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llvm-project/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp

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//===-- FunctionLoweringInfo.cpp ------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This implements routines for translating functions from LLVM IR into
// Machine IR.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "function-lowering-info"
#include "llvm/CodeGen/FunctionLoweringInfo.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include <algorithm>
using namespace llvm;
/// isUsedOutsideOfDefiningBlock - Return true if this instruction is used by
/// PHI nodes or outside of the basic block that defines it, or used by a
/// switch or atomic instruction, which may expand to multiple basic blocks.
static bool isUsedOutsideOfDefiningBlock(const Instruction *I) {
if (I->use_empty()) return false;
if (isa<PHINode>(I)) return true;
const BasicBlock *BB = I->getParent();
for (const User *U : I->users())
if (cast<Instruction>(U)->getParent() != BB || isa<PHINode>(U))
return true;
return false;
}
void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
SelectionDAG *DAG) {
const TargetLowering *TLI = TM.getTargetLowering();
Fn = &fn;
MF = &mf;
RegInfo = &MF->getRegInfo();
// Check whether the function can return without sret-demotion.
SmallVector<ISD::OutputArg, 4> Outs;
GetReturnInfo(Fn->getReturnType(), Fn->getAttributes(), Outs, *TLI);
CanLowerReturn = TLI->CanLowerReturn(Fn->getCallingConv(), *MF,
Fn->isVarArg(),
Outs, Fn->getContext());
// Initialize the mapping of values to registers. This is only set up for
// instruction values that are used outside of the block that defines
// them.
Function::const_iterator BB = Fn->begin(), EB = Fn->end();
for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
if (const AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
// Don't fold inalloca allocas or other dynamic allocas into the initial
// stack frame allocation, even if they are in the entry block.
if (!AI->isStaticAlloca())
continue;
if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
Type *Ty = AI->getAllocatedType();
uint64_t TySize = TLI->getDataLayout()->getTypeAllocSize(Ty);
unsigned Align =
std::max((unsigned)TLI->getDataLayout()->getPrefTypeAlignment(Ty),
AI->getAlignment());
TySize *= CUI->getZExtValue(); // Get total allocated size.
if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
StaticAllocaMap[AI] =
MF->getFrameInfo()->CreateStackObject(TySize, Align, false, AI);
}
}
for (; BB != EB; ++BB)
for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
I != E; ++I) {
// Look for dynamic allocas.
if (const AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
if (!AI->isStaticAlloca()) {
unsigned Align = std::max(
(unsigned)TLI->getDataLayout()->getPrefTypeAlignment(
AI->getAllocatedType()),
AI->getAlignment());
unsigned StackAlign = TM.getFrameLowering()->getStackAlignment();
if (Align <= StackAlign)
Align = 0;
// Inform the Frame Information that we have variable-sized objects.
MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1, AI);
}
}
// Look for inline asm that clobbers the SP register.
if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
ImmutableCallSite CS(I);
if (isa<InlineAsm>(CS.getCalledValue())) {
unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
std::vector<TargetLowering::AsmOperandInfo> Ops =
TLI->ParseConstraints(CS);
for (size_t I = 0, E = Ops.size(); I != E; ++I) {
TargetLowering::AsmOperandInfo &Op = Ops[I];
if (Op.Type == InlineAsm::isClobber) {
// Clobbers don't have SDValue operands, hence SDValue().
TLI->ComputeConstraintToUse(Op, SDValue(), DAG);
std::pair<unsigned, const TargetRegisterClass*> PhysReg =
TLI->getRegForInlineAsmConstraint(Op.ConstraintCode,
Op.ConstraintVT);
if (PhysReg.first == SP)
MF->getFrameInfo()->setHasInlineAsmWithSPAdjust(true);
}
}
}
}
// Mark values used outside their block as exported, by allocating
// a virtual register for them.
if (isUsedOutsideOfDefiningBlock(I))
if (!isa<AllocaInst>(I) ||
!StaticAllocaMap.count(cast<AllocaInst>(I)))
InitializeRegForValue(I);
// Collect llvm.dbg.declare information. This is done now instead of
// during the initial isel pass through the IR so that it is done
// in a predictable order.
if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
MachineModuleInfo &MMI = MF->getMMI();
DIVariable DIVar(DI->getVariable());
assert((!DIVar || DIVar.isVariable()) &&
"Variable in DbgDeclareInst should be either null or a DIVariable.");
if (MMI.hasDebugInfo() &&
DIVar &&
!DI->getDebugLoc().isUnknown()) {
// Don't handle byval struct arguments or VLAs, for example.
// Non-byval arguments are handled here (they refer to the stack
// temporary alloca at this point).
const Value *Address = DI->getAddress();
if (Address) {
if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
Address = BCI->getOperand(0);
if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
DenseMap<const AllocaInst *, int>::iterator SI =
StaticAllocaMap.find(AI);
if (SI != StaticAllocaMap.end()) { // Check for VLAs.
int FI = SI->second;
MMI.setVariableDbgInfo(DI->getVariable(),
FI, DI->getDebugLoc());
}
}
}
}
}
}
// Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
// also creates the initial PHI MachineInstrs, though none of the input
// operands are populated.
for (BB = Fn->begin(); BB != EB; ++BB) {
MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
MBBMap[BB] = MBB;
MF->push_back(MBB);
// Transfer the address-taken flag. This is necessary because there could
// be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
// the first one should be marked.
if (BB->hasAddressTaken())
MBB->setHasAddressTaken();
// Create Machine PHI nodes for LLVM PHI nodes, lowering them as
// appropriate.
for (BasicBlock::const_iterator I = BB->begin();
const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
if (PN->use_empty()) continue;
// Skip empty types
if (PN->getType()->isEmptyTy())
continue;
DebugLoc DL = PN->getDebugLoc();
unsigned PHIReg = ValueMap[PN];
assert(PHIReg && "PHI node does not have an assigned virtual register!");
SmallVector<EVT, 4> ValueVTs;
ComputeValueVTs(*TLI, PN->getType(), ValueVTs);
for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
EVT VT = ValueVTs[vti];
unsigned NumRegisters = TLI->getNumRegisters(Fn->getContext(), VT);
const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
for (unsigned i = 0; i != NumRegisters; ++i)
BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
PHIReg += NumRegisters;
}
}
}
// Mark landing pad blocks.
for (BB = Fn->begin(); BB != EB; ++BB)
if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
}
/// clear - Clear out all the function-specific state. This returns this
/// FunctionLoweringInfo to an empty state, ready to be used for a
/// different function.
void FunctionLoweringInfo::clear() {
assert(CatchInfoFound.size() == CatchInfoLost.size() &&
"Not all catch info was assigned to a landing pad!");
MBBMap.clear();
ValueMap.clear();
StaticAllocaMap.clear();
#ifndef NDEBUG
CatchInfoLost.clear();
CatchInfoFound.clear();
#endif
LiveOutRegInfo.clear();
VisitedBBs.clear();
ArgDbgValues.clear();
ByValArgFrameIndexMap.clear();
RegFixups.clear();
}
/// CreateReg - Allocate a single virtual register for the given type.
unsigned FunctionLoweringInfo::CreateReg(MVT VT) {
return RegInfo->
createVirtualRegister(TM.getTargetLowering()->getRegClassFor(VT));
}
/// CreateRegs - Allocate the appropriate number of virtual registers of
/// the correctly promoted or expanded types. Assign these registers
/// consecutive vreg numbers and return the first assigned number.
///
/// In the case that the given value has struct or array type, this function
/// will assign registers for each member or element.
///
unsigned FunctionLoweringInfo::CreateRegs(Type *Ty) {
const TargetLowering *TLI = TM.getTargetLowering();
SmallVector<EVT, 4> ValueVTs;
ComputeValueVTs(*TLI, Ty, ValueVTs);
unsigned FirstReg = 0;
for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
EVT ValueVT = ValueVTs[Value];
MVT RegisterVT = TLI->getRegisterType(Ty->getContext(), ValueVT);
unsigned NumRegs = TLI->getNumRegisters(Ty->getContext(), ValueVT);
for (unsigned i = 0; i != NumRegs; ++i) {
unsigned R = CreateReg(RegisterVT);
if (!FirstReg) FirstReg = R;
}
}
return FirstReg;
}
/// GetLiveOutRegInfo - Gets LiveOutInfo for a register, returning NULL if the
/// register is a PHI destination and the PHI's LiveOutInfo is not valid. If
/// the register's LiveOutInfo is for a smaller bit width, it is extended to
/// the larger bit width by zero extension. The bit width must be no smaller
/// than the LiveOutInfo's existing bit width.
const FunctionLoweringInfo::LiveOutInfo *
FunctionLoweringInfo::GetLiveOutRegInfo(unsigned Reg, unsigned BitWidth) {
if (!LiveOutRegInfo.inBounds(Reg))
return NULL;
LiveOutInfo *LOI = &LiveOutRegInfo[Reg];
if (!LOI->IsValid)
return NULL;
if (BitWidth > LOI->KnownZero.getBitWidth()) {
LOI->NumSignBits = 1;
LOI->KnownZero = LOI->KnownZero.zextOrTrunc(BitWidth);
LOI->KnownOne = LOI->KnownOne.zextOrTrunc(BitWidth);
}
return LOI;
}
/// ComputePHILiveOutRegInfo - Compute LiveOutInfo for a PHI's destination
/// register based on the LiveOutInfo of its operands.
void FunctionLoweringInfo::ComputePHILiveOutRegInfo(const PHINode *PN) {
Type *Ty = PN->getType();
if (!Ty->isIntegerTy() || Ty->isVectorTy())
return;
const TargetLowering *TLI = TM.getTargetLowering();
SmallVector<EVT, 1> ValueVTs;
ComputeValueVTs(*TLI, Ty, ValueVTs);
assert(ValueVTs.size() == 1 &&
"PHIs with non-vector integer types should have a single VT.");
EVT IntVT = ValueVTs[0];
if (TLI->getNumRegisters(PN->getContext(), IntVT) != 1)
return;
IntVT = TLI->getTypeToTransformTo(PN->getContext(), IntVT);
unsigned BitWidth = IntVT.getSizeInBits();
unsigned DestReg = ValueMap[PN];
if (!TargetRegisterInfo::isVirtualRegister(DestReg))
return;
LiveOutRegInfo.grow(DestReg);
LiveOutInfo &DestLOI = LiveOutRegInfo[DestReg];
Value *V = PN->getIncomingValue(0);
if (isa<UndefValue>(V) || isa<ConstantExpr>(V)) {
DestLOI.NumSignBits = 1;
APInt Zero(BitWidth, 0);
DestLOI.KnownZero = Zero;
DestLOI.KnownOne = Zero;
return;
}
if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
APInt Val = CI->getValue().zextOrTrunc(BitWidth);
DestLOI.NumSignBits = Val.getNumSignBits();
DestLOI.KnownZero = ~Val;
DestLOI.KnownOne = Val;
} else {
assert(ValueMap.count(V) && "V should have been placed in ValueMap when its"
"CopyToReg node was created.");
unsigned SrcReg = ValueMap[V];
if (!TargetRegisterInfo::isVirtualRegister(SrcReg)) {
DestLOI.IsValid = false;
return;
}
const LiveOutInfo *SrcLOI = GetLiveOutRegInfo(SrcReg, BitWidth);
if (!SrcLOI) {
DestLOI.IsValid = false;
return;
}
DestLOI = *SrcLOI;
}
assert(DestLOI.KnownZero.getBitWidth() == BitWidth &&
DestLOI.KnownOne.getBitWidth() == BitWidth &&
"Masks should have the same bit width as the type.");
for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *V = PN->getIncomingValue(i);
if (isa<UndefValue>(V) || isa<ConstantExpr>(V)) {
DestLOI.NumSignBits = 1;
APInt Zero(BitWidth, 0);
DestLOI.KnownZero = Zero;
DestLOI.KnownOne = Zero;
return;
}
if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
APInt Val = CI->getValue().zextOrTrunc(BitWidth);
DestLOI.NumSignBits = std::min(DestLOI.NumSignBits, Val.getNumSignBits());
DestLOI.KnownZero &= ~Val;
DestLOI.KnownOne &= Val;
continue;
}
assert(ValueMap.count(V) && "V should have been placed in ValueMap when "
"its CopyToReg node was created.");
unsigned SrcReg = ValueMap[V];
if (!TargetRegisterInfo::isVirtualRegister(SrcReg)) {
DestLOI.IsValid = false;
return;
}
const LiveOutInfo *SrcLOI = GetLiveOutRegInfo(SrcReg, BitWidth);
if (!SrcLOI) {
DestLOI.IsValid = false;
return;
}
DestLOI.NumSignBits = std::min(DestLOI.NumSignBits, SrcLOI->NumSignBits);
DestLOI.KnownZero &= SrcLOI->KnownZero;
DestLOI.KnownOne &= SrcLOI->KnownOne;
}
}
/// setArgumentFrameIndex - Record frame index for the byval
/// argument. This overrides previous frame index entry for this argument,
/// if any.
void FunctionLoweringInfo::setArgumentFrameIndex(const Argument *A,
int FI) {
ByValArgFrameIndexMap[A] = FI;
}
/// getArgumentFrameIndex - Get frame index for the byval argument.
/// If the argument does not have any assigned frame index then 0 is
/// returned.
int FunctionLoweringInfo::getArgumentFrameIndex(const Argument *A) {
DenseMap<const Argument *, int>::iterator I =
ByValArgFrameIndexMap.find(A);
if (I != ByValArgFrameIndexMap.end())
return I->second;
DEBUG(dbgs() << "Argument does not have assigned frame index!\n");
return 0;
}
/// ComputeUsesVAFloatArgument - Determine if any floating-point values are
/// being passed to this variadic function, and set the MachineModuleInfo's
/// usesVAFloatArgument flag if so. This flag is used to emit an undefined
/// reference to _fltused on Windows, which will link in MSVCRT's
/// floating-point support.
void llvm::ComputeUsesVAFloatArgument(const CallInst &I,
MachineModuleInfo *MMI)
{
FunctionType *FT = cast<FunctionType>(
I.getCalledValue()->getType()->getContainedType(0));
if (FT->isVarArg() && !MMI->usesVAFloatArgument()) {
for (unsigned i = 0, e = I.getNumArgOperands(); i != e; ++i) {
Type* T = I.getArgOperand(i)->getType();
for (po_iterator<Type*> i = po_begin(T), e = po_end(T);
i != e; ++i) {
if (i->isFloatingPointTy()) {
MMI->setUsesVAFloatArgument(true);
return;
}
}
}
}
}
/// AddCatchInfo - Extract the personality and type infos from an eh.selector
/// call, and add them to the specified machine basic block.
void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
MachineBasicBlock *MBB) {
// Inform the MachineModuleInfo of the personality for this landing pad.
const ConstantExpr *CE = cast<ConstantExpr>(I.getArgOperand(1));
assert(CE->getOpcode() == Instruction::BitCast &&
isa<Function>(CE->getOperand(0)) &&
"Personality should be a function");
MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
// Gather all the type infos for this landing pad and pass them along to
// MachineModuleInfo.
std::vector<const GlobalVariable *> TyInfo;
unsigned N = I.getNumArgOperands();
for (unsigned i = N - 1; i > 1; --i) {
if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getArgOperand(i))) {
unsigned FilterLength = CI->getZExtValue();
unsigned FirstCatch = i + FilterLength + !FilterLength;
assert(FirstCatch <= N && "Invalid filter length");
if (FirstCatch < N) {
TyInfo.reserve(N - FirstCatch);
for (unsigned j = FirstCatch; j < N; ++j)
TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
MMI->addCatchTypeInfo(MBB, TyInfo);
TyInfo.clear();
}
if (!FilterLength) {
// Cleanup.
MMI->addCleanup(MBB);
} else {
// Filter.
TyInfo.reserve(FilterLength - 1);
for (unsigned j = i + 1; j < FirstCatch; ++j)
TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
MMI->addFilterTypeInfo(MBB, TyInfo);
TyInfo.clear();
}
N = i;
}
}
if (N > 2) {
TyInfo.reserve(N - 2);
for (unsigned j = 2; j < N; ++j)
TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
MMI->addCatchTypeInfo(MBB, TyInfo);
}
}
/// AddLandingPadInfo - Extract the exception handling information from the
/// landingpad instruction and add them to the specified machine module info.
void llvm::AddLandingPadInfo(const LandingPadInst &I, MachineModuleInfo &MMI,
MachineBasicBlock *MBB) {
MMI.addPersonality(MBB,
cast<Function>(I.getPersonalityFn()->stripPointerCasts()));
if (I.isCleanup())
MMI.addCleanup(MBB);
// FIXME: New EH - Add the clauses in reverse order. This isn't 100% correct,
// but we need to do it this way because of how the DWARF EH emitter
// processes the clauses.
for (unsigned i = I.getNumClauses(); i != 0; --i) {
Value *Val = I.getClause(i - 1);
if (I.isCatch(i - 1)) {
MMI.addCatchTypeInfo(MBB,
dyn_cast<GlobalVariable>(Val->stripPointerCasts()));
} else {
// Add filters in a list.
Constant *CVal = cast<Constant>(Val);
SmallVector<const GlobalVariable*, 4> FilterList;
for (User::op_iterator
II = CVal->op_begin(), IE = CVal->op_end(); II != IE; ++II)
FilterList.push_back(cast<GlobalVariable>((*II)->stripPointerCasts()));
MMI.addFilterTypeInfo(MBB, FilterList);
}
}
}
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