+/// appropriate register to use.
+void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) {
+ // Run through the instructions and find any virtual registers.
+ for (MachineFunction::iterator BB = Fn.begin(),
+ E = Fn.end(); BB != E; ++BB) {
+ RS->enterBasicBlock(BB);
+
+ unsigned CurrentVirtReg = 0;
+ unsigned CurrentScratchReg = 0;
+ bool havePrevValue = false;
+ unsigned PrevScratchReg = 0;
+ int PrevValue;
+ MachineInstr *PrevLastUseMI = NULL;
+ unsigned PrevLastUseOp = 0;
+ bool trackingCurrentValue = false;
+ int SPAdj = 0;
+ int Value = 0;
+
+ // The instruction stream may change in the loop, so check BB->end()
+ // directly.
+ for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) {
+ MachineInstr *MI = I;
+ // Likewise, call getNumOperands() each iteration, as the MI may change
+ // inside the loop (with 'i' updated accordingly).
+ for (unsigned i = 0; i != MI->getNumOperands(); ++i)
+ if (MI->getOperand(i).isReg()) {
+ MachineOperand &MO = MI->getOperand(i);
+ unsigned Reg = MO.getReg();
+ if (Reg == 0)
+ continue;
+ if (!TargetRegisterInfo::isVirtualRegister(Reg)) {
+ // If we have an active scavenged register, we shouldn't be
+ // seeing any references to it.
+ assert (Reg != CurrentScratchReg
+ && "overlapping use of scavenged frame index register!");
+
+ // If we have a previous scratch reg, check and see if anything
+ // here kills whatever value is in there.
+ if (Reg == PrevScratchReg) {
+ if (MO.isUse()) {
+ // Two-address operands implicitly kill
+ if (MO.isKill() || MI->isRegTiedToDefOperand(i)) {
+ havePrevValue = false;
+ PrevScratchReg = 0;
+ }
+ } else {
+ assert (MO.isDef());
+ havePrevValue = false;
+ PrevScratchReg = 0;
+ }
+ }
+ continue;
+ }
+
+ // Have we already allocated a scratch register for this virtual?
+ if (Reg != CurrentVirtReg) {
+ // When we first encounter a new virtual register, it
+ // must be a definition.
+ assert(MI->getOperand(i).isDef() &&
+ "frame index virtual missing def!");
+ // We can't have nested virtual register live ranges because
+ // there's only a guarantee of one scavenged register at a time.
+ assert (CurrentVirtReg == 0 &&
+ "overlapping frame index virtual registers!");
+
+ // If the target gave us information about what's in the register,
+ // we can use that to re-use scratch regs.
+ DenseMap<unsigned, FrameConstantEntry>::iterator Entry =
+ FrameConstantRegMap.find(Reg);
+ trackingCurrentValue = Entry != FrameConstantRegMap.end();
+ if (trackingCurrentValue) {
+ SPAdj = (*Entry).second.second;
+ Value = (*Entry).second.first;
+ } else
+ SPAdj = Value = 0;
+
+ // If the scratch register from the last allocation is still
+ // available, see if the value matches. If it does, just re-use it.
+ if (trackingCurrentValue && havePrevValue && PrevValue == Value) {
+ // FIXME: This assumes that the instructions in the live range
+ // for the virtual register are exclusively for the purpose
+ // of populating the value in the register. That's reasonable
+ // for these frame index registers, but it's still a very, very
+ // strong assumption. Perhaps this implies that the frame index
+ // elimination should be before register allocation, with
+ // conservative heuristics since we'll know less then, and
+ // the reuse calculations done directly when doing the code-gen?
+
+ // Find the last use of the new virtual register. Remove all
+ // instruction between here and there, and update the current
+ // instruction to reference the last use insn instead.
+ MachineBasicBlock::iterator LastUseMI =
+ findLastUseReg(I, BB->end(), Reg, &i);
+ // Remove all instructions up 'til the last use, since they're
+ // just calculating the value we already have.
+ BB->erase(I, LastUseMI);
+ MI = I = LastUseMI;
+
+ CurrentScratchReg = PrevScratchReg;
+ // Extend the live range of the register
+ PrevLastUseMI->getOperand(PrevLastUseOp).setIsKill(false);
+ RS->setUsed(CurrentScratchReg);
+ } else {
+ CurrentVirtReg = Reg;
+ const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg);
+ CurrentScratchReg = RS->FindUnusedReg(RC);
+ if (CurrentScratchReg == 0)
+ // No register is "free". Scavenge a register.
+ CurrentScratchReg = RS->scavengeRegister(RC, I, SPAdj);
+
+ PrevValue = Value;
+ }
+ }
+ assert (CurrentScratchReg && "Missing scratch register!");
+ MI->getOperand(i).setReg(CurrentScratchReg);
+
+ // If this is the last use of the register, stop tracking it.
+ if (MI->getOperand(i).isKill()) {
+ PrevScratchReg = CurrentScratchReg;
+ PrevLastUseMI = MI;
+ PrevLastUseOp = i;
+ CurrentScratchReg = CurrentVirtReg = 0;
+ havePrevValue = trackingCurrentValue;
+ }
+ }
+ RS->forward(MI);
+ }
+ }
+}
OpenPOWER on IntegriCloud