485 lines
18 KiB
C++
485 lines
18 KiB
C++
//===-- FunctionLoweringInfo.cpp ------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This implements routines for translating functions from LLVM IR into
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// Machine IR.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "function-lowering-info"
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#include "llvm/ADT/PostOrderIterator.h"
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#include "llvm/CodeGen/FunctionLoweringInfo.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Function.h"
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#include "llvm/Instructions.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Module.h"
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#include "llvm/Analysis/DebugInfo.h"
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#include "llvm/CodeGen/Analysis.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetLowering.h"
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#include "llvm/Target/TargetOptions.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/MathExtras.h"
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#include <algorithm>
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using namespace llvm;
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/// isUsedOutsideOfDefiningBlock - Return true if this instruction is used by
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/// PHI nodes or outside of the basic block that defines it, or used by a
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/// switch or atomic instruction, which may expand to multiple basic blocks.
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static bool isUsedOutsideOfDefiningBlock(const Instruction *I) {
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if (I->use_empty()) return false;
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if (isa<PHINode>(I)) return true;
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const BasicBlock *BB = I->getParent();
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for (Value::const_use_iterator UI = I->use_begin(), E = I->use_end();
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UI != E; ++UI) {
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const User *U = *UI;
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if (cast<Instruction>(U)->getParent() != BB || isa<PHINode>(U))
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return true;
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}
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return false;
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}
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FunctionLoweringInfo::FunctionLoweringInfo(const TargetLowering &tli)
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: TLI(tli) {
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}
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void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
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Fn = &fn;
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MF = &mf;
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RegInfo = &MF->getRegInfo();
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// Check whether the function can return without sret-demotion.
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SmallVector<ISD::OutputArg, 4> Outs;
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GetReturnInfo(Fn->getReturnType(),
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Fn->getAttributes().getRetAttributes(), Outs, TLI);
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CanLowerReturn = TLI.CanLowerReturn(Fn->getCallingConv(), *MF,
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Fn->isVarArg(),
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Outs, Fn->getContext());
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// Initialize the mapping of values to registers. This is only set up for
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// instruction values that are used outside of the block that defines
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// them.
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Function::const_iterator BB = Fn->begin(), EB = Fn->end();
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for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
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if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
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if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
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Type *Ty = AI->getAllocatedType();
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uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
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unsigned Align =
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std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
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AI->getAlignment());
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TySize *= CUI->getZExtValue(); // Get total allocated size.
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if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
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// The object may need to be placed onto the stack near the stack
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// protector if one exists. Determine here if this object is a suitable
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// candidate. I.e., it would trigger the creation of a stack protector.
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bool MayNeedSP =
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(AI->isArrayAllocation() ||
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(TySize >= 8 && isa<ArrayType>(Ty) &&
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cast<ArrayType>(Ty)->getElementType()->isIntegerTy(8)));
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StaticAllocaMap[AI] =
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MF->getFrameInfo()->CreateStackObject(TySize, Align, false,
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MayNeedSP);
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}
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for (; BB != EB; ++BB)
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for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
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I != E; ++I) {
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// Mark values used outside their block as exported, by allocating
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// a virtual register for them.
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if (isUsedOutsideOfDefiningBlock(I))
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if (!isa<AllocaInst>(I) ||
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!StaticAllocaMap.count(cast<AllocaInst>(I)))
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InitializeRegForValue(I);
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// Collect llvm.dbg.declare information. This is done now instead of
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// during the initial isel pass through the IR so that it is done
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// in a predictable order.
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if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
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MachineModuleInfo &MMI = MF->getMMI();
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if (MMI.hasDebugInfo() &&
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DIVariable(DI->getVariable()).Verify() &&
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!DI->getDebugLoc().isUnknown()) {
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// Don't handle byval struct arguments or VLAs, for example.
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// Non-byval arguments are handled here (they refer to the stack
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// temporary alloca at this point).
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const Value *Address = DI->getAddress();
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if (Address) {
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if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
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Address = BCI->getOperand(0);
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if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
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DenseMap<const AllocaInst *, int>::iterator SI =
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StaticAllocaMap.find(AI);
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if (SI != StaticAllocaMap.end()) { // Check for VLAs.
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int FI = SI->second;
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MMI.setVariableDbgInfo(DI->getVariable(),
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FI, DI->getDebugLoc());
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}
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}
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}
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}
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}
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}
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// Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
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// also creates the initial PHI MachineInstrs, though none of the input
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// operands are populated.
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for (BB = Fn->begin(); BB != EB; ++BB) {
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MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
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MBBMap[BB] = MBB;
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MF->push_back(MBB);
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// Transfer the address-taken flag. This is necessary because there could
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// be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
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// the first one should be marked.
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if (BB->hasAddressTaken())
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MBB->setHasAddressTaken();
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// Create Machine PHI nodes for LLVM PHI nodes, lowering them as
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// appropriate.
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for (BasicBlock::const_iterator I = BB->begin();
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const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
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if (PN->use_empty()) continue;
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// Skip empty types
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if (PN->getType()->isEmptyTy())
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continue;
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DebugLoc DL = PN->getDebugLoc();
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unsigned PHIReg = ValueMap[PN];
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assert(PHIReg && "PHI node does not have an assigned virtual register!");
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SmallVector<EVT, 4> ValueVTs;
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ComputeValueVTs(TLI, PN->getType(), ValueVTs);
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for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
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EVT VT = ValueVTs[vti];
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unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
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const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
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for (unsigned i = 0; i != NumRegisters; ++i)
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BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
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PHIReg += NumRegisters;
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}
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}
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}
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// Mark landing pad blocks.
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for (BB = Fn->begin(); BB != EB; ++BB)
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if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
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MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
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}
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/// clear - Clear out all the function-specific state. This returns this
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/// FunctionLoweringInfo to an empty state, ready to be used for a
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/// different function.
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void FunctionLoweringInfo::clear() {
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assert(CatchInfoFound.size() == CatchInfoLost.size() &&
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"Not all catch info was assigned to a landing pad!");
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MBBMap.clear();
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ValueMap.clear();
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StaticAllocaMap.clear();
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#ifndef NDEBUG
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CatchInfoLost.clear();
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CatchInfoFound.clear();
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#endif
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LiveOutRegInfo.clear();
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VisitedBBs.clear();
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ArgDbgValues.clear();
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ByValArgFrameIndexMap.clear();
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RegFixups.clear();
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}
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/// CreateReg - Allocate a single virtual register for the given type.
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unsigned FunctionLoweringInfo::CreateReg(EVT VT) {
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return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
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}
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/// CreateRegs - Allocate the appropriate number of virtual registers of
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/// the correctly promoted or expanded types. Assign these registers
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/// consecutive vreg numbers and return the first assigned number.
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///
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/// In the case that the given value has struct or array type, this function
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/// will assign registers for each member or element.
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///
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unsigned FunctionLoweringInfo::CreateRegs(Type *Ty) {
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SmallVector<EVT, 4> ValueVTs;
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ComputeValueVTs(TLI, Ty, ValueVTs);
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unsigned FirstReg = 0;
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for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
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EVT ValueVT = ValueVTs[Value];
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EVT RegisterVT = TLI.getRegisterType(Ty->getContext(), ValueVT);
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unsigned NumRegs = TLI.getNumRegisters(Ty->getContext(), ValueVT);
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for (unsigned i = 0; i != NumRegs; ++i) {
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unsigned R = CreateReg(RegisterVT);
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if (!FirstReg) FirstReg = R;
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}
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}
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return FirstReg;
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}
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/// GetLiveOutRegInfo - Gets LiveOutInfo for a register, returning NULL if the
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/// register is a PHI destination and the PHI's LiveOutInfo is not valid. If
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/// the register's LiveOutInfo is for a smaller bit width, it is extended to
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/// the larger bit width by zero extension. The bit width must be no smaller
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/// than the LiveOutInfo's existing bit width.
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const FunctionLoweringInfo::LiveOutInfo *
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FunctionLoweringInfo::GetLiveOutRegInfo(unsigned Reg, unsigned BitWidth) {
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if (!LiveOutRegInfo.inBounds(Reg))
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return NULL;
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LiveOutInfo *LOI = &LiveOutRegInfo[Reg];
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if (!LOI->IsValid)
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return NULL;
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if (BitWidth > LOI->KnownZero.getBitWidth()) {
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LOI->NumSignBits = 1;
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LOI->KnownZero = LOI->KnownZero.zextOrTrunc(BitWidth);
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LOI->KnownOne = LOI->KnownOne.zextOrTrunc(BitWidth);
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}
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return LOI;
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}
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/// ComputePHILiveOutRegInfo - Compute LiveOutInfo for a PHI's destination
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/// register based on the LiveOutInfo of its operands.
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void FunctionLoweringInfo::ComputePHILiveOutRegInfo(const PHINode *PN) {
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Type *Ty = PN->getType();
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if (!Ty->isIntegerTy() || Ty->isVectorTy())
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return;
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SmallVector<EVT, 1> ValueVTs;
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ComputeValueVTs(TLI, Ty, ValueVTs);
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assert(ValueVTs.size() == 1 &&
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"PHIs with non-vector integer types should have a single VT.");
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EVT IntVT = ValueVTs[0];
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if (TLI.getNumRegisters(PN->getContext(), IntVT) != 1)
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return;
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IntVT = TLI.getTypeToTransformTo(PN->getContext(), IntVT);
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unsigned BitWidth = IntVT.getSizeInBits();
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unsigned DestReg = ValueMap[PN];
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if (!TargetRegisterInfo::isVirtualRegister(DestReg))
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return;
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LiveOutRegInfo.grow(DestReg);
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LiveOutInfo &DestLOI = LiveOutRegInfo[DestReg];
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Value *V = PN->getIncomingValue(0);
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if (isa<UndefValue>(V) || isa<ConstantExpr>(V)) {
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DestLOI.NumSignBits = 1;
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APInt Zero(BitWidth, 0);
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DestLOI.KnownZero = Zero;
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DestLOI.KnownOne = Zero;
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return;
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}
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if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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APInt Val = CI->getValue().zextOrTrunc(BitWidth);
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DestLOI.NumSignBits = Val.getNumSignBits();
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DestLOI.KnownZero = ~Val;
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DestLOI.KnownOne = Val;
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} else {
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assert(ValueMap.count(V) && "V should have been placed in ValueMap when its"
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"CopyToReg node was created.");
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unsigned SrcReg = ValueMap[V];
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if (!TargetRegisterInfo::isVirtualRegister(SrcReg)) {
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DestLOI.IsValid = false;
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return;
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}
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const LiveOutInfo *SrcLOI = GetLiveOutRegInfo(SrcReg, BitWidth);
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if (!SrcLOI) {
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DestLOI.IsValid = false;
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return;
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}
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DestLOI = *SrcLOI;
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}
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assert(DestLOI.KnownZero.getBitWidth() == BitWidth &&
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DestLOI.KnownOne.getBitWidth() == BitWidth &&
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"Masks should have the same bit width as the type.");
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for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) {
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Value *V = PN->getIncomingValue(i);
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if (isa<UndefValue>(V) || isa<ConstantExpr>(V)) {
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DestLOI.NumSignBits = 1;
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APInt Zero(BitWidth, 0);
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DestLOI.KnownZero = Zero;
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DestLOI.KnownOne = Zero;
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return;
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}
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if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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APInt Val = CI->getValue().zextOrTrunc(BitWidth);
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DestLOI.NumSignBits = std::min(DestLOI.NumSignBits, Val.getNumSignBits());
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DestLOI.KnownZero &= ~Val;
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DestLOI.KnownOne &= Val;
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continue;
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}
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assert(ValueMap.count(V) && "V should have been placed in ValueMap when "
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"its CopyToReg node was created.");
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unsigned SrcReg = ValueMap[V];
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if (!TargetRegisterInfo::isVirtualRegister(SrcReg)) {
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DestLOI.IsValid = false;
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return;
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}
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const LiveOutInfo *SrcLOI = GetLiveOutRegInfo(SrcReg, BitWidth);
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if (!SrcLOI) {
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DestLOI.IsValid = false;
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return;
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}
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DestLOI.NumSignBits = std::min(DestLOI.NumSignBits, SrcLOI->NumSignBits);
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DestLOI.KnownZero &= SrcLOI->KnownZero;
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DestLOI.KnownOne &= SrcLOI->KnownOne;
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}
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}
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/// setArgumentFrameIndex - Record frame index for the byval
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/// argument. This overrides previous frame index entry for this argument,
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/// if any.
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void FunctionLoweringInfo::setArgumentFrameIndex(const Argument *A,
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int FI) {
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ByValArgFrameIndexMap[A] = FI;
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}
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/// getArgumentFrameIndex - Get frame index for the byval argument.
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/// If the argument does not have any assigned frame index then 0 is
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/// returned.
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int FunctionLoweringInfo::getArgumentFrameIndex(const Argument *A) {
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DenseMap<const Argument *, int>::iterator I =
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ByValArgFrameIndexMap.find(A);
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if (I != ByValArgFrameIndexMap.end())
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return I->second;
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DEBUG(dbgs() << "Argument does not have assigned frame index!\n");
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return 0;
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}
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/// ComputeUsesVAFloatArgument - Determine if any floating-point values are
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/// being passed to this variadic function, and set the MachineModuleInfo's
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/// usesVAFloatArgument flag if so. This flag is used to emit an undefined
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/// reference to _fltused on Windows, which will link in MSVCRT's
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/// floating-point support.
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void llvm::ComputeUsesVAFloatArgument(const CallInst &I,
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MachineModuleInfo *MMI)
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{
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FunctionType *FT = cast<FunctionType>(
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I.getCalledValue()->getType()->getContainedType(0));
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if (FT->isVarArg() && !MMI->usesVAFloatArgument()) {
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for (unsigned i = 0, e = I.getNumArgOperands(); i != e; ++i) {
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Type* T = I.getArgOperand(i)->getType();
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for (po_iterator<Type*> i = po_begin(T), e = po_end(T);
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i != e; ++i) {
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if (i->isFloatingPointTy()) {
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MMI->setUsesVAFloatArgument(true);
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return;
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}
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}
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}
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}
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}
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/// AddCatchInfo - Extract the personality and type infos from an eh.selector
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/// call, and add them to the specified machine basic block.
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void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
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MachineBasicBlock *MBB) {
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// Inform the MachineModuleInfo of the personality for this landing pad.
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const ConstantExpr *CE = cast<ConstantExpr>(I.getArgOperand(1));
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assert(CE->getOpcode() == Instruction::BitCast &&
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isa<Function>(CE->getOperand(0)) &&
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"Personality should be a function");
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MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
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// Gather all the type infos for this landing pad and pass them along to
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// MachineModuleInfo.
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std::vector<const GlobalVariable *> TyInfo;
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unsigned N = I.getNumArgOperands();
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for (unsigned i = N - 1; i > 1; --i) {
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if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getArgOperand(i))) {
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unsigned FilterLength = CI->getZExtValue();
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unsigned FirstCatch = i + FilterLength + !FilterLength;
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assert(FirstCatch <= N && "Invalid filter length");
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if (FirstCatch < N) {
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TyInfo.reserve(N - FirstCatch);
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for (unsigned j = FirstCatch; j < N; ++j)
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TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
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MMI->addCatchTypeInfo(MBB, TyInfo);
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TyInfo.clear();
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}
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if (!FilterLength) {
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// Cleanup.
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MMI->addCleanup(MBB);
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} else {
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// Filter.
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TyInfo.reserve(FilterLength - 1);
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for (unsigned j = i + 1; j < FirstCatch; ++j)
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TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
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MMI->addFilterTypeInfo(MBB, TyInfo);
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TyInfo.clear();
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}
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N = i;
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}
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}
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if (N > 2) {
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TyInfo.reserve(N - 2);
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for (unsigned j = 2; j < N; ++j)
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TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
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MMI->addCatchTypeInfo(MBB, TyInfo);
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}
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}
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/// AddLandingPadInfo - Extract the exception handling information from the
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/// landingpad instruction and add them to the specified machine module info.
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void llvm::AddLandingPadInfo(const LandingPadInst &I, MachineModuleInfo &MMI,
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MachineBasicBlock *MBB) {
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MMI.addPersonality(MBB,
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cast<Function>(I.getPersonalityFn()->stripPointerCasts()));
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if (I.isCleanup())
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MMI.addCleanup(MBB);
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// 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);
|
|
}
|
|
}
|
|
}
|