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llvm-6502/lib/CodeGen/SelectionDAG/FastISel.cpp
Hans Wennborg 4cd53531fd Fast-ISel: Remove dead code after falling back from selecting call instructions (PR20863) 
Previously, fast-isel would not clean up after failing to select a call
instruction, because it would have called flushLocalValueMap() which moves
the insertion point, making SavedInsertPt in selectInstruction() invalid.

Fixing this by making SavedInsertPt a member variable, and having
flushLocalValueMap() update it.

This removes some redundant code at -O0, and more importantly fixes PR20863.

Differential Revision: http://reviews.llvm.org/D5249

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217401 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-08 20:24:10 +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/CodeGen/Analysis.h"
#include "llvm/CodeGen/FastISel.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/FunctionLoweringInfo.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Operator.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
#define DEBUG_TYPE "isel"
STATISTIC(NumFastIselSuccessIndependent, "Number of insts selected by "
"target-independent selector");
STATISTIC(NumFastIselSuccessTarget, "Number of insts selected by "
"target-specific selector");
STATISTIC(NumFastIselDead, "Number of dead insts removed on failure");
void FastISel::ArgListEntry::setAttributes(ImmutableCallSite *CS,
unsigned AttrIdx) {
IsSExt = CS->paramHasAttr(AttrIdx, Attribute::SExt);
IsZExt = CS->paramHasAttr(AttrIdx, Attribute::ZExt);
IsInReg = CS->paramHasAttr(AttrIdx, Attribute::InReg);
IsSRet = CS->paramHasAttr(AttrIdx, Attribute::StructRet);
IsNest = CS->paramHasAttr(AttrIdx, Attribute::Nest);
IsByVal = CS->paramHasAttr(AttrIdx, Attribute::ByVal);
IsInAlloca = CS->paramHasAttr(AttrIdx, Attribute::InAlloca);
IsReturned = CS->paramHasAttr(AttrIdx, Attribute::Returned);
Alignment = CS->getParamAlignment(AttrIdx);
}
/// Set the current block to which generated machine instructions will be
/// appended, and clear the local CSE map.
void FastISel::startNewBlock() {
LocalValueMap.clear();
// Instructions are appended to FuncInfo.MBB. If the basic block already
// contains labels or copies, use the last instruction as the last local
// value.
EmitStartPt = nullptr;
if (!FuncInfo.MBB->empty())
EmitStartPt = &FuncInfo.MBB->back();
LastLocalValue = EmitStartPt;
}
bool FastISel::lowerArguments() {
if (!FuncInfo.CanLowerReturn)
// Fallback to SDISel argument lowering code to deal with sret pointer
// parameter.
return false;
if (!fastLowerArguments())
return false;
// Enter arguments into ValueMap for uses in non-entry BBs.
for (Function::const_arg_iterator I = FuncInfo.Fn->arg_begin(),
E = FuncInfo.Fn->arg_end();
I != E; ++I) {
DenseMap<const Value *, unsigned>::iterator VI = LocalValueMap.find(I);
assert(VI != LocalValueMap.end() && "Missed an argument?");
FuncInfo.ValueMap[I] = VI->second;
}
return true;
}
void FastISel::flushLocalValueMap() {
LocalValueMap.clear();
LastLocalValue = EmitStartPt;
recomputeInsertPt();
SavedInsertPt = FuncInfo.InsertPt;
}
bool FastISel::hasTrivialKill(const Value *V) {
// Don't consider constants or arguments to have trivial kills.
const Instruction *I = dyn_cast<Instruction>(V);
if (!I)
return false;
// No-op casts are trivially coalesced by fast-isel.
if (const auto *Cast = dyn_cast<CastInst>(I))
if (Cast->isNoopCast(DL.getIntPtrType(Cast->getContext())) &&
!hasTrivialKill(Cast->getOperand(0)))
return false;
// Even the value might have only one use in the LLVM IR, it is possible that
// FastISel might fold the use into another instruction and now there is more
// than one use at the Machine Instruction level.
unsigned Reg = lookUpRegForValue(V);
if (Reg && !MRI.use_empty(Reg))
return false;
// GEPs with all zero indices are trivially coalesced by fast-isel.
if (const auto *GEP = dyn_cast<GetElementPtrInst>(I))
if (GEP->hasAllZeroIndices() && !hasTrivialKill(GEP->getOperand(0)))
return false;
// Only instructions with a single use in the same basic block are considered
// to have trivial kills.
return I->hasOneUse() &&
!(I->getOpcode() == Instruction::BitCast ||
I->getOpcode() == Instruction::PtrToInt ||
I->getOpcode() == Instruction::IntToPtr) &&
cast<Instruction>(*I->user_begin())->getParent() == I->getParent();
}
unsigned FastISel::getRegForValue(const 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)) {
// Handle integer promotions, though, because they're common and easy.
if (VT == MVT::i1 || VT == MVT::i8 || VT == MVT::i16)
VT = TLI.getTypeToTransformTo(V->getContext(), VT).getSimpleVT();
else
return 0;
}
// Look up the value to see if we already have a register for it.
unsigned Reg = lookUpRegForValue(V);
if (Reg)
return Reg;
// In bottom-up mode, just create the virtual register which will be used
// to hold the value. It will be materialized later.
if (isa<Instruction>(V) &&
(!isa<AllocaInst>(V) ||
!FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(V))))
return FuncInfo.InitializeRegForValue(V);
SavePoint SaveInsertPt = enterLocalValueArea();
// Materialize the value in a register. Emit any instructions in the
// local value area.
Reg = materializeRegForValue(V, VT);
leaveLocalValueArea(SaveInsertPt);
return Reg;
}
unsigned FastISel::materializeConstant(const Value *V, MVT VT) {
unsigned Reg = 0;
if (const auto *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 = fastMaterializeAlloca(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(DL.getIntPtrType(V->getContext())));
else if (const auto *CF = dyn_cast<ConstantFP>(V)) {
if (CF->isNullValue())
Reg = fastMaterializeFloatZero(CF);
else
// Try to emit the constant directly.
Reg = fastEmit_f(VT, VT, ISD::ConstantFP, CF);
if (!Reg) {
// Try to emit the constant by using an integer constant with a cast.
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, x);
unsigned IntegerReg =
getRegForValue(ConstantInt::get(V->getContext(), IntVal));
if (IntegerReg != 0)
Reg = fastEmit_r(IntVT.getSimpleVT(), VT, ISD::SINT_TO_FP, IntegerReg,
/*Kill=*/false);
}
}
} else if (const auto *Op = dyn_cast<Operator>(V)) {
if (!selectOperator(Op, Op->getOpcode()))
if (!isa<Instruction>(Op) ||
!fastSelectInstruction(cast<Instruction>(Op)))
return 0;
Reg = lookUpRegForValue(Op);
} else if (isa<UndefValue>(V)) {
Reg = createResultReg(TLI.getRegClassFor(VT));
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::IMPLICIT_DEF), Reg);
}
return Reg;
}
/// Helper for getRegForValue. This function is called when the value isn't
/// already available in a register and must be materialized with new
/// instructions.
unsigned FastISel::materializeRegForValue(const Value *V, MVT VT) {
unsigned Reg = 0;
// Give the target-specific code a try first.
if (isa<Constant>(V))
Reg = fastMaterializeConstant(cast<Constant>(V));
// If target-specific code couldn't or didn't want to handle the value, then
// give target-independent code a try.
if (!Reg)
Reg = materializeConstant(V, VT);
// Don't cache constant materializations in the general ValueMap.
// To do so would require tracking what uses they dominate.
if (Reg) {
LocalValueMap[V] = Reg;
LastLocalValue = MRI.getVRegDef(Reg);
}
return Reg;
}
unsigned FastISel::lookUpRegForValue(const 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-dominates-use requirement enforced.
DenseMap<const Value *, unsigned>::iterator I = FuncInfo.ValueMap.find(V);
if (I != FuncInfo.ValueMap.end())
return I->second;
return LocalValueMap[V];
}
void FastISel::updateValueMap(const Value *I, unsigned Reg, unsigned NumRegs) {
if (!isa<Instruction>(I)) {
LocalValueMap[I] = Reg;
return;
}
unsigned &AssignedReg = FuncInfo.ValueMap[I];
if (AssignedReg == 0)
// Use the new register.
AssignedReg = Reg;
else if (Reg != AssignedReg) {
// Arrange for uses of AssignedReg to be replaced by uses of Reg.
for (unsigned i = 0; i < NumRegs; i++)
FuncInfo.RegFixups[AssignedReg + i] = Reg + i;
AssignedReg = Reg;
}
}
std::pair<unsigned, bool> FastISel::getRegForGEPIndex(const Value *Idx) {
unsigned IdxN = getRegForValue(Idx);
if (IdxN == 0)
// Unhandled operand. Halt "fast" selection and bail.
return std::pair<unsigned, bool>(0, false);
bool IdxNIsKill = hasTrivialKill(Idx);
// 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,
IdxNIsKill);
IdxNIsKill = true;
} else if (IdxVT.bitsGT(PtrVT)) {
IdxN =
fastEmit_r(IdxVT.getSimpleVT(), PtrVT, ISD::TRUNCATE, IdxN, IdxNIsKill);
IdxNIsKill = true;
}
return std::pair<unsigned, bool>(IdxN, IdxNIsKill);
}
void FastISel::recomputeInsertPt() {
if (getLastLocalValue()) {
FuncInfo.InsertPt = getLastLocalValue();
FuncInfo.MBB = FuncInfo.InsertPt->getParent();
++FuncInfo.InsertPt;
} else
FuncInfo.InsertPt = FuncInfo.MBB->getFirstNonPHI();
// Now skip past any EH_LABELs, which must remain at the beginning.
while (FuncInfo.InsertPt != FuncInfo.MBB->end() &&
FuncInfo.InsertPt->getOpcode() == TargetOpcode::EH_LABEL)
++FuncInfo.InsertPt;
}
void FastISel::removeDeadCode(MachineBasicBlock::iterator I,
MachineBasicBlock::iterator E) {
assert(I && E && std::distance(I, E) > 0 && "Invalid iterator!");
while (I != E) {
MachineInstr *Dead = &*I;
++I;
Dead->eraseFromParent();
++NumFastIselDead;
}
recomputeInsertPt();
}
FastISel::SavePoint FastISel::enterLocalValueArea() {
MachineBasicBlock::iterator OldInsertPt = FuncInfo.InsertPt;
DebugLoc OldDL = DbgLoc;
recomputeInsertPt();
DbgLoc = DebugLoc();
SavePoint SP = {OldInsertPt, OldDL};
return SP;
}
void FastISel::leaveLocalValueArea(SavePoint OldInsertPt) {
if (FuncInfo.InsertPt != FuncInfo.MBB->begin())
LastLocalValue = std::prev(FuncInfo.InsertPt);
// Restore the previous insert position.
FuncInfo.InsertPt = OldInsertPt.InsertPt;
DbgLoc = OldInsertPt.DL;
}
bool FastISel::selectBinaryOp(const User *I, unsigned 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;
}
// Check if the first operand is a constant, and handle it as "ri". At -O0,
// we don't have anything that canonicalizes operand order.
if (const auto *CI = dyn_cast<ConstantInt>(I->getOperand(0)))
if (isa<Instruction>(I) && cast<Instruction>(I)->isCommutative()) {
unsigned Op1 = getRegForValue(I->getOperand(1));
if (!Op1)
return false;
bool Op1IsKill = hasTrivialKill(I->getOperand(1));
unsigned ResultReg =
fastEmit_ri_(VT.getSimpleVT(), ISDOpcode, Op1, Op1IsKill,
CI->getZExtValue(), VT.getSimpleVT());
if (!ResultReg)
return false;
// We successfully emitted code for the given LLVM Instruction.
updateValueMap(I, ResultReg);
return true;
}
unsigned Op0 = getRegForValue(I->getOperand(0));
if (!Op0) // Unhandled operand. Halt "fast" selection and bail.
return false;
bool Op0IsKill = hasTrivialKill(I->getOperand(0));
// Check if the second operand is a constant and handle it appropriately.
if (const auto *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
uint64_t Imm = CI->getZExtValue();
// Transform "sdiv exact X, 8" -> "sra X, 3".
if (ISDOpcode == ISD::SDIV && isa<BinaryOperator>(I) &&
cast<BinaryOperator>(I)->isExact() && isPowerOf2_64(Imm)) {
Imm = Log2_64(Imm);
ISDOpcode = ISD::SRA;
}
// Transform "urem x, pow2" -> "and x, pow2-1".
if (ISDOpcode == ISD::UREM && isa<BinaryOperator>(I) &&
isPowerOf2_64(Imm)) {
--Imm;
ISDOpcode = ISD::AND;
}
unsigned ResultReg = fastEmit_ri_(VT.getSimpleVT(), ISDOpcode, Op0,
Op0IsKill, Imm, VT.getSimpleVT());
if (!ResultReg)
return false;
// We successfully emitted code for the given LLVM Instruction.
updateValueMap(I, ResultReg);
return true;
}
// Check if the second operand is a constant float.
if (const auto *CF = dyn_cast<ConstantFP>(I->getOperand(1))) {
unsigned ResultReg = fastEmit_rf(VT.getSimpleVT(), VT.getSimpleVT(),
ISDOpcode, Op0, Op0IsKill, CF);
if (ResultReg) {
// We successfully emitted code for the given LLVM Instruction.
updateValueMap(I, ResultReg);
return true;
}
}
unsigned Op1 = getRegForValue(I->getOperand(1));
if (!Op1) // Unhandled operand. Halt "fast" selection and bail.
return false;
bool Op1IsKill = hasTrivialKill(I->getOperand(1));
// Now we have both operands in registers. Emit the instruction.
unsigned ResultReg = fastEmit_rr(VT.getSimpleVT(), VT.getSimpleVT(),
ISDOpcode, Op0, Op0IsKill, Op1, Op1IsKill);
if (!ResultReg)
// 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(const User *I) {
unsigned N = getRegForValue(I->getOperand(0));
if (!N) // Unhandled operand. Halt "fast" selection and bail.
return false;
bool NIsKill = hasTrivialKill(I->getOperand(0));
// Keep a running tab of the total offset to coalesce multiple N = N + Offset
// into a single N = N + TotalOffset.
uint64_t TotalOffs = 0;
// FIXME: What's a good SWAG number for MaxOffs?
uint64_t MaxOffs = 2048;
Type *Ty = I->getOperand(0)->getType();
MVT VT = TLI.getPointerTy();
for (GetElementPtrInst::const_op_iterator OI = I->op_begin() + 1,
E = I->op_end();
OI != E; ++OI) {
const Value *Idx = *OI;
if (auto *StTy = dyn_cast<StructType>(Ty)) {
unsigned Field = cast<ConstantInt>(Idx)->getZExtValue();
if (Field) {
// N = N + Offset
TotalOffs += DL.getStructLayout(StTy)->getElementOffset(Field);
if (TotalOffs >= MaxOffs) {
N = fastEmit_ri_(VT, ISD::ADD, N, NIsKill, TotalOffs, VT);
if (!N) // Unhandled operand. Halt "fast" selection and bail.
return false;
NIsKill = true;
TotalOffs = 0;
}
}
Ty = StTy->getElementType(Field);
} else {
Ty = cast<SequentialType>(Ty)->getElementType();
// If this is a constant subscript, handle it quickly.
if (const auto *CI = dyn_cast<ConstantInt>(Idx)) {
if (CI->isZero())
continue;
// N = N + Offset
TotalOffs +=
DL.getTypeAllocSize(Ty) * cast<ConstantInt>(CI)->getSExtValue();
if (TotalOffs >= MaxOffs) {
N = fastEmit_ri_(VT, ISD::ADD, N, NIsKill, TotalOffs, VT);
if (!N) // Unhandled operand. Halt "fast" selection and bail.
return false;
NIsKill = true;
TotalOffs = 0;
}
continue;
}
if (TotalOffs) {
N = fastEmit_ri_(VT, ISD::ADD, N, NIsKill, TotalOffs, VT);
if (!N) // Unhandled operand. Halt "fast" selection and bail.
return false;
NIsKill = true;
TotalOffs = 0;
}
// N = N + Idx * ElementSize;
uint64_t ElementSize = DL.getTypeAllocSize(Ty);
std::pair<unsigned, bool> Pair = getRegForGEPIndex(Idx);
unsigned IdxN = Pair.first;
bool IdxNIsKill = Pair.second;
if (!IdxN) // Unhandled operand. Halt "fast" selection and bail.
return false;
if (ElementSize != 1) {
IdxN = fastEmit_ri_(VT, ISD::MUL, IdxN, IdxNIsKill, ElementSize, VT);
if (!IdxN) // Unhandled operand. Halt "fast" selection and bail.
return false;
IdxNIsKill = true;
}
N = fastEmit_rr(VT, VT, ISD::ADD, N, NIsKill, IdxN, IdxNIsKill);
if (!N) // Unhandled operand. Halt "fast" selection and bail.
return false;
}
}
if (TotalOffs) {
N = fastEmit_ri_(VT, ISD::ADD, N, NIsKill, TotalOffs, VT);
if (!N) // 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::addStackMapLiveVars(SmallVectorImpl<MachineOperand> &Ops,
const CallInst *CI, unsigned StartIdx) {
for (unsigned i = StartIdx, e = CI->getNumArgOperands(); i != e; ++i) {
Value *Val = CI->getArgOperand(i);
// Check for constants and encode them with a StackMaps::ConstantOp prefix.
if (const auto *C = dyn_cast<ConstantInt>(Val)) {
Ops.push_back(MachineOperand::CreateImm(StackMaps::ConstantOp));
Ops.push_back(MachineOperand::CreateImm(C->getSExtValue()));
} else if (isa<ConstantPointerNull>(Val)) {
Ops.push_back(MachineOperand::CreateImm(StackMaps::ConstantOp));
Ops.push_back(MachineOperand::CreateImm(0));
} else if (auto *AI = dyn_cast<AllocaInst>(Val)) {
// Values coming from a stack location also require a sepcial encoding,
// but that is added later on by the target specific frame index
// elimination implementation.
auto SI = FuncInfo.StaticAllocaMap.find(AI);
if (SI != FuncInfo.StaticAllocaMap.end())
Ops.push_back(MachineOperand::CreateFI(SI->second));
else
return false;
} else {
unsigned Reg = getRegForValue(Val);
if (!Reg)
return false;
Ops.push_back(MachineOperand::CreateReg(Reg, /*IsDef=*/false));
}
}
return true;
}
bool FastISel::selectStackmap(const CallInst *I) {
// void @llvm.experimental.stackmap(i64 <id>, i32 <numShadowBytes>,
// [live variables...])
assert(I->getCalledFunction()->getReturnType()->isVoidTy() &&
"Stackmap cannot return a value.");
// The stackmap intrinsic only records the live variables (the arguments
// passed to it) and emits NOPS (if requested). Unlike the patchpoint
// intrinsic, this won't be lowered to a function call. This means we don't
// have to worry about calling conventions and target-specific lowering code.
// Instead we perform the call lowering right here.
//
// CALLSEQ_START(0)
// STACKMAP(id, nbytes, ...)
// CALLSEQ_END(0, 0)
//
SmallVector<MachineOperand, 32> Ops;
// Add the <id> and <numBytes> constants.
assert(isa<ConstantInt>(I->getOperand(PatchPointOpers::IDPos)) &&
"Expected a constant integer.");
const auto *ID = cast<ConstantInt>(I->getOperand(PatchPointOpers::IDPos));
Ops.push_back(MachineOperand::CreateImm(ID->getZExtValue()));
assert(isa<ConstantInt>(I->getOperand(PatchPointOpers::NBytesPos)) &&
"Expected a constant integer.");
const auto *NumBytes =
cast<ConstantInt>(I->getOperand(PatchPointOpers::NBytesPos));
Ops.push_back(MachineOperand::CreateImm(NumBytes->getZExtValue()));
// Push live variables for the stack map (skipping the first two arguments
// <id> and <numBytes>).
if (!addStackMapLiveVars(Ops, I, 2))
return false;
// We are not adding any register mask info here, because the stackmap doesn't
// clobber anything.
// Add scratch registers as implicit def and early clobber.
CallingConv::ID CC = I->getCallingConv();
const MCPhysReg *ScratchRegs = TLI.getScratchRegisters(CC);
for (unsigned i = 0; ScratchRegs[i]; ++i)
Ops.push_back(MachineOperand::CreateReg(
ScratchRegs[i], /*IsDef=*/true, /*IsImp=*/true, /*IsKill=*/false,
/*IsDead=*/false, /*IsUndef=*/false, /*IsEarlyClobber=*/true));
// Issue CALLSEQ_START
unsigned AdjStackDown = TII.getCallFrameSetupOpcode();
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(AdjStackDown))
.addImm(0);
// Issue STACKMAP.
MachineInstrBuilder MIB = BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::STACKMAP));
for (auto const &MO : Ops)
MIB.addOperand(MO);
// Issue CALLSEQ_END
unsigned AdjStackUp = TII.getCallFrameDestroyOpcode();
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(AdjStackUp))
.addImm(0)
.addImm(0);
// Inform the Frame Information that we have a stackmap in this function.
FuncInfo.MF->getFrameInfo()->setHasStackMap();
return true;
}
/// \brief Lower an argument list according to the target calling convention.
///
/// This is a helper for lowering intrinsics that follow a target calling
/// convention or require stack pointer adjustment. Only a subset of the
/// intrinsic's operands need to participate in the calling convention.
bool FastISel::lowerCallOperands(const CallInst *CI, unsigned ArgIdx,
unsigned NumArgs, const Value *Callee,
bool ForceRetVoidTy, CallLoweringInfo &CLI) {
ArgListTy Args;
Args.reserve(NumArgs);
// Populate the argument list.
// Attributes for args start at offset 1, after the return attribute.
ImmutableCallSite CS(CI);
for (unsigned ArgI = ArgIdx, ArgE = ArgIdx + NumArgs, AttrI = ArgIdx + 1;
ArgI != ArgE; ++ArgI) {
Value *V = CI->getOperand(ArgI);
assert(!V->getType()->isEmptyTy() && "Empty type passed to intrinsic.");
ArgListEntry Entry;
Entry.Val = V;
Entry.Ty = V->getType();
Entry.setAttributes(&CS, AttrI);
Args.push_back(Entry);
}
Type *RetTy = ForceRetVoidTy ? Type::getVoidTy(CI->getType()->getContext())
: CI->getType();
CLI.setCallee(CI->getCallingConv(), RetTy, Callee, std::move(Args), NumArgs);
return lowerCallTo(CLI);
}
bool FastISel::selectPatchpoint(const CallInst *I) {
// void|i64 @llvm.experimental.patchpoint.void|i64(i64 <id>,
// i32 <numBytes>,
// i8* <target>,
// i32 <numArgs>,
// [Args...],
// [live variables...])
CallingConv::ID CC = I->getCallingConv();
bool IsAnyRegCC = CC == CallingConv::AnyReg;
bool HasDef = !I->getType()->isVoidTy();
Value *Callee = I->getOperand(PatchPointOpers::TargetPos);
// Get the real number of arguments participating in the call <numArgs>
assert(isa<ConstantInt>(I->getOperand(PatchPointOpers::NArgPos)) &&
"Expected a constant integer.");
const auto *NumArgsVal =
cast<ConstantInt>(I->getOperand(PatchPointOpers::NArgPos));
unsigned NumArgs = NumArgsVal->getZExtValue();
// Skip the four meta args: <id>, <numNopBytes>, <target>, <numArgs>
// This includes all meta-operands up to but not including CC.
unsigned NumMetaOpers = PatchPointOpers::CCPos;
assert(I->getNumArgOperands() >= NumMetaOpers + NumArgs &&
"Not enough arguments provided to the patchpoint intrinsic");
// For AnyRegCC the arguments are lowered later on manually.
unsigned NumCallArgs = IsAnyRegCC ? 0 : NumArgs;
CallLoweringInfo CLI;
if (!lowerCallOperands(I, NumMetaOpers, NumCallArgs, Callee, IsAnyRegCC, CLI))
return false;
assert(CLI.Call && "No call instruction specified.");
SmallVector<MachineOperand, 32> Ops;
// Add an explicit result reg if we use the anyreg calling convention.
if (IsAnyRegCC && HasDef) {
assert(CLI.NumResultRegs == 0 && "Unexpected result register.");
CLI.ResultReg = createResultReg(TLI.getRegClassFor(MVT::i64));
CLI.NumResultRegs = 1;
Ops.push_back(MachineOperand::CreateReg(CLI.ResultReg, /*IsDef=*/true));
}
// Add the <id> and <numBytes> constants.
assert(isa<ConstantInt>(I->getOperand(PatchPointOpers::IDPos)) &&
"Expected a constant integer.");
const auto *ID = cast<ConstantInt>(I->getOperand(PatchPointOpers::IDPos));
Ops.push_back(MachineOperand::CreateImm(ID->getZExtValue()));
assert(isa<ConstantInt>(I->getOperand(PatchPointOpers::NBytesPos)) &&
"Expected a constant integer.");
const auto *NumBytes =
cast<ConstantInt>(I->getOperand(PatchPointOpers::NBytesPos));
Ops.push_back(MachineOperand::CreateImm(NumBytes->getZExtValue()));
// Assume that the callee is a constant address or null pointer.
// FIXME: handle function symbols in the future.
uint64_t CalleeAddr;
if (const auto *C = dyn_cast<IntToPtrInst>(Callee))
CalleeAddr = cast<ConstantInt>(C->getOperand(0))->getZExtValue();
else if (const auto *C = dyn_cast<ConstantExpr>(Callee)) {
if (C->getOpcode() == Instruction::IntToPtr)
CalleeAddr = cast<ConstantInt>(C->getOperand(0))->getZExtValue();
else
llvm_unreachable("Unsupported ConstantExpr.");
} else if (isa<ConstantPointerNull>(Callee))
CalleeAddr = 0;
else
llvm_unreachable("Unsupported callee address.");
Ops.push_back(MachineOperand::CreateImm(CalleeAddr));
// Adjust <numArgs> to account for any arguments that have been passed on
// the stack instead.
unsigned NumCallRegArgs = IsAnyRegCC ? NumArgs : CLI.OutRegs.size();
Ops.push_back(MachineOperand::CreateImm(NumCallRegArgs));
// Add the calling convention
Ops.push_back(MachineOperand::CreateImm((unsigned)CC));
// Add the arguments we omitted previously. The register allocator should
// place these in any free register.
if (IsAnyRegCC) {
for (unsigned i = NumMetaOpers, e = NumMetaOpers + NumArgs; i != e; ++i) {
unsigned Reg = getRegForValue(I->getArgOperand(i));
if (!Reg)
return false;
Ops.push_back(MachineOperand::CreateReg(Reg, /*IsDef=*/false));
}
}
// Push the arguments from the call instruction.
for (auto Reg : CLI.OutRegs)
Ops.push_back(MachineOperand::CreateReg(Reg, /*IsDef=*/false));
// Push live variables for the stack map.
if (!addStackMapLiveVars(Ops, I, NumMetaOpers + NumArgs))
return false;
// Push the register mask info.
Ops.push_back(MachineOperand::CreateRegMask(TRI.getCallPreservedMask(CC)));
// Add scratch registers as implicit def and early clobber.
const MCPhysReg *ScratchRegs = TLI.getScratchRegisters(CC);
for (unsigned i = 0; ScratchRegs[i]; ++i)
Ops.push_back(MachineOperand::CreateReg(
ScratchRegs[i], /*IsDef=*/true, /*IsImp=*/true, /*IsKill=*/false,
/*IsDead=*/false, /*IsUndef=*/false, /*IsEarlyClobber=*/true));
// Add implicit defs (return values).
for (auto Reg : CLI.InRegs)
Ops.push_back(MachineOperand::CreateReg(Reg, /*IsDef=*/true,
/*IsImpl=*/true));
// Insert the patchpoint instruction before the call generated by the target.
MachineInstrBuilder MIB = BuildMI(*FuncInfo.MBB, CLI.Call, DbgLoc,
TII.get(TargetOpcode::PATCHPOINT));
for (auto &MO : Ops)
MIB.addOperand(MO);
MIB->setPhysRegsDeadExcept(CLI.InRegs, TRI);
// Delete the original call instruction.
CLI.Call->eraseFromParent();
// Inform the Frame Information that we have a patchpoint in this function.
FuncInfo.MF->getFrameInfo()->setHasPatchPoint();
if (CLI.NumResultRegs)
updateValueMap(I, CLI.ResultReg, CLI.NumResultRegs);
return true;
}
/// Returns an AttributeSet representing the attributes applied to the return
/// value of the given call.
static AttributeSet getReturnAttrs(FastISel::CallLoweringInfo &CLI) {
SmallVector<Attribute::AttrKind, 2> Attrs;
if (CLI.RetSExt)
Attrs.push_back(Attribute::SExt);
if (CLI.RetZExt)
Attrs.push_back(Attribute::ZExt);
if (CLI.IsInReg)
Attrs.push_back(Attribute::InReg);
return AttributeSet::get(CLI.RetTy->getContext(), AttributeSet::ReturnIndex,
Attrs);
}
bool FastISel::lowerCallTo(const CallInst *CI, const char *SymName,
unsigned NumArgs) {
ImmutableCallSite CS(CI);
PointerType *PT = cast<PointerType>(CS.getCalledValue()->getType());
FunctionType *FTy = cast<FunctionType>(PT->getElementType());
Type *RetTy = FTy->getReturnType();
ArgListTy Args;
Args.reserve(NumArgs);
// Populate the argument list.
// Attributes for args start at offset 1, after the return attribute.
for (unsigned ArgI = 0; ArgI != NumArgs; ++ArgI) {
Value *V = CI->getOperand(ArgI);
assert(!V->getType()->isEmptyTy() && "Empty type passed to intrinsic.");
ArgListEntry Entry;
Entry.Val = V;
Entry.Ty = V->getType();
Entry.setAttributes(&CS, ArgI + 1);
Args.push_back(Entry);
}
CallLoweringInfo CLI;
CLI.setCallee(RetTy, FTy, SymName, std::move(Args), CS, NumArgs);
return lowerCallTo(CLI);
}
bool FastISel::lowerCallTo(CallLoweringInfo &CLI) {
// Handle the incoming return values from the call.
CLI.clearIns();
SmallVector<EVT, 4> RetTys;
ComputeValueVTs(TLI, CLI.RetTy, RetTys);
SmallVector<ISD::OutputArg, 4> Outs;
GetReturnInfo(CLI.RetTy, getReturnAttrs(CLI), Outs, TLI);
bool CanLowerReturn = TLI.CanLowerReturn(
CLI.CallConv, *FuncInfo.MF, CLI.IsVarArg, Outs, CLI.RetTy->getContext());
// FIXME: sret demotion isn't supported yet - bail out.
if (!CanLowerReturn)
return false;
for (unsigned I = 0, E = RetTys.size(); I != E; ++I) {
EVT VT = RetTys[I];
MVT RegisterVT = TLI.getRegisterType(CLI.RetTy->getContext(), VT);
unsigned NumRegs = TLI.getNumRegisters(CLI.RetTy->getContext(), VT);
for (unsigned i = 0; i != NumRegs; ++i) {
ISD::InputArg MyFlags;
MyFlags.VT = RegisterVT;
MyFlags.ArgVT = VT;
MyFlags.Used = CLI.IsReturnValueUsed;
if (CLI.RetSExt)
MyFlags.Flags.setSExt();
if (CLI.RetZExt)
MyFlags.Flags.setZExt();
if (CLI.IsInReg)
MyFlags.Flags.setInReg();
CLI.Ins.push_back(MyFlags);
}
}
// Handle all of the outgoing arguments.
CLI.clearOuts();
for (auto &Arg : CLI.getArgs()) {
Type *FinalType = Arg.Ty;
if (Arg.IsByVal)
FinalType = cast<PointerType>(Arg.Ty)->getElementType();
bool NeedsRegBlock = TLI.functionArgumentNeedsConsecutiveRegisters(
FinalType, CLI.CallConv, CLI.IsVarArg);
ISD::ArgFlagsTy Flags;
if (Arg.IsZExt)
Flags.setZExt();
if (Arg.IsSExt)
Flags.setSExt();
if (Arg.IsInReg)
Flags.setInReg();
if (Arg.IsSRet)
Flags.setSRet();
if (Arg.IsByVal)
Flags.setByVal();
if (Arg.IsInAlloca) {
Flags.setInAlloca();
// Set the byval flag for CCAssignFn callbacks that don't know about
// inalloca. This way we can know how many bytes we should've allocated
// and how many bytes a callee cleanup function will pop. If we port
// inalloca to more targets, we'll have to add custom inalloca handling in
// the various CC lowering callbacks.
Flags.setByVal();
}
if (Arg.IsByVal || Arg.IsInAlloca) {
PointerType *Ty = cast<PointerType>(Arg.Ty);
Type *ElementTy = Ty->getElementType();
unsigned FrameSize = DL.getTypeAllocSize(ElementTy);
// For ByVal, alignment should come from FE. BE will guess if this info is
// not there, but there are cases it cannot get right.
unsigned FrameAlign = Arg.Alignment;
if (!FrameAlign)
FrameAlign = TLI.getByValTypeAlignment(ElementTy);
Flags.setByValSize(FrameSize);
Flags.setByValAlign(FrameAlign);
}
if (Arg.IsNest)
Flags.setNest();
if (NeedsRegBlock)
Flags.setInConsecutiveRegs();
unsigned OriginalAlignment = DL.getABITypeAlignment(Arg.Ty);
Flags.setOrigAlign(OriginalAlignment);
CLI.OutVals.push_back(Arg.Val);
CLI.OutFlags.push_back(Flags);
}
if (!fastLowerCall(CLI))
return false;
// Set all unused physreg defs as dead.
assert(CLI.Call && "No call instruction specified.");
CLI.Call->setPhysRegsDeadExcept(CLI.InRegs, TRI);
if (CLI.NumResultRegs && CLI.CS)
updateValueMap(CLI.CS->getInstruction(), CLI.ResultReg, CLI.NumResultRegs);
return true;
}
bool FastISel::lowerCall(const CallInst *CI) {
ImmutableCallSite CS(CI);
PointerType *PT = cast<PointerType>(CS.getCalledValue()->getType());
FunctionType *FuncTy = cast<FunctionType>(PT->getElementType());
Type *RetTy = FuncTy->getReturnType();
ArgListTy Args;
ArgListEntry Entry;
Args.reserve(CS.arg_size());
for (ImmutableCallSite::arg_iterator i = CS.arg_begin(), e = CS.arg_end();
i != e; ++i) {
Value *V = *i;
// Skip empty types
if (V->getType()->isEmptyTy())
continue;
Entry.Val = V;
Entry.Ty = V->getType();
// Skip the first return-type Attribute to get to params.
Entry.setAttributes(&CS, i - CS.arg_begin() + 1);
Args.push_back(Entry);
}
// Check if target-independent constraints permit a tail call here.
// Target-dependent constraints are checked within fastLowerCall.
bool IsTailCall = CI->isTailCall();
if (IsTailCall && !isInTailCallPosition(CS, TM))
IsTailCall = false;
CallLoweringInfo CLI;
CLI.setCallee(RetTy, FuncTy, CI->getCalledValue(), std::move(Args), CS)
.setTailCall(IsTailCall);
return lowerCallTo(CLI);
}
bool FastISel::selectCall(const User *I) {
const CallInst *Call = cast<CallInst>(I);
// Handle simple inline asms.
if (const InlineAsm *IA = dyn_cast<InlineAsm>(Call->getCalledValue())) {
// If the inline asm has side effects, then make sure that no local value
// lives across by flushing the local value map.
if (IA->hasSideEffects())
flushLocalValueMap();
// Don't attempt to handle constraints.
if (!IA->getConstraintString().empty())
return false;
unsigned ExtraInfo = 0;
if (IA->hasSideEffects())
ExtraInfo |= InlineAsm::Extra_HasSideEffects;
if (IA->isAlignStack())
ExtraInfo |= InlineAsm::Extra_IsAlignStack;
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::INLINEASM))
.addExternalSymbol(IA->getAsmString().c_str())
.addImm(ExtraInfo);
return true;
}
MachineModuleInfo &MMI = FuncInfo.MF->getMMI();
ComputeUsesVAFloatArgument(*Call, &MMI);
// Handle intrinsic function calls.
if (const auto *II = dyn_cast<IntrinsicInst>(Call))
return selectIntrinsicCall(II);
// Usually, it does not make sense to initialize a value,
// make an unrelated function call and use the value, because
// it tends to be spilled on the stack. So, we move the pointer
// to the last local value to the beginning of the block, so that
// all the values which have already been materialized,
// appear after the call. It also makes sense to skip intrinsics
// since they tend to be inlined.
flushLocalValueMap();
return lowerCall(Call);
}
bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
switch (II->getIntrinsicID()) {
default:
break;
// At -O0 we don't care about the lifetime intrinsics.
case Intrinsic::lifetime_start:
case Intrinsic::lifetime_end:
// The donothing intrinsic does, well, nothing.
case Intrinsic::donothing:
return true;
case Intrinsic::dbg_declare: {
const DbgDeclareInst *DI = cast<DbgDeclareInst>(II);
DIVariable DIVar(DI->getVariable());
assert((!DIVar || DIVar.isVariable()) &&
"Variable in DbgDeclareInst should be either null or a DIVariable.");
if (!DIVar || !FuncInfo.MF->getMMI().hasDebugInfo()) {
DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
return true;
}
const Value *Address = DI->getAddress();
if (!Address || isa<UndefValue>(Address)) {
DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
return true;
}
unsigned Offset = 0;
Optional<MachineOperand> Op;
if (const auto *Arg = dyn_cast<Argument>(Address))
// Some arguments' frame index is recorded during argument lowering.
Offset = FuncInfo.getArgumentFrameIndex(Arg);
if (Offset)
Op = MachineOperand::CreateFI(Offset);
if (!Op)
if (unsigned Reg = lookUpRegForValue(Address))
Op = MachineOperand::CreateReg(Reg, false);
// If we have a VLA that has a "use" in a metadata node that's then used
// here but it has no other uses, then we have a problem. E.g.,
//
// int foo (const int *x) {
// char a[*x];
// return 0;
// }
//
// If we assign 'a' a vreg and fast isel later on has to use the selection
// DAG isel, it will want to copy the value to the vreg. However, there are
// no uses, which goes counter to what selection DAG isel expects.
if (!Op && !Address->use_empty() && isa<Instruction>(Address) &&
(!isa<AllocaInst>(Address) ||
!FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(Address))))
Op = MachineOperand::CreateReg(FuncInfo.InitializeRegForValue(Address),
false);
if (Op) {
if (Op->isReg()) {
Op->setIsDebug(true);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::DBG_VALUE), false, Op->getReg(), 0,
DI->getVariable());
} else
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::DBG_VALUE))
.addOperand(*Op)
.addImm(0)
.addMetadata(DI->getVariable());
} else {
// We can't yet handle anything else here because it would require
// generating code, thus altering codegen because of debug info.
DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
}
return true;
}
case Intrinsic::dbg_value: {
// This form of DBG_VALUE is target-independent.
const DbgValueInst *DI = cast<DbgValueInst>(II);
const MCInstrDesc &II = TII.get(TargetOpcode::DBG_VALUE);
const Value *V = DI->getValue();
if (!V) {
// Currently the optimizer can produce this; insert an undef to
// help debugging. Probably the optimizer should not do this.
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addReg(0U)
.addImm(DI->getOffset())
.addMetadata(DI->getVariable());
} else if (const auto *CI = dyn_cast<ConstantInt>(V)) {
if (CI->getBitWidth() > 64)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addCImm(CI)
.addImm(DI->getOffset())
.addMetadata(DI->getVariable());
else
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addImm(CI->getZExtValue())
.addImm(DI->getOffset())
.addMetadata(DI->getVariable());
} else if (const auto *CF = dyn_cast<ConstantFP>(V)) {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addFPImm(CF)
.addImm(DI->getOffset())
.addMetadata(DI->getVariable());
} else if (unsigned Reg = lookUpRegForValue(V)) {
// FIXME: This does not handle register-indirect values at offset 0.
bool IsIndirect = DI->getOffset() != 0;
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, IsIndirect, Reg,
DI->getOffset(), DI->getVariable());
} else {
// We can't yet handle anything else here because it would require
// generating code, thus altering codegen because of debug info.
DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
}
return true;
}
case Intrinsic::objectsize: {
ConstantInt *CI = cast<ConstantInt>(II->getArgOperand(1));
unsigned long long Res = CI->isZero() ? -1ULL : 0;
Constant *ResCI = ConstantInt::get(II->getType(), Res);
unsigned ResultReg = getRegForValue(ResCI);
if (!ResultReg)
return false;
updateValueMap(II, ResultReg);
return true;
}
case Intrinsic::expect: {
unsigned ResultReg = getRegForValue(II->getArgOperand(0));
if (!ResultReg)
return false;
updateValueMap(II, ResultReg);
return true;
}
case Intrinsic::experimental_stackmap:
return selectStackmap(II);
case Intrinsic::experimental_patchpoint_void:
case Intrinsic::experimental_patchpoint_i64:
return selectPatchpoint(II);
}
return fastLowerIntrinsicCall(II);
}
bool FastISel::selectCast(const User *I, unsigned 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.
if (!TLI.isTypeLegal(DstVT))
return false;
// Check if the source operand is legal.
if (!TLI.isTypeLegal(SrcVT))
return false;
unsigned InputReg = getRegForValue(I->getOperand(0));
if (!InputReg)
// Unhandled operand. Halt "fast" selection and bail.
return false;
bool InputRegIsKill = hasTrivialKill(I->getOperand(0));
unsigned ResultReg = fastEmit_r(SrcVT.getSimpleVT(), DstVT.getSimpleVT(),
Opcode, InputReg, InputRegIsKill);
if (!ResultReg)
return false;
updateValueMap(I, ResultReg);
return true;
}
bool FastISel::selectBitCast(const 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)
return false;
updateValueMap(I, Reg);
return true;
}
// Bitcasts of other values become reg-reg copies or BITCAST operators.
EVT SrcEVT = TLI.getValueType(I->getOperand(0)->getType());
EVT DstEVT = TLI.getValueType(I->getType());
if (SrcEVT == MVT::Other || DstEVT == MVT::Other ||
!TLI.isTypeLegal(SrcEVT) || !TLI.isTypeLegal(DstEVT))
// Unhandled type. Halt "fast" selection and bail.
return false;
MVT SrcVT = SrcEVT.getSimpleVT();
MVT DstVT = DstEVT.getSimpleVT();
unsigned Op0 = getRegForValue(I->getOperand(0));
if (!Op0) // Unhandled operand. Halt "fast" selection and bail.
return false;
bool Op0IsKill = hasTrivialKill(I->getOperand(0));
// First, try to perform the bitcast by inserting a reg-reg copy.
unsigned ResultReg = 0;
if (SrcVT == DstVT) {
const TargetRegisterClass *SrcClass = TLI.getRegClassFor(SrcVT);
const TargetRegisterClass *DstClass = TLI.getRegClassFor(DstVT);
// Don't attempt a cross-class copy. It will likely fail.
if (SrcClass == DstClass) {
ResultReg = createResultReg(DstClass);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(Op0);
}
}
// If the reg-reg copy failed, select a BITCAST opcode.
if (!ResultReg)
ResultReg = fastEmit_r(SrcVT, DstVT, ISD::BITCAST, Op0, Op0IsKill);
if (!ResultReg)
return false;
updateValueMap(I, ResultReg);
return true;
}
bool FastISel::selectInstruction(const Instruction *I) {
// Just before the terminator instruction, insert instructions to
// feed PHI nodes in successor blocks.
if (isa<TerminatorInst>(I))
if (!handlePHINodesInSuccessorBlocks(I->getParent()))
return false;
DbgLoc = I->getDebugLoc();
SavedInsertPt = FuncInfo.InsertPt;
if (const auto *Call = dyn_cast<CallInst>(I)) {
const Function *F = Call->getCalledFunction();
LibFunc::Func Func;
// As a special case, don't handle calls to builtin library functions that
// may be translated directly to target instructions.
if (F && !F->hasLocalLinkage() && F->hasName() &&
LibInfo->getLibFunc(F->getName(), Func) &&
LibInfo->hasOptimizedCodeGen(Func))
return false;
// Don't handle Intrinsic::trap if a trap funciton is specified.
if (F && F->getIntrinsicID() == Intrinsic::trap &&
!TM.Options.getTrapFunctionName().empty())
return false;
}
// First, try doing target-independent selection.
if (!SkipTargetIndependentISel) {
if (selectOperator(I, I->getOpcode())) {
++NumFastIselSuccessIndependent;
DbgLoc = DebugLoc();
return true;
}
// Remove dead code.
recomputeInsertPt();
if (SavedInsertPt != FuncInfo.InsertPt)
removeDeadCode(FuncInfo.InsertPt, SavedInsertPt);
SavedInsertPt = FuncInfo.InsertPt;
}
// Next, try calling the target to attempt to handle the instruction.
if (fastSelectInstruction(I)) {
++NumFastIselSuccessTarget;
DbgLoc = DebugLoc();
return true;
}
// Remove dead code.
recomputeInsertPt();
if (SavedInsertPt != FuncInfo.InsertPt)
removeDeadCode(FuncInfo.InsertPt, SavedInsertPt);
DbgLoc = DebugLoc();
// Undo phi node updates, because they will be added again by SelectionDAG.
if (isa<TerminatorInst>(I))
FuncInfo.PHINodesToUpdate.resize(FuncInfo.OrigNumPHINodesToUpdate);
return false;
}
/// 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, DebugLoc DbgLoc) {
if (FuncInfo.MBB->getBasicBlock()->size() > 1 &&
FuncInfo.MBB->isLayoutSuccessor(MSucc)) {
// For more accurate line information if this is the only instruction
// in the block then emit it, otherwise we have the unconditional
// fall-through case, which needs no instructions.
} else {
// The unconditional branch case.
TII.InsertBranch(*FuncInfo.MBB, MSucc, nullptr,
SmallVector<MachineOperand, 0>(), DbgLoc);
}
uint32_t BranchWeight = 0;
if (FuncInfo.BPI)
BranchWeight = FuncInfo.BPI->getEdgeWeight(FuncInfo.MBB->getBasicBlock(),
MSucc->getBasicBlock());
FuncInfo.MBB->addSuccessor(MSucc, BranchWeight);
}
/// Emit an FNeg operation.
bool FastISel::selectFNeg(const User *I) {
unsigned OpReg = getRegForValue(BinaryOperator::getFNegArgument(I));
if (!OpReg)
return false;
bool OpRegIsKill = hasTrivialKill(I);
// 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, OpRegIsKill);
if (ResultReg) {
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::BITCAST, OpReg, OpRegIsKill);
if (!IntReg)
return false;
unsigned IntResultReg = fastEmit_ri_(
IntVT.getSimpleVT(), ISD::XOR, IntReg, /*IsKill=*/true,
UINT64_C(1) << (VT.getSizeInBits() - 1), IntVT.getSimpleVT());
if (!IntResultReg)
return false;
ResultReg = fastEmit_r(IntVT.getSimpleVT(), VT.getSimpleVT(), ISD::BITCAST,
IntResultReg, /*IsKill=*/true);
if (!ResultReg)
return false;
updateValueMap(I, ResultReg);
return true;
}
bool FastISel::selectExtractValue(const User *U) {
const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(U);
if (!EVI)
return false;
// Make sure we only try to handle extracts with a legal result. But also
// allow i1 because it's easy.
EVT RealVT = TLI.getValueType(EVI->getType(), /*AllowUnknown=*/true);
if (!RealVT.isSimple())
return false;
MVT VT = RealVT.getSimpleVT();
if (!TLI.isTypeLegal(VT) && VT != MVT::i1)
return false;
const Value *Op0 = EVI->getOperand(0);
Type *AggTy = Op0->getType();
// Get the base result register.
unsigned ResultReg;
DenseMap<const Value *, unsigned>::iterator I = FuncInfo.ValueMap.find(Op0);
if (I != FuncInfo.ValueMap.end())
ResultReg = I->second;
else if (isa<Instruction>(Op0))
ResultReg = FuncInfo.InitializeRegForValue(Op0);
else
return false; // fast-isel can't handle aggregate constants at the moment
// Get the actual result register, which is an offset from the base register.
unsigned VTIndex = ComputeLinearIndex(AggTy, EVI->getIndices());
SmallVector<EVT, 4> AggValueVTs;
ComputeValueVTs(TLI, AggTy, AggValueVTs);
for (unsigned i = 0; i < VTIndex; i++)
ResultReg += TLI.getNumRegisters(FuncInfo.Fn->getContext(), AggValueVTs[i]);
updateValueMap(EVI, ResultReg);
return true;
}
bool FastISel::selectOperator(const 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: {
const BranchInst *BI = cast<BranchInst>(I);
if (BI->isUnconditional()) {
const BasicBlock *LLVMSucc = BI->getSuccessor(0);
MachineBasicBlock *MSucc = FuncInfo.MBBMap[LLVMSucc];
fastEmitBranch(MSucc, BI->getDebugLoc());
return true;
}
// Conditional branches are not handed yet.
// Halt "fast" selection and bail.
return false;
}
case Instruction::Unreachable:
if (TM.Options.TrapUnreachable)
return fastEmit_(MVT::Other, MVT::Other, ISD::TRAP) != 0;
else
return true;
case Instruction::Alloca:
// FunctionLowering has the static-sized case covered.
if (FuncInfo.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)
return false;
updateValueMap(I, Reg);
return true;
}
case Instruction::ExtractValue:
return selectExtractValue(I);
case Instruction::PHI:
llvm_unreachable("FastISel shouldn't visit PHI nodes!");
default:
// Unhandled instruction. Halt "fast" selection and bail.
return false;
}
}
FastISel::FastISel(FunctionLoweringInfo &FuncInfo,
const TargetLibraryInfo *LibInfo,
bool SkipTargetIndependentISel)
: FuncInfo(FuncInfo), MF(FuncInfo.MF), MRI(FuncInfo.MF->getRegInfo()),
MFI(*FuncInfo.MF->getFrameInfo()), MCP(*FuncInfo.MF->getConstantPool()),
TM(FuncInfo.MF->getTarget()), DL(*TM.getSubtargetImpl()->getDataLayout()),
TII(*TM.getSubtargetImpl()->getInstrInfo()),
TLI(*TM.getSubtargetImpl()->getTargetLowering()),
TRI(*TM.getSubtargetImpl()->getRegisterInfo()), LibInfo(LibInfo),
SkipTargetIndependentISel(SkipTargetIndependentISel) {}
FastISel::~FastISel() {}
bool FastISel::fastLowerArguments() { return false; }
bool FastISel::fastLowerCall(CallLoweringInfo & /*CLI*/) { return false; }
bool FastISel::fastLowerIntrinsicCall(const IntrinsicInst * /*II*/) {
return false;
}
unsigned FastISel::fastEmit_(MVT, MVT, unsigned) { return 0; }
unsigned FastISel::fastEmit_r(MVT, MVT, unsigned, unsigned /*Op0*/,
bool /*Op0IsKill*/) {
return 0;
}
unsigned FastISel::fastEmit_rr(MVT, MVT, unsigned, unsigned /*Op0*/,
bool /*Op0IsKill*/, unsigned /*Op1*/,
bool /*Op1IsKill*/) {
return 0;
}
unsigned FastISel::fastEmit_i(MVT, MVT, unsigned, uint64_t /*Imm*/) {
return 0;
}
unsigned FastISel::fastEmit_f(MVT, MVT, unsigned,
const ConstantFP * /*FPImm*/) {
return 0;
}
unsigned FastISel::fastEmit_ri(MVT, MVT, unsigned, unsigned /*Op0*/,
bool /*Op0IsKill*/, uint64_t /*Imm*/) {
return 0;
}
unsigned FastISel::fastEmit_rf(MVT, MVT, unsigned, unsigned /*Op0*/,
bool /*Op0IsKill*/,
const ConstantFP * /*FPImm*/) {
return 0;
}
unsigned FastISel::fastEmit_rri(MVT, MVT, unsigned, unsigned /*Op0*/,
bool /*Op0IsKill*/, unsigned /*Op1*/,
bool /*Op1IsKill*/, uint64_t /*Imm*/) {
return 0;
}
/// 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, unsigned Opcode, unsigned Op0,
bool Op0IsKill, uint64_t Imm, MVT ImmType) {
// If this is a multiply by a power of two, emit this as a shift left.
if (Opcode == ISD::MUL && isPowerOf2_64(Imm)) {
Opcode = ISD::SHL;
Imm = Log2_64(Imm);
} else if (Opcode == ISD::UDIV && isPowerOf2_64(Imm)) {
// div x, 8 -> srl x, 3
Opcode = ISD::SRL;
Imm = Log2_64(Imm);
}
// Horrible hack (to be removed), check to make sure shift amounts are
// in-range.
if ((Opcode == ISD::SHL || Opcode == ISD::SRA || Opcode == ISD::SRL) &&
Imm >= VT.getSizeInBits())
return 0;
// First check if immediate type is legal. If not, we can't use the ri form.
unsigned ResultReg = fastEmit_ri(VT, VT, Opcode, Op0, Op0IsKill, Imm);
if (ResultReg)
return ResultReg;
unsigned MaterialReg = fastEmit_i(ImmType, ImmType, ISD::Constant, Imm);
if (!MaterialReg) {
// This is a bit ugly/slow, but failing here means falling out of
// fast-isel, which would be very slow.
IntegerType *ITy =
IntegerType::get(FuncInfo.Fn->getContext(), VT.getSizeInBits());
MaterialReg = getRegForValue(ConstantInt::get(ITy, Imm));
if (!MaterialReg)
return 0;
}
return fastEmit_rr(VT, VT, Opcode, Op0, Op0IsKill, MaterialReg,
/*IsKill=*/true);
}
unsigned FastISel::createResultReg(const TargetRegisterClass *RC) {
return MRI.createVirtualRegister(RC);
}
unsigned FastISel::constrainOperandRegClass(const MCInstrDesc &II, unsigned Op,
unsigned OpNum) {
if (TargetRegisterInfo::isVirtualRegister(Op)) {
const TargetRegisterClass *RegClass =
TII.getRegClass(II, OpNum, &TRI, *FuncInfo.MF);
if (!MRI.constrainRegClass(Op, RegClass)) {
// If it's not legal to COPY between the register classes, something
// has gone very wrong before we got here.
unsigned NewOp = createResultReg(RegClass);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), NewOp).addReg(Op);
return NewOp;
}
}
return Op;
}
unsigned FastISel::fastEmitInst_(unsigned MachineInstOpcode,
const TargetRegisterClass *RC) {
unsigned ResultReg = createResultReg(RC);
const MCInstrDesc &II = TII.get(MachineInstOpcode);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg);
return ResultReg;
}
unsigned FastISel::fastEmitInst_r(unsigned MachineInstOpcode,
const TargetRegisterClass *RC, unsigned Op0,
bool Op0IsKill) {
const MCInstrDesc &II = TII.get(MachineInstOpcode);
unsigned ResultReg = createResultReg(RC);
Op0 = constrainOperandRegClass(II, Op0, II.getNumDefs());
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addReg(Op0, getKillRegState(Op0IsKill));
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addReg(Op0, getKillRegState(Op0IsKill));
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_rr(unsigned MachineInstOpcode,
const TargetRegisterClass *RC, unsigned Op0,
bool Op0IsKill, unsigned Op1,
bool Op1IsKill) {
const MCInstrDesc &II = TII.get(MachineInstOpcode);
unsigned ResultReg = createResultReg(RC);
Op0 = constrainOperandRegClass(II, Op0, II.getNumDefs());
Op1 = constrainOperandRegClass(II, Op1, II.getNumDefs() + 1);
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addReg(Op0, getKillRegState(Op0IsKill))
.addReg(Op1, getKillRegState(Op1IsKill));
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addReg(Op0, getKillRegState(Op0IsKill))
.addReg(Op1, getKillRegState(Op1IsKill));
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_rrr(unsigned MachineInstOpcode,
const TargetRegisterClass *RC, unsigned Op0,
bool Op0IsKill, unsigned Op1,
bool Op1IsKill, unsigned Op2,
bool Op2IsKill) {
const MCInstrDesc &II = TII.get(MachineInstOpcode);
unsigned ResultReg = createResultReg(RC);
Op0 = constrainOperandRegClass(II, Op0, II.getNumDefs());
Op1 = constrainOperandRegClass(II, Op1, II.getNumDefs() + 1);
Op2 = constrainOperandRegClass(II, Op2, II.getNumDefs() + 2);
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addReg(Op0, getKillRegState(Op0IsKill))
.addReg(Op1, getKillRegState(Op1IsKill))
.addReg(Op2, getKillRegState(Op2IsKill));
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addReg(Op0, getKillRegState(Op0IsKill))
.addReg(Op1, getKillRegState(Op1IsKill))
.addReg(Op2, getKillRegState(Op2IsKill));
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_ri(unsigned MachineInstOpcode,
const TargetRegisterClass *RC, unsigned Op0,
bool Op0IsKill, uint64_t Imm) {
const MCInstrDesc &II = TII.get(MachineInstOpcode);
unsigned ResultReg = createResultReg(RC);
Op0 = constrainOperandRegClass(II, Op0, II.getNumDefs());
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addReg(Op0, getKillRegState(Op0IsKill))
.addImm(Imm);
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addReg(Op0, getKillRegState(Op0IsKill))
.addImm(Imm);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_rii(unsigned MachineInstOpcode,
const TargetRegisterClass *RC, unsigned Op0,
bool Op0IsKill, uint64_t Imm1,
uint64_t Imm2) {
const MCInstrDesc &II = TII.get(MachineInstOpcode);
unsigned ResultReg = createResultReg(RC);
Op0 = constrainOperandRegClass(II, Op0, II.getNumDefs());
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addReg(Op0, getKillRegState(Op0IsKill))
.addImm(Imm1)
.addImm(Imm2);
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addReg(Op0, getKillRegState(Op0IsKill))
.addImm(Imm1)
.addImm(Imm2);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_rf(unsigned MachineInstOpcode,
const TargetRegisterClass *RC, unsigned Op0,
bool Op0IsKill, const ConstantFP *FPImm) {
const MCInstrDesc &II = TII.get(MachineInstOpcode);
unsigned ResultReg = createResultReg(RC);
Op0 = constrainOperandRegClass(II, Op0, II.getNumDefs());
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addReg(Op0, getKillRegState(Op0IsKill))
.addFPImm(FPImm);
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addReg(Op0, getKillRegState(Op0IsKill))
.addFPImm(FPImm);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_rri(unsigned MachineInstOpcode,
const TargetRegisterClass *RC, unsigned Op0,
bool Op0IsKill, unsigned Op1,
bool Op1IsKill, uint64_t Imm) {
const MCInstrDesc &II = TII.get(MachineInstOpcode);
unsigned ResultReg = createResultReg(RC);
Op0 = constrainOperandRegClass(II, Op0, II.getNumDefs());
Op1 = constrainOperandRegClass(II, Op1, II.getNumDefs() + 1);
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addReg(Op0, getKillRegState(Op0IsKill))
.addReg(Op1, getKillRegState(Op1IsKill))
.addImm(Imm);
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addReg(Op0, getKillRegState(Op0IsKill))
.addReg(Op1, getKillRegState(Op1IsKill))
.addImm(Imm);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_rrii(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, bool Op0IsKill, unsigned Op1,
bool Op1IsKill, uint64_t Imm1,
uint64_t Imm2) {
const MCInstrDesc &II = TII.get(MachineInstOpcode);
unsigned ResultReg = createResultReg(RC);
Op0 = constrainOperandRegClass(II, Op0, II.getNumDefs());
Op1 = constrainOperandRegClass(II, Op1, II.getNumDefs() + 1);
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addReg(Op0, getKillRegState(Op0IsKill))
.addReg(Op1, getKillRegState(Op1IsKill))
.addImm(Imm1)
.addImm(Imm2);
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II)
.addReg(Op0, getKillRegState(Op0IsKill))
.addReg(Op1, getKillRegState(Op1IsKill))
.addImm(Imm1)
.addImm(Imm2);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_i(unsigned MachineInstOpcode,
const TargetRegisterClass *RC, uint64_t Imm) {
unsigned ResultReg = createResultReg(RC);
const MCInstrDesc &II = TII.get(MachineInstOpcode);
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addImm(Imm);
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II).addImm(Imm);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_ii(unsigned MachineInstOpcode,
const TargetRegisterClass *RC, uint64_t Imm1,
uint64_t Imm2) {
unsigned ResultReg = createResultReg(RC);
const MCInstrDesc &II = TII.get(MachineInstOpcode);
if (II.getNumDefs() >= 1)
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg)
.addImm(Imm1)
.addImm(Imm2);
else {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II).addImm(Imm1)
.addImm(Imm2);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
TII.get(TargetOpcode::COPY), ResultReg).addReg(II.ImplicitDefs[0]);
}
return ResultReg;
}
unsigned FastISel::fastEmitInst_extractsubreg(MVT RetVT, unsigned Op0,
bool Op0IsKill, uint32_t Idx) {
unsigned ResultReg = createResultReg(TLI.getRegClassFor(RetVT));
assert(TargetRegisterInfo::isVirtualRegister(Op0) &&
"Cannot yet extract from physregs");
const TargetRegisterClass *RC = MRI.getRegClass(Op0);
MRI.constrainRegClass(Op0, TRI.getSubClassWithSubReg(RC, Idx));
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(TargetOpcode::COPY),
ResultReg).addReg(Op0, getKillRegState(Op0IsKill), Idx);
return ResultReg;
}
/// Emit MachineInstrs to compute the value of Op with all but the least
/// significant bit set to zero.
unsigned FastISel::fastEmitZExtFromI1(MVT VT, unsigned Op0, bool Op0IsKill) {
return fastEmit_ri(VT, VT, ISD::AND, Op0, Op0IsKill, 1);
}
/// HandlePHINodesInSuccessorBlocks - Handle PHI nodes in successor blocks.
/// Emit code to ensure constants are copied into registers when needed.
/// Remember the virtual registers that need to be added to the Machine PHI
/// nodes as input. We cannot just directly add them, because expansion
/// might result in multiple MBB's for one BB. As such, the start of the
/// BB might correspond to a different MBB than the end.
bool FastISel::handlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB) {
const TerminatorInst *TI = LLVMBB->getTerminator();
SmallPtrSet<MachineBasicBlock *, 4> SuccsHandled;
FuncInfo.OrigNumPHINodesToUpdate = FuncInfo.PHINodesToUpdate.size();
// Check successor nodes' PHI nodes that expect a constant to be available
// from this block.
for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) {
const BasicBlock *SuccBB = TI->getSuccessor(succ);
if (!isa<PHINode>(SuccBB->begin()))
continue;
MachineBasicBlock *SuccMBB = FuncInfo.MBBMap[SuccBB];
// If this terminator has multiple identical successors (common for
// switches), only handle each succ once.
if (!SuccsHandled.insert(SuccMBB))
continue;
MachineBasicBlock::iterator MBBI = SuccMBB->begin();
// At this point we know that there is a 1-1 correspondence between LLVM PHI
// nodes and Machine PHI nodes, but the incoming operands have not been
// emitted yet.
for (BasicBlock::const_iterator I = SuccBB->begin();
const auto *PN = dyn_cast<PHINode>(I); ++I) {
// Ignore dead phi's.
if (PN->use_empty())
continue;
// Only handle legal types. Two interesting things to note here. First,
// by bailing out early, we may leave behind some dead instructions,
// since SelectionDAG's HandlePHINodesInSuccessorBlocks will insert its
// own moves. Second, this check is necessary because FastISel doesn't
// use CreateRegs to create registers, so it always creates
// exactly one register for each non-void instruction.
EVT VT = TLI.getValueType(PN->getType(), /*AllowUnknown=*/true);
if (VT == MVT::Other || !TLI.isTypeLegal(VT)) {
// Handle integer promotions, though, because they're common and easy.
if (VT == MVT::i1 || VT == MVT::i8 || VT == MVT::i16)
VT = TLI.getTypeToTransformTo(LLVMBB->getContext(), VT);
else {
FuncInfo.PHINodesToUpdate.resize(FuncInfo.OrigNumPHINodesToUpdate);
return false;
}
}
const Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
// Set the DebugLoc for the copy. Prefer the location of the operand
// if there is one; use the location of the PHI otherwise.
DbgLoc = PN->getDebugLoc();
if (const auto *Inst = dyn_cast<Instruction>(PHIOp))
DbgLoc = Inst->getDebugLoc();
unsigned Reg = getRegForValue(PHIOp);
if (!Reg) {
FuncInfo.PHINodesToUpdate.resize(FuncInfo.OrigNumPHINodesToUpdate);
return false;
}
FuncInfo.PHINodesToUpdate.push_back(std::make_pair(MBBI++, Reg));
DbgLoc = DebugLoc();
}
}
return true;
}
bool FastISel::tryToFoldLoad(const LoadInst *LI, const Instruction *FoldInst) {
assert(LI->hasOneUse() &&
"tryToFoldLoad expected a LoadInst with a single use");
// We know that the load has a single use, but don't know what it is. If it
// isn't one of the folded instructions, then we can't succeed here. Handle
// this by scanning the single-use users of the load until we get to FoldInst.
unsigned MaxUsers = 6; // Don't scan down huge single-use chains of instrs.
const Instruction *TheUser = LI->user_back();
while (TheUser != FoldInst && // Scan up until we find FoldInst.
// Stay in the right block.
TheUser->getParent() == FoldInst->getParent() &&
--MaxUsers) { // Don't scan too far.
// If there are multiple or no uses of this instruction, then bail out.
if (!TheUser->hasOneUse())
return false;
TheUser = TheUser->user_back();
}
// If we didn't find the fold instruction, then we failed to collapse the
// sequence.
if (TheUser != FoldInst)
return false;
// Don't try to fold volatile loads. Target has to deal with alignment
// constraints.
if (LI->isVolatile())
return false;
// Figure out which vreg this is going into. If there is no assigned vreg yet
// then there actually was no reference to it. Perhaps the load is referenced
// by a dead instruction.
unsigned LoadReg = getRegForValue(LI);
if (!LoadReg)
return false;
// We can't fold if this vreg has no uses or more than one use. Multiple uses
// may mean that the instruction got lowered to multiple MIs, or the use of
// the loaded value ended up being multiple operands of the result.
if (!MRI.hasOneUse(LoadReg))
return false;
MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(LoadReg);
MachineInstr *User = RI->getParent();
// Set the insertion point properly. Folding the load can cause generation of
// other random instructions (like sign extends) for addressing modes; make
// sure they get inserted in a logical place before the new instruction.
FuncInfo.InsertPt = User;
FuncInfo.MBB = User->getParent();
// Ask the target to try folding the load.
return tryToFoldLoadIntoMI(User, RI.getOperandNo(), LI);
}
bool FastISel::canFoldAddIntoGEP(const User *GEP, const Value *Add) {
// Must be an add.
if (!isa<AddOperator>(Add))
return false;
// Type size needs to match.
if (DL.getTypeSizeInBits(GEP->getType()) !=
DL.getTypeSizeInBits(Add->getType()))
return false;
// Must be in the same basic block.
if (isa<Instruction>(Add) &&
FuncInfo.MBBMap[cast<Instruction>(Add)->getParent()] != FuncInfo.MBB)
return false;
// Must have a constant operand.
return isa<ConstantInt>(cast<AddOperator>(Add)->getOperand(1));
}
MachineMemOperand *
FastISel::createMachineMemOperandFor(const Instruction *I) const {
const Value *Ptr;
Type *ValTy;
unsigned Alignment;
unsigned Flags;
bool IsVolatile;
if (const auto *LI = dyn_cast<LoadInst>(I)) {
Alignment = LI->getAlignment();
IsVolatile = LI->isVolatile();
Flags = MachineMemOperand::MOLoad;
Ptr = LI->getPointerOperand();
ValTy = LI->getType();
} else if (const auto *SI = dyn_cast<StoreInst>(I)) {
Alignment = SI->getAlignment();
IsVolatile = SI->isVolatile();
Flags = MachineMemOperand::MOStore;
Ptr = SI->getPointerOperand();
ValTy = SI->getValueOperand()->getType();
} else
return nullptr;
bool IsNonTemporal = I->getMetadata("nontemporal") != nullptr;
bool IsInvariant = I->getMetadata("invariant.load") != nullptr;
const MDNode *Ranges = I->getMetadata(LLVMContext::MD_range);
AAMDNodes AAInfo;
I->getAAMetadata(AAInfo);
if (Alignment == 0) // Ensure that codegen never sees alignment 0.
Alignment = DL.getABITypeAlignment(ValTy);
unsigned Size =
TM.getSubtargetImpl()->getDataLayout()->getTypeStoreSize(ValTy);
if (IsVolatile)
Flags |= MachineMemOperand::MOVolatile;
if (IsNonTemporal)
Flags |= MachineMemOperand::MONonTemporal;
if (IsInvariant)
Flags |= MachineMemOperand::MOInvariant;
return FuncInfo.MF->getMachineMemOperand(MachinePointerInfo(Ptr), Flags, Size,
Alignment, AAInfo, Ranges);
}
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