#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
char PEI::ID = 0;
char &llvm::PrologEpilogCodeInserterID = PEI::ID;
+static cl::opt<unsigned>
+WarnStackSize("warn-stack-size", cl::Hidden, cl::init((unsigned)-1),
+ cl::desc("Warn for stack size bigger than the given"
+ " number"));
+
INITIALIZE_PASS_BEGIN(PEI, "prologepilog",
"Prologue/Epilogue Insertion", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
"Prologue/Epilogue Insertion & Frame Finalization",
false, false)
-STATISTIC(NumVirtualFrameRegs, "Number of virtual frame regs encountered");
STATISTIC(NumScavengedRegs, "Number of frame index regs scavenged");
STATISTIC(NumBytesStackSpace,
"Number of bytes used for stack in all functions");
// Clear any vregs created by virtual scavenging.
Fn.getRegInfo().clearVirtRegs();
+ // Warn on stack size when we exceeds the given limit.
+ MachineFrameInfo *MFI = Fn.getFrameInfo();
+ if (WarnStackSize.getNumOccurrences() > 0 &&
+ WarnStackSize < MFI->getStackSize())
+ errs() << "warning: Stack size limit exceeded (" << MFI->getStackSize()
+ << ") in " << Fn.getName() << ".\n";
+
delete RS;
clearAllSets();
return true;
std::vector<CalleeSavedInfo> CSI;
for (unsigned i = 0; CSRegs[i]; ++i) {
unsigned Reg = CSRegs[i];
- if (F.getRegInfo().isPhysRegUsed(Reg)) {
+ // Functions which call __builtin_unwind_init get all their registers saved.
+ if (F.getRegInfo().isPhysRegUsed(Reg) || F.getMMI().callsUnwindInit()) {
// If the reg is modified, save it!
CSI.push_back(CalleeSavedInfo(Reg));
}
unsigned MaxAlign = MFI->getMaxAlignment();
// Make sure the special register scavenging spill slot is closest to the
- // frame pointer if a frame pointer is required.
+ // incoming stack pointer if a frame pointer is required and is closer
+ // to the incoming rather than the final stack pointer.
const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
- if (RS && TFI.hasFP(Fn) && RegInfo->useFPForScavengingIndex(Fn) &&
- !RegInfo->needsStackRealignment(Fn)) {
+ bool EarlyScavengingSlots = (TFI.hasFP(Fn) &&
+ TFI.isFPCloseToIncomingSP() &&
+ RegInfo->useFPForScavengingIndex(Fn) &&
+ !RegInfo->needsStackRealignment(Fn));
+ if (RS && EarlyScavengingSlots) {
SmallVector<int, 2> SFIs;
RS->getScavengingFrameIndices(SFIs);
- for (SmallVector<int, 2>::iterator I = SFIs.begin(),
- IE = SFIs.end(); I != IE; ++I)
+ for (SmallVectorImpl<int>::iterator I = SFIs.begin(),
+ IE = SFIs.end(); I != IE; ++I)
AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign);
}
// Make sure the special register scavenging spill slot is closest to the
// stack pointer.
- if (RS && (!TFI.hasFP(Fn) || RegInfo->needsStackRealignment(Fn) ||
- !RegInfo->useFPForScavengingIndex(Fn))) {
+ if (RS && !EarlyScavengingSlots) {
SmallVector<int, 2> SFIs;
RS->getScavengingFrameIndices(SFIs);
- for (SmallVector<int, 2>::iterator I = SFIs.begin(),
- IE = SFIs.end(); I != IE; ++I)
+ for (SmallVectorImpl<int>::iterator I = SFIs.begin(),
+ IE = SFIs.end(); I != IE; ++I)
AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign);
}
bool DoIncr = true;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
if (!MI->getOperand(i).isFI())
- continue;
+ continue;
+
+ // Frame indicies in debug values are encoded in a target independent
+ // way with simply the frame index and offset rather than any
+ // target-specific addressing mode.
+ if (MI->isDebugValue()) {
+ assert(i == 0 && "Frame indicies can only appear as the first "
+ "operand of a DBG_VALUE machine instruction");
+ unsigned Reg;
+ MachineOperand &Offset = MI->getOperand(1);
+ Offset.setImm(Offset.getImm() +
+ TFI->getFrameIndexReference(
+ Fn, MI->getOperand(0).getIndex(), Reg));
+ MI->getOperand(0).ChangeToRegister(Reg, false /*isDef*/);
+ continue;
+ }
// Some instructions (e.g. inline asm instructions) can have
// multiple frame indices and/or cause eliminateFrameIndex
E = Fn.end(); BB != E; ++BB) {
RS->enterBasicBlock(BB);
- unsigned VirtReg = 0;
- unsigned ScratchReg = 0;
int SPAdj = 0;
// The instruction stream may change in the loop, so check BB->end()
// directly.
for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
+ // We might end up here again with a NULL iterator if we scavenged a
+ // register for which we inserted spill code for definition by what was
+ // originally the first instruction in BB.
+ if (I == MachineBasicBlock::iterator(NULL))
+ I = BB->begin();
+
MachineInstr *MI = I;
+ MachineBasicBlock::iterator J = llvm::next(I);
+ MachineBasicBlock::iterator P = I == BB->begin() ?
+ MachineBasicBlock::iterator(NULL) : llvm::prior(I);
+
+ // RS should process this instruction before we might scavenge at this
+ // location. This is because we might be replacing a virtual register
+ // defined by this instruction, and if so, registers killed by this
+ // instruction are available, and defined registers are not.
+ RS->forward(I);
+
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
if (MI->getOperand(i).isReg()) {
MachineOperand &MO = MI->getOperand(i);
if (!TargetRegisterInfo::isVirtualRegister(Reg))
continue;
- ++NumVirtualFrameRegs;
-
- // Have we already allocated a scratch register for this virtual?
- if (Reg != VirtReg) {
- // When we first encounter a new virtual register, it
- // must be a definition.
- assert(MI->getOperand(i).isDef() &&
- "frame index virtual missing def!");
- // Scavenge a new scratch register
- VirtReg = Reg;
- const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg);
- ScratchReg = RS->scavengeRegister(RC, I, SPAdj);
- ++NumScavengedRegs;
- }
+ // When we first encounter a new virtual register, it
+ // must be a definition.
+ assert(MI->getOperand(i).isDef() &&
+ "frame index virtual missing def!");
+ // Scavenge a new scratch register
+ const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg);
+ unsigned ScratchReg = RS->scavengeRegister(RC, J, SPAdj);
+
+ ++NumScavengedRegs;
+
// Replace this reference to the virtual register with the
// scratch register.
assert (ScratchReg && "Missing scratch register!");
- MI->getOperand(i).setReg(ScratchReg);
+ Fn.getRegInfo().replaceRegWith(Reg, ScratchReg);
+ // Because this instruction was processed by the RS before this
+ // register was allocated, make sure that the RS now records the
+ // register as being used.
+ RS->setUsed(ScratchReg);
}
}
- RS->forward(I);
- ++I;
+
+ // If the scavenger needed to use one of its spill slots, the
+ // spill code will have been inserted in between I and J. This is a
+ // problem because we need the spill code before I: Move I to just
+ // prior to J.
+ if (I != llvm::prior(J)) {
+ BB->splice(J, BB, I);
+
+ // Before we move I, we need to prepare the RS to visit I again.
+ // Specifically, RS will assert if it sees uses of registers that
+ // it believes are undefined. Because we have already processed
+ // register kills in I, when it visits I again, it will believe that
+ // those registers are undefined. To avoid this situation, unprocess
+ // the instruction I.
+ assert(RS->getCurrentPosition() == I &&
+ "The register scavenger has an unexpected position");
+ I = P;
+ RS->unprocess(P);
+ } else
+ ++I;
}
}
}
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