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llvm-mirror/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
Chris Lattner 8df3ffd7ac zap dead code. 
llvm-svn: 113073
2010-09-04 18:12:00 +00:00

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//===-- AlphaISelDAGToDAG.cpp - Alpha pattern matching inst selector ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a pattern matching instruction selector for Alpha,
// converting from a legalized dag to a Alpha dag.
//
//===----------------------------------------------------------------------===//
#include "Alpha.h"
#include "AlphaTargetMachine.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalValue.h"
#include "llvm/Intrinsics.h"
#include "llvm/LLVMContext.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
using namespace llvm;
namespace {
//===--------------------------------------------------------------------===//
/// AlphaDAGToDAGISel - Alpha specific code to select Alpha machine
/// instructions for SelectionDAG operations.
class AlphaDAGToDAGISel : public SelectionDAGISel {
static const int64_t IMM_LOW = -32768;
static const int64_t IMM_HIGH = 32767;
static const int64_t IMM_MULT = 65536;
static const int64_t IMM_FULLHIGH = IMM_HIGH + IMM_HIGH * IMM_MULT;
static const int64_t IMM_FULLLOW = IMM_LOW + IMM_LOW * IMM_MULT;
static int64_t get_ldah16(int64_t x) {
int64_t y = x / IMM_MULT;
if (x % IMM_MULT > IMM_HIGH)
++y;
return y;
}
static int64_t get_lda16(int64_t x) {
return x - get_ldah16(x) * IMM_MULT;
}
/// get_zapImm - Return a zap mask if X is a valid immediate for a zapnot
/// instruction (if not, return 0). Note that this code accepts partial
/// zap masks. For example (and LHS, 1) is a valid zap, as long we know
/// that the bits 1-7 of LHS are already zero. If LHS is non-null, we are
/// in checking mode. If LHS is null, we assume that the mask has already
/// been validated before.
uint64_t get_zapImm(SDValue LHS, uint64_t Constant) const {
uint64_t BitsToCheck = 0;
unsigned Result = 0;
for (unsigned i = 0; i != 8; ++i) {
if (((Constant >> 8*i) & 0xFF) == 0) {
// nothing to do.
} else {
Result |= 1 << i;
if (((Constant >> 8*i) & 0xFF) == 0xFF) {
// If the entire byte is set, zapnot the byte.
} else if (LHS.getNode() == 0) {
// Otherwise, if the mask was previously validated, we know its okay
// to zapnot this entire byte even though all the bits aren't set.
} else {
// Otherwise we don't know that the it's okay to zapnot this entire
// byte. Only do this iff we can prove that the missing bits are
// already null, so the bytezap doesn't need to really null them.
BitsToCheck |= ~Constant & (0xFF << 8*i);
}
}
}
// If there are missing bits in a byte (for example, X & 0xEF00), check to
// see if the missing bits (0x1000) are already known zero if not, the zap
// isn't okay to do, as it won't clear all the required bits.
if (BitsToCheck &&
!CurDAG->MaskedValueIsZero(LHS,
APInt(LHS.getValueSizeInBits(),
BitsToCheck)))
return 0;
return Result;
}
static uint64_t get_zapImm(uint64_t x) {
unsigned build = 0;
for(int i = 0; i != 8; ++i) {
if ((x & 0x00FF) == 0x00FF)
build |= 1 << i;
else if ((x & 0x00FF) != 0)
return 0;
x >>= 8;
}
return build;
}
static uint64_t getNearPower2(uint64_t x) {
if (!x) return 0;
unsigned at = CountLeadingZeros_64(x);
uint64_t complow = 1ULL << (63 - at);
uint64_t comphigh = 1ULL << (64 - at);
//cerr << x << ":" << complow << ":" << comphigh << "\n";
if (abs64(complow - x) <= abs64(comphigh - x))
return complow;
else
return comphigh;
}
static bool chkRemNearPower2(uint64_t x, uint64_t r, bool swap) {
uint64_t y = getNearPower2(x);
if (swap)
return (y - x) == r;
else
return (x - y) == r;
}
public:
explicit AlphaDAGToDAGISel(AlphaTargetMachine &TM)
: SelectionDAGISel(TM)
{}
/// getI64Imm - Return a target constant with the specified value, of type
/// i64.
inline SDValue getI64Imm(int64_t Imm) {
return CurDAG->getTargetConstant(Imm, MVT::i64);
}
// Select - Convert the specified operand from a target-independent to a
// target-specific node if it hasn't already been changed.
SDNode *Select(SDNode *N);
virtual const char *getPassName() const {
return "Alpha DAG->DAG Pattern Instruction Selection";
}
/// SelectInlineAsmMemoryOperand - Implement addressing mode selection for
/// inline asm expressions.
virtual bool SelectInlineAsmMemoryOperand(const SDValue &Op,
char ConstraintCode,
std::vector<SDValue> &OutOps) {
SDValue Op0;
switch (ConstraintCode) {
default: return true;
case 'm': // memory
Op0 = Op;
break;
}
OutOps.push_back(Op0);
return false;
}
// Include the pieces autogenerated from the target description.
#include "AlphaGenDAGISel.inc"
private:
/// getTargetMachine - Return a reference to the TargetMachine, casted
/// to the target-specific type.
const AlphaTargetMachine &getTargetMachine() {
return static_cast<const AlphaTargetMachine &>(TM);
}
/// getInstrInfo - Return a reference to the TargetInstrInfo, casted
/// to the target-specific type.
const AlphaInstrInfo *getInstrInfo() {
return getTargetMachine().getInstrInfo();
}
SDNode *getGlobalBaseReg();
SDNode *getGlobalRetAddr();
void SelectCALL(SDNode *Op);
};
}
/// getGlobalBaseReg - Output the instructions required to put the
/// GOT address into a register.
///
SDNode *AlphaDAGToDAGISel::getGlobalBaseReg() {
unsigned GlobalBaseReg = getInstrInfo()->getGlobalBaseReg(MF);
return CurDAG->getRegister(GlobalBaseReg, TLI.getPointerTy()).getNode();
}
/// getGlobalRetAddr - Grab the return address.
///
SDNode *AlphaDAGToDAGISel::getGlobalRetAddr() {
unsigned GlobalRetAddr = getInstrInfo()->getGlobalRetAddr(MF);
return CurDAG->getRegister(GlobalRetAddr, TLI.getPointerTy()).getNode();
}
// Select - Convert the specified operand from a target-independent to a
// target-specific node if it hasn't already been changed.
SDNode *AlphaDAGToDAGISel::Select(SDNode *N) {
if (N->isMachineOpcode())
return NULL; // Already selected.
DebugLoc dl = N->getDebugLoc();
switch (N->getOpcode()) {
default: break;
case AlphaISD::CALL:
SelectCALL(N);
return NULL;
case ISD::FrameIndex: {
int FI = cast<FrameIndexSDNode>(N)->getIndex();
return CurDAG->SelectNodeTo(N, Alpha::LDA, MVT::i64,
CurDAG->getTargetFrameIndex(FI, MVT::i32),
getI64Imm(0));
}
case ISD::GLOBAL_OFFSET_TABLE:
return getGlobalBaseReg();
case AlphaISD::GlobalRetAddr:
return getGlobalRetAddr();
case AlphaISD::DivCall: {
SDValue Chain = CurDAG->getEntryNode();
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
Chain = CurDAG->getCopyToReg(Chain, dl, Alpha::R24, N1,
SDValue(0,0));
Chain = CurDAG->getCopyToReg(Chain, dl, Alpha::R25, N2,
Chain.getValue(1));
Chain = CurDAG->getCopyToReg(Chain, dl, Alpha::R27, N0,
Chain.getValue(1));
SDNode *CNode =
CurDAG->getMachineNode(Alpha::JSRs, dl, MVT::Other, MVT::Flag,
Chain, Chain.getValue(1));
Chain = CurDAG->getCopyFromReg(Chain, dl, Alpha::R27, MVT::i64,
SDValue(CNode, 1));
return CurDAG->SelectNodeTo(N, Alpha::BISr, MVT::i64, Chain, Chain);
}
case ISD::READCYCLECOUNTER: {
SDValue Chain = N->getOperand(0);
return CurDAG->getMachineNode(Alpha::RPCC, dl, MVT::i64, MVT::Other,
Chain);
}
case ISD::Constant: {
uint64_t uval = cast<ConstantSDNode>(N)->getZExtValue();
if (uval == 0) {
SDValue Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
Alpha::R31, MVT::i64);
ReplaceUses(SDValue(N, 0), Result);
return NULL;
}
int64_t val = (int64_t)uval;
int32_t val32 = (int32_t)val;
if (val <= IMM_HIGH + IMM_HIGH * IMM_MULT &&
val >= IMM_LOW + IMM_LOW * IMM_MULT)
break; //(LDAH (LDA))
if ((uval >> 32) == 0 && //empty upper bits
val32 <= IMM_HIGH + IMM_HIGH * IMM_MULT)
// val32 >= IMM_LOW + IMM_LOW * IMM_MULT) //always true
break; //(zext (LDAH (LDA)))
//Else use the constant pool
ConstantInt *C = ConstantInt::get(
Type::getInt64Ty(*CurDAG->getContext()), uval);
SDValue CPI = CurDAG->getTargetConstantPool(C, MVT::i64);
SDNode *Tmp = CurDAG->getMachineNode(Alpha::LDAHr, dl, MVT::i64, CPI,
SDValue(getGlobalBaseReg(), 0));
return CurDAG->SelectNodeTo(N, Alpha::LDQr, MVT::i64, MVT::Other,
CPI, SDValue(Tmp, 0), CurDAG->getEntryNode());
}
case ISD::TargetConstantFP:
case ISD::ConstantFP: {
ConstantFPSDNode *CN = cast<ConstantFPSDNode>(N);
bool isDouble = N->getValueType(0) == MVT::f64;
EVT T = isDouble ? MVT::f64 : MVT::f32;
if (CN->getValueAPF().isPosZero()) {
return CurDAG->SelectNodeTo(N, isDouble ? Alpha::CPYST : Alpha::CPYSS,
T, CurDAG->getRegister(Alpha::F31, T),
CurDAG->getRegister(Alpha::F31, T));
} else if (CN->getValueAPF().isNegZero()) {
return CurDAG->SelectNodeTo(N, isDouble ? Alpha::CPYSNT : Alpha::CPYSNS,
T, CurDAG->getRegister(Alpha::F31, T),
CurDAG->getRegister(Alpha::F31, T));
} else {
report_fatal_error("Unhandled FP constant type");
}
break;
}
case ISD::SETCC:
if (N->getOperand(0).getNode()->getValueType(0).isFloatingPoint()) {
ISD::CondCode CC = cast<CondCodeSDNode>(N->getOperand(2))->get();
unsigned Opc = Alpha::WTF;
bool rev = false;
bool inv = false;
switch(CC) {
default: DEBUG(N->dump(CurDAG)); llvm_unreachable("Unknown FP comparison!");
case ISD::SETEQ: case ISD::SETOEQ: case ISD::SETUEQ:
Opc = Alpha::CMPTEQ; break;
case ISD::SETLT: case ISD::SETOLT: case ISD::SETULT:
Opc = Alpha::CMPTLT; break;
case ISD::SETLE: case ISD::SETOLE: case ISD::SETULE:
Opc = Alpha::CMPTLE; break;
case ISD::SETGT: case ISD::SETOGT: case ISD::SETUGT:
Opc = Alpha::CMPTLT; rev = true; break;
case ISD::SETGE: case ISD::SETOGE: case ISD::SETUGE:
Opc = Alpha::CMPTLE; rev = true; break;
case ISD::SETNE: case ISD::SETONE: case ISD::SETUNE:
Opc = Alpha::CMPTEQ; inv = true; break;
case ISD::SETO:
Opc = Alpha::CMPTUN; inv = true; break;
case ISD::SETUO:
Opc = Alpha::CMPTUN; break;
};
SDValue tmp1 = N->getOperand(rev?1:0);
SDValue tmp2 = N->getOperand(rev?0:1);
SDNode *cmp = CurDAG->getMachineNode(Opc, dl, MVT::f64, tmp1, tmp2);
if (inv)
cmp = CurDAG->getMachineNode(Alpha::CMPTEQ, dl,
MVT::f64, SDValue(cmp, 0),
CurDAG->getRegister(Alpha::F31, MVT::f64));
switch(CC) {
case ISD::SETUEQ: case ISD::SETULT: case ISD::SETULE:
case ISD::SETUNE: case ISD::SETUGT: case ISD::SETUGE:
{
SDNode* cmp2 = CurDAG->getMachineNode(Alpha::CMPTUN, dl, MVT::f64,
tmp1, tmp2);
cmp = CurDAG->getMachineNode(Alpha::ADDT, dl, MVT::f64,
SDValue(cmp2, 0), SDValue(cmp, 0));
break;
}
default: break;
}
SDNode* LD = CurDAG->getMachineNode(Alpha::FTOIT, dl,
MVT::i64, SDValue(cmp, 0));
return CurDAG->getMachineNode(Alpha::CMPULT, dl, MVT::i64,
CurDAG->getRegister(Alpha::R31, MVT::i64),
SDValue(LD,0));
}
break;
case ISD::AND: {
ConstantSDNode* SC = NULL;
ConstantSDNode* MC = NULL;
if (N->getOperand(0).getOpcode() == ISD::SRL &&
(MC = dyn_cast<ConstantSDNode>(N->getOperand(1))) &&
(SC = dyn_cast<ConstantSDNode>(N->getOperand(0).getOperand(1)))) {
uint64_t sval = SC->getZExtValue();
uint64_t mval = MC->getZExtValue();
// If the result is a zap, let the autogened stuff handle it.
if (get_zapImm(N->getOperand(0), mval))
break;
// given mask X, and shift S, we want to see if there is any zap in the
// mask if we play around with the botton S bits
uint64_t dontcare = (~0ULL) >> (64 - sval);
uint64_t mask = mval << sval;
if (get_zapImm(mask | dontcare))
mask = mask | dontcare;
if (get_zapImm(mask)) {
SDValue Z =
SDValue(CurDAG->getMachineNode(Alpha::ZAPNOTi, dl, MVT::i64,
N->getOperand(0).getOperand(0),
getI64Imm(get_zapImm(mask))), 0);
return CurDAG->getMachineNode(Alpha::SRLr, dl, MVT::i64, Z,
getI64Imm(sval));
}
}
break;
}
}
return SelectCode(N);
}
void AlphaDAGToDAGISel::SelectCALL(SDNode *N) {
//TODO: add flag stuff to prevent nondeturministic breakage!
SDValue Chain = N->getOperand(0);
SDValue Addr = N->getOperand(1);
SDValue InFlag = N->getOperand(N->getNumOperands() - 1);
DebugLoc dl = N->getDebugLoc();
if (Addr.getOpcode() == AlphaISD::GPRelLo) {
SDValue GOT = SDValue(getGlobalBaseReg(), 0);
Chain = CurDAG->getCopyToReg(Chain, dl, Alpha::R29, GOT, InFlag);
InFlag = Chain.getValue(1);
Chain = SDValue(CurDAG->getMachineNode(Alpha::BSR, dl, MVT::Other,
MVT::Flag, Addr.getOperand(0),
Chain, InFlag), 0);
} else {
Chain = CurDAG->getCopyToReg(Chain, dl, Alpha::R27, Addr, InFlag);
InFlag = Chain.getValue(1);
Chain = SDValue(CurDAG->getMachineNode(Alpha::JSR, dl, MVT::Other,
MVT::Flag, Chain, InFlag), 0);
}
InFlag = Chain.getValue(1);
ReplaceUses(SDValue(N, 0), Chain);
ReplaceUses(SDValue(N, 1), InFlag);
}
/// createAlphaISelDag - This pass converts a legalized DAG into a
/// Alpha-specific DAG, ready for instruction scheduling.
///
FunctionPass *llvm::createAlphaISelDag(AlphaTargetMachine &TM) {
return new AlphaDAGToDAGISel(TM);
}
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