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/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.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 (Value::const_use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI)
if (cast<Instruction>(*UI)->getParent() != BB || isa<PHINode>(*UI))
return true;
return false;
}
/// isOnlyUsedInEntryBlock - If the specified argument is only used in the
/// entry block, return true. This includes arguments used by switches, since
/// the switch may expand into multiple basic blocks.
static bool isOnlyUsedInEntryBlock(const Argument *A, bool EnableFastISel) {
// With FastISel active, we may be splitting blocks, so force creation
// of virtual registers for all non-dead arguments.
if (EnableFastISel)
return A->use_empty();
const BasicBlock *Entry = A->getParent()->begin();
for (Value::const_use_iterator UI = A->use_begin(), E = A->use_end();
UI != E; ++UI)
if (cast<Instruction>(*UI)->getParent() != Entry || isa<SwitchInst>(*UI))
return false; // Use not in entry block.
return true;
}
FunctionLoweringInfo::FunctionLoweringInfo(const TargetLowering &tli)
: TLI(tli) {
}
void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
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().getRetAttributes(), Outs, TLI);
CanLowerReturn = TLI.CanLowerReturn(Fn->getCallingConv(), Fn->isVarArg(),
Outs, Fn->getContext());
// Create a vreg for each argument register that is not dead and is used
// outside of the entry block for the function.
for (Function::const_arg_iterator AI = Fn->arg_begin(), E = Fn->arg_end();
AI != E; ++AI)
if (!isOnlyUsedInEntryBlock(AI, EnableFastISel))
InitializeRegForValue(AI);
// 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))
if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
const Type *Ty = AI->getAllocatedType();
uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
unsigned Align =
std::max((unsigned)TLI.getTargetData()->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);
}
for (; BB != EB; ++BB)
for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
if (isUsedOutsideOfDefiningBlock(I))
if (!isa<AllocaInst>(I) ||
!StaticAllocaMap.count(cast<AllocaInst>(I)))
InitializeRegForValue(I);
// 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;
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();
ArgDbgValues.clear();
RegFixups.clear();
}
/// CreateReg - Allocate a single virtual register for the given type.
unsigned FunctionLoweringInfo::CreateReg(EVT VT) {
return RegInfo->createVirtualRegister(TLI.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(const Type *Ty) {
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];
EVT 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;
}
/// 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);
}
}
void llvm::CopyCatchInfo(const BasicBlock *SrcBB, const BasicBlock *DestBB,
MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
for (BasicBlock::const_iterator I = SrcBB->begin(), E = --SrcBB->end();
I != E; ++I)
if (const EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
// Apply the catch info to DestBB.
AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
#ifndef NDEBUG
if (!FLI.MBBMap[SrcBB]->isLandingPad())
FLI.CatchInfoFound.insert(EHSel);
#endif
}
}