X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FPrologEpilogInserter.cpp;h=7b6747363663249a39644c410f3e33468ea05533;hb=fecdea0bf77599038eb368db3bc6a38a14900308;hp=322c28bd4ddbfc0dc20a3f918d5e4374440eece6;hpb=8fc2d0ee8dd4e077ee90a1fcc36fd0101c2947a2;p=oota-llvm.git diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp index 322c28bd4dd..7b674736366 100644 --- a/lib/CodeGen/PrologEpilogInserter.cpp +++ b/lib/CodeGen/PrologEpilogInserter.cpp @@ -14,139 +14,145 @@ // This pass must be run after register allocation. After this pass is // executed, it is illegal to construct MO_FrameIndex operands. // +// This pass provides an optional shrink wrapping variant of prolog/epilog +// insertion, enabled via --shrink-wrap. See ShrinkWrapping.cpp. +// //===----------------------------------------------------------------------===// -#include "llvm/CodeGen/Passes.h" -#include "llvm/CodeGen/MachineFunctionPass.h" +#define DEBUG_TYPE "pei" +#include "PrologEpilogInserter.h" +#include "llvm/CodeGen/MachineDominators.h" +#include "llvm/CodeGen/MachineLoopInfo.h" #include "llvm/CodeGen/MachineInstr.h" #include "llvm/CodeGen/MachineFrameInfo.h" -#include "llvm/CodeGen/MachineModuleInfo.h" #include "llvm/CodeGen/MachineRegisterInfo.h" #include "llvm/CodeGen/RegisterScavenging.h" #include "llvm/Target/TargetMachine.h" #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/Support/Debug.h" +#include "llvm/ADT/IndexedMap.h" +#include "llvm/ADT/SmallSet.h" #include "llvm/ADT/STLExtras.h" #include -using namespace llvm; - -namespace { - struct VISIBILITY_HIDDEN PEI : public MachineFunctionPass { - static char ID; - PEI() : MachineFunctionPass(&ID) {} - const char *getPassName() const { - return "Prolog/Epilog Insertion & Frame Finalization"; - } +using namespace llvm; - virtual void getAnalysisUsage(AnalysisUsage &AU) const { - AU.addPreservedID(MachineLoopInfoID); - AU.addPreservedID(MachineDominatorsID); - MachineFunctionPass::getAnalysisUsage(AU); - } +// FIXME: For testing purposes only. Remove once the pre-allocation pass +// is done. +extern cl::opt EnableLocalStackAlloc; - /// runOnMachineFunction - Insert prolog/epilog code and replace abstract - /// frame indexes with appropriate references. - /// - bool runOnMachineFunction(MachineFunction &Fn) { - const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo(); - RS = TRI->requiresRegisterScavenging(Fn) ? new RegScavenger() : NULL; - - // Get MachineModuleInfo so that we can track the construction of the - // frame. - if (MachineModuleInfo *MMI = getAnalysisIfAvailable()) - Fn.getFrameInfo()->setMachineModuleInfo(MMI); - - // 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. - calculateCalleeSavedRegisters(Fn); - - // Add the code to save and restore the callee saved registers - saveCalleeSavedRegisters(Fn); - - // Allow the target machine to make final modifications to the function - // before the frame layout is finalized. - TRI->processFunctionBeforeFrameFinalized(Fn); - - // Calculate actual frame offsets for all of the abstract stack objects... - calculateFrameObjectOffsets(Fn); - - // Add prolog and epilog code to the function. This function is required - // to align the stack frame as necessary for any stack variables or - // called functions. Because of this, calculateCalleeSavedRegisters - // must be called before this function in order to set the HasCalls - // and MaxCallFrameSize variables. - insertPrologEpilogCode(Fn); - - // Replace all MO_FrameIndex operands with physical register references - // and actual offsets. - // - replaceFrameIndices(Fn); - - delete RS; - return true; - } - - private: - RegScavenger *RS; - - // MinCSFrameIndex, MaxCSFrameIndex - Keeps the range of callee saved - // stack frame indexes. - unsigned MinCSFrameIndex, MaxCSFrameIndex; - - void calculateCalleeSavedRegisters(MachineFunction &Fn); - void saveCalleeSavedRegisters(MachineFunction &Fn); - void calculateFrameObjectOffsets(MachineFunction &Fn); - void replaceFrameIndices(MachineFunction &Fn); - void insertPrologEpilogCode(MachineFunction &Fn); - }; - char PEI::ID = 0; -} +char PEI::ID = 0; +INITIALIZE_PASS(PEI, "prologepilog", + "Prologue/Epilogue Insertion", false, false); /// createPrologEpilogCodeInserter - This function returns a pass that inserts /// prolog and epilog code, and eliminates abstract frame references. /// FunctionPass *llvm::createPrologEpilogCodeInserter() { return new PEI(); } - -/// 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. +/// runOnMachineFunction - Insert prolog/epilog code and replace abstract +/// frame indexes with appropriate references. /// -void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) { +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); + FrameConstantRegMap.clear(); + + // Calculate the MaxCallFrameSize and AdjustsStack 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. + calculateCalleeSavedRegisters(Fn); + + // Determine placement of CSR spill/restore code: + // - With shrink wrapping, place spills and restores to tightly + // enclose regions in the Machine CFG of the function where + // they are used. + // - Without shink wrapping (default), place all spills in the + // entry block, all restores in return blocks. + placeCSRSpillsAndRestores(Fn); + + // Add the code to save and restore the callee saved registers + if (!F->hasFnAttr(Attribute::Naked)) + insertCSRSpillsAndRestores(Fn); + + // Allow the target machine to make final modifications to the function + // before the frame layout is finalized. + TRI->processFunctionBeforeFrameFinalized(Fn); + + // Calculate actual frame offsets for all abstract stack objects... + calculateFrameObjectOffsets(Fn); + + // Add prolog and epilog code to the function. This function is required + // to align the stack frame as necessary for any stack variables or + // called functions. Because of this, calculateCalleeSavedRegisters() + // must be called before this function in order to set the AdjustsStack + // and MaxCallFrameSize variables. + 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; +} + +#if 0 +void PEI::getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesCFG(); + if (ShrinkWrapping || ShrinkWrapFunc != "") { + AU.addRequired(); + AU.addRequired(); + } + AU.addPreserved(); + AU.addPreserved(); + MachineFunctionPass::getAnalysisUsage(AU); +} +#endif + +/// calculateCallsInformation - Calculate the MaxCallFrameSize and AdjustsStack +/// 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(); + MachineFrameInfo *MFI = Fn.getFrameInfo(); - // Get the callee saved register list... - const unsigned *CSRegs = RegInfo->getCalleeSavedRegs(&Fn); + unsigned MaxCallFrameSize = 0; + bool AdjustsStack = MFI->adjustsStack(); // 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 FrameSDOps; for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) @@ -156,39 +162,64 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) { " instructions should have a single immediate argument!"); unsigned Size = I->getOperand(0).getImm(); if (Size > MaxCallFrameSize) MaxCallFrameSize = Size; - HasCalls = true; + AdjustsStack = true; FrameSDOps.push_back(I); + } else if (I->isInlineAsm()) { + // Some inline asm's need a stack frame, as indicated by operand 1. + if (I->getOperand(1).getImm()) + AdjustsStack = true; } - MachineFrameInfo *FFI = Fn.getFrameInfo(); - FFI->setHasCalls(HasCalls); - FFI->setMaxCallFrameSize(MaxCallFrameSize); + MFI->setAdjustsStack(AdjustsStack); + MFI->setMaxCallFrameSize(MaxCallFrameSize); + + for (std::vector::iterator + i = FrameSDOps.begin(), e = FrameSDOps.end(); i != e; ++i) { + MachineBasicBlock::iterator I = *i; - 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. - if (RegInfo->hasReservedCallFrame(Fn) || RegInfo->hasFP(Fn)) + // If call frames are not being included as part of the stack frame, and + // the target doesn't indicate otherwise, remove the call frame pseudos + // here. The sub/add sp instruction pairs are still inserted, but we don't + // need to track the SP adjustment for frame index elimination. + if (RegInfo->canSimplifyCallFramePseudos(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 *MFI = 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; + + // In Naked functions we aren't going to save any registers. + if (Fn.getFunction()->hasFnAttr(Attribute::Naked)) + return; - // Now 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 = - RegInfo->getCalleeSavedRegClasses(&Fn); std::vector CSI; for (unsigned i = 0; CSRegs[i]; ++i) { unsigned Reg = CSRegs[i]; if (Fn.getRegInfo().isPhysRegUsed(Reg)) { - // If the reg is modified, save it! - CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i])); + // If the reg is modified, save it! + CSI.push_back(CalleeSavedInfo(Reg)); } else { for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg); *AliasSet; ++AliasSet) { // Check alias registers too. if (Fn.getRegInfo().isPhysRegUsed(*AliasSet)) { - CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i])); + CSI.push_back(CalleeSavedInfo(Reg)); break; } } @@ -199,78 +230,90 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) { return; // Early exit if no callee saved registers are modified! unsigned NumFixedSpillSlots; - const std::pair *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::iterator + I = CSI.begin(), E = CSI.end(); I != E; ++I) { + unsigned Reg = I->getReg(); + const TargetRegisterClass *RC = RegInfo->getMinimalPhysRegClass(Reg); + + 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 *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); + FrameIdx = MFI->CreateStackObject(RC->getSize(), Align, true); 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 = MFI->CreateFixedObject(RC->getSize(), FixedSlot->Offset, true); } - CSI[i].setFrameIdx(FrameIdx); + + I->setFrameIdx(FrameIdx); } - FFI->setCalleeSavedInfo(CSI); + MFI->setCalleeSavedInfo(CSI); } -/// saveCalleeSavedRegisters - Insert spill code for any callee saved registers -/// that are modified in the function. +/// insertCSRSpillsAndRestores - Insert spill and restore code for +/// callee saved registers used in the function, handling shrink wrapping. /// -void PEI::saveCalleeSavedRegisters(MachineFunction &Fn) { +void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) { // Get callee saved register information. - MachineFrameInfo *FFI = Fn.getFrameInfo(); - const std::vector &CSI = FFI->getCalleeSavedInfo(); - + MachineFrameInfo *MFI = Fn.getFrameInfo(); + const std::vector &CSI = MFI->getCalleeSavedInfo(); + + MFI->setCalleeSavedInfoValid(true); + // Early exit if no callee saved registers are modified! if (CSI.empty()) return; const TargetInstrInfo &TII = *Fn.getTarget().getInstrInfo(); - - // Now that we have a stack slot for each register to be saved, insert spill - // code into the entry block. - MachineBasicBlock *MBB = Fn.begin(); - MachineBasicBlock::iterator I = MBB->begin(); - - if (!TII.spillCalleeSavedRegisters(*MBB, I, CSI)) { - for (unsigned i = 0, e = CSI.size(); i != e; ++i) { - // Add the callee-saved register as live-in. It's killed at the spill. - MBB->addLiveIn(CSI[i].getReg()); - - // Insert the spill to the stack frame. - TII.storeRegToStackSlot(*MBB, I, CSI[i].getReg(), true, - CSI[i].getFrameIdx(), CSI[i].getRegClass()); + const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo(); + MachineBasicBlock::iterator I; + + if (! ShrinkWrapThisFunction) { + // Spill using target interface. + I = EntryBlock->begin(); + if (!TII.spillCalleeSavedRegisters(*EntryBlock, I, CSI, TRI)) { + for (unsigned i = 0, e = CSI.size(); i != e; ++i) { + // Add the callee-saved register as live-in. + // It's killed at the spill. + EntryBlock->addLiveIn(CSI[i].getReg()); + + // Insert the spill to the stack frame. + unsigned Reg = CSI[i].getReg(); + const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); + TII.storeRegToStackSlot(*EntryBlock, I, Reg, true, + CSI[i].getFrameIdx(), RC, TRI); + } } - } - // Add code to restore the callee-save registers in each exiting block. - for (MachineFunction::iterator FI = Fn.begin(), E = Fn.end(); FI != E; ++FI) - // If last instruction is a return instruction, add an epilogue. - if (!FI->empty() && FI->back().getDesc().isReturn()) { - MBB = FI; + // Restore using target interface. + for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri) { + MachineBasicBlock* MBB = ReturnBlocks[ri]; I = MBB->end(); --I; // Skip over all terminator instructions, which are part of the return @@ -283,18 +326,20 @@ void PEI::saveCalleeSavedRegisters(MachineFunction &Fn) { MachineBasicBlock::iterator BeforeI = I; if (!AtStart) --BeforeI; - - // Restore all registers immediately before the return and any terminators - // that preceed it. - if (!TII.restoreCalleeSavedRegisters(*MBB, I, CSI)) { + + // Restore all registers immediately before the return and any + // terminators that preceed it. + if (!TII.restoreCalleeSavedRegisters(*MBB, I, CSI, TRI)) { for (unsigned i = 0, e = CSI.size(); i != e; ++i) { - TII.loadRegFromStackSlot(*MBB, I, CSI[i].getReg(), - CSI[i].getFrameIdx(), - CSI[i].getRegClass()); + unsigned Reg = CSI[i].getReg(); + const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); + TII.loadRegFromStackSlot(*MBB, I, Reg, + CSI[i].getFrameIdx(), + RC, TRI); assert(I != MBB->begin() && "loadRegFromStackSlot didn't insert any code!"); - // Insert in reverse order. loadRegFromStackSlot can insert multiple - // instructions. + // Insert in reverse order. loadRegFromStackSlot can insert + // multiple instructions. if (AtStart) I = MBB->begin(); else { @@ -304,19 +349,116 @@ void PEI::saveCalleeSavedRegisters(MachineFunction &Fn) { } } } + return; + } + + // Insert spills. + std::vector blockCSI; + for (CSRegBlockMap::iterator BI = CSRSave.begin(), + BE = CSRSave.end(); BI != BE; ++BI) { + MachineBasicBlock* MBB = BI->first; + CSRegSet save = BI->second; + + if (save.empty()) + continue; + + blockCSI.clear(); + for (CSRegSet::iterator RI = save.begin(), + RE = save.end(); RI != RE; ++RI) { + blockCSI.push_back(CSI[*RI]); + } + assert(blockCSI.size() > 0 && + "Could not collect callee saved register info"); + + I = MBB->begin(); + + // When shrink wrapping, use stack slot stores/loads. + for (unsigned i = 0, e = blockCSI.size(); i != e; ++i) { + // Add the callee-saved register as live-in. + // It's killed at the spill. + MBB->addLiveIn(blockCSI[i].getReg()); + + // Insert the spill to the stack frame. + unsigned Reg = blockCSI[i].getReg(); + const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); + TII.storeRegToStackSlot(*MBB, I, Reg, + true, + blockCSI[i].getFrameIdx(), + RC, TRI); + } + } + + for (CSRegBlockMap::iterator BI = CSRRestore.begin(), + BE = CSRRestore.end(); BI != BE; ++BI) { + MachineBasicBlock* MBB = BI->first; + CSRegSet restore = BI->second; + + if (restore.empty()) + continue; + + blockCSI.clear(); + for (CSRegSet::iterator RI = restore.begin(), + RE = restore.end(); RI != RE; ++RI) { + blockCSI.push_back(CSI[*RI]); + } + assert(blockCSI.size() > 0 && + "Could not find callee saved register info"); + + // If MBB is empty and needs restores, insert at the _beginning_. + if (MBB->empty()) { + I = MBB->begin(); + } else { + I = MBB->end(); + --I; + + // Skip over all terminator instructions, which are part of the + // return sequence. + if (! I->getDesc().isTerminator()) { + ++I; + } else { + MachineBasicBlock::iterator I2 = I; + while (I2 != MBB->begin() && (--I2)->getDesc().isTerminator()) + I = I2; + } + } + + bool AtStart = I == MBB->begin(); + MachineBasicBlock::iterator BeforeI = I; + if (!AtStart) + --BeforeI; + + // Restore all registers immediately before the return and any + // terminators that preceed it. + for (unsigned i = 0, e = blockCSI.size(); i != e; ++i) { + unsigned Reg = blockCSI[i].getReg(); + const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); + TII.loadRegFromStackSlot(*MBB, I, Reg, + blockCSI[i].getFrameIdx(), + RC, TRI); + assert(I != MBB->begin() && + "loadRegFromStackSlot didn't insert any code!"); + // Insert in reverse order. loadRegFromStackSlot can insert + // multiple instructions. + if (AtStart) + I = MBB->begin(); + else { + I = BeforeI; + ++I; + } + } + } } /// AdjustStackOffset - Helper function used to adjust the stack frame offset. static inline void -AdjustStackOffset(MachineFrameInfo *FFI, int FrameIdx, +AdjustStackOffset(MachineFrameInfo *MFI, 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); + Offset += MFI->getObjectSize(FrameIdx); - unsigned Align = FFI->getObjectAlignment(FrameIdx); + unsigned Align = MFI->getObjectAlignment(FrameIdx); // If the alignment of this object is greater than that of the stack, then // increase the stack alignment to match. @@ -326,10 +468,12 @@ AdjustStackOffset(MachineFrameInfo *FFI, int FrameIdx, Offset = (Offset + Align - 1) / Align * Align; if (StackGrowsDown) { - FFI->setObjectOffset(FrameIdx, -Offset); // Set the computed offset + DEBUG(dbgs() << "alloc FI(" << FrameIdx << ") at SP[" << -Offset << "]\n"); + MFI->setObjectOffset(FrameIdx, -Offset); // Set the computed offset } else { - FFI->setObjectOffset(FrameIdx, Offset); - Offset += FFI->getObjectSize(FrameIdx); + DEBUG(dbgs() << "alloc FI(" << FrameIdx << ") at SP[" << Offset << "]\n"); + MFI->setObjectOffset(FrameIdx, Offset); + Offset += MFI->getObjectSize(FrameIdx); } } @@ -343,35 +487,34 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) { TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown; // Loop over all of the stack objects, assigning sequential addresses... - MachineFrameInfo *FFI = Fn.getFrameInfo(); - - unsigned MaxAlign = FFI->getMaxAlignment(); + MachineFrameInfo *MFI = Fn.getFrameInfo(); // 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. - // We currently don't support filling in holes in between fixed sized objects, - // so we adjust 'Offset' to point to the end of last fixed sized + // We currently don't support filling in holes in between fixed sized + // objects, so we adjust 'Offset' to point to the end of last fixed sized // preallocated object. - for (int i = FFI->getObjectIndexBegin(); i != 0; ++i) { + for (int i = MFI->getObjectIndexBegin(); i != 0; ++i) { int64_t FixedOff; if (StackGrowsDown) { // The maximum distance from the stack pointer is at lower address of // the object -- which is given by offset. For down growing stack // the offset is negative, so we negate the offset to get the distance. - FixedOff = -FFI->getObjectOffset(i); + FixedOff = -MFI->getObjectOffset(i); } else { // The maximum distance from the start pointer is at the upper // address of the object. - FixedOff = FFI->getObjectOffset(i) + FFI->getObjectSize(i); + FixedOff = MFI->getObjectOffset(i) + MFI->getObjectSize(i); } if (FixedOff > Offset) Offset = FixedOff; } @@ -380,101 +523,151 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) { // callee saved registers. if (StackGrowsDown) { for (unsigned i = MinCSFrameIndex; i <= MaxCSFrameIndex; ++i) { - // If stack grows down, we need to add size of find the lowest + // If the stack grows down, we need to add the size to find the lowest // address of the object. - Offset += FFI->getObjectSize(i); + Offset += MFI->getObjectSize(i); - unsigned Align = FFI->getObjectAlignment(i); - // If the alignment of this object is greater than that of the stack, then - // increase the stack alignment to match. - MaxAlign = std::max(MaxAlign, Align); + unsigned Align = MFI->getObjectAlignment(i); // Adjust to alignment boundary Offset = (Offset+Align-1)/Align*Align; - FFI->setObjectOffset(i, -Offset); // Set the computed offset + MFI->setObjectOffset(i, -Offset); // Set the computed offset } } else { int MaxCSFI = MaxCSFrameIndex, MinCSFI = MinCSFrameIndex; for (int i = MaxCSFI; i >= MinCSFI ; --i) { - unsigned Align = FFI->getObjectAlignment(i); - // If the alignment of this object is greater than that of the stack, then - // increase the stack alignment to match. - MaxAlign = std::max(MaxAlign, Align); + unsigned Align = MFI->getObjectAlignment(i); // Adjust to alignment boundary Offset = (Offset+Align-1)/Align*Align; - FFI->setObjectOffset(i, Offset); - Offset += FFI->getObjectSize(i); + MFI->setObjectOffset(i, Offset); + Offset += MFI->getObjectSize(i); } } + unsigned MaxAlign = MFI->getMaxAlignment(); + // Make sure the special register scavenging spill slot is closest to the // frame pointer if a frame pointer is required. const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo(); - if (RS && RegInfo->hasFP(Fn)) { + if (RS && RegInfo->hasFP(Fn) && !RegInfo->needsStackRealignment(Fn)) { int SFI = RS->getScavengingFrameIndex(); if (SFI >= 0) - AdjustStackOffset(FFI, SFI, StackGrowsDown, Offset, MaxAlign); + AdjustStackOffset(MFI, SFI, StackGrowsDown, Offset, MaxAlign); + } + + // FIXME: Once this is working, then enable flag will change to a target + // check for whether the frame is large enough to want to use virtual + // frame index registers. Functions which don't want/need this optimization + // will continue to use the existing code path. + if (EnableLocalStackAlloc) { + unsigned Align = MFI->getLocalFrameMaxAlign(); + + // Adjust to alignment boundary. + Offset = (Offset + Align - 1) / Align * Align; + + // Store the offset of the start of the local allocation block. This + // will be used later when resolving frame base virtual register pseudos. + MFI->setLocalFrameBaseOffset(Offset); + + DEBUG(dbgs() << "Local frame base offset: " << Offset << "\n"); + + // Allocate the local block + Offset += MFI->getLocalFrameSize(); + + // Resolve offsets for objects in the local block. + for (unsigned i = 0, e = MFI->getLocalFrameObjectCount(); i != e; ++i) { + std::pair Entry = MFI->getLocalFrameObjectMap(i); + int64_t FIOffset = MFI->getLocalFrameBaseOffset() + Entry.second; + + AdjustStackOffset(MFI, Entry.first, StackGrowsDown, FIOffset, MaxAlign); + } } // Make sure that the stack protector comes before the local variables on the // stack. - if (FFI->getStackProtectorIndex() >= 0) - AdjustStackOffset(FFI, FFI->getStackProtectorIndex(), StackGrowsDown, + SmallSet LargeStackObjs; + if (MFI->getStackProtectorIndex() >= 0) { + AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), StackGrowsDown, Offset, MaxAlign); + // Assign large stack objects first. + for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) { + if (MFI->isObjectPreAllocated(i)) + continue; + if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex) + continue; + if (RS && (int)i == RS->getScavengingFrameIndex()) + continue; + if (MFI->isDeadObjectIndex(i)) + continue; + if (MFI->getStackProtectorIndex() == (int)i) + continue; + if (!MFI->MayNeedStackProtector(i)) + continue; + + AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign); + LargeStackObjs.insert(i); + } + } + // Then assign frame offsets to stack objects that are not used to spill // callee saved registers. - for (unsigned i = 0, e = FFI->getObjectIndexEnd(); i != e; ++i) { + for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) { + if (MFI->isObjectPreAllocated(i)) + continue; if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex) continue; if (RS && (int)i == RS->getScavengingFrameIndex()) continue; - if (FFI->isDeadObjectIndex(i)) + if (MFI->isDeadObjectIndex(i)) + continue; + if (MFI->getStackProtectorIndex() == (int)i) continue; - if (FFI->getStackProtectorIndex() == (int)i) + if (LargeStackObjs.count(i)) continue; - AdjustStackOffset(FFI, i, StackGrowsDown, Offset, MaxAlign); + AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign); } // Make sure the special register scavenging spill slot is closest to the // stack pointer. - if (RS && !RegInfo->hasFP(Fn)) { + if (RS && (!RegInfo->hasFP(Fn) || RegInfo->needsStackRealignment(Fn))) { int SFI = RS->getScavengingFrameIndex(); if (SFI >= 0) - AdjustStackOffset(FFI, SFI, StackGrowsDown, Offset, MaxAlign); + AdjustStackOffset(MFI, 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)) - Offset += FFI->getMaxCallFrameSize(); - - unsigned AlignMask = std::max(TFI.getStackAlignment(),MaxAlign) - 1; + if (MFI->adjustsStack() && RegInfo->hasReservedCallFrame(Fn)) + Offset += MFI->getMaxCallFrameSize(); + + // 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 (MFI->adjustsStack() || MFI->hasVarSizedObjects() || + (RegInfo->needsStackRealignment(Fn) && MFI->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()); - - // Remember the required stack alignment in case targets need it to perform - // dynamic stack alignment. - FFI->setMaxAlignment(MaxAlign); + MFI->setStackSize(Offset - LocalAreaOffset); } - /// insertPrologEpilogCode - Scan the function for modified callee saved /// registers, insert spill code for these callee saved registers, then add /// prolog and epilog code to the function. @@ -493,7 +686,6 @@ void PEI::insertPrologEpilogCode(MachineFunction &Fn) { } } - /// replaceFrameIndices - Replace all MO_FrameIndex operands with physical /// register references and actual offsets. /// @@ -509,20 +701,22 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) { int FrameSetupOpcode = TRI.getCallFrameSetupOpcode(); int FrameDestroyOpcode = TRI.getCallFrameDestroyOpcode(); - for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) { + for (MachineFunction::iterator BB = Fn.begin(), + E = Fn.end(); BB != E; ++BB) { +#ifndef NDEBUG + int SPAdjCount = 0; // frame setup / destroy count. +#endif int SPAdj = 0; // SP offset due to call frame setup / destroy. - if (RS) RS->enterBasicBlock(BB); - for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) { - MachineInstr *MI = I; + if (RS && !FrameIndexVirtualScavenging) RS->enterBasicBlock(BB); - if (I->getOpcode() == TargetInstrInfo::DECLARE) { - // Ignore it. - ++I; - continue; - } + for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) { if (I->getOpcode() == FrameSetupOpcode || I->getOpcode() == FrameDestroyOpcode) { +#ifndef NDEBUG + // Track whether we see even pairs of them + SPAdjCount += I->getOpcode() == FrameSetupOpcode ? 1 : -1; +#endif // Remember how much SP has been adjusted to create the call // frame. int Size = I->getOperand(0).getImm(); @@ -541,12 +735,12 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) { if (PrevI == BB->end()) I = BB->begin(); // The replaced instr was the first in the block. else - I = next(PrevI); + I = llvm::next(PrevI); continue; } + MachineInstr *MI = I; bool DoIncr = true; - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) if (MI->getOperand(i).isFI()) { // Some instructions (e.g. inline asm instructions) can have @@ -562,7 +756,16 @@ 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); + TargetRegisterInfo::FrameIndexValue 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) { @@ -577,9 +780,207 @@ 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?"); + // If we have evenly matched pairs of frame setup / destroy instructions, + // make sure the adjustments come out to zero. If we don't have matched + // pairs, we can't be sure the missing bit isn't in another basic block + // due to a custom inserter playing tricks, so just asserting SPAdj==0 + // isn't sufficient. See tMOVCC on Thumb1, for example. + assert((SPAdjCount || 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) { + // Scan forward to find the last use of this virtual register + for (++I; I != ME; ++I) { + MachineInstr *MI = I; + bool isDefInsn = false; + bool isKillInsn = false; + 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 have a candidate. + if (MI->getOperand(i).isKill()) + isKillInsn = true; + else if (MI->getOperand(i).isDef()) + isDefInsn = true; + } + if (isKillInsn && !isDefInsn) + 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); + + // FIXME: The logic flow in this function is still too convoluted. + // It needs a cleanup refactoring. Do that in preparation for tracking + // more than one scratch register value and using ranges to find + // available scratch registers. + unsigned CurrentVirtReg = 0; + unsigned CurrentScratchReg = 0; + bool havePrevValue = false; + TargetRegisterInfo::FrameIndexValue PrevValue(0,0); + TargetRegisterInfo::FrameIndexValue Value(0,0); + MachineInstr *PrevLastUseMI = NULL; + unsigned PrevLastUseOp = 0; + bool trackingCurrentValue = false; + 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(); ) { + MachineInstr *MI = I; + bool isDefInsn = false; + bool isKillInsn = false; + bool clobbersScratchReg = false; + bool DoIncr = true; + for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++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 a previous scratch reg, check and see if anything + // here kills whatever value is in there. + if (Reg == CurrentScratchReg) { + if (MO.isUse()) { + // Two-address operands implicitly kill + if (MO.isKill() || MI->isRegTiedToDefOperand(i)) + clobbersScratchReg = true; + } else { + assert (MO.isDef()); + clobbersScratchReg = true; + } + } + continue; + } + // If this is a def, remember that this insn defines the value. + // This lets us properly consider insns which re-use the scratch + // register, such as r2 = sub r2, #imm, in the middle of the + // scratch range. + if (MO.isDef()) + isDefInsn = true; + + // 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::iterator Entry = + FrameConstantRegMap.find(Reg); + trackingCurrentValue = Entry != FrameConstantRegMap.end(); + if (trackingCurrentValue) { + SPAdj = (*Entry).second.second; + Value = (*Entry).second.first; + } else { + SPAdj = 0; + Value.first = 0; + Value.second = 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. rdar://7322732. Better would be to + // explicitly check each instruction in the range for references + // to the virtual register. Only delete those insns that + // touch the virtual register. + + // 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); + + // Remove all instructions up 'til the last use, since they're + // just calculating the value we already have. + BB->erase(I, LastUseMI); + I = LastUseMI; + + // Extend the live range of the scratch register + PrevLastUseMI->getOperand(PrevLastUseOp).setIsKill(false); + RS->setUsed(CurrentScratchReg); + CurrentVirtReg = Reg; + + // We deleted the instruction we were scanning the operands of. + // Jump back to the instruction iterator loop. Don't increment + // past this instruction since we updated the iterator already. + DoIncr = false; + break; + } + + // Scavenge a new scratch register + CurrentVirtReg = Reg; + const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg); + CurrentScratchReg = RS->scavengeRegister(RC, I, SPAdj); + PrevValue = Value; + } + // replace this reference to the virtual register with the + // scratch register. + assert (CurrentScratchReg && "Missing scratch register!"); + MI->getOperand(i).setReg(CurrentScratchReg); + + if (MI->getOperand(i).isKill()) { + isKillInsn = true; + PrevLastUseOp = i; + PrevLastUseMI = MI; + } + } + } + // If this is the last use of the scratch, stop tracking it. The + // last use will be a kill operand in an instruction that does + // not also define the scratch register. + if (isKillInsn && !isDefInsn) { + CurrentVirtReg = 0; + havePrevValue = trackingCurrentValue; + } + // Similarly, notice if instruction clobbered the value in the + // register we're tracking for possible later reuse. This is noted + // above, but enforced here since the value is still live while we + // process the rest of the operands of the instruction. + if (clobbersScratchReg) { + havePrevValue = false; + CurrentScratchReg = 0; + } + if (DoIncr) { + RS->forward(I); + ++I; + } + } } }