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llvm-mirror/lib/Target/Hexagon/HexagonFrameLowering.cpp
Chandler Carruth 8079aabce6 [MI] Change the array of MachineMemOperand pointers to be 
a generically extensible collection of extra info attached to
a `MachineInstr`.

The primary change here is cleaning up the APIs used for setting and
manipulating the `MachineMemOperand` pointer arrays so chat we can
change how they are allocated.

Then we introduce an extra info object that using the trailing object
pattern to attach some number of MMOs but also other extra info. The
design of this is specifically so that this extra info has a fixed
necessary cost (the header tracking what extra info is included) and
everything else can be tail allocated. This pattern works especially
well with a `BumpPtrAllocator` which we use here.

I've also added the basic scaffolding for putting interesting pointers
into this, namely pre- and post-instruction symbols. These aren't used
anywhere yet, they're just there to ensure I've actually gotten the data
structure types correct. I'll flesh out support for these in
a subsequent patch (MIR dumping, parsing, the works).

Finally, I've included an optimization where we store any single pointer
inline in the `MachineInstr` to avoid the allocation overhead. This is
expected to be the overwhelmingly most common case and so should avoid
any memory usage growth due to slightly less clever / dense allocation
when dealing with >1 MMO. This did require several ergonomic
improvements to the `PointerSumType` to reasonably support the various
usage models.

This also has a side effect of freeing up 8 bits within the
`MachineInstr` which could be repurposed for something else.

The suggested direction here came largely from Hal Finkel. I hope it was
worth it. ;] It does hopefully clear a path for subsequent extensions
w/o nearly as much leg work. Lots of thanks to Reid and Justin for
careful reviews and ideas about how to do all of this.

Differential Revision: https://reviews.llvm.org/D50701

llvm-svn: 339940
2018-08-16 21:30:05 +00:00

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//===- HexagonFrameLowering.cpp - Define frame lowering -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//
//===----------------------------------------------------------------------===//
#include "HexagonFrameLowering.h"
#include "HexagonBlockRanges.h"
#include "HexagonInstrInfo.h"
#include "HexagonMachineFunctionInfo.h"
#include "HexagonRegisterInfo.h"
#include "HexagonSubtarget.h"
#include "HexagonTargetMachine.h"
#include "MCTargetDesc/HexagonBaseInfo.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/LivePhysRegs.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachinePostDominators.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/Function.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Pass.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <iterator>
#include <limits>
#include <map>
#include <utility>
#include <vector>
#define DEBUG_TYPE "hexagon-pei"
// Hexagon stack frame layout as defined by the ABI:
//
// Incoming arguments
// passed via stack
// |
// |
// SP during function's FP during function's |
// +-- runtime (top of stack) runtime (bottom) --+ |
// | | |
// --++---------------------+------------------+-----------------++-+-------
// | parameter area for | variable-size | fixed-size |LR| arg
// | called functions | local objects | local objects |FP|
// --+----------------------+------------------+-----------------+--+-------
// <- size known -> <- size unknown -> <- size known ->
//
// Low address High address
//
// <--- stack growth
//
//
// - In any circumstances, the outgoing function arguments are always accessi-
// ble using the SP, and the incoming arguments are accessible using the FP.
// - If the local objects are not aligned, they can always be accessed using
// the FP.
// - If there are no variable-sized objects, the local objects can always be
// accessed using the SP, regardless whether they are aligned or not. (The
// alignment padding will be at the bottom of the stack (highest address),
// and so the offset with respect to the SP will be known at the compile-
// -time.)
//
// The only complication occurs if there are both, local aligned objects, and
// dynamically allocated (variable-sized) objects. The alignment pad will be
// placed between the FP and the local objects, thus preventing the use of the
// FP to access the local objects. At the same time, the variable-sized objects
// will be between the SP and the local objects, thus introducing an unknown
// distance from the SP to the locals.
//
// To avoid this problem, a new register is created that holds the aligned
// address of the bottom of the stack, referred in the sources as AP (aligned
// pointer). The AP will be equal to "FP-p", where "p" is the smallest pad
// that aligns AP to the required boundary (a maximum of the alignments of
// all stack objects, fixed- and variable-sized). All local objects[1] will
// then use AP as the base pointer.
// [1] The exception is with "fixed" stack objects. "Fixed" stack objects get
// their name from being allocated at fixed locations on the stack, relative
// to the FP. In the presence of dynamic allocation and local alignment, such
// objects can only be accessed through the FP.
//
// Illustration of the AP:
// FP --+
// |
// ---------------+---------------------+-----+-----------------------++-+--
// Rest of the | Local stack objects | Pad | Fixed stack objects |LR|
// stack frame | (aligned) | | (CSR, spills, etc.) |FP|
// ---------------+---------------------+-----+-----------------+-----+--+--
// |<-- Multiple of the -->|
// stack alignment +-- AP
//
// The AP is set up at the beginning of the function. Since it is not a dedi-
// cated (reserved) register, it needs to be kept live throughout the function
// to be available as the base register for local object accesses.
// Normally, an address of a stack objects is obtained by a pseudo-instruction
// PS_fi. To access local objects with the AP register present, a different
// pseudo-instruction needs to be used: PS_fia. The PS_fia takes one extra
// argument compared to PS_fi: the first input register is the AP register.
// This keeps the register live between its definition and its uses.
// The AP register is originally set up using pseudo-instruction PS_aligna:
// AP = PS_aligna A
// where
// A - required stack alignment
// The alignment value must be the maximum of all alignments required by
// any stack object.
// The dynamic allocation uses a pseudo-instruction PS_alloca:
// Rd = PS_alloca Rs, A
// where
// Rd - address of the allocated space
// Rs - minimum size (the actual allocated can be larger to accommodate
// alignment)
// A - required alignment
using namespace llvm;
static cl::opt<bool> DisableDeallocRet("disable-hexagon-dealloc-ret",
cl::Hidden, cl::desc("Disable Dealloc Return for Hexagon target"));
static cl::opt<unsigned> NumberScavengerSlots("number-scavenger-slots",
cl::Hidden, cl::desc("Set the number of scavenger slots"), cl::init(2),
cl::ZeroOrMore);
static cl::opt<int> SpillFuncThreshold("spill-func-threshold",
cl::Hidden, cl::desc("Specify O2(not Os) spill func threshold"),
cl::init(6), cl::ZeroOrMore);
static cl::opt<int> SpillFuncThresholdOs("spill-func-threshold-Os",
cl::Hidden, cl::desc("Specify Os spill func threshold"),
cl::init(1), cl::ZeroOrMore);
static cl::opt<bool> EnableStackOVFSanitizer("enable-stackovf-sanitizer",
cl::Hidden, cl::desc("Enable runtime checks for stack overflow."),
cl::init(false), cl::ZeroOrMore);
static cl::opt<bool> EnableShrinkWrapping("hexagon-shrink-frame",
cl::init(true), cl::Hidden, cl::ZeroOrMore,
cl::desc("Enable stack frame shrink wrapping"));
static cl::opt<unsigned> ShrinkLimit("shrink-frame-limit",
cl::init(std::numeric_limits<unsigned>::max()), cl::Hidden, cl::ZeroOrMore,
cl::desc("Max count of stack frame shrink-wraps"));
static cl::opt<bool> EnableSaveRestoreLong("enable-save-restore-long",
cl::Hidden, cl::desc("Enable long calls for save-restore stubs."),
cl::init(false), cl::ZeroOrMore);
static cl::opt<bool> EliminateFramePointer("hexagon-fp-elim", cl::init(true),
cl::Hidden, cl::desc("Refrain from using FP whenever possible"));
static cl::opt<bool> OptimizeSpillSlots("hexagon-opt-spill", cl::Hidden,
cl::init(true), cl::desc("Optimize spill slots"));
#ifndef NDEBUG
static cl::opt<unsigned> SpillOptMax("spill-opt-max", cl::Hidden,
cl::init(std::numeric_limits<unsigned>::max()));
static unsigned SpillOptCount = 0;
#endif
namespace llvm {
void initializeHexagonCallFrameInformationPass(PassRegistry&);
FunctionPass *createHexagonCallFrameInformation();
} // end namespace llvm
namespace {
class HexagonCallFrameInformation : public MachineFunctionPass {
public:
static char ID;
HexagonCallFrameInformation() : MachineFunctionPass(ID) {
PassRegistry &PR = *PassRegistry::getPassRegistry();
initializeHexagonCallFrameInformationPass(PR);
}
bool runOnMachineFunction(MachineFunction &MF) override;
MachineFunctionProperties getRequiredProperties() const override {
return MachineFunctionProperties().set(
MachineFunctionProperties::Property::NoVRegs);
}
};
char HexagonCallFrameInformation::ID = 0;
} // end anonymous namespace
bool HexagonCallFrameInformation::runOnMachineFunction(MachineFunction &MF) {
auto &HFI = *MF.getSubtarget<HexagonSubtarget>().getFrameLowering();
bool NeedCFI = MF.getMMI().hasDebugInfo() ||
MF.getFunction().needsUnwindTableEntry();
if (!NeedCFI)
return false;
HFI.insertCFIInstructions(MF);
return true;
}
INITIALIZE_PASS(HexagonCallFrameInformation, "hexagon-cfi",
"Hexagon call frame information", false, false)
FunctionPass *llvm::createHexagonCallFrameInformation() {
return new HexagonCallFrameInformation();
}
/// Map a register pair Reg to the subregister that has the greater "number",
/// i.e. D3 (aka R7:6) will be mapped to R7, etc.
static unsigned getMax32BitSubRegister(unsigned Reg,
const TargetRegisterInfo &TRI,
bool hireg = true) {
if (Reg < Hexagon::D0 || Reg > Hexagon::D15)
return Reg;
unsigned RegNo = 0;
for (MCSubRegIterator SubRegs(Reg, &TRI); SubRegs.isValid(); ++SubRegs) {
if (hireg) {
if (*SubRegs > RegNo)
RegNo = *SubRegs;
} else {
if (!RegNo || *SubRegs < RegNo)
RegNo = *SubRegs;
}
}
return RegNo;
}
/// Returns the callee saved register with the largest id in the vector.
static unsigned getMaxCalleeSavedReg(const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo &TRI) {
static_assert(Hexagon::R1 > 0,
"Assume physical registers are encoded as positive integers");
if (CSI.empty())
return 0;
unsigned Max = getMax32BitSubRegister(CSI[0].getReg(), TRI);
for (unsigned I = 1, E = CSI.size(); I < E; ++I) {
unsigned Reg = getMax32BitSubRegister(CSI[I].getReg(), TRI);
if (Reg > Max)
Max = Reg;
}
return Max;
}
/// Checks if the basic block contains any instruction that needs a stack
/// frame to be already in place.
static bool needsStackFrame(const MachineBasicBlock &MBB, const BitVector &CSR,
const HexagonRegisterInfo &HRI) {
for (auto &I : MBB) {
const MachineInstr *MI = &I;
if (MI->isCall())
return true;
unsigned Opc = MI->getOpcode();
switch (Opc) {
case Hexagon::PS_alloca:
case Hexagon::PS_aligna:
return true;
default:
break;
}
// Check individual operands.
for (const MachineOperand &MO : MI->operands()) {
// While the presence of a frame index does not prove that a stack
// frame will be required, all frame indexes should be within alloc-
// frame/deallocframe. Otherwise, the code that translates a frame
// index into an offset would have to be aware of the placement of
// the frame creation/destruction instructions.
if (MO.isFI())
return true;
if (MO.isReg()) {
unsigned R = MO.getReg();
// Virtual registers will need scavenging, which then may require
// a stack slot.
if (TargetRegisterInfo::isVirtualRegister(R))
return true;
for (MCSubRegIterator S(R, &HRI, true); S.isValid(); ++S)
if (CSR[*S])
return true;
continue;
}
if (MO.isRegMask()) {
// A regmask would normally have all callee-saved registers marked
// as preserved, so this check would not be needed, but in case of
// ever having other regmasks (for other calling conventions),
// make sure they would be processed correctly.
const uint32_t *BM = MO.getRegMask();
for (int x = CSR.find_first(); x >= 0; x = CSR.find_next(x)) {
unsigned R = x;
// If this regmask does not preserve a CSR, a frame will be needed.
if (!(BM[R/32] & (1u << (R%32))))
return true;
}
}
}
}
return false;
}
/// Returns true if MBB has a machine instructions that indicates a tail call
/// in the block.
static bool hasTailCall(const MachineBasicBlock &MBB) {
MachineBasicBlock::const_iterator I = MBB.getLastNonDebugInstr();
if (I == MBB.end())
return false;
unsigned RetOpc = I->getOpcode();
return RetOpc == Hexagon::PS_tailcall_i || RetOpc == Hexagon::PS_tailcall_r;
}
/// Returns true if MBB contains an instruction that returns.
static bool hasReturn(const MachineBasicBlock &MBB) {
for (auto I = MBB.getFirstTerminator(), E = MBB.end(); I != E; ++I)
if (I->isReturn())
return true;
return false;
}
/// Returns the "return" instruction from this block, or nullptr if there
/// isn't any.
static MachineInstr *getReturn(MachineBasicBlock &MBB) {
for (auto &I : MBB)
if (I.isReturn())
return &I;
return nullptr;
}
static bool isRestoreCall(unsigned Opc) {
switch (Opc) {
case Hexagon::RESTORE_DEALLOC_RET_JMP_V4:
case Hexagon::RESTORE_DEALLOC_RET_JMP_V4_PIC:
case Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT:
case Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT_PIC:
case Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT:
case Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT_PIC:
case Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4:
case Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_PIC:
return true;
}
return false;
}
static inline bool isOptNone(const MachineFunction &MF) {
return MF.getFunction().hasFnAttribute(Attribute::OptimizeNone) ||
MF.getTarget().getOptLevel() == CodeGenOpt::None;
}
static inline bool isOptSize(const MachineFunction &MF) {
const Function &F = MF.getFunction();
return F.optForSize() && !F.optForMinSize();
}
static inline bool isMinSize(const MachineFunction &MF) {
return MF.getFunction().optForMinSize();
}
/// Implements shrink-wrapping of the stack frame. By default, stack frame
/// is created in the function entry block, and is cleaned up in every block
/// that returns. This function finds alternate blocks: one for the frame
/// setup (prolog) and one for the cleanup (epilog).
void HexagonFrameLowering::findShrunkPrologEpilog(MachineFunction &MF,
MachineBasicBlock *&PrologB, MachineBasicBlock *&EpilogB) const {
static unsigned ShrinkCounter = 0;
if (ShrinkLimit.getPosition()) {
if (ShrinkCounter >= ShrinkLimit)
return;
ShrinkCounter++;
}
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MachineDominatorTree MDT;
MDT.runOnMachineFunction(MF);
MachinePostDominatorTree MPT;
MPT.runOnMachineFunction(MF);
using UnsignedMap = DenseMap<unsigned, unsigned>;
using RPOTType = ReversePostOrderTraversal<const MachineFunction *>;
UnsignedMap RPO;
RPOTType RPOT(&MF);
unsigned RPON = 0;
for (RPOTType::rpo_iterator I = RPOT.begin(), E = RPOT.end(); I != E; ++I)
RPO[(*I)->getNumber()] = RPON++;
// Don't process functions that have loops, at least for now. Placement
// of prolog and epilog must take loop structure into account. For simpli-
// city don't do it right now.
for (auto &I : MF) {
unsigned BN = RPO[I.getNumber()];
for (auto SI = I.succ_begin(), SE = I.succ_end(); SI != SE; ++SI) {
// If found a back-edge, return.
if (RPO[(*SI)->getNumber()] <= BN)
return;
}
}
// Collect the set of blocks that need a stack frame to execute. Scan
// each block for uses/defs of callee-saved registers, calls, etc.
SmallVector<MachineBasicBlock*,16> SFBlocks;
BitVector CSR(Hexagon::NUM_TARGET_REGS);
for (const MCPhysReg *P = HRI.getCalleeSavedRegs(&MF); *P; ++P)
for (MCSubRegIterator S(*P, &HRI, true); S.isValid(); ++S)
CSR[*S] = true;
for (auto &I : MF)
if (needsStackFrame(I, CSR, HRI))
SFBlocks.push_back(&I);
LLVM_DEBUG({
dbgs() << "Blocks needing SF: {";
for (auto &B : SFBlocks)
dbgs() << " " << printMBBReference(*B);
dbgs() << " }\n";
});
// No frame needed?
if (SFBlocks.empty())
return;
// Pick a common dominator and a common post-dominator.
MachineBasicBlock *DomB = SFBlocks[0];
for (unsigned i = 1, n = SFBlocks.size(); i < n; ++i) {
DomB = MDT.findNearestCommonDominator(DomB, SFBlocks[i]);
if (!DomB)
break;
}
MachineBasicBlock *PDomB = SFBlocks[0];
for (unsigned i = 1, n = SFBlocks.size(); i < n; ++i) {
PDomB = MPT.findNearestCommonDominator(PDomB, SFBlocks[i]);
if (!PDomB)
break;
}
LLVM_DEBUG({
dbgs() << "Computed dom block: ";
if (DomB)
dbgs() << printMBBReference(*DomB);
else
dbgs() << "<null>";
dbgs() << ", computed pdom block: ";
if (PDomB)
dbgs() << printMBBReference(*PDomB);
else
dbgs() << "<null>";
dbgs() << "\n";
});
if (!DomB || !PDomB)
return;
// Make sure that DomB dominates PDomB and PDomB post-dominates DomB.
if (!MDT.dominates(DomB, PDomB)) {
LLVM_DEBUG(dbgs() << "Dom block does not dominate pdom block\n");
return;
}
if (!MPT.dominates(PDomB, DomB)) {
LLVM_DEBUG(dbgs() << "PDom block does not post-dominate dom block\n");
return;
}
// Finally, everything seems right.
PrologB = DomB;
EpilogB = PDomB;
}
/// Perform most of the PEI work here:
/// - saving/restoring of the callee-saved registers,
/// - stack frame creation and destruction.
/// Normally, this work is distributed among various functions, but doing it
/// in one place allows shrink-wrapping of the stack frame.
void HexagonFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MachineFrameInfo &MFI = MF.getFrameInfo();
const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
MachineBasicBlock *PrologB = &MF.front(), *EpilogB = nullptr;
if (EnableShrinkWrapping)
findShrunkPrologEpilog(MF, PrologB, EpilogB);
bool PrologueStubs = false;
insertCSRSpillsInBlock(*PrologB, CSI, HRI, PrologueStubs);
insertPrologueInBlock(*PrologB, PrologueStubs);
updateEntryPaths(MF, *PrologB);
if (EpilogB) {
insertCSRRestoresInBlock(*EpilogB, CSI, HRI);
insertEpilogueInBlock(*EpilogB);
} else {
for (auto &B : MF)
if (B.isReturnBlock())
insertCSRRestoresInBlock(B, CSI, HRI);
for (auto &B : MF)
if (B.isReturnBlock())
insertEpilogueInBlock(B);
for (auto &B : MF) {
if (B.empty())
continue;
MachineInstr *RetI = getReturn(B);
if (!RetI || isRestoreCall(RetI->getOpcode()))
continue;
for (auto &R : CSI)
RetI->addOperand(MachineOperand::CreateReg(R.getReg(), false, true));
}
}
if (EpilogB) {
// If there is an epilog block, it may not have a return instruction.
// In such case, we need to add the callee-saved registers as live-ins
// in all blocks on all paths from the epilog to any return block.
unsigned MaxBN = MF.getNumBlockIDs();
BitVector DoneT(MaxBN+1), DoneF(MaxBN+1), Path(MaxBN+1);
updateExitPaths(*EpilogB, *EpilogB, DoneT, DoneF, Path);
}
}
void HexagonFrameLowering::insertPrologueInBlock(MachineBasicBlock &MBB,
bool PrologueStubs) const {
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = MF.getFrameInfo();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
unsigned MaxAlign = std::max(MFI.getMaxAlignment(), getStackAlignment());
// Calculate the total stack frame size.
// Get the number of bytes to allocate from the FrameInfo.
unsigned FrameSize = MFI.getStackSize();
// Round up the max call frame size to the max alignment on the stack.
unsigned MaxCFA = alignTo(MFI.getMaxCallFrameSize(), MaxAlign);
MFI.setMaxCallFrameSize(MaxCFA);
FrameSize = MaxCFA + alignTo(FrameSize, MaxAlign);
MFI.setStackSize(FrameSize);
bool AlignStack = (MaxAlign > getStackAlignment());
// Get the number of bytes to allocate from the FrameInfo.
unsigned NumBytes = MFI.getStackSize();
unsigned SP = HRI.getStackRegister();
unsigned MaxCF = MFI.getMaxCallFrameSize();
MachineBasicBlock::iterator InsertPt = MBB.begin();
SmallVector<MachineInstr *, 4> AdjustRegs;
for (auto &MBB : MF)
for (auto &MI : MBB)
if (MI.getOpcode() == Hexagon::PS_alloca)
AdjustRegs.push_back(&MI);
for (auto MI : AdjustRegs) {
assert((MI->getOpcode() == Hexagon::PS_alloca) && "Expected alloca");
expandAlloca(MI, HII, SP, MaxCF);
MI->eraseFromParent();
}
DebugLoc dl = MBB.findDebugLoc(InsertPt);
if (hasFP(MF)) {
insertAllocframe(MBB, InsertPt, NumBytes);
if (AlignStack) {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_andir), SP)
.addReg(SP)
.addImm(-int64_t(MaxAlign));
}
// If the stack-checking is enabled, and we spilled the callee-saved
// registers inline (i.e. did not use a spill function), then call
// the stack checker directly.
if (EnableStackOVFSanitizer && !PrologueStubs)
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::PS_call_stk))
.addExternalSymbol("__runtime_stack_check");
} else if (NumBytes > 0) {
assert(alignTo(NumBytes, 8) == NumBytes);
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_addi), SP)
.addReg(SP)
.addImm(-int(NumBytes));
}
}
void HexagonFrameLowering::insertEpilogueInBlock(MachineBasicBlock &MBB) const {
MachineFunction &MF = *MBB.getParent();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
unsigned SP = HRI.getStackRegister();
MachineBasicBlock::iterator InsertPt = MBB.getFirstTerminator();
DebugLoc dl = MBB.findDebugLoc(InsertPt);
if (!hasFP(MF)) {
MachineFrameInfo &MFI = MF.getFrameInfo();
if (unsigned NumBytes = MFI.getStackSize()) {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_addi), SP)
.addReg(SP)
.addImm(NumBytes);
}
return;
}
MachineInstr *RetI = getReturn(MBB);
unsigned RetOpc = RetI ? RetI->getOpcode() : 0;
// Handle EH_RETURN.
if (RetOpc == Hexagon::EH_RETURN_JMPR) {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::L2_deallocframe))
.addDef(Hexagon::D15)
.addReg(Hexagon::R30);
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_add), SP)
.addReg(SP)
.addReg(Hexagon::R28);
return;
}
// Check for RESTORE_DEALLOC_RET* tail call. Don't emit an extra dealloc-
// frame instruction if we encounter it.
if (RetOpc == Hexagon::RESTORE_DEALLOC_RET_JMP_V4 ||
RetOpc == Hexagon::RESTORE_DEALLOC_RET_JMP_V4_PIC ||
RetOpc == Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT ||
RetOpc == Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT_PIC) {
MachineBasicBlock::iterator It = RetI;
++It;
// Delete all instructions after the RESTORE (except labels).
while (It != MBB.end()) {
if (!It->isLabel())
It = MBB.erase(It);
else
++It;
}
return;
}
// It is possible that the restoring code is a call to a library function.
// All of the restore* functions include "deallocframe", so we need to make
// sure that we don't add an extra one.
bool NeedsDeallocframe = true;
if (!MBB.empty() && InsertPt != MBB.begin()) {
MachineBasicBlock::iterator PrevIt = std::prev(InsertPt);
unsigned COpc = PrevIt->getOpcode();
if (COpc == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4 ||
COpc == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_PIC ||
COpc == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT ||
COpc == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT_PIC ||
COpc == Hexagon::PS_call_nr || COpc == Hexagon::PS_callr_nr)
NeedsDeallocframe = false;
}
if (!NeedsDeallocframe)
return;
// If the returning instruction is PS_jmpret, replace it with dealloc_return,
// otherwise just add deallocframe. The function could be returning via a
// tail call.
if (RetOpc != Hexagon::PS_jmpret || DisableDeallocRet) {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::L2_deallocframe))
.addDef(Hexagon::D15)
.addReg(Hexagon::R30);
return;
}
unsigned NewOpc = Hexagon::L4_return;
MachineInstr *NewI = BuildMI(MBB, RetI, dl, HII.get(NewOpc))
.addDef(Hexagon::D15)
.addReg(Hexagon::R30);
// Transfer the function live-out registers.
NewI->copyImplicitOps(MF, *RetI);
MBB.erase(RetI);
}
void HexagonFrameLowering::insertAllocframe(MachineBasicBlock &MBB,
MachineBasicBlock::iterator InsertPt, unsigned NumBytes) const {
MachineFunction &MF = *MBB.getParent();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
// Check for overflow.
// Hexagon_TODO: Ugh! hardcoding. Is there an API that can be used?
const unsigned int ALLOCFRAME_MAX = 16384;
// Create a dummy memory operand to avoid allocframe from being treated as
// a volatile memory reference.
auto *MMO = MF.getMachineMemOperand(MachinePointerInfo::getStack(MF, 0),
MachineMemOperand::MOStore, 4, 4);
DebugLoc dl = MBB.findDebugLoc(InsertPt);
unsigned SP = HRI.getStackRegister();
if (NumBytes >= ALLOCFRAME_MAX) {
// Emit allocframe(#0).
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::S2_allocframe))
.addDef(SP)
.addReg(SP)
.addImm(0)
.addMemOperand(MMO);
// Subtract the size from the stack pointer.
unsigned SP = HRI.getStackRegister();
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_addi), SP)
.addReg(SP)
.addImm(-int(NumBytes));
} else {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::S2_allocframe))
.addDef(SP)
.addReg(SP)
.addImm(NumBytes)
.addMemOperand(MMO);
}
}
void HexagonFrameLowering::updateEntryPaths(MachineFunction &MF,
MachineBasicBlock &SaveB) const {
SetVector<unsigned> Worklist;
MachineBasicBlock &EntryB = MF.front();
Worklist.insert(EntryB.getNumber());
unsigned SaveN = SaveB.getNumber();
auto &CSI = MF.getFrameInfo().getCalleeSavedInfo();
for (unsigned i = 0; i < Worklist.size(); ++i) {
unsigned BN = Worklist[i];
MachineBasicBlock &MBB = *MF.getBlockNumbered(BN);
for (auto &R : CSI)
if (!MBB.isLiveIn(R.getReg()))
MBB.addLiveIn(R.getReg());
if (BN != SaveN)
for (auto &SB : MBB.successors())
Worklist.insert(SB->getNumber());
}
}
bool HexagonFrameLowering::updateExitPaths(MachineBasicBlock &MBB,
MachineBasicBlock &RestoreB, BitVector &DoneT, BitVector &DoneF,
BitVector &Path) const {
assert(MBB.getNumber() >= 0);
unsigned BN = MBB.getNumber();
if (Path[BN] || DoneF[BN])
return false;
if (DoneT[BN])
return true;
auto &CSI = MBB.getParent()->getFrameInfo().getCalleeSavedInfo();
Path[BN] = true;
bool ReachedExit = false;
for (auto &SB : MBB.successors())
ReachedExit |= updateExitPaths(*SB, RestoreB, DoneT, DoneF, Path);
if (!MBB.empty() && MBB.back().isReturn()) {
// Add implicit uses of all callee-saved registers to the reached
// return instructions. This is to prevent the anti-dependency breaker
// from renaming these registers.
MachineInstr &RetI = MBB.back();
if (!isRestoreCall(RetI.getOpcode()))
for (auto &R : CSI)
RetI.addOperand(MachineOperand::CreateReg(R.getReg(), false, true));
ReachedExit = true;
}
// We don't want to add unnecessary live-ins to the restore block: since
// the callee-saved registers are being defined in it, the entry of the
// restore block cannot be on the path from the definitions to any exit.
if (ReachedExit && &MBB != &RestoreB) {
for (auto &R : CSI)
if (!MBB.isLiveIn(R.getReg()))
MBB.addLiveIn(R.getReg());
DoneT[BN] = true;
}
if (!ReachedExit)
DoneF[BN] = true;
Path[BN] = false;
return ReachedExit;
}
static Optional<MachineBasicBlock::iterator>
findCFILocation(MachineBasicBlock &B) {
// The CFI instructions need to be inserted right after allocframe.
// An exception to this is a situation where allocframe is bundled
// with a call: then the CFI instructions need to be inserted before
// the packet with the allocframe+call (in case the call throws an
// exception).
auto End = B.instr_end();
for (MachineInstr &I : B) {
MachineBasicBlock::iterator It = I.getIterator();
if (!I.isBundle()) {
if (I.getOpcode() == Hexagon::S2_allocframe)
return std::next(It);
continue;
}
// I is a bundle.
bool HasCall = false, HasAllocFrame = false;
auto T = It.getInstrIterator();
while (++T != End && T->isBundled()) {
if (T->getOpcode() == Hexagon::S2_allocframe)
HasAllocFrame = true;
else if (T->isCall())
HasCall = true;
}
if (HasAllocFrame)
return HasCall ? It : std::next(It);
}
return None;
}
void HexagonFrameLowering::insertCFIInstructions(MachineFunction &MF) const {
for (auto &B : MF) {
auto At = findCFILocation(B);
if (At.hasValue())
insertCFIInstructionsAt(B, At.getValue());
}
}
void HexagonFrameLowering::insertCFIInstructionsAt(MachineBasicBlock &MBB,
MachineBasicBlock::iterator At) const {
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = MF.getFrameInfo();
MachineModuleInfo &MMI = MF.getMMI();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
// If CFI instructions have debug information attached, something goes
// wrong with the final assembly generation: the prolog_end is placed
// in a wrong location.
DebugLoc DL;
const MCInstrDesc &CFID = HII.get(TargetOpcode::CFI_INSTRUCTION);
MCSymbol *FrameLabel = MMI.getContext().createTempSymbol();
bool HasFP = hasFP(MF);
if (HasFP) {
unsigned DwFPReg = HRI.getDwarfRegNum(HRI.getFrameRegister(), true);
unsigned DwRAReg = HRI.getDwarfRegNum(HRI.getRARegister(), true);
// Define CFA via an offset from the value of FP.
//
// -8 -4 0 (SP)
// --+----+----+---------------------
// | FP | LR | increasing addresses -->
// --+----+----+---------------------
// | +-- Old SP (before allocframe)
// +-- New FP (after allocframe)
//
// MCCFIInstruction::createDefCfa subtracts the offset from the register.
// MCCFIInstruction::createOffset takes the offset without sign change.
auto DefCfa = MCCFIInstruction::createDefCfa(FrameLabel, DwFPReg, -8);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(DefCfa));
// R31 (return addr) = CFA - 4
auto OffR31 = MCCFIInstruction::createOffset(FrameLabel, DwRAReg, -4);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffR31));
// R30 (frame ptr) = CFA - 8
auto OffR30 = MCCFIInstruction::createOffset(FrameLabel, DwFPReg, -8);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffR30));
}
static unsigned int RegsToMove[] = {
Hexagon::R1, Hexagon::R0, Hexagon::R3, Hexagon::R2,
Hexagon::R17, Hexagon::R16, Hexagon::R19, Hexagon::R18,
Hexagon::R21, Hexagon::R20, Hexagon::R23, Hexagon::R22,
Hexagon::R25, Hexagon::R24, Hexagon::R27, Hexagon::R26,
Hexagon::D0, Hexagon::D1, Hexagon::D8, Hexagon::D9,
Hexagon::D10, Hexagon::D11, Hexagon::D12, Hexagon::D13,
Hexagon::NoRegister
};
const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
for (unsigned i = 0; RegsToMove[i] != Hexagon::NoRegister; ++i) {
unsigned Reg = RegsToMove[i];
auto IfR = [Reg] (const CalleeSavedInfo &C) -> bool {
return C.getReg() == Reg;
};
auto F = find_if(CSI, IfR);
if (F == CSI.end())
continue;
int64_t Offset;
if (HasFP) {
// If the function has a frame pointer (i.e. has an allocframe),
// then the CFA has been defined in terms of FP. Any offsets in
// the following CFI instructions have to be defined relative
// to FP, which points to the bottom of the stack frame.
// The function getFrameIndexReference can still choose to use SP
// for the offset calculation, so we cannot simply call it here.
// Instead, get the offset (relative to the FP) directly.
Offset = MFI.getObjectOffset(F->getFrameIdx());
} else {
unsigned FrameReg;
Offset = getFrameIndexReference(MF, F->getFrameIdx(), FrameReg);
}
// Subtract 8 to make room for R30 and R31, which are added above.
Offset -= 8;
if (Reg < Hexagon::D0 || Reg > Hexagon::D15) {
unsigned DwarfReg = HRI.getDwarfRegNum(Reg, true);
auto OffReg = MCCFIInstruction::createOffset(FrameLabel, DwarfReg,
Offset);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffReg));
} else {
// Split the double regs into subregs, and generate appropriate
// cfi_offsets.
// The only reason, we are split double regs is, llvm-mc does not
// understand paired registers for cfi_offset.
// Eg .cfi_offset r1:0, -64
unsigned HiReg = HRI.getSubReg(Reg, Hexagon::isub_hi);
unsigned LoReg = HRI.getSubReg(Reg, Hexagon::isub_lo);
unsigned HiDwarfReg = HRI.getDwarfRegNum(HiReg, true);
unsigned LoDwarfReg = HRI.getDwarfRegNum(LoReg, true);
auto OffHi = MCCFIInstruction::createOffset(FrameLabel, HiDwarfReg,
Offset+4);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffHi));
auto OffLo = MCCFIInstruction::createOffset(FrameLabel, LoDwarfReg,
Offset);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffLo));
}
}
}
bool HexagonFrameLowering::hasFP(const MachineFunction &MF) const {
if (MF.getFunction().hasFnAttribute(Attribute::Naked))
return false;
auto &MFI = MF.getFrameInfo();
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
bool HasExtraAlign = HRI.needsStackRealignment(MF);
bool HasAlloca = MFI.hasVarSizedObjects();
// Insert ALLOCFRAME if we need to or at -O0 for the debugger. Think
// that this shouldn't be required, but doing so now because gcc does and
// gdb can't break at the start of the function without it. Will remove if
// this turns out to be a gdb bug.
//
if (MF.getTarget().getOptLevel() == CodeGenOpt::None)
return true;
// By default we want to use SP (since it's always there). FP requires
// some setup (i.e. ALLOCFRAME).
// Both, alloca and stack alignment modify the stack pointer by an
// undetermined value, so we need to save it at the entry to the function
// (i.e. use allocframe).
if (HasAlloca || HasExtraAlign)
return true;
if (MFI.getStackSize() > 0) {
// If FP-elimination is disabled, we have to use FP at this point.
const TargetMachine &TM = MF.getTarget();
if (TM.Options.DisableFramePointerElim(MF) || !EliminateFramePointer)
return true;
if (EnableStackOVFSanitizer)
return true;
}
const auto &HMFI = *MF.getInfo<HexagonMachineFunctionInfo>();
if (MFI.hasCalls() || HMFI.hasClobberLR())
return true;
return false;
}
enum SpillKind {
SK_ToMem,
SK_FromMem,
SK_FromMemTailcall
};
static const char *getSpillFunctionFor(unsigned MaxReg, SpillKind SpillType,
bool Stkchk = false) {
const char * V4SpillToMemoryFunctions[] = {
"__save_r16_through_r17",
"__save_r16_through_r19",
"__save_r16_through_r21",
"__save_r16_through_r23",
"__save_r16_through_r25",
"__save_r16_through_r27" };
const char * V4SpillToMemoryStkchkFunctions[] = {
"__save_r16_through_r17_stkchk",
"__save_r16_through_r19_stkchk",
"__save_r16_through_r21_stkchk",
"__save_r16_through_r23_stkchk",
"__save_r16_through_r25_stkchk",
"__save_r16_through_r27_stkchk" };
const char * V4SpillFromMemoryFunctions[] = {
"__restore_r16_through_r17_and_deallocframe",
"__restore_r16_through_r19_and_deallocframe",
"__restore_r16_through_r21_and_deallocframe",
"__restore_r16_through_r23_and_deallocframe",
"__restore_r16_through_r25_and_deallocframe",
"__restore_r16_through_r27_and_deallocframe" };
const char * V4SpillFromMemoryTailcallFunctions[] = {
"__restore_r16_through_r17_and_deallocframe_before_tailcall",
"__restore_r16_through_r19_and_deallocframe_before_tailcall",
"__restore_r16_through_r21_and_deallocframe_before_tailcall",
"__restore_r16_through_r23_and_deallocframe_before_tailcall",
"__restore_r16_through_r25_and_deallocframe_before_tailcall",
"__restore_r16_through_r27_and_deallocframe_before_tailcall"
};
const char **SpillFunc = nullptr;
switch(SpillType) {
case SK_ToMem:
SpillFunc = Stkchk ? V4SpillToMemoryStkchkFunctions
: V4SpillToMemoryFunctions;
break;
case SK_FromMem:
SpillFunc = V4SpillFromMemoryFunctions;
break;
case SK_FromMemTailcall:
SpillFunc = V4SpillFromMemoryTailcallFunctions;
break;
}
assert(SpillFunc && "Unknown spill kind");
// Spill all callee-saved registers up to the highest register used.
switch (MaxReg) {
case Hexagon::R17:
return SpillFunc[0];
case Hexagon::R19:
return SpillFunc[1];
case Hexagon::R21:
return SpillFunc[2];
case Hexagon::R23:
return SpillFunc[3];
case Hexagon::R25:
return SpillFunc[4];
case Hexagon::R27:
return SpillFunc[5];
default:
llvm_unreachable("Unhandled maximum callee save register");
}
return nullptr;
}
int HexagonFrameLowering::getFrameIndexReference(const MachineFunction &MF,
int FI, unsigned &FrameReg) const {
auto &MFI = MF.getFrameInfo();
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
int Offset = MFI.getObjectOffset(FI);
bool HasAlloca = MFI.hasVarSizedObjects();
bool HasExtraAlign = HRI.needsStackRealignment(MF);
bool NoOpt = MF.getTarget().getOptLevel() == CodeGenOpt::None;
auto &HMFI = *MF.getInfo<HexagonMachineFunctionInfo>();
unsigned FrameSize = MFI.getStackSize();
unsigned SP = HRI.getStackRegister();
unsigned FP = HRI.getFrameRegister();
unsigned AP = HMFI.getStackAlignBasePhysReg();
// It may happen that AP will be absent even HasAlloca && HasExtraAlign
// is true. HasExtraAlign may be set because of vector spills, without
// aligned locals or aligned outgoing function arguments. Since vector
// spills will ultimately be "unaligned", it is safe to use FP as the
// base register.
// In fact, in such a scenario the stack is actually not required to be
// aligned, although it may end up being aligned anyway, since this
// particular case is not easily detectable. The alignment will be
// unnecessary, but not incorrect.
// Unfortunately there is no quick way to verify that the above is
// indeed the case (and that it's not a result of an error), so just
// assume that missing AP will be replaced by FP.
// (A better fix would be to rematerialize AP from FP and always align
// vector spills.)
if (AP == 0)
AP = FP;
bool UseFP = false, UseAP = false; // Default: use SP (except at -O0).
// Use FP at -O0, except when there are objects with extra alignment.
// That additional alignment requirement may cause a pad to be inserted,
// which will make it impossible to use FP to access objects located
// past the pad.
if (NoOpt && !HasExtraAlign)
UseFP = true;
if (MFI.isFixedObjectIndex(FI) || MFI.isObjectPreAllocated(FI)) {
// Fixed and preallocated objects will be located before any padding
// so FP must be used to access them.
UseFP |= (HasAlloca || HasExtraAlign);
} else {
if (HasAlloca) {
if (HasExtraAlign)
UseAP = true;
else
UseFP = true;
}
}
// If FP was picked, then there had better be FP.
bool HasFP = hasFP(MF);
assert((HasFP || !UseFP) && "This function must have frame pointer");
// Having FP implies allocframe. Allocframe will store extra 8 bytes:
// FP/LR. If the base register is used to access an object across these
// 8 bytes, then the offset will need to be adjusted by 8.
//
// After allocframe:
// HexagonISelLowering adds 8 to ---+
// the offsets of all stack-based |
// arguments (*) |
// |
// getObjectOffset < 0 0 8 getObjectOffset >= 8
// ------------------------+-----+------------------------> increasing
// <local objects> |FP/LR| <input arguments> addresses
// -----------------+------+-----+------------------------>
// | |
// SP/AP point --+ +-- FP points here (**)
// somewhere on
// this side of FP/LR
//
// (*) See LowerFormalArguments. The FP/LR is assumed to be present.
// (**) *FP == old-FP. FP+0..7 are the bytes of FP/LR.
// The lowering assumes that FP/LR is present, and so the offsets of
// the formal arguments start at 8. If FP/LR is not there we need to
// reduce the offset by 8.
if (Offset > 0 && !HasFP)
Offset -= 8;
if (UseFP)
FrameReg = FP;
else if (UseAP)
FrameReg = AP;
else
FrameReg = SP;
// Calculate the actual offset in the instruction. If there is no FP
// (in other words, no allocframe), then SP will not be adjusted (i.e.
// there will be no SP -= FrameSize), so the frame size should not be
// added to the calculated offset.
int RealOffset = Offset;
if (!UseFP && !UseAP)
RealOffset = FrameSize+Offset;
return RealOffset;
}
bool HexagonFrameLowering::insertCSRSpillsInBlock(MachineBasicBlock &MBB,
const CSIVect &CSI, const HexagonRegisterInfo &HRI,
bool &PrologueStubs) const {
if (CSI.empty())
return true;
MachineBasicBlock::iterator MI = MBB.begin();
PrologueStubs = false;
MachineFunction &MF = *MBB.getParent();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
if (useSpillFunction(MF, CSI)) {
PrologueStubs = true;
unsigned MaxReg = getMaxCalleeSavedReg(CSI, HRI);
bool StkOvrFlowEnabled = EnableStackOVFSanitizer;
const char *SpillFun = getSpillFunctionFor(MaxReg, SK_ToMem,
StkOvrFlowEnabled);
auto &HTM = static_cast<const HexagonTargetMachine&>(MF.getTarget());
bool IsPIC = HTM.isPositionIndependent();
bool LongCalls = HST.useLongCalls() || EnableSaveRestoreLong;
// Call spill function.
DebugLoc DL = MI != MBB.end() ? MI->getDebugLoc() : DebugLoc();
unsigned SpillOpc;
if (StkOvrFlowEnabled) {
if (LongCalls)
SpillOpc = IsPIC ? Hexagon::SAVE_REGISTERS_CALL_V4STK_EXT_PIC
: Hexagon::SAVE_REGISTERS_CALL_V4STK_EXT;
else
SpillOpc = IsPIC ? Hexagon::SAVE_REGISTERS_CALL_V4STK_PIC
: Hexagon::SAVE_REGISTERS_CALL_V4STK;
} else {
if (LongCalls)
SpillOpc = IsPIC ? Hexagon::SAVE_REGISTERS_CALL_V4_EXT_PIC
: Hexagon::SAVE_REGISTERS_CALL_V4_EXT;
else
SpillOpc = IsPIC ? Hexagon::SAVE_REGISTERS_CALL_V4_PIC
: Hexagon::SAVE_REGISTERS_CALL_V4;
}
MachineInstr *SaveRegsCall =
BuildMI(MBB, MI, DL, HII.get(SpillOpc))
.addExternalSymbol(SpillFun);
// Add callee-saved registers as use.
addCalleeSaveRegistersAsImpOperand(SaveRegsCall, CSI, false, true);
// Add live in registers.
for (unsigned I = 0; I < CSI.size(); ++I)
MBB.addLiveIn(CSI[I].getReg());
return true;
}
for (unsigned i = 0, n = CSI.size(); i < n; ++i) {
unsigned Reg = CSI[i].getReg();
// Add live in registers. We treat eh_return callee saved register r0 - r3
// specially. They are not really callee saved registers as they are not
// supposed to be killed.
bool IsKill = !HRI.isEHReturnCalleeSaveReg(Reg);
int FI = CSI[i].getFrameIdx();
const TargetRegisterClass *RC = HRI.getMinimalPhysRegClass(Reg);
HII.storeRegToStackSlot(MBB, MI, Reg, IsKill, FI, RC, &HRI);
if (IsKill)
MBB.addLiveIn(Reg);
}
return true;
}
bool HexagonFrameLowering::insertCSRRestoresInBlock(MachineBasicBlock &MBB,
const CSIVect &CSI, const HexagonRegisterInfo &HRI) const {
if (CSI.empty())
return false;
MachineBasicBlock::iterator MI = MBB.getFirstTerminator();
MachineFunction &MF = *MBB.getParent();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
if (useRestoreFunction(MF, CSI)) {
bool HasTC = hasTailCall(MBB) || !hasReturn(MBB);
unsigned MaxR = getMaxCalleeSavedReg(CSI, HRI);
SpillKind Kind = HasTC ? SK_FromMemTailcall : SK_FromMem;
const char *RestoreFn = getSpillFunctionFor(MaxR, Kind);
auto &HTM = static_cast<const HexagonTargetMachine&>(MF.getTarget());
bool IsPIC = HTM.isPositionIndependent();
bool LongCalls = HST.useLongCalls() || EnableSaveRestoreLong;
// Call spill function.
DebugLoc DL = MI != MBB.end() ? MI->getDebugLoc()
: MBB.getLastNonDebugInstr()->getDebugLoc();
MachineInstr *DeallocCall = nullptr;
if (HasTC) {
unsigned RetOpc;
if (LongCalls)
RetOpc = IsPIC ? Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT_PIC
: Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT;
else
RetOpc = IsPIC ? Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_PIC
: Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4;
DeallocCall = BuildMI(MBB, MI, DL, HII.get(RetOpc))
.addExternalSymbol(RestoreFn);
} else {
// The block has a return.
MachineBasicBlock::iterator It = MBB.getFirstTerminator();
assert(It->isReturn() && std::next(It) == MBB.end());
unsigned RetOpc;
if (LongCalls)
RetOpc = IsPIC ? Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT_PIC
: Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT;
else
RetOpc = IsPIC ? Hexagon::RESTORE_DEALLOC_RET_JMP_V4_PIC
: Hexagon::RESTORE_DEALLOC_RET_JMP_V4;
DeallocCall = BuildMI(MBB, It, DL, HII.get(RetOpc))
.addExternalSymbol(RestoreFn);
// Transfer the function live-out registers.
DeallocCall->copyImplicitOps(MF, *It);
}
addCalleeSaveRegistersAsImpOperand(DeallocCall, CSI, true, false);
return true;
}
for (unsigned i = 0; i < CSI.size(); ++i) {
unsigned Reg = CSI[i].getReg();
const TargetRegisterClass *RC = HRI.getMinimalPhysRegClass(Reg);
int FI = CSI[i].getFrameIdx();
HII.loadRegFromStackSlot(MBB, MI, Reg, FI, RC, &HRI);
}
return true;
}
MachineBasicBlock::iterator HexagonFrameLowering::eliminateCallFramePseudoInstr(
MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
MachineInstr &MI = *I;
unsigned Opc = MI.getOpcode();
(void)Opc; // Silence compiler warning.
assert((Opc == Hexagon::ADJCALLSTACKDOWN || Opc == Hexagon::ADJCALLSTACKUP) &&
"Cannot handle this call frame pseudo instruction");
return MBB.erase(I);
}
void HexagonFrameLowering::processFunctionBeforeFrameFinalized(
MachineFunction &MF, RegScavenger *RS) const {
// If this function has uses aligned stack and also has variable sized stack
// objects, then we need to map all spill slots to fixed positions, so that
// they can be accessed through FP. Otherwise they would have to be accessed
// via AP, which may not be available at the particular place in the program.
MachineFrameInfo &MFI = MF.getFrameInfo();
bool HasAlloca = MFI.hasVarSizedObjects();
bool NeedsAlign = (MFI.getMaxAlignment() > getStackAlignment());
if (!HasAlloca || !NeedsAlign)
return;
unsigned LFS = MFI.getLocalFrameSize();
for (int i = 0, e = MFI.getObjectIndexEnd(); i != e; ++i) {
if (!MFI.isSpillSlotObjectIndex(i) || MFI.isDeadObjectIndex(i))
continue;
unsigned S = MFI.getObjectSize(i);
// Reduce the alignment to at most 8. This will require unaligned vector
// stores if they happen here.
unsigned A = std::max(MFI.getObjectAlignment(i), 8U);
MFI.setObjectAlignment(i, 8);
LFS = alignTo(LFS+S, A);
MFI.mapLocalFrameObject(i, -LFS);
}
MFI.setLocalFrameSize(LFS);
unsigned A = MFI.getLocalFrameMaxAlign();
assert(A <= 8 && "Unexpected local frame alignment");
if (A == 0)
MFI.setLocalFrameMaxAlign(8);
MFI.setUseLocalStackAllocationBlock(true);
// Set the physical aligned-stack base address register.
unsigned AP = 0;
if (const MachineInstr *AI = getAlignaInstr(MF))
AP = AI->getOperand(0).getReg();
auto &HMFI = *MF.getInfo<HexagonMachineFunctionInfo>();
HMFI.setStackAlignBasePhysReg(AP);
}
/// Returns true if there are no caller-saved registers available in class RC.
static bool needToReserveScavengingSpillSlots(MachineFunction &MF,
const HexagonRegisterInfo &HRI, const TargetRegisterClass *RC) {
MachineRegisterInfo &MRI = MF.getRegInfo();
auto IsUsed = [&HRI,&MRI] (unsigned Reg) -> bool {
for (MCRegAliasIterator AI(Reg, &HRI, true); AI.isValid(); ++AI)
if (MRI.isPhysRegUsed(*AI))
return true;
return false;
};
// Check for an unused caller-saved register. Callee-saved registers
// have become pristine by now.
for (const MCPhysReg *P = HRI.getCallerSavedRegs(&MF, RC); *P; ++P)
if (!IsUsed(*P))
return false;
// All caller-saved registers are used.
return true;
}
#ifndef NDEBUG
static void dump_registers(BitVector &Regs, const TargetRegisterInfo &TRI) {
dbgs() << '{';
for (int x = Regs.find_first(); x >= 0; x = Regs.find_next(x)) {
unsigned R = x;
dbgs() << ' ' << printReg(R, &TRI);
}
dbgs() << " }";
}
#endif
bool HexagonFrameLowering::assignCalleeSavedSpillSlots(MachineFunction &MF,
const TargetRegisterInfo *TRI, std::vector<CalleeSavedInfo> &CSI) const {
LLVM_DEBUG(dbgs() << __func__ << " on " << MF.getName() << '\n');
MachineFrameInfo &MFI = MF.getFrameInfo();
BitVector SRegs(Hexagon::NUM_TARGET_REGS);
// Generate a set of unique, callee-saved registers (SRegs), where each
// register in the set is maximal in terms of sub-/super-register relation,
// i.e. for each R in SRegs, no proper super-register of R is also in SRegs.
// (1) For each callee-saved register, add that register and all of its
// sub-registers to SRegs.
LLVM_DEBUG(dbgs() << "Initial CS registers: {");
for (unsigned i = 0, n = CSI.size(); i < n; ++i) {
unsigned R = CSI[i].getReg();
LLVM_DEBUG(dbgs() << ' ' << printReg(R, TRI));
for (MCSubRegIterator SR(R, TRI, true); SR.isValid(); ++SR)
SRegs[*SR] = true;
}
LLVM_DEBUG(dbgs() << " }\n");
LLVM_DEBUG(dbgs() << "SRegs.1: "; dump_registers(SRegs, *TRI);
dbgs() << "\n");
// (2) For each reserved register, remove that register and all of its
// sub- and super-registers from SRegs.
BitVector Reserved = TRI->getReservedRegs(MF);
for (int x = Reserved.find_first(); x >= 0; x = Reserved.find_next(x)) {
unsigned R = x;
for (MCSuperRegIterator SR(R, TRI, true); SR.isValid(); ++SR)
SRegs[*SR] = false;
}
LLVM_DEBUG(dbgs() << "Res: "; dump_registers(Reserved, *TRI);
dbgs() << "\n");
LLVM_DEBUG(dbgs() << "SRegs.2: "; dump_registers(SRegs, *TRI);
dbgs() << "\n");
// (3) Collect all registers that have at least one sub-register in SRegs,
// and also have no sub-registers that are reserved. These will be the can-
// didates for saving as a whole instead of their individual sub-registers.
// (Saving R17:16 instead of R16 is fine, but only if R17 was not reserved.)
BitVector TmpSup(Hexagon::NUM_TARGET_REGS);
for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
unsigned R = x;
for (MCSuperRegIterator SR(R, TRI); SR.isValid(); ++SR)
TmpSup[*SR] = true;
}
for (int x = TmpSup.find_first(); x >= 0; x = TmpSup.find_next(x)) {
unsigned R = x;
for (MCSubRegIterator SR(R, TRI, true); SR.isValid(); ++SR) {
if (!Reserved[*SR])
continue;
TmpSup[R] = false;
break;
}
}
LLVM_DEBUG(dbgs() << "TmpSup: "; dump_registers(TmpSup, *TRI);
dbgs() << "\n");
// (4) Include all super-registers found in (3) into SRegs.
SRegs |= TmpSup;
LLVM_DEBUG(dbgs() << "SRegs.4: "; dump_registers(SRegs, *TRI);
dbgs() << "\n");
// (5) For each register R in SRegs, if any super-register of R is in SRegs,
// remove R from SRegs.
for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
unsigned R = x;
for (MCSuperRegIterator SR(R, TRI); SR.isValid(); ++SR) {
if (!SRegs[*SR])
continue;
SRegs[R] = false;
break;
}
}
LLVM_DEBUG(dbgs() << "SRegs.5: "; dump_registers(SRegs, *TRI);
dbgs() << "\n");
// Now, for each register that has a fixed stack slot, create the stack
// object for it.
CSI.clear();
using SpillSlot = TargetFrameLowering::SpillSlot;
unsigned NumFixed;
int MinOffset = 0; // CS offsets are negative.
const SpillSlot *FixedSlots = getCalleeSavedSpillSlots(NumFixed);
for (const SpillSlot *S = FixedSlots; S != FixedSlots+NumFixed; ++S) {
if (!SRegs[S->Reg])
continue;
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(S->Reg);
int FI = MFI.CreateFixedSpillStackObject(TRI->getSpillSize(*RC), S->Offset);
MinOffset = std::min(MinOffset, S->Offset);
CSI.push_back(CalleeSavedInfo(S->Reg, FI));
SRegs[S->Reg] = false;
}
// There can be some registers that don't have fixed slots. For example,
// we need to store R0-R3 in functions with exception handling. For each
// such register, create a non-fixed stack object.
for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
unsigned R = x;
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(R);
unsigned Size = TRI->getSpillSize(*RC);
int Off = MinOffset - Size;
unsigned Align = std::min(TRI->getSpillAlignment(*RC), getStackAlignment());
assert(isPowerOf2_32(Align));
Off &= -Align;
int FI = MFI.CreateFixedSpillStackObject(Size, Off);
MinOffset = std::min(MinOffset, Off);
CSI.push_back(CalleeSavedInfo(R, FI));
SRegs[R] = false;
}
LLVM_DEBUG({
dbgs() << "CS information: {";
for (unsigned i = 0, n = CSI.size(); i < n; ++i) {
int FI = CSI[i].getFrameIdx();
int Off = MFI.getObjectOffset(FI);
dbgs() << ' ' << printReg(CSI[i].getReg(), TRI) << ":fi#" << FI << ":sp";
if (Off >= 0)
dbgs() << '+';
dbgs() << Off;
}
dbgs() << " }\n";
});
#ifndef NDEBUG
// Verify that all registers were handled.
bool MissedReg = false;
for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
unsigned R = x;
dbgs() << printReg(R, TRI) << ' ';
MissedReg = true;
}
if (MissedReg)
llvm_unreachable("...there are unhandled callee-saved registers!");
#endif
return true;
}
bool HexagonFrameLowering::expandCopy(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<unsigned> &NewRegs) const {
MachineInstr *MI = &*It;
DebugLoc DL = MI->getDebugLoc();
unsigned DstR = MI->getOperand(0).getReg();
unsigned SrcR = MI->getOperand(1).getReg();
if (!Hexagon::ModRegsRegClass.contains(DstR) ||
!Hexagon::ModRegsRegClass.contains(SrcR))
return false;
unsigned TmpR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
BuildMI(B, It, DL, HII.get(TargetOpcode::COPY), TmpR).add(MI->getOperand(1));
BuildMI(B, It, DL, HII.get(TargetOpcode::COPY), DstR)
.addReg(TmpR, RegState::Kill);
NewRegs.push_back(TmpR);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandStoreInt(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<unsigned> &NewRegs) const {
MachineInstr *MI = &*It;
if (!MI->getOperand(0).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
unsigned Opc = MI->getOpcode();
unsigned SrcR = MI->getOperand(2).getReg();
bool IsKill = MI->getOperand(2).isKill();
int FI = MI->getOperand(0).getIndex();
// TmpR = C2_tfrpr SrcR if SrcR is a predicate register
// TmpR = A2_tfrcrr SrcR if SrcR is a modifier register
unsigned TmpR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
unsigned TfrOpc = (Opc == Hexagon::STriw_pred) ? Hexagon::C2_tfrpr
: Hexagon::A2_tfrcrr;
BuildMI(B, It, DL, HII.get(TfrOpc), TmpR)
.addReg(SrcR, getKillRegState(IsKill));
// S2_storeri_io FI, 0, TmpR
BuildMI(B, It, DL, HII.get(Hexagon::S2_storeri_io))
.addFrameIndex(FI)
.addImm(0)
.addReg(TmpR, RegState::Kill)
.cloneMemRefs(*MI);
NewRegs.push_back(TmpR);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandLoadInt(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<unsigned> &NewRegs) const {
MachineInstr *MI = &*It;
if (!MI->getOperand(1).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
unsigned Opc = MI->getOpcode();
unsigned DstR = MI->getOperand(0).getReg();
int FI = MI->getOperand(1).getIndex();
// TmpR = L2_loadri_io FI, 0
unsigned TmpR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
BuildMI(B, It, DL, HII.get(Hexagon::L2_loadri_io), TmpR)
.addFrameIndex(FI)
.addImm(0)
.cloneMemRefs(*MI);
// DstR = C2_tfrrp TmpR if DstR is a predicate register
// DstR = A2_tfrrcr TmpR if DstR is a modifier register
unsigned TfrOpc = (Opc == Hexagon::LDriw_pred) ? Hexagon::C2_tfrrp
: Hexagon::A2_tfrrcr;
BuildMI(B, It, DL, HII.get(TfrOpc), DstR)
.addReg(TmpR, RegState::Kill);
NewRegs.push_back(TmpR);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandStoreVecPred(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<unsigned> &NewRegs) const {
MachineInstr *MI = &*It;
if (!MI->getOperand(0).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
unsigned SrcR = MI->getOperand(2).getReg();
bool IsKill = MI->getOperand(2).isKill();
int FI = MI->getOperand(0).getIndex();
auto *RC = &Hexagon::HvxVRRegClass;
// Insert transfer to general vector register.
// TmpR0 = A2_tfrsi 0x01010101
// TmpR1 = V6_vandqrt Qx, TmpR0
// store FI, 0, TmpR1
unsigned TmpR0 = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
unsigned TmpR1 = MRI.createVirtualRegister(RC);
BuildMI(B, It, DL, HII.get(Hexagon::A2_tfrsi), TmpR0)
.addImm(0x01010101);
BuildMI(B, It, DL, HII.get(Hexagon::V6_vandqrt), TmpR1)
.addReg(SrcR, getKillRegState(IsKill))
.addReg(TmpR0, RegState::Kill);
auto *HRI = B.getParent()->getSubtarget<HexagonSubtarget>().getRegisterInfo();
HII.storeRegToStackSlot(B, It, TmpR1, true, FI, RC, HRI);
expandStoreVec(B, std::prev(It), MRI, HII, NewRegs);
NewRegs.push_back(TmpR0);
NewRegs.push_back(TmpR1);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandLoadVecPred(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<unsigned> &NewRegs) const {
MachineInstr *MI = &*It;
if (!MI->getOperand(1).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
unsigned DstR = MI->getOperand(0).getReg();
int FI = MI->getOperand(1).getIndex();
auto *RC = &Hexagon::HvxVRRegClass;
// TmpR0 = A2_tfrsi 0x01010101
// TmpR1 = load FI, 0
// DstR = V6_vandvrt TmpR1, TmpR0
unsigned TmpR0 = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
unsigned TmpR1 = MRI.createVirtualRegister(RC);
BuildMI(B, It, DL, HII.get(Hexagon::A2_tfrsi), TmpR0)
.addImm(0x01010101);
MachineFunction &MF = *B.getParent();
auto *HRI = MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
HII.loadRegFromStackSlot(B, It, TmpR1, FI, RC, HRI);
expandLoadVec(B, std::prev(It), MRI, HII, NewRegs);
BuildMI(B, It, DL, HII.get(Hexagon::V6_vandvrt), DstR)
.addReg(TmpR1, RegState::Kill)
.addReg(TmpR0, RegState::Kill);
NewRegs.push_back(TmpR0);
NewRegs.push_back(TmpR1);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandStoreVec2(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<unsigned> &NewRegs) const {
MachineFunction &MF = *B.getParent();
auto &MFI = MF.getFrameInfo();
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MachineInstr *MI = &*It;
if (!MI->getOperand(0).isFI())
return false;
// It is possible that the double vector being stored is only partially
// defined. From the point of view of the liveness tracking, it is ok to
// store it as a whole, but if we break it up we may end up storing a
// register that is entirely undefined.
LivePhysRegs LPR(HRI);
LPR.addLiveIns(B);
SmallVector<std::pair<unsigned, const MachineOperand*>,2> Clobbers;
for (auto R = B.begin(); R != It; ++R) {
Clobbers.clear();
LPR.stepForward(*R, Clobbers);
}
DebugLoc DL = MI->getDebugLoc();
unsigned SrcR = MI->getOperand(2).getReg();
unsigned SrcLo = HRI.getSubReg(SrcR, Hexagon::vsub_lo);
unsigned SrcHi = HRI.getSubReg(SrcR, Hexagon::vsub_hi);
bool IsKill = MI->getOperand(2).isKill();
int FI = MI->getOperand(0).getIndex();
unsigned Size = HRI.getSpillSize(Hexagon::HvxVRRegClass);
unsigned NeedAlign = HRI.getSpillAlignment(Hexagon::HvxVRRegClass);
unsigned HasAlign = MFI.getObjectAlignment(FI);
unsigned StoreOpc;
// Store low part.
if (LPR.contains(SrcLo)) {
StoreOpc = NeedAlign <= HasAlign ? Hexagon::V6_vS32b_ai
: Hexagon::V6_vS32Ub_ai;
BuildMI(B, It, DL, HII.get(StoreOpc))
.addFrameIndex(FI)
.addImm(0)
.addReg(SrcLo, getKillRegState(IsKill))
.cloneMemRefs(*MI);
}
// Store high part.
if (LPR.contains(SrcHi)) {
StoreOpc = NeedAlign <= MinAlign(HasAlign, Size) ? Hexagon::V6_vS32b_ai
: Hexagon::V6_vS32Ub_ai;
BuildMI(B, It, DL, HII.get(StoreOpc))
.addFrameIndex(FI)
.addImm(Size)
.addReg(SrcHi, getKillRegState(IsKill))
.cloneMemRefs(*MI);
}
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandLoadVec2(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<unsigned> &NewRegs) const {
MachineFunction &MF = *B.getParent();
auto &MFI = MF.getFrameInfo();
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MachineInstr *MI = &*It;
if (!MI->getOperand(1).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
unsigned DstR = MI->getOperand(0).getReg();
unsigned DstHi = HRI.getSubReg(DstR, Hexagon::vsub_hi);
unsigned DstLo = HRI.getSubReg(DstR, Hexagon::vsub_lo);
int FI = MI->getOperand(1).getIndex();
unsigned Size = HRI.getSpillSize(Hexagon::HvxVRRegClass);
unsigned NeedAlign = HRI.getSpillAlignment(Hexagon::HvxVRRegClass);
unsigned HasAlign = MFI.getObjectAlignment(FI);
unsigned LoadOpc;
// Load low part.
LoadOpc = NeedAlign <= HasAlign ? Hexagon::V6_vL32b_ai
: Hexagon::V6_vL32Ub_ai;
BuildMI(B, It, DL, HII.get(LoadOpc), DstLo)
.addFrameIndex(FI)
.addImm(0)
.cloneMemRefs(*MI);
// Load high part.
LoadOpc = NeedAlign <= MinAlign(HasAlign, Size) ? Hexagon::V6_vL32b_ai
: Hexagon::V6_vL32Ub_ai;
BuildMI(B, It, DL, HII.get(LoadOpc), DstHi)
.addFrameIndex(FI)
.addImm(Size)
.cloneMemRefs(*MI);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandStoreVec(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<unsigned> &NewRegs) const {
MachineFunction &MF = *B.getParent();
auto &MFI = MF.getFrameInfo();
MachineInstr *MI = &*It;
if (!MI->getOperand(0).isFI())
return false;
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
DebugLoc DL = MI->getDebugLoc();
unsigned SrcR = MI->getOperand(2).getReg();
bool IsKill = MI->getOperand(2).isKill();
int FI = MI->getOperand(0).getIndex();
unsigned NeedAlign = HRI.getSpillAlignment(Hexagon::HvxVRRegClass);
unsigned HasAlign = MFI.getObjectAlignment(FI);
unsigned StoreOpc = NeedAlign <= HasAlign ? Hexagon::V6_vS32b_ai
: Hexagon::V6_vS32Ub_ai;
BuildMI(B, It, DL, HII.get(StoreOpc))
.addFrameIndex(FI)
.addImm(0)
.addReg(SrcR, getKillRegState(IsKill))
.cloneMemRefs(*MI);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandLoadVec(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<unsigned> &NewRegs) const {
MachineFunction &MF = *B.getParent();
auto &MFI = MF.getFrameInfo();
MachineInstr *MI = &*It;
if (!MI->getOperand(1).isFI())
return false;
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
DebugLoc DL = MI->getDebugLoc();
unsigned DstR = MI->getOperand(0).getReg();
int FI = MI->getOperand(1).getIndex();
unsigned NeedAlign = HRI.getSpillAlignment(Hexagon::HvxVRRegClass);
unsigned HasAlign = MFI.getObjectAlignment(FI);
unsigned LoadOpc = NeedAlign <= HasAlign ? Hexagon::V6_vL32b_ai
: Hexagon::V6_vL32Ub_ai;
BuildMI(B, It, DL, HII.get(LoadOpc), DstR)
.addFrameIndex(FI)
.addImm(0)
.cloneMemRefs(*MI);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandSpillMacros(MachineFunction &MF,
SmallVectorImpl<unsigned> &NewRegs) const {
auto &HII = *MF.getSubtarget<HexagonSubtarget>().getInstrInfo();
MachineRegisterInfo &MRI = MF.getRegInfo();
bool Changed = false;
for (auto &B : MF) {
// Traverse the basic block.
MachineBasicBlock::iterator NextI;
for (auto I = B.begin(), E = B.end(); I != E; I = NextI) {
MachineInstr *MI = &*I;
NextI = std::next(I);
unsigned Opc = MI->getOpcode();
switch (Opc) {
case TargetOpcode::COPY:
Changed |= expandCopy(B, I, MRI, HII, NewRegs);
break;
case Hexagon::STriw_pred:
case Hexagon::STriw_ctr:
Changed |= expandStoreInt(B, I, MRI, HII, NewRegs);
break;
case Hexagon::LDriw_pred:
case Hexagon::LDriw_ctr:
Changed |= expandLoadInt(B, I, MRI, HII, NewRegs);
break;
case Hexagon::PS_vstorerq_ai:
Changed |= expandStoreVecPred(B, I, MRI, HII, NewRegs);
break;
case Hexagon::PS_vloadrq_ai:
Changed |= expandLoadVecPred(B, I, MRI, HII, NewRegs);
break;
case Hexagon::PS_vloadrw_ai:
case Hexagon::PS_vloadrwu_ai:
Changed |= expandLoadVec2(B, I, MRI, HII, NewRegs);
break;
case Hexagon::PS_vstorerw_ai:
case Hexagon::PS_vstorerwu_ai:
Changed |= expandStoreVec2(B, I, MRI, HII, NewRegs);
break;
}
}
}
return Changed;
}
void HexagonFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
SavedRegs.resize(HRI.getNumRegs());
// If we have a function containing __builtin_eh_return we want to spill and
// restore all callee saved registers. Pretend that they are used.
if (MF.getInfo<HexagonMachineFunctionInfo>()->hasEHReturn())
for (const MCPhysReg *R = HRI.getCalleeSavedRegs(&MF); *R; ++R)
SavedRegs.set(*R);
// Replace predicate register pseudo spill code.
SmallVector<unsigned,8> NewRegs;
expandSpillMacros(MF, NewRegs);
if (OptimizeSpillSlots && !isOptNone(MF))
optimizeSpillSlots(MF, NewRegs);
// We need to reserve a spill slot if scavenging could potentially require
// spilling a scavenged register.
if (!NewRegs.empty() || mayOverflowFrameOffset(MF)) {
MachineFrameInfo &MFI = MF.getFrameInfo();
MachineRegisterInfo &MRI = MF.getRegInfo();
SetVector<const TargetRegisterClass*> SpillRCs;
// Reserve an int register in any case, because it could be used to hold
// the stack offset in case it does not fit into a spill instruction.
SpillRCs.insert(&Hexagon::IntRegsRegClass);
for (unsigned VR : NewRegs)
SpillRCs.insert(MRI.getRegClass(VR));
for (auto *RC : SpillRCs) {
if (!needToReserveScavengingSpillSlots(MF, HRI, RC))
continue;
unsigned Num = RC == &Hexagon::IntRegsRegClass ? NumberScavengerSlots : 1;
unsigned S = HRI.getSpillSize(*RC), A = HRI.getSpillAlignment(*RC);
for (unsigned i = 0; i < Num; i++) {
int NewFI = MFI.CreateSpillStackObject(S, A);
RS->addScavengingFrameIndex(NewFI);
}
}
}
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
}
unsigned HexagonFrameLowering::findPhysReg(MachineFunction &MF,
HexagonBlockRanges::IndexRange &FIR,
HexagonBlockRanges::InstrIndexMap &IndexMap,
HexagonBlockRanges::RegToRangeMap &DeadMap,
const TargetRegisterClass *RC) const {
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
auto &MRI = MF.getRegInfo();
auto isDead = [&FIR,&DeadMap] (unsigned Reg) -> bool {
auto F = DeadMap.find({Reg,0});
if (F == DeadMap.end())
return false;
for (auto &DR : F->second)
if (DR.contains(FIR))
return true;
return false;
};
for (unsigned Reg : RC->getRawAllocationOrder(MF)) {
bool Dead = true;
for (auto R : HexagonBlockRanges::expandToSubRegs({Reg,0}, MRI, HRI)) {
if (isDead(R.Reg))
continue;
Dead = false;
break;
}
if (Dead)
return Reg;
}
return 0;
}
void HexagonFrameLowering::optimizeSpillSlots(MachineFunction &MF,
SmallVectorImpl<unsigned> &VRegs) const {
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
auto &MRI = MF.getRegInfo();
HexagonBlockRanges HBR(MF);
using BlockIndexMap =
std::map<MachineBasicBlock *, HexagonBlockRanges::InstrIndexMap>;
using BlockRangeMap =
std::map<MachineBasicBlock *, HexagonBlockRanges::RangeList>;
using IndexType = HexagonBlockRanges::IndexType;
struct SlotInfo {
BlockRangeMap Map;
unsigned Size = 0;
const TargetRegisterClass *RC = nullptr;
SlotInfo() = default;
};
BlockIndexMap BlockIndexes;
SmallSet<int,4> BadFIs;
std::map<int,SlotInfo> FIRangeMap;
// Accumulate register classes: get a common class for a pre-existing
// class HaveRC and a new class NewRC. Return nullptr if a common class
// cannot be found, otherwise return the resulting class. If HaveRC is
// nullptr, assume that it is still unset.
auto getCommonRC =
[](const TargetRegisterClass *HaveRC,
const TargetRegisterClass *NewRC) -> const TargetRegisterClass * {
if (HaveRC == nullptr || HaveRC == NewRC)
return NewRC;
// Different classes, both non-null. Pick the more general one.
if (HaveRC->hasSubClassEq(NewRC))
return HaveRC;
if (NewRC->hasSubClassEq(HaveRC))
return NewRC;
return nullptr;
};
// Scan all blocks in the function. Check all occurrences of frame indexes,
// and collect relevant information.
for (auto &B : MF) {
std::map<int,IndexType> LastStore, LastLoad;
// Emplace appears not to be supported in gcc 4.7.2-4.
//auto P = BlockIndexes.emplace(&B, HexagonBlockRanges::InstrIndexMap(B));
auto P = BlockIndexes.insert(
std::make_pair(&B, HexagonBlockRanges::InstrIndexMap(B)));
auto &IndexMap = P.first->second;
LLVM_DEBUG(dbgs() << "Index map for " << printMBBReference(B) << "\n"
<< IndexMap << '\n');
for (auto &In : B) {
int LFI, SFI;
bool Load = HII.isLoadFromStackSlot(In, LFI) && !HII.isPredicated(In);
bool Store = HII.isStoreToStackSlot(In, SFI) && !HII.isPredicated(In);
if (Load && Store) {
// If it's both a load and a store, then we won't handle it.
BadFIs.insert(LFI);
BadFIs.insert(SFI);
continue;
}
// Check for register classes of the register used as the source for
// the store, and the register used as the destination for the load.
// Also, only accept base+imm_offset addressing modes. Other addressing
// modes can have side-effects (post-increments, etc.). For stack
// slots they are very unlikely, so there is not much loss due to
// this restriction.
if (Load || Store) {
int TFI = Load ? LFI : SFI;
unsigned AM = HII.getAddrMode(In);
SlotInfo &SI = FIRangeMap[TFI];
bool Bad = (AM != HexagonII::BaseImmOffset);
if (!Bad) {
// If the addressing mode is ok, check the register class.
unsigned OpNum = Load ? 0 : 2;
auto *RC = HII.getRegClass(In.getDesc(), OpNum, &HRI, MF);
RC = getCommonRC(SI.RC, RC);
if (RC == nullptr)
Bad = true;
else
SI.RC = RC;
}
if (!Bad) {
// Check sizes.
unsigned S = HII.getMemAccessSize(In);
if (SI.Size != 0 && SI.Size != S)
Bad = true;
else
SI.Size = S;
}
if (!Bad) {
for (auto *Mo : In.memoperands()) {
if (!Mo->isVolatile())
continue;
Bad = true;
break;
}
}
if (Bad)
BadFIs.insert(TFI);
}
// Locate uses of frame indices.
for (unsigned i = 0, n = In.getNumOperands(); i < n; ++i) {
const MachineOperand &Op = In.getOperand(i);
if (!Op.isFI())
continue;
int FI = Op.getIndex();
// Make sure that the following operand is an immediate and that
// it is 0. This is the offset in the stack object.
if (i+1 >= n || !In.getOperand(i+1).isImm() ||
In.getOperand(i+1).getImm() != 0)
BadFIs.insert(FI);
if (BadFIs.count(FI))
continue;
IndexType Index = IndexMap.getIndex(&In);
if (Load) {
if (LastStore[FI] == IndexType::None)
LastStore[FI] = IndexType::Entry;
LastLoad[FI] = Index;
} else if (Store) {
HexagonBlockRanges::RangeList &RL = FIRangeMap[FI].Map[&B];
if (LastStore[FI] != IndexType::None)
RL.add(LastStore[FI], LastLoad[FI], false, false);
else if (LastLoad[FI] != IndexType::None)
RL.add(IndexType::Entry, LastLoad[FI], false, false);
LastLoad[FI] = IndexType::None;
LastStore[FI] = Index;
} else {
BadFIs.insert(FI);
}
}
}
for (auto &I : LastLoad) {
IndexType LL = I.second;
if (LL == IndexType::None)
continue;
auto &RL = FIRangeMap[I.first].Map[&B];
IndexType &LS = LastStore[I.first];
if (LS != IndexType::None)
RL.add(LS, LL, false, false);
else
RL.add(IndexType::Entry, LL, false, false);
LS = IndexType::None;
}
for (auto &I : LastStore) {
IndexType LS = I.second;
if (LS == IndexType::None)
continue;
auto &RL = FIRangeMap[I.first].Map[&B];
RL.add(LS, IndexType::None, false, false);
}
}
LLVM_DEBUG({
for (auto &P : FIRangeMap) {
dbgs() << "fi#" << P.first;
if (BadFIs.count(P.first))
dbgs() << " (bad)";
dbgs() << " RC: ";
if (P.second.RC != nullptr)
dbgs() << HRI.getRegClassName(P.second.RC) << '\n';
else
dbgs() << "<null>\n";
for (auto &R : P.second.Map)
dbgs() << " " << printMBBReference(*R.first) << " { " << R.second
<< "}\n";
}
});
// When a slot is loaded from in a block without being stored to in the
// same block, it is live-on-entry to this block. To avoid CFG analysis,
// consider this slot to be live-on-exit from all blocks.
SmallSet<int,4> LoxFIs;
std::map<MachineBasicBlock*,std::vector<int>> BlockFIMap;
for (auto &P : FIRangeMap) {
// P = pair(FI, map: BB->RangeList)
if (BadFIs.count(P.first))
continue;
for (auto &B : MF) {
auto F = P.second.Map.find(&B);
// F = pair(BB, RangeList)
if (F == P.second.Map.end() || F->second.empty())
continue;
HexagonBlockRanges::IndexRange &IR = F->second.front();
if (IR.start() == IndexType::Entry)
LoxFIs.insert(P.first);
BlockFIMap[&B].push_back(P.first);
}
}
LLVM_DEBUG({
dbgs() << "Block-to-FI map (* -- live-on-exit):\n";
for (auto &P : BlockFIMap) {
auto &FIs = P.second;
if (FIs.empty())
continue;
dbgs() << " " << printMBBReference(*P.first) << ": {";
for (auto I : FIs) {
dbgs() << " fi#" << I;
if (LoxFIs.count(I))
dbgs() << '*';
}
dbgs() << " }\n";
}
});
#ifndef NDEBUG
bool HasOptLimit = SpillOptMax.getPosition();
#endif
// eliminate loads, when all loads eliminated, eliminate all stores.
for (auto &B : MF) {
auto F = BlockIndexes.find(&B);
assert(F != BlockIndexes.end());
HexagonBlockRanges::InstrIndexMap &IM = F->second;
HexagonBlockRanges::RegToRangeMap LM = HBR.computeLiveMap(IM);
HexagonBlockRanges::RegToRangeMap DM = HBR.computeDeadMap(IM, LM);
LLVM_DEBUG(dbgs() << printMBBReference(B) << " dead map\n"
<< HexagonBlockRanges::PrintRangeMap(DM, HRI));
for (auto FI : BlockFIMap[&B]) {
if (BadFIs.count(FI))
continue;
LLVM_DEBUG(dbgs() << "Working on fi#" << FI << '\n');
HexagonBlockRanges::RangeList &RL = FIRangeMap[FI].Map[&B];
for (auto &Range : RL) {
LLVM_DEBUG(dbgs() << "--Examining range:" << RL << '\n');
if (!IndexType::isInstr(Range.start()) ||
!IndexType::isInstr(Range.end()))
continue;
MachineInstr &SI = *IM.getInstr(Range.start());
MachineInstr &EI = *IM.getInstr(Range.end());
assert(SI.mayStore() && "Unexpected start instruction");
assert(EI.mayLoad() && "Unexpected end instruction");
MachineOperand &SrcOp = SI.getOperand(2);
HexagonBlockRanges::RegisterRef SrcRR = { SrcOp.getReg(),
SrcOp.getSubReg() };
auto *RC = HII.getRegClass(SI.getDesc(), 2, &HRI, MF);
// The this-> is needed to unconfuse MSVC.
unsigned FoundR = this->findPhysReg(MF, Range, IM, DM, RC);
LLVM_DEBUG(dbgs() << "Replacement reg:" << printReg(FoundR, &HRI)
<< '\n');
if (FoundR == 0)
continue;
#ifndef NDEBUG
if (HasOptLimit) {
if (SpillOptCount >= SpillOptMax)
return;
SpillOptCount++;
}
#endif
// Generate the copy-in: "FoundR = COPY SrcR" at the store location.
MachineBasicBlock::iterator StartIt = SI.getIterator(), NextIt;
MachineInstr *CopyIn = nullptr;
if (SrcRR.Reg != FoundR || SrcRR.Sub != 0) {
const DebugLoc &DL = SI.getDebugLoc();
CopyIn = BuildMI(B, StartIt, DL, HII.get(TargetOpcode::COPY), FoundR)
.add(SrcOp);
}
++StartIt;
// Check if this is a last store and the FI is live-on-exit.
if (LoxFIs.count(FI) && (&Range == &RL.back())) {
// Update store's source register.
if (unsigned SR = SrcOp.getSubReg())
SrcOp.setReg(HRI.getSubReg(FoundR, SR));
else
SrcOp.setReg(FoundR);
SrcOp.setSubReg(0);
// We are keeping this register live.
SrcOp.setIsKill(false);
} else {
B.erase(&SI);
IM.replaceInstr(&SI, CopyIn);
}
auto EndIt = std::next(EI.getIterator());
for (auto It = StartIt; It != EndIt; It = NextIt) {
MachineInstr &MI = *It;
NextIt = std::next(It);
int TFI;
if (!HII.isLoadFromStackSlot(MI, TFI) || TFI != FI)
continue;
unsigned DstR = MI.getOperand(0).getReg();
assert(MI.getOperand(0).getSubReg() == 0);
MachineInstr *CopyOut = nullptr;
if (DstR != FoundR) {
DebugLoc DL = MI.getDebugLoc();
unsigned MemSize = HII.getMemAccessSize(MI);
assert(HII.getAddrMode(MI) == HexagonII::BaseImmOffset);
unsigned CopyOpc = TargetOpcode::COPY;
if (HII.isSignExtendingLoad(MI))
CopyOpc = (MemSize == 1) ? Hexagon::A2_sxtb : Hexagon::A2_sxth;
else if (HII.isZeroExtendingLoad(MI))
CopyOpc = (MemSize == 1) ? Hexagon::A2_zxtb : Hexagon::A2_zxth;
CopyOut = BuildMI(B, It, DL, HII.get(CopyOpc), DstR)
.addReg(FoundR, getKillRegState(&MI == &EI));
}
IM.replaceInstr(&MI, CopyOut);
B.erase(It);
}
// Update the dead map.
HexagonBlockRanges::RegisterRef FoundRR = { FoundR, 0 };
for (auto RR : HexagonBlockRanges::expandToSubRegs(FoundRR, MRI, HRI))
DM[RR].subtract(Range);
} // for Range in range list
}
}
}
void HexagonFrameLowering::expandAlloca(MachineInstr *AI,
const HexagonInstrInfo &HII, unsigned SP, unsigned CF) const {
MachineBasicBlock &MB = *AI->getParent();
DebugLoc DL = AI->getDebugLoc();
unsigned A = AI->getOperand(2).getImm();
// Have
// Rd = alloca Rs, #A
//
// If Rs and Rd are different registers, use this sequence:
// Rd = sub(r29, Rs)
// r29 = sub(r29, Rs)
// Rd = and(Rd, #-A) ; if necessary
// r29 = and(r29, #-A) ; if necessary
// Rd = add(Rd, #CF) ; CF size aligned to at most A
// otherwise, do
// Rd = sub(r29, Rs)
// Rd = and(Rd, #-A) ; if necessary
// r29 = Rd
// Rd = add(Rd, #CF) ; CF size aligned to at most A
MachineOperand &RdOp = AI->getOperand(0);
MachineOperand &RsOp = AI->getOperand(1);
unsigned Rd = RdOp.getReg(), Rs = RsOp.getReg();
// Rd = sub(r29, Rs)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_sub), Rd)
.addReg(SP)
.addReg(Rs);
if (Rs != Rd) {
// r29 = sub(r29, Rs)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_sub), SP)
.addReg(SP)
.addReg(Rs);
}
if (A > 8) {
// Rd = and(Rd, #-A)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_andir), Rd)
.addReg(Rd)
.addImm(-int64_t(A));
if (Rs != Rd)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_andir), SP)
.addReg(SP)
.addImm(-int64_t(A));
}
if (Rs == Rd) {
// r29 = Rd
BuildMI(MB, AI, DL, HII.get(TargetOpcode::COPY), SP)
.addReg(Rd);
}
if (CF > 0) {
// Rd = add(Rd, #CF)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_addi), Rd)
.addReg(Rd)
.addImm(CF);
}
}
bool HexagonFrameLowering::needsAligna(const MachineFunction &MF) const {
const MachineFrameInfo &MFI = MF.getFrameInfo();
if (!MFI.hasVarSizedObjects())
return false;
unsigned MaxA = MFI.getMaxAlignment();
if (MaxA <= getStackAlignment())
return false;
return true;
}
const MachineInstr *HexagonFrameLowering::getAlignaInstr(
const MachineFunction &MF) const {
for (auto &B : MF)
for (auto &I : B)
if (I.getOpcode() == Hexagon::PS_aligna)
return &I;
return nullptr;
}
/// Adds all callee-saved registers as implicit uses or defs to the
/// instruction.
void HexagonFrameLowering::addCalleeSaveRegistersAsImpOperand(MachineInstr *MI,
const CSIVect &CSI, bool IsDef, bool IsKill) const {
// Add the callee-saved registers as implicit uses.
for (auto &R : CSI)
MI->addOperand(MachineOperand::CreateReg(R.getReg(), IsDef, true, IsKill));
}
/// Determine whether the callee-saved register saves and restores should
/// be generated via inline code. If this function returns "true", inline
/// code will be generated. If this function returns "false", additional
/// checks are performed, which may still lead to the inline code.
bool HexagonFrameLowering::shouldInlineCSR(const MachineFunction &MF,
const CSIVect &CSI) const {
if (MF.getInfo<HexagonMachineFunctionInfo>()->hasEHReturn())
return true;
if (!hasFP(MF))
return true;
if (!isOptSize(MF) && !isMinSize(MF))
if (MF.getTarget().getOptLevel() > CodeGenOpt::Default)
return true;
// Check if CSI only has double registers, and if the registers form
// a contiguous block starting from D8.
BitVector Regs(Hexagon::NUM_TARGET_REGS);
for (unsigned i = 0, n = CSI.size(); i < n; ++i) {
unsigned R = CSI[i].getReg();
if (!Hexagon::DoubleRegsRegClass.contains(R))
return true;
Regs[R] = true;
}
int F = Regs.find_first();
if (F != Hexagon::D8)
return true;
while (F >= 0) {
int N = Regs.find_next(F);
if (N >= 0 && N != F+1)
return true;
F = N;
}
return false;
}
bool HexagonFrameLowering::useSpillFunction(const MachineFunction &MF,
const CSIVect &CSI) const {
if (shouldInlineCSR(MF, CSI))
return false;
unsigned NumCSI = CSI.size();
if (NumCSI <= 1)
return false;
unsigned Threshold = isOptSize(MF) ? SpillFuncThresholdOs
: SpillFuncThreshold;
return Threshold < NumCSI;
}
bool HexagonFrameLowering::useRestoreFunction(const MachineFunction &MF,
const CSIVect &CSI) const {
if (shouldInlineCSR(MF, CSI))
return false;
// The restore functions do a bit more than just restoring registers.
// The non-returning versions will go back directly to the caller's
// caller, others will clean up the stack frame in preparation for
// a tail call. Using them can still save code size even if only one
// register is getting restores. Make the decision based on -Oz:
// using -Os will use inline restore for a single register.
if (isMinSize(MF))
return true;
unsigned NumCSI = CSI.size();
if (NumCSI <= 1)
return false;
unsigned Threshold = isOptSize(MF) ? SpillFuncThresholdOs-1
: SpillFuncThreshold;
return Threshold < NumCSI;
}
bool HexagonFrameLowering::mayOverflowFrameOffset(MachineFunction &MF) const {
unsigned StackSize = MF.getFrameInfo().estimateStackSize(MF);
auto &HST = MF.getSubtarget<HexagonSubtarget>();
// A fairly simplistic guess as to whether a potential load/store to a
// stack location could require an extra register.
if (HST.useHVXOps() && StackSize > 256)
return true;
// Check if the function has store-immediate instructions that access
// the stack. Since the offset field is not extendable, if the stack
// size exceeds the offset limit (6 bits, shifted), the stores will
// require a new base register.
bool HasImmStack = false;
unsigned MinLS = ~0u; // Log_2 of the memory access size.
for (const MachineBasicBlock &B : MF) {
for (const MachineInstr &MI : B) {
unsigned LS = 0;
switch (MI.getOpcode()) {
case Hexagon::S4_storeirit_io:
case Hexagon::S4_storeirif_io:
case Hexagon::S4_storeiri_io:
++LS;
LLVM_FALLTHROUGH;
case Hexagon::S4_storeirht_io:
case Hexagon::S4_storeirhf_io:
case Hexagon::S4_storeirh_io:
++LS;
LLVM_FALLTHROUGH;
case Hexagon::S4_storeirbt_io:
case Hexagon::S4_storeirbf_io:
case Hexagon::S4_storeirb_io:
if (MI.getOperand(0).isFI())
HasImmStack = true;
MinLS = std::min(MinLS, LS);
break;
}
}
}
if (HasImmStack)
return !isUInt<6>(StackSize >> MinLS);
return false;
}
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