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llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
Duncan Sands b01bbdcc1a I don't see any point in having both eh.selector.i32 and eh.selector.i64, 
so get rid of eh.selector.i64 and rename eh.selector.i32 to eh.selector.
Likewise for eh.typeid.for.  This aligns us with gcc, which always uses a
32 bit value for the selector on all platforms.  My understanding is that
the register allocator used to assert if the selector intrinsic size didn't
match the pointer size, and this was the reason for introducing the two
variants.  However my testing shows that this is no longer the case (I
fixed some bugs in selector lowering yesterday, and some more today in the
fastisel path; these might have caused the original problems).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84106 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-14 16:11:37 +00:00

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///===-- FastISel.cpp - Implementation of the FastISel class --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the implementation of the FastISel class.
//
// "Fast" instruction selection is designed to emit very poor code quickly.
// Also, it is not designed to be able to do much lowering, so most illegal
// types (e.g. i64 on 32-bit targets) and operations are not supported. It is
// also not intended to be able to do much optimization, except in a few cases
// where doing optimizations reduces overall compile time. For example, folding
// constants into immediate fields is often done, because it's cheap and it
// reduces the number of instructions later phases have to examine.
//
// "Fast" instruction selection is able to fail gracefully and transfer
// control to the SelectionDAG selector for operations that it doesn't
// support. In many cases, this allows us to avoid duplicating a lot of
// the complicated lowering logic that SelectionDAG currently has.
//
// The intended use for "fast" instruction selection is "-O0" mode
// compilation, where the quality of the generated code is irrelevant when
// weighed against the speed at which the code can be generated. Also,
// at -O0, the LLVM optimizers are not running, and this makes the
// compile time of codegen a much higher portion of the overall compile
// time. Despite its limitations, "fast" instruction selection is able to
// handle enough code on its own to provide noticeable overall speedups
// in -O0 compiles.
//
// Basic operations are supported in a target-independent way, by reading
// the same instruction descriptions that the SelectionDAG selector reads,
// and identifying simple arithmetic operations that can be directly selected
// from simple operators. More complicated operations currently require
// target-specific code.
//
//===----------------------------------------------------------------------===//
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/CodeGen/FastISel.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/DwarfWriter.h"
#include "llvm/Analysis/DebugInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "SelectionDAGBuild.h"
using namespace llvm;
unsigned FastISel::getRegForValue(Value *V) {
EVT RealVT = TLI.getValueType(V->getType(), /*AllowUnknown=*/true);
// Don't handle non-simple values in FastISel.
if (!RealVT.isSimple())
return 0;
// Ignore illegal types. We must do this before looking up the value
// in ValueMap because Arguments are given virtual registers regardless
// of whether FastISel can handle them.
MVT VT = RealVT.getSimpleVT();
if (!TLI.isTypeLegal(VT)) {
// Promote MVT::i1 to a legal type though, because it's common and easy.
if (VT == MVT::i1)
VT = TLI.getTypeToTransformTo(V->getContext(), VT).getSimpleVT();
else
return 0;
}
// Look up the value to see if we already have a register for it. We
// cache values defined by Instructions across blocks, and other values
// only locally. This is because Instructions already have the SSA
// def-dominatess-use requirement enforced.
if (ValueMap.count(V))
return ValueMap[V];
unsigned Reg = LocalValueMap[V];
if (Reg != 0)
return Reg;
if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
if (CI->getValue().getActiveBits() <= 64)
Reg = FastEmit_i(VT, VT, ISD::Constant, CI->getZExtValue());
} else if (isa<AllocaInst>(V)) {
Reg = TargetMaterializeAlloca(cast<AllocaInst>(V));
} else if (isa<ConstantPointerNull>(V)) {
// Translate this as an integer zero so that it can be
// local-CSE'd with actual integer zeros.
Reg =
getRegForValue(Constant::getNullValue(TD.getIntPtrType(V->getContext())));
} else if (ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
Reg = FastEmit_f(VT, VT, ISD::ConstantFP, CF);
if (!Reg) {
const APFloat &Flt = CF->getValueAPF();
EVT IntVT = TLI.getPointerTy();
uint64_t x[2];
uint32_t IntBitWidth = IntVT.getSizeInBits();
bool isExact;
(void) Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true,
APFloat::rmTowardZero, &isExact);
if (isExact) {
APInt IntVal(IntBitWidth, 2, x);
unsigned IntegerReg =
getRegForValue(ConstantInt::get(V->getContext(), IntVal));
if (IntegerReg != 0)
Reg = FastEmit_r(IntVT.getSimpleVT(), VT, ISD::SINT_TO_FP, IntegerReg);
}
}
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (!SelectOperator(CE, CE->getOpcode())) return 0;
Reg = LocalValueMap[CE];
} else if (isa<UndefValue>(V)) {
Reg = createResultReg(TLI.getRegClassFor(VT));
BuildMI(MBB, DL, TII.get(TargetInstrInfo::IMPLICIT_DEF), Reg);
}
// If target-independent code couldn't handle the value, give target-specific
// code a try.
if (!Reg && isa<Constant>(V))
Reg = TargetMaterializeConstant(cast<Constant>(V));
// Don't cache constant materializations in the general ValueMap.
// To do so would require tracking what uses they dominate.
if (Reg != 0)
LocalValueMap[V] = Reg;
return Reg;
}
unsigned FastISel::lookUpRegForValue(Value *V) {
// Look up the value to see if we already have a register for it. We
// cache values defined by Instructions across blocks, and other values
// only locally. This is because Instructions already have the SSA
// def-dominatess-use requirement enforced.
if (ValueMap.count(V))
return ValueMap[V];
return LocalValueMap[V];
}
/// UpdateValueMap - Update the value map to include the new mapping for this
/// instruction, or insert an extra copy to get the result in a previous
/// determined register.
/// NOTE: This is only necessary because we might select a block that uses
/// a value before we select the block that defines the value. It might be
/// possible to fix this by selecting blocks in reverse postorder.
unsigned FastISel::UpdateValueMap(Value* I, unsigned Reg) {
if (!isa<Instruction>(I)) {
LocalValueMap[I] = Reg;
return Reg;
}
unsigned &AssignedReg = ValueMap[I];
if (AssignedReg == 0)
AssignedReg = Reg;
else if (Reg != AssignedReg) {
const TargetRegisterClass *RegClass = MRI.getRegClass(Reg);
TII.copyRegToReg(*MBB, MBB->end(), AssignedReg,
Reg, RegClass, RegClass);
}
return AssignedReg;
}
unsigned FastISel::getRegForGEPIndex(Value *Idx) {
unsigned IdxN = getRegForValue(Idx);
if (IdxN == 0)
// Unhandled operand. Halt "fast" selection and bail.
return 0;
// If the index is smaller or larger than intptr_t, truncate or extend it.
MVT PtrVT = TLI.getPointerTy();
EVT IdxVT = EVT::getEVT(Idx->getType(), /*HandleUnknown=*/false);
if (IdxVT.bitsLT(PtrVT))
IdxN = FastEmit_r(IdxVT.getSimpleVT(), PtrVT, ISD::SIGN_EXTEND, IdxN);
else if (IdxVT.bitsGT(PtrVT))
IdxN = FastEmit_r(IdxVT.getSimpleVT(), PtrVT, ISD::TRUNCATE, IdxN);
return IdxN;
}
/// SelectBinaryOp - Select and emit code for a binary operator instruction,
/// which has an opcode which directly corresponds to the given ISD opcode.
///
bool FastISel::SelectBinaryOp(User *I, ISD::NodeType ISDOpcode) {
EVT VT = EVT::getEVT(I->getType(), /*HandleUnknown=*/true);
if (VT == MVT::Other || !VT.isSimple())
// Unhandled type. Halt "fast" selection and bail.
return false;
// We only handle legal types. For example, on x86-32 the instruction
// selector contains all of the 64-bit instructions from x86-64,
// under the assumption that i64 won't be used if the target doesn't
// support it.
if (!TLI.isTypeLegal(VT)) {
// MVT::i1 is special. Allow AND, OR, or XOR because they
// don't require additional zeroing, which makes them easy.
if (VT == MVT::i1 &&
(ISDOpcode == ISD::AND || ISDOpcode == ISD::OR ||
ISDOpcode == ISD::XOR))
VT = TLI.getTypeToTransformTo(I->getContext(), VT);
else
return false;
}
unsigned Op0 = getRegForValue(I->getOperand(0));
if (Op0 == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
// Check if the second operand is a constant and handle it appropriately.
if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
unsigned ResultReg = FastEmit_ri(VT.getSimpleVT(), VT.getSimpleVT(),
ISDOpcode, Op0, CI->getZExtValue());
if (ResultReg != 0) {
// We successfully emitted code for the given LLVM Instruction.
UpdateValueMap(I, ResultReg);
return true;
}
}
// Check if the second operand is a constant float.
if (ConstantFP *CF = dyn_cast<ConstantFP>(I->getOperand(1))) {
unsigned ResultReg = FastEmit_rf(VT.getSimpleVT(), VT.getSimpleVT(),
ISDOpcode, Op0, CF);
if (ResultReg != 0) {
// We successfully emitted code for the given LLVM Instruction.
UpdateValueMap(I, ResultReg);
return true;
}
}
unsigned Op1 = getRegForValue(I->getOperand(1));
if (Op1 == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
// Now we have both operands in registers. Emit the instruction.
unsigned ResultReg = FastEmit_rr(VT.getSimpleVT(), VT.getSimpleVT(),
ISDOpcode, Op0, Op1);
if (ResultReg == 0)
// Target-specific code wasn't able to find a machine opcode for
// the given ISD opcode and type. Halt "fast" selection and bail.
return false;
// We successfully emitted code for the given LLVM Instruction.
UpdateValueMap(I, ResultReg);
return true;
}
bool FastISel::SelectGetElementPtr(User *I) {
unsigned N = getRegForValue(I->getOperand(0));
if (N == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
const Type *Ty = I->getOperand(0)->getType();
MVT VT = TLI.getPointerTy();
for (GetElementPtrInst::op_iterator OI = I->op_begin()+1, E = I->op_end();
OI != E; ++OI) {
Value *Idx = *OI;
if (const StructType *StTy = dyn_cast<StructType>(Ty)) {
unsigned Field = cast<ConstantInt>(Idx)->getZExtValue();
if (Field) {
// N = N + Offset
uint64_t Offs = TD.getStructLayout(StTy)->getElementOffset(Field);
// FIXME: This can be optimized by combining the add with a
// subsequent one.
N = FastEmit_ri_(VT, ISD::ADD, N, Offs, VT);
if (N == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
}
Ty = StTy->getElementType(Field);
} else {
Ty = cast<SequentialType>(Ty)->getElementType();
// If this is a constant subscript, handle it quickly.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
if (CI->getZExtValue() == 0) continue;
uint64_t Offs =
TD.getTypeAllocSize(Ty)*cast<ConstantInt>(CI)->getSExtValue();
N = FastEmit_ri_(VT, ISD::ADD, N, Offs, VT);
if (N == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
continue;
}
// N = N + Idx * ElementSize;
uint64_t ElementSize = TD.getTypeAllocSize(Ty);
unsigned IdxN = getRegForGEPIndex(Idx);
if (IdxN == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
if (ElementSize != 1) {
IdxN = FastEmit_ri_(VT, ISD::MUL, IdxN, ElementSize, VT);
if (IdxN == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
}
N = FastEmit_rr(VT, VT, ISD::ADD, N, IdxN);
if (N == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
}
}
// We successfully emitted code for the given LLVM Instruction.
UpdateValueMap(I, N);
return true;
}
bool FastISel::SelectCall(User *I) {
Function *F = cast<CallInst>(I)->getCalledFunction();
if (!F) return false;
unsigned IID = F->getIntrinsicID();
switch (IID) {
default: break;
case Intrinsic::dbg_stoppoint: {
DbgStopPointInst *SPI = cast<DbgStopPointInst>(I);
if (isValidDebugInfoIntrinsic(*SPI, CodeGenOpt::None))
setCurDebugLoc(ExtractDebugLocation(*SPI, MF.getDebugLocInfo()));
return true;
}
case Intrinsic::dbg_region_start: {
DbgRegionStartInst *RSI = cast<DbgRegionStartInst>(I);
if (isValidDebugInfoIntrinsic(*RSI, CodeGenOpt::None) && DW
&& DW->ShouldEmitDwarfDebug()) {
unsigned ID =
DW->RecordRegionStart(RSI->getContext());
const TargetInstrDesc &II = TII.get(TargetInstrInfo::DBG_LABEL);
BuildMI(MBB, DL, II).addImm(ID);
}
return true;
}
case Intrinsic::dbg_region_end: {
DbgRegionEndInst *REI = cast<DbgRegionEndInst>(I);
if (isValidDebugInfoIntrinsic(*REI, CodeGenOpt::None) && DW
&& DW->ShouldEmitDwarfDebug()) {
unsigned ID = 0;
DISubprogram Subprogram(REI->getContext());
if (isInlinedFnEnd(*REI, MF.getFunction())) {
// This is end of an inlined function.
const TargetInstrDesc &II = TII.get(TargetInstrInfo::DBG_LABEL);
ID = DW->RecordInlinedFnEnd(Subprogram);
if (ID)
// Returned ID is 0 if this is unbalanced "end of inlined
// scope". This could happen if optimizer eats dbg intrinsics
// or "beginning of inlined scope" is not recoginized due to
// missing location info. In such cases, ignore this region.end.
BuildMI(MBB, DL, II).addImm(ID);
} else {
const TargetInstrDesc &II = TII.get(TargetInstrInfo::DBG_LABEL);
ID = DW->RecordRegionEnd(REI->getContext());
BuildMI(MBB, DL, II).addImm(ID);
}
}
return true;
}
case Intrinsic::dbg_func_start: {
DbgFuncStartInst *FSI = cast<DbgFuncStartInst>(I);
if (!isValidDebugInfoIntrinsic(*FSI, CodeGenOpt::None) || !DW
|| !DW->ShouldEmitDwarfDebug())
return true;
if (isInlinedFnStart(*FSI, MF.getFunction())) {
// This is a beginning of an inlined function.
// If llvm.dbg.func.start is seen in a new block before any
// llvm.dbg.stoppoint intrinsic then the location info is unknown.
// FIXME : Why DebugLoc is reset at the beginning of each block ?
DebugLoc PrevLoc = DL;
if (PrevLoc.isUnknown())
return true;
// Record the source line.
setCurDebugLoc(ExtractDebugLocation(*FSI, MF.getDebugLocInfo()));
DebugLocTuple PrevLocTpl = MF.getDebugLocTuple(PrevLoc);
DISubprogram SP(FSI->getSubprogram());
unsigned LabelID =
DW->RecordInlinedFnStart(SP,DICompileUnit(PrevLocTpl.Scope),
PrevLocTpl.Line, PrevLocTpl.Col);
const TargetInstrDesc &II = TII.get(TargetInstrInfo::DBG_LABEL);
BuildMI(MBB, DL, II).addImm(LabelID);
return true;
}
// This is a beginning of a new function.
MF.setDefaultDebugLoc(ExtractDebugLocation(*FSI, MF.getDebugLocInfo()));
// llvm.dbg.func_start also defines beginning of function scope.
DW->RecordRegionStart(FSI->getSubprogram());
return true;
}
case Intrinsic::dbg_declare: {
DbgDeclareInst *DI = cast<DbgDeclareInst>(I);
if (!isValidDebugInfoIntrinsic(*DI, CodeGenOpt::None) || !DW
|| !DW->ShouldEmitDwarfDebug())
return true;
Value *Address = DI->getAddress();
if (BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
Address = BCI->getOperand(0);
AllocaInst *AI = dyn_cast<AllocaInst>(Address);
// Don't handle byval struct arguments or VLAs, for example.
if (!AI) break;
DenseMap<const AllocaInst*, int>::iterator SI =
StaticAllocaMap.find(AI);
if (SI == StaticAllocaMap.end()) break; // VLAs.
int FI = SI->second;
if (MMI)
MMI->setVariableDbgInfo(DI->getVariable(), FI);
#ifndef ATTACH_DEBUG_INFO_TO_AN_INSN
DW->RecordVariable(DI->getVariable(), FI);
#endif
return true;
}
case Intrinsic::eh_exception: {
EVT VT = TLI.getValueType(I->getType());
switch (TLI.getOperationAction(ISD::EXCEPTIONADDR, VT)) {
default: break;
case TargetLowering::Expand: {
assert(MBB->isLandingPad() && "Call to eh.exception not in landing pad!");
unsigned Reg = TLI.getExceptionAddressRegister();
const TargetRegisterClass *RC = TLI.getRegClassFor(VT);
unsigned ResultReg = createResultReg(RC);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
Reg, RC, RC);
assert(InsertedCopy && "Can't copy address registers!");
InsertedCopy = InsertedCopy;
UpdateValueMap(I, ResultReg);
return true;
}
}
break;
}
case Intrinsic::eh_selector: {
EVT VT = TLI.getValueType(I->getType());
switch (TLI.getOperationAction(ISD::EHSELECTION, VT)) {
default: break;
case TargetLowering::Expand: {
if (MMI) {
if (MBB->isLandingPad())
AddCatchInfo(*cast<CallInst>(I), MMI, MBB);
else {
#ifndef NDEBUG
CatchInfoLost.insert(cast<CallInst>(I));
#endif
// FIXME: Mark exception selector register as live in. Hack for PR1508.
unsigned Reg = TLI.getExceptionSelectorRegister();
if (Reg) MBB->addLiveIn(Reg);
}
unsigned Reg = TLI.getExceptionSelectorRegister();
EVT SrcVT = TLI.getPointerTy();
const TargetRegisterClass *RC = TLI.getRegClassFor(SrcVT);
unsigned ResultReg = createResultReg(RC);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, Reg,
RC, RC);
assert(InsertedCopy && "Can't copy address registers!");
InsertedCopy = InsertedCopy;
// Cast the register to the type of the selector.
if (SrcVT.bitsGT(MVT::i32))
ResultReg = FastEmit_r(SrcVT.getSimpleVT(), MVT::i32, ISD::TRUNCATE,
ResultReg);
else if (SrcVT.bitsLT(MVT::i32))
ResultReg = FastEmit_r(SrcVT.getSimpleVT(), MVT::i32,
ISD::SIGN_EXTEND, ResultReg);
if (ResultReg == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
UpdateValueMap(I, ResultReg);
} else {
unsigned ResultReg =
getRegForValue(Constant::getNullValue(I->getType()));
UpdateValueMap(I, ResultReg);
}
return true;
}
}
break;
}
}
return false;
}
bool FastISel::SelectCast(User *I, ISD::NodeType Opcode) {
EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
EVT DstVT = TLI.getValueType(I->getType());
if (SrcVT == MVT::Other || !SrcVT.isSimple() ||
DstVT == MVT::Other || !DstVT.isSimple())
// Unhandled type. Halt "fast" selection and bail.
return false;
// Check if the destination type is legal. Or as a special case,
// it may be i1 if we're doing a truncate because that's
// easy and somewhat common.
if (!TLI.isTypeLegal(DstVT))
if (DstVT != MVT::i1 || Opcode != ISD::TRUNCATE)
// Unhandled type. Halt "fast" selection and bail.
return false;
// Check if the source operand is legal. Or as a special case,
// it may be i1 if we're doing zero-extension because that's
// easy and somewhat common.
if (!TLI.isTypeLegal(SrcVT))
if (SrcVT != MVT::i1 || Opcode != ISD::ZERO_EXTEND)
// Unhandled type. Halt "fast" selection and bail.
return false;
unsigned InputReg = getRegForValue(I->getOperand(0));
if (!InputReg)
// Unhandled operand. Halt "fast" selection and bail.
return false;
// If the operand is i1, arrange for the high bits in the register to be zero.
if (SrcVT == MVT::i1) {
SrcVT = TLI.getTypeToTransformTo(I->getContext(), SrcVT);
InputReg = FastEmitZExtFromI1(SrcVT.getSimpleVT(), InputReg);
if (!InputReg)
return false;
}
// If the result is i1, truncate to the target's type for i1 first.
if (DstVT == MVT::i1)
DstVT = TLI.getTypeToTransformTo(I->getContext(), DstVT);
unsigned ResultReg = FastEmit_r(SrcVT.getSimpleVT(),
DstVT.getSimpleVT(),
Opcode,
InputReg);
if (!ResultReg)
return false;
UpdateValueMap(I, ResultReg);
return true;
}
bool FastISel::SelectBitCast(User *I) {
// If the bitcast doesn't change the type, just use the operand value.
if (I->getType() == I->getOperand(0)->getType()) {
unsigned Reg = getRegForValue(I->getOperand(0));
if (Reg == 0)
return false;
UpdateValueMap(I, Reg);
return true;
}
// Bitcasts of other values become reg-reg copies or BIT_CONVERT operators.
EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
EVT DstVT = TLI.getValueType(I->getType());
if (SrcVT == MVT::Other || !SrcVT.isSimple() ||
DstVT == MVT::Other || !DstVT.isSimple() ||
!TLI.isTypeLegal(SrcVT) || !TLI.isTypeLegal(DstVT))
// Unhandled type. Halt "fast" selection and bail.
return false;
unsigned Op0 = getRegForValue(I->getOperand(0));
if (Op0 == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
// First, try to perform the bitcast by inserting a reg-reg copy.
unsigned ResultReg = 0;
if (SrcVT.getSimpleVT() == DstVT.getSimpleVT()) {
TargetRegisterClass* SrcClass = TLI.getRegClassFor(SrcVT);
TargetRegisterClass* DstClass = TLI.getRegClassFor(DstVT);
ResultReg = createResultReg(DstClass);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
Op0, DstClass, SrcClass);
if (!InsertedCopy)
ResultReg = 0;
}
// If the reg-reg copy failed, select a BIT_CONVERT opcode.
if (!ResultReg)
ResultReg = FastEmit_r(SrcVT.getSimpleVT(), DstVT.getSimpleVT(),
ISD::BIT_CONVERT, Op0);
if (!ResultReg)
return false;
UpdateValueMap(I, ResultReg);
return true;
}
bool
FastISel::SelectInstruction(Instruction *I) {
return SelectOperator(I, I->getOpcode());
}
/// FastEmitBranch - Emit an unconditional branch to the given block,
/// unless it is the immediate (fall-through) successor, and update
/// the CFG.
void
FastISel::FastEmitBranch(MachineBasicBlock *MSucc) {
MachineFunction::iterator NextMBB =
next(MachineFunction::iterator(MBB));
if (MBB->isLayoutSuccessor(MSucc)) {
// The unconditional fall-through case, which needs no instructions.
} else {
// The unconditional branch case.
TII.InsertBranch(*MBB, MSucc, NULL, SmallVector<MachineOperand, 0>());
}
MBB->addSuccessor(MSucc);
}
/// SelectFNeg - Emit an FNeg operation.
///
bool
FastISel::SelectFNeg(User *I) {
unsigned OpReg = getRegForValue(BinaryOperator::getFNegArgument(I));
if (OpReg == 0) return false;
// If the target has ISD::FNEG, use it.
EVT VT = TLI.getValueType(I->getType());
unsigned ResultReg = FastEmit_r(VT.getSimpleVT(), VT.getSimpleVT(),
ISD::FNEG, OpReg);
if (ResultReg != 0) {
UpdateValueMap(I, ResultReg);
return true;
}
// Bitcast the value to integer, twiddle the sign bit with xor,
// and then bitcast it back to floating-point.
if (VT.getSizeInBits() > 64) return false;
EVT IntVT = EVT::getIntegerVT(I->getContext(), VT.getSizeInBits());
if (!TLI.isTypeLegal(IntVT))
return false;
unsigned IntReg = FastEmit_r(VT.getSimpleVT(), IntVT.getSimpleVT(),
ISD::BIT_CONVERT, OpReg);
if (IntReg == 0)
return false;
unsigned IntResultReg = FastEmit_ri_(IntVT.getSimpleVT(), ISD::XOR, IntReg,
UINT64_C(1) << (VT.getSizeInBits()-1),
IntVT.getSimpleVT());
if (IntResultReg == 0)
return false;
ResultReg = FastEmit_r(IntVT.getSimpleVT(), VT.getSimpleVT(),
ISD::BIT_CONVERT, IntResultReg);
if (ResultReg == 0)
return false;
UpdateValueMap(I, ResultReg);
return true;
}
bool
FastISel::SelectOperator(User *I, unsigned Opcode) {
switch (Opcode) {
case Instruction::Add:
return SelectBinaryOp(I, ISD::ADD);
case Instruction::FAdd:
return SelectBinaryOp(I, ISD::FADD);
case Instruction::Sub:
return SelectBinaryOp(I, ISD::SUB);
case Instruction::FSub:
// FNeg is currently represented in LLVM IR as a special case of FSub.
if (BinaryOperator::isFNeg(I))
return SelectFNeg(I);
return SelectBinaryOp(I, ISD::FSUB);
case Instruction::Mul:
return SelectBinaryOp(I, ISD::MUL);
case Instruction::FMul:
return SelectBinaryOp(I, ISD::FMUL);
case Instruction::SDiv:
return SelectBinaryOp(I, ISD::SDIV);
case Instruction::UDiv:
return SelectBinaryOp(I, ISD::UDIV);
case Instruction::FDiv:
return SelectBinaryOp(I, ISD::FDIV);
case Instruction::SRem:
return SelectBinaryOp(I, ISD::SREM);
case Instruction::URem:
return SelectBinaryOp(I, ISD::UREM);
case Instruction::FRem:
return SelectBinaryOp(I, ISD::FREM);
case Instruction::Shl:
return SelectBinaryOp(I, ISD::SHL);
case Instruction::LShr:
return SelectBinaryOp(I, ISD::SRL);
case Instruction::AShr:
return SelectBinaryOp(I, ISD::SRA);
case Instruction::And:
return SelectBinaryOp(I, ISD::AND);
case Instruction::Or:
return SelectBinaryOp(I, ISD::OR);
case Instruction::Xor:
return SelectBinaryOp(I, ISD::XOR);
case Instruction::GetElementPtr:
return SelectGetElementPtr(I);
case Instruction::Br: {
BranchInst *BI = cast<BranchInst>(I);
if (BI->isUnconditional()) {
BasicBlock *LLVMSucc = BI->getSuccessor(0);
MachineBasicBlock *MSucc = MBBMap[LLVMSucc];
FastEmitBranch(MSucc);
return true;
}
// Conditional branches are not handed yet.
// Halt "fast" selection and bail.
return false;
}
case Instruction::Unreachable:
// Nothing to emit.
return true;
case Instruction::PHI:
// PHI nodes are already emitted.
return true;
case Instruction::Alloca:
// FunctionLowering has the static-sized case covered.
if (StaticAllocaMap.count(cast<AllocaInst>(I)))
return true;
// Dynamic-sized alloca is not handled yet.
return false;
case Instruction::Call:
return SelectCall(I);
case Instruction::BitCast:
return SelectBitCast(I);
case Instruction::FPToSI:
return SelectCast(I, ISD::FP_TO_SINT);
case Instruction::ZExt:
return SelectCast(I, ISD::ZERO_EXTEND);
case Instruction::SExt:
return SelectCast(I, ISD::SIGN_EXTEND);
case Instruction::Trunc:
return SelectCast(I, ISD::TRUNCATE);
case Instruction::SIToFP:
return SelectCast(I, ISD::SINT_TO_FP);
case Instruction::IntToPtr: // Deliberate fall-through.
case Instruction::PtrToInt: {
EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
EVT DstVT = TLI.getValueType(I->getType());
if (DstVT.bitsGT(SrcVT))
return SelectCast(I, ISD::ZERO_EXTEND);
if (DstVT.bitsLT(SrcVT))
return SelectCast(I, ISD::TRUNCATE);
unsigned Reg = getRegForValue(I->getOperand(0));
if (Reg == 0) return false;
UpdateValueMap(I, Reg);
return true;
}
default:
// Unhandled instruction. Halt "fast" selection and bail.
return false;
}
}
FastISel::FastISel(MachineFunction &mf,
MachineModuleInfo *mmi,
DwarfWriter *dw,
DenseMap<const Value *, unsigned> &vm,
DenseMap<const BasicBlock *, MachineBasicBlock *> &bm,
DenseMap<const AllocaInst *, int> &am
#ifndef NDEBUG
, SmallSet<Instruction*, 8> &cil
#endif
)
: MBB(0),
ValueMap(vm),
MBBMap(bm),
StaticAllocaMap(am),
#ifndef NDEBUG
CatchInfoLost(cil),
#endif
MF(mf),
MMI(mmi),
DW(dw),
MRI(MF.getRegInfo()),
MFI(*MF.getFrameInfo()),
MCP(*MF.getConstantPool()),
TM(MF.getTarget()),
TD(*TM.getTargetData()),
TII(*TM.getInstrInfo()),
TLI(*TM.getTargetLowering()) {
}
FastISel::~FastISel() {}
unsigned FastISel::FastEmit_(MVT, MVT,
ISD::NodeType) {
return 0;
}
unsigned FastISel::FastEmit_r(MVT, MVT,
ISD::NodeType, unsigned /*Op0*/) {
return 0;
}
unsigned FastISel::FastEmit_rr(MVT, MVT,
ISD::NodeType, unsigned /*Op0*/,
unsigned /*Op0*/) {
return 0;
}
unsigned FastISel::FastEmit_i(MVT, MVT, ISD::NodeType, uint64_t /*Imm*/) {
return 0;
}
unsigned FastISel::FastEmit_f(MVT, MVT,
ISD::NodeType, ConstantFP * /*FPImm*/) {
return 0;
}
unsigned FastISel::FastEmit_ri(MVT, MVT,
ISD::NodeType, unsigned /*Op0*/,
uint64_t /*Imm*/) {
return 0;
}
unsigned FastISel::FastEmit_rf(MVT, MVT,
ISD::NodeType, unsigned /*Op0*/,
ConstantFP * /*FPImm*/) {
return 0;
}
unsigned FastISel::FastEmit_rri(MVT, MVT,
ISD::NodeType,
unsigned /*Op0*/, unsigned /*Op1*/,
uint64_t /*Imm*/) {
return 0;
}
/// FastEmit_ri_ - This method is a wrapper of FastEmit_ri. It first tries
/// to emit an instruction with an immediate operand using FastEmit_ri.
/// If that fails, it materializes the immediate into a register and try
/// FastEmit_rr instead.
unsigned FastISel::FastEmit_ri_(MVT VT, ISD::NodeType Opcode,
unsigned Op0, uint64_t Imm,
MVT ImmType) {
// First check if immediate type is legal. If not, we can't use the ri form.
unsigned ResultReg = FastEmit_ri(VT, VT, Opcode, Op0, Imm);
if (ResultReg != 0)
return ResultReg;
unsigned MaterialReg = FastEmit_i(ImmType, ImmType, ISD::Constant, Imm);
if (MaterialReg == 0)
return 0;
return FastEmit_rr(VT, VT, Opcode, Op0, MaterialReg);
}
/// FastEmit_rf_ - This method is a wrapper of FastEmit_ri. It first tries
/// to emit an instruction with a floating-point immediate operand using
/// FastEmit_rf. If that fails, it materializes the immediate into a register
/// and try FastEmit_rr instead.
unsigned FastISel::FastEmit_rf_(MVT VT, ISD::NodeType Opcode,
unsigned Op0, ConstantFP *FPImm,
MVT ImmType) {
// First check if immediate type is legal. If not, we can't use the rf form.
unsigned ResultReg = FastEmit_rf(VT, VT, Opcode, Op0, FPImm);
if (ResultReg != 0)
return ResultReg;
// Materialize the constant in a register.
unsigned MaterialReg = FastEmit_f(ImmType, ImmType, ISD::ConstantFP, FPImm);
if (MaterialReg == 0) {
// If the target doesn't have a way to directly enter a floating-point
// value into a register, use an alternate approach.
// TODO: The current approach only supports floating-point constants
// that can be constructed by conversion from integer values. This should
// be replaced by code that creates a load from a constant-pool entry,
// which will require some target-specific work.
const APFloat &Flt = FPImm->getValueAPF();
EVT IntVT = TLI.getPointerTy();
uint64_t x[2];
uint32_t IntBitWidth = IntVT.getSizeInBits();
bool isExact;
(void) Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true,
APFloat::rmTowardZero, &isExact);
if (!isExact)
return 0;
APInt IntVal(IntBitWidth, 2, x);
unsigned IntegerReg = FastEmit_i(IntVT.getSimpleVT(), IntVT.getSimpleVT(),
ISD::Constant, IntVal.getZExtValue());
if (IntegerReg == 0)
return 0;
MaterialReg = FastEmit_r(IntVT.getSimpleVT(), VT,
ISD::SINT_TO_FP, IntegerReg);
if (MaterialReg == 0)
return 0;
}
return FastEmit_rr(VT, VT, Opcode, Op0, MaterialReg);
}
unsigned FastISel::createResultReg(const TargetRegisterClass* RC) {
return MRI.createVirtualRegister(RC);
}
unsigned FastISel::FastEmitInst_(unsigned MachineInstOpcode,
const TargetRegisterClass* RC) {
unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
BuildMI(MBB, DL, II, ResultReg);
return ResultReg;
}
unsigned FastISel::FastEmitInst_r(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0) {
unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
if (II.getNumDefs() >= 1)
BuildMI(MBB, DL, II, ResultReg).addReg(Op0);
else {
BuildMI(MBB, DL, II).addReg(Op0);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
II.ImplicitDefs[0], RC, RC);
if (!InsertedCopy)
ResultReg = 0;
}
return ResultReg;
}
unsigned FastISel::FastEmitInst_rr(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, unsigned Op1) {
unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
if (II.getNumDefs() >= 1)
BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addReg(Op1);
else {
BuildMI(MBB, DL, II).addReg(Op0).addReg(Op1);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
II.ImplicitDefs[0], RC, RC);
if (!InsertedCopy)
ResultReg = 0;
}
return ResultReg;
}
unsigned FastISel::FastEmitInst_ri(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, uint64_t Imm) {
unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
if (II.getNumDefs() >= 1)
BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addImm(Imm);
else {
BuildMI(MBB, DL, II).addReg(Op0).addImm(Imm);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
II.ImplicitDefs[0], RC, RC);
if (!InsertedCopy)
ResultReg = 0;
}
return ResultReg;
}
unsigned FastISel::FastEmitInst_rf(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, ConstantFP *FPImm) {
unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
if (II.getNumDefs() >= 1)
BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addFPImm(FPImm);
else {
BuildMI(MBB, DL, II).addReg(Op0).addFPImm(FPImm);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
II.ImplicitDefs[0], RC, RC);
if (!InsertedCopy)
ResultReg = 0;
}
return ResultReg;
}
unsigned FastISel::FastEmitInst_rri(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, unsigned Op1, uint64_t Imm) {
unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
if (II.getNumDefs() >= 1)
BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addReg(Op1).addImm(Imm);
else {
BuildMI(MBB, DL, II).addReg(Op0).addReg(Op1).addImm(Imm);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
II.ImplicitDefs[0], RC, RC);
if (!InsertedCopy)
ResultReg = 0;
}
return ResultReg;
}
unsigned FastISel::FastEmitInst_i(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
uint64_t Imm) {
unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
if (II.getNumDefs() >= 1)
BuildMI(MBB, DL, II, ResultReg).addImm(Imm);
else {
BuildMI(MBB, DL, II).addImm(Imm);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
II.ImplicitDefs[0], RC, RC);
if (!InsertedCopy)
ResultReg = 0;
}
return ResultReg;
}
unsigned FastISel::FastEmitInst_extractsubreg(MVT RetVT,
unsigned Op0, uint32_t Idx) {
const TargetRegisterClass* RC = MRI.getRegClass(Op0);
unsigned ResultReg = createResultReg(TLI.getRegClassFor(RetVT));
const TargetInstrDesc &II = TII.get(TargetInstrInfo::EXTRACT_SUBREG);
if (II.getNumDefs() >= 1)
BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addImm(Idx);
else {
BuildMI(MBB, DL, II).addReg(Op0).addImm(Idx);
bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
II.ImplicitDefs[0], RC, RC);
if (!InsertedCopy)
ResultReg = 0;
}
return ResultReg;
}
/// FastEmitZExtFromI1 - Emit MachineInstrs to compute the value of Op
/// with all but the least significant bit set to zero.
unsigned FastISel::FastEmitZExtFromI1(MVT VT, unsigned Op) {
return FastEmit_ri(VT, VT, ISD::AND, Op, 1);
}
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