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62bdec0de3
llvm-6502/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
Dan Gohman e8be6c6391 Add a new function, ReplaceAllUsesOfValuesWith, which handles bulk 
replacement of multiple values. This is slightly more efficient
than doing multiple ReplaceAllUsesOfValueWith calls, and theoretically
could be optimized even further. However, an important property of this
new function is that it handles the case where the source value set and
destination value set overlap. This makes it feasible for isel to use
SelectNodeTo in many very common cases, which is advantageous because
SelectNodeTo avoids a temporary node and it doesn't require CSEMap
updates for users of values that don't change position.

Revamp MorphNodeTo, which is what does all the work of SelectNodeTo, to
handle operand lists more efficiently, and to correctly handle a number
of corner cases to which its new wider use exposes it.

This commit also includes a change to the encoding of post-isel opcodes
in SDNodes; now instead of being sandwiched between the target-independent
pre-isel opcodes and the target-dependent pre-isel opcodes, post-isel
opcodes are now represented as negative values. This makes it possible
to test if an opcode is pre-isel or post-isel without having to know
the size of the current target's post-isel instruction set.

These changes speed up llc overall by 3% and reduce memory usage by 10%
on the InstructionCombining.cpp testcase with -fast and -regalloc=local.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53728 91177308-0d34-0410-b5e6-96231b3b80d8
2008-07-17 19:10:17 +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 "AlphaISelLowering.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/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include <algorithm>
#include <queue>
#include <set>
using namespace llvm;
namespace {
//===--------------------------------------------------------------------===//
/// AlphaDAGToDAGISel - Alpha specific code to select Alpha machine
/// instructions for SelectionDAG operations.
class AlphaDAGToDAGISel : public SelectionDAGISel {
AlphaTargetLowering AlphaLowering;
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(SDOperand LHS, uint64_t Constant) {
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.Val == 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 = 1 << (63 - at);
uint64_t comphigh = 1 << (64 - at);
//cerr << x << ":" << complow << ":" << comphigh << "\n";
if (abs(complow - x) <= abs(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;
}
static bool isFPZ(SDOperand N) {
ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(N);
return (CN && (CN->getValueAPF().isZero()));
}
static bool isFPZn(SDOperand N) {
ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(N);
return (CN && CN->getValueAPF().isNegZero());
}
static bool isFPZp(SDOperand N) {
ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(N);
return (CN && CN->getValueAPF().isPosZero());
}
public:
explicit AlphaDAGToDAGISel(AlphaTargetMachine &TM)
: SelectionDAGISel(AlphaLowering),
AlphaLowering(*TM.getTargetLowering())
{}
/// getI64Imm - Return a target constant with the specified value, of type
/// i64.
inline SDOperand 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(SDOperand Op);
/// InstructionSelect - This callback is invoked by
/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
virtual void InstructionSelect(SelectionDAG &DAG);
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 SDOperand &Op,
char ConstraintCode,
std::vector<SDOperand> &OutOps,
SelectionDAG &DAG) {
SDOperand Op0;
switch (ConstraintCode) {
default: return true;
case 'm': // memory
Op0 = Op;
AddToISelQueue(Op0);
break;
}
OutOps.push_back(Op0);
return false;
}
// Include the pieces autogenerated from the target description.
#include "AlphaGenDAGISel.inc"
private:
SDOperand getGlobalBaseReg();
SDOperand getGlobalRetAddr();
void SelectCALL(SDOperand Op);
};
}
/// getGlobalBaseReg - Output the instructions required to put the
/// GOT address into a register.
///
SDOperand AlphaDAGToDAGISel::getGlobalBaseReg() {
unsigned GP = 0;
for(MachineRegisterInfo::livein_iterator ii = RegInfo->livein_begin(),
ee = RegInfo->livein_end(); ii != ee; ++ii)
if (ii->first == Alpha::R29) {
GP = ii->second;
break;
}
assert(GP && "GOT PTR not in liveins");
return CurDAG->getCopyFromReg(CurDAG->getEntryNode(),
GP, MVT::i64);
}
/// getRASaveReg - Grab the return address
///
SDOperand AlphaDAGToDAGISel::getGlobalRetAddr() {
unsigned RA = 0;
for(MachineRegisterInfo::livein_iterator ii = RegInfo->livein_begin(),
ee = RegInfo->livein_end(); ii != ee; ++ii)
if (ii->first == Alpha::R26) {
RA = ii->second;
break;
}
assert(RA && "RA PTR not in liveins");
return CurDAG->getCopyFromReg(CurDAG->getEntryNode(),
RA, MVT::i64);
}
/// InstructionSelect - This callback is invoked by
/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
void AlphaDAGToDAGISel::InstructionSelect(SelectionDAG &DAG) {
DEBUG(BB->dump());
// Select target instructions for the DAG.
DAG.setRoot(SelectRoot(DAG.getRoot()));
DAG.RemoveDeadNodes();
}
// Select - Convert the specified operand from a target-independent to a
// target-specific node if it hasn't already been changed.
SDNode *AlphaDAGToDAGISel::Select(SDOperand Op) {
SDNode *N = Op.Val;
if (N->isMachineOpcode()) {
return NULL; // Already selected.
}
switch (N->getOpcode()) {
default: break;
case AlphaISD::CALL:
SelectCALL(Op);
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: {
SDOperand Result = getGlobalBaseReg();
ReplaceUses(Op, Result);
return NULL;
}
case AlphaISD::GlobalRetAddr: {
SDOperand Result = getGlobalRetAddr();
ReplaceUses(Op, Result);
return NULL;
}
case AlphaISD::DivCall: {
SDOperand Chain = CurDAG->getEntryNode();
SDOperand N0 = Op.getOperand(0);
SDOperand N1 = Op.getOperand(1);
SDOperand N2 = Op.getOperand(2);
AddToISelQueue(N0);
AddToISelQueue(N1);
AddToISelQueue(N2);
Chain = CurDAG->getCopyToReg(Chain, Alpha::R24, N1,
SDOperand(0,0));
Chain = CurDAG->getCopyToReg(Chain, Alpha::R25, N2,
Chain.getValue(1));
Chain = CurDAG->getCopyToReg(Chain, Alpha::R27, N0,
Chain.getValue(1));
SDNode *CNode =
CurDAG->getTargetNode(Alpha::JSRs, MVT::Other, MVT::Flag,
Chain, Chain.getValue(1));
Chain = CurDAG->getCopyFromReg(Chain, Alpha::R27, MVT::i64,
SDOperand(CNode, 1));
return CurDAG->SelectNodeTo(N, Alpha::BISr, MVT::i64, Chain, Chain);
}
case ISD::READCYCLECOUNTER: {
SDOperand Chain = N->getOperand(0);
AddToISelQueue(Chain); //Select chain
return CurDAG->getTargetNode(Alpha::RPCC, MVT::i64, MVT::Other,
Chain);
}
case ISD::Constant: {
uint64_t uval = cast<ConstantSDNode>(N)->getValue();
if (uval == 0) {
SDOperand Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(),
Alpha::R31, MVT::i64);
ReplaceUses(Op, 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::Int64Ty, uval);
SDOperand CPI = CurDAG->getTargetConstantPool(C, MVT::i64);
SDNode *Tmp = CurDAG->getTargetNode(Alpha::LDAHr, MVT::i64, CPI,
getGlobalBaseReg());
return CurDAG->SelectNodeTo(N, Alpha::LDQr, MVT::i64, MVT::Other,
CPI, SDOperand(Tmp, 0), CurDAG->getEntryNode());
}
case ISD::TargetConstantFP: {
ConstantFPSDNode *CN = cast<ConstantFPSDNode>(N);
bool isDouble = N->getValueType(0) == MVT::f64;
MVT 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 {
abort();
}
break;
}
case ISD::SETCC:
if (N->getOperand(0).Val->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)); assert(0 && "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;
};
SDOperand tmp1 = N->getOperand(rev?1:0);
SDOperand tmp2 = N->getOperand(rev?0:1);
AddToISelQueue(tmp1);
AddToISelQueue(tmp2);
SDNode *cmp = CurDAG->getTargetNode(Opc, MVT::f64, tmp1, tmp2);
if (inv)
cmp = CurDAG->getTargetNode(Alpha::CMPTEQ, MVT::f64, SDOperand(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->getTargetNode(Alpha::CMPTUN, MVT::f64,
tmp1, tmp2);
cmp = CurDAG->getTargetNode(Alpha::ADDT, MVT::f64,
SDOperand(cmp2, 0), SDOperand(cmp, 0));
break;
}
default: break;
}
SDNode* LD = CurDAG->getTargetNode(Alpha::FTOIT, MVT::i64, SDOperand(cmp, 0));
return CurDAG->getTargetNode(Alpha::CMPULT, MVT::i64,
CurDAG->getRegister(Alpha::R31, MVT::i64),
SDOperand(LD,0));
}
break;
case ISD::SELECT:
if (N->getValueType(0).isFloatingPoint() &&
(N->getOperand(0).getOpcode() != ISD::SETCC ||
!N->getOperand(0).getOperand(1).getValueType().isFloatingPoint())) {
//This should be the condition not covered by the Patterns
//FIXME: Don't have SelectCode die, but rather return something testable
// so that things like this can be caught in fall though code
//move int to fp
bool isDouble = N->getValueType(0) == MVT::f64;
SDOperand cond = N->getOperand(0);
SDOperand TV = N->getOperand(1);
SDOperand FV = N->getOperand(2);
AddToISelQueue(cond);
AddToISelQueue(TV);
AddToISelQueue(FV);
SDNode* LD = CurDAG->getTargetNode(Alpha::ITOFT, MVT::f64, cond);
return CurDAG->getTargetNode(isDouble?Alpha::FCMOVNET:Alpha::FCMOVNES,
MVT::f64, FV, TV, SDOperand(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->getValue();
uint64_t mval = MC->getValue();
// 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)) {
AddToISelQueue(N->getOperand(0).getOperand(0));
SDOperand Z =
SDOperand(CurDAG->getTargetNode(Alpha::ZAPNOTi, MVT::i64,
N->getOperand(0).getOperand(0),
getI64Imm(get_zapImm(mask))), 0);
return CurDAG->getTargetNode(Alpha::SRLr, MVT::i64, Z,
getI64Imm(sval));
}
}
break;
}
}
return SelectCode(Op);
}
void AlphaDAGToDAGISel::SelectCALL(SDOperand Op) {
//TODO: add flag stuff to prevent nondeturministic breakage!
SDNode *N = Op.Val;
SDOperand Chain = N->getOperand(0);
SDOperand Addr = N->getOperand(1);
SDOperand InFlag(0,0); // Null incoming flag value.
AddToISelQueue(Chain);
std::vector<SDOperand> CallOperands;
std::vector<MVT> TypeOperands;
//grab the arguments
for(int i = 2, e = N->getNumOperands(); i < e; ++i) {
TypeOperands.push_back(N->getOperand(i).getValueType());
AddToISelQueue(N->getOperand(i));
CallOperands.push_back(N->getOperand(i));
}
int count = N->getNumOperands() - 2;
static const unsigned args_int[] = {Alpha::R16, Alpha::R17, Alpha::R18,
Alpha::R19, Alpha::R20, Alpha::R21};
static const unsigned args_float[] = {Alpha::F16, Alpha::F17, Alpha::F18,
Alpha::F19, Alpha::F20, Alpha::F21};
for (int i = 6; i < count; ++i) {
unsigned Opc = Alpha::WTF;
if (TypeOperands[i].isInteger()) {
Opc = Alpha::STQ;
} else if (TypeOperands[i] == MVT::f32) {
Opc = Alpha::STS;
} else if (TypeOperands[i] == MVT::f64) {
Opc = Alpha::STT;
} else
assert(0 && "Unknown operand");
SDOperand Ops[] = { CallOperands[i], getI64Imm((i - 6) * 8),
CurDAG->getCopyFromReg(Chain, Alpha::R30, MVT::i64),
Chain };
Chain = SDOperand(CurDAG->getTargetNode(Opc, MVT::Other, Ops, 4), 0);
}
for (int i = 0; i < std::min(6, count); ++i) {
if (TypeOperands[i].isInteger()) {
Chain = CurDAG->getCopyToReg(Chain, args_int[i], CallOperands[i], InFlag);
InFlag = Chain.getValue(1);
} else if (TypeOperands[i] == MVT::f32 || TypeOperands[i] == MVT::f64) {
Chain = CurDAG->getCopyToReg(Chain, args_float[i], CallOperands[i], InFlag);
InFlag = Chain.getValue(1);
} else
assert(0 && "Unknown operand");
}
// Finally, once everything is in registers to pass to the call, emit the
// call itself.
if (Addr.getOpcode() == AlphaISD::GPRelLo) {
SDOperand GOT = getGlobalBaseReg();
Chain = CurDAG->getCopyToReg(Chain, Alpha::R29, GOT, InFlag);
InFlag = Chain.getValue(1);
Chain = SDOperand(CurDAG->getTargetNode(Alpha::BSR, MVT::Other, MVT::Flag,
Addr.getOperand(0), Chain, InFlag), 0);
} else {
AddToISelQueue(Addr);
Chain = CurDAG->getCopyToReg(Chain, Alpha::R27, Addr, InFlag);
InFlag = Chain.getValue(1);
Chain = SDOperand(CurDAG->getTargetNode(Alpha::JSR, MVT::Other, MVT::Flag,
Chain, InFlag), 0);
}
InFlag = Chain.getValue(1);
std::vector<SDOperand> CallResults;
switch (N->getValueType(0).getSimpleVT()) {
default: assert(0 && "Unexpected ret value!");
case MVT::Other: break;
case MVT::i64:
Chain = CurDAG->getCopyFromReg(Chain, Alpha::R0, MVT::i64, InFlag).getValue(1);
CallResults.push_back(Chain.getValue(0));
break;
case MVT::f32:
Chain = CurDAG->getCopyFromReg(Chain, Alpha::F0, MVT::f32, InFlag).getValue(1);
CallResults.push_back(Chain.getValue(0));
break;
case MVT::f64:
Chain = CurDAG->getCopyFromReg(Chain, Alpha::F0, MVT::f64, InFlag).getValue(1);
CallResults.push_back(Chain.getValue(0));
break;
}
CallResults.push_back(Chain);
for (unsigned i = 0, e = CallResults.size(); i != e; ++i)
ReplaceUses(Op.getValue(i), CallResults[i]);
}
/// 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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