llvm-6502/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
Chris Lattner a5a91b1026 initial hack at a dag->dag instruction selector. This is obviously woefully
incomplete, but it is a start.  It handles basic argument/retval stuff, immediates,
add and sub.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22836 91177308-0d34-0410-b5e6-96231b3b80d8
2005-08-17 19:33:03 +00:00

326 lines
12 KiB
C++

//===-- PPC32ISelDAGToDAG.cpp - PPC32 pattern matching inst selector ------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a pattern matching instruction selector for 32 bit PowerPC,
// converting from a legalized dag to a PPC dag.
//
//===----------------------------------------------------------------------===//
#include "PowerPC.h"
#include "PPC32TargetMachine.h"
#include "PPC32ISelLowering.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
using namespace llvm;
namespace {
Statistic<> Recorded("ppc-codegen", "Number of recording ops emitted");
Statistic<> FusedFP ("ppc-codegen", "Number of fused fp operations");
Statistic<> FrameOff("ppc-codegen", "Number of frame idx offsets collapsed");
//===--------------------------------------------------------------------===//
/// PPC32DAGToDAGISel - PPC32 specific code to select PPC32 machine
/// instructions for SelectionDAG operations.
///
class PPC32DAGToDAGISel : public SelectionDAGISel {
PPC32TargetLowering PPC32Lowering;
unsigned GlobalBaseReg;
bool GlobalBaseInitialized;
public:
PPC32DAGToDAGISel(TargetMachine &TM)
: SelectionDAGISel(PPC32Lowering), PPC32Lowering(TM) {}
/// runOnFunction - Override this function in order to reset our
/// per-function variables.
virtual bool runOnFunction(Function &Fn) {
// Make sure we re-emit a set of the global base reg if necessary
GlobalBaseInitialized = false;
return SelectionDAGISel::runOnFunction(Fn);
}
/// getI32Imm - Return a target constant with the specified value, of type
/// i32.
inline SDOperand getI32Imm(unsigned Imm) {
return CurDAG->getTargetConstant(Imm, MVT::i32);
}
// Select - Convert the specified operand from a target-independent to a
// target-specific node if it hasn't already been changed.
SDOperand Select(SDOperand Op);
SDNode *SelectIntImmediateExpr(SDOperand LHS, SDOperand RHS,
unsigned OCHi, unsigned OCLo,
bool IsArithmetic = false,
bool Negate = false);
/// InstructionSelectBasicBlock - This callback is invoked by
/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
virtual void InstructionSelectBasicBlock(SelectionDAG &DAG) {
DEBUG(BB->dump());
// Codegen the basic block.
Select(DAG.getRoot());
DAG.RemoveDeadNodes();
DAG.viewGraph();
}
virtual const char *getPassName() const {
return "PowerPC DAG->DAG Pattern Instruction Selection";
}
};
}
// Immediate constant composers.
// Lo16 - grabs the lo 16 bits from a 32 bit constant.
// Hi16 - grabs the hi 16 bits from a 32 bit constant.
// HA16 - computes the hi bits required if the lo bits are add/subtracted in
// arithmethically.
static unsigned Lo16(unsigned x) { return x & 0x0000FFFF; }
static unsigned Hi16(unsigned x) { return Lo16(x >> 16); }
static unsigned HA16(unsigned x) { return Hi16((signed)x - (signed short)x); }
// isIntImmediate - This method tests to see if a constant operand.
// If so Imm will receive the 32 bit value.
static bool isIntImmediate(SDOperand N, unsigned& Imm) {
if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N)) {
Imm = (unsigned)CN->getSignExtended();
return true;
}
return false;
}
// SelectIntImmediateExpr - Choose code for integer operations with an immediate
// operand.
SDNode *PPC32DAGToDAGISel::SelectIntImmediateExpr(SDOperand LHS, SDOperand RHS,
unsigned OCHi, unsigned OCLo,
bool IsArithmetic,
bool Negate) {
// Check to make sure this is a constant.
ConstantSDNode *CN = dyn_cast<ConstantSDNode>(RHS);
// Exit if not a constant.
if (!CN) return 0;
// Extract immediate.
unsigned C = (unsigned)CN->getValue();
// Negate if required (ISD::SUB).
if (Negate) C = -C;
// Get the hi and lo portions of constant.
unsigned Hi = IsArithmetic ? HA16(C) : Hi16(C);
unsigned Lo = Lo16(C);
// If two instructions are needed and usage indicates it would be better to
// load immediate into a register, bail out.
if (Hi && Lo && CN->use_size() > 2) return false;
// Select the first operand.
SDOperand Opr0 = Select(LHS);
if (Lo) // Add in the lo-part.
Opr0 = CurDAG->getTargetNode(OCLo, MVT::i32, Opr0, getI32Imm(Lo));
if (Hi) // Add in the hi-part.
Opr0 = CurDAG->getTargetNode(OCHi, MVT::i32, Opr0, getI32Imm(Hi));
return Opr0.Val;
}
// Select - Convert the specified operand from a target-independent to a
// target-specific node if it hasn't already been changed.
SDOperand PPC32DAGToDAGISel::Select(SDOperand Op) {
SDNode *N = Op.Val;
if (N->getOpcode() >= ISD::BUILTIN_OP_END)
return Op; // Already selected.
switch (N->getOpcode()) {
default:
std::cerr << "Cannot yet select: ";
N->dump();
std::cerr << "\n";
abort();
case ISD::EntryToken: // These leaves remain the same.
case ISD::UNDEF:
return Op;
case ISD::TokenFactor: {
SDOperand New;
if (N->getNumOperands() == 2) {
SDOperand Op0 = Select(N->getOperand(0));
SDOperand Op1 = Select(N->getOperand(1));
New = CurDAG->getNode(ISD::TokenFactor, MVT::Other, Op0, Op1);
} else {
std::vector<SDOperand> Ops;
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
Ops.push_back(Select(N->getOperand(0)));
New = CurDAG->getNode(ISD::TokenFactor, MVT::Other, Ops);
}
if (New.Val != N) {
CurDAG->ReplaceAllUsesWith(N, New.Val);
N = New.Val;
}
break;
}
case ISD::CopyFromReg: {
SDOperand Chain = Select(N->getOperand(0));
if (Chain == N->getOperand(0)) return Op; // No change
SDOperand New = CurDAG->getCopyFromReg(Chain,
cast<RegisterSDNode>(N->getOperand(1))->getReg(), N->getValueType(0));
return New.getValue(Op.ResNo);
}
case ISD::CopyToReg: {
SDOperand Chain = Select(N->getOperand(0));
SDOperand Reg = N->getOperand(1);
SDOperand Val = Select(N->getOperand(2));
if (Chain != N->getOperand(0) || Val != N->getOperand(2)) {
SDOperand New = CurDAG->getNode(ISD::CopyToReg, MVT::Other,
Chain, Reg, Val);
CurDAG->ReplaceAllUsesWith(N, New.Val);
N = New.Val;
}
break;
}
case ISD::Constant: {
assert(N->getValueType(0) == MVT::i32);
unsigned v = (unsigned)cast<ConstantSDNode>(N)->getValue();
if ((unsigned)(short)v == v) {
CurDAG->SelectNodeTo(N, MVT::i32, PPC::LI, getI32Imm(v));
break;
} else {
SDOperand Top = CurDAG->getTargetNode(PPC::LIS, MVT::i32,
getI32Imm(unsigned(v) >> 16));
CurDAG->SelectNodeTo(N, MVT::i32, PPC::ORI, Top, getI32Imm(v & 0xFFFF));
break;
}
}
case ISD::ADD: {
MVT::ValueType Ty = N->getValueType(0);
if (Ty == MVT::i32) {
if (SDNode *I = SelectIntImmediateExpr(N->getOperand(0), N->getOperand(1),
PPC::ADDIS, PPC::ADDI, true)) {
CurDAG->ReplaceAllUsesWith(N, I);
N = I;
} else {
CurDAG->SelectNodeTo(N, Ty, PPC::ADD, Select(N->getOperand(0)),
Select(N->getOperand(1)));
}
break;
}
if (!NoExcessFPPrecision) { // Match FMA ops
if (N->getOperand(0).getOpcode() == ISD::MUL &&
N->getOperand(0).Val->hasOneUse()) {
++FusedFP; // Statistic
CurDAG->SelectNodeTo(N, Ty, Ty == MVT::f64 ? PPC::FMADD : PPC::FMADDS,
Select(N->getOperand(0).getOperand(0)),
Select(N->getOperand(0).getOperand(1)),
Select(N->getOperand(1)));
break;
} else if (N->getOperand(1).getOpcode() == ISD::MUL &&
N->getOperand(1).hasOneUse()) {
++FusedFP; // Statistic
CurDAG->SelectNodeTo(N, Ty, Ty == MVT::f64 ? PPC::FMADD : PPC::FMADDS,
Select(N->getOperand(1).getOperand(0)),
Select(N->getOperand(1).getOperand(1)),
Select(N->getOperand(0)));
break;
}
}
CurDAG->SelectNodeTo(N, Ty, Ty == MVT::f64 ? PPC::FADD : PPC::FADDS,
Select(N->getOperand(0)), Select(N->getOperand(1)));
break;
}
case ISD::SUB: {
MVT::ValueType Ty = N->getValueType(0);
if (Ty == MVT::i32) {
unsigned Imm;
if (isIntImmediate(N->getOperand(0), Imm) && isInt16(Imm)) {
CurDAG->SelectNodeTo(N, Ty, PPC::SUBFIC, Select(N->getOperand(1)),
getI32Imm(Lo16(Imm)));
break;
}
if (SDNode *I = SelectIntImmediateExpr(N->getOperand(0), N->getOperand(1),
PPC::ADDIS, PPC::ADDI, true, true)) {
CurDAG->ReplaceAllUsesWith(N, I);
N = I;
} else {
CurDAG->SelectNodeTo(N, Ty, PPC::SUBF, Select(N->getOperand(1)),
Select(N->getOperand(0)));
}
break;
}
if (!NoExcessFPPrecision) { // Match FMA ops
if (N->getOperand(0).getOpcode() == ISD::MUL &&
N->getOperand(0).Val->hasOneUse()) {
++FusedFP; // Statistic
CurDAG->SelectNodeTo(N, Ty, Ty == MVT::f64 ? PPC::FMSUB : PPC::FMSUBS,
Select(N->getOperand(0).getOperand(0)),
Select(N->getOperand(0).getOperand(1)),
Select(N->getOperand(1)));
break;
} else if (N->getOperand(1).getOpcode() == ISD::MUL &&
N->getOperand(1).Val->hasOneUse()) {
++FusedFP; // Statistic
CurDAG->SelectNodeTo(N, Ty, Ty == MVT::f64 ? PPC::FNMSUB : PPC::FNMSUBS,
Select(N->getOperand(1).getOperand(0)),
Select(N->getOperand(1).getOperand(1)),
Select(N->getOperand(0)));
break;
}
}
CurDAG->SelectNodeTo(N, Ty, Ty == MVT::f64 ? PPC::FSUB : PPC::FSUBS,
Select(N->getOperand(0)),
Select(N->getOperand(1)));
break;
}
case ISD::RET: {
SDOperand Chain = Select(N->getOperand(0)); // Token chain.
if (N->getNumOperands() > 1) {
SDOperand Val = Select(N->getOperand(1));
switch (N->getOperand(1).getValueType()) {
default: assert(0 && "Unknown return type!");
case MVT::f64:
case MVT::f32:
Chain = CurDAG->getCopyToReg(Chain, PPC::F1, Val);
break;
case MVT::i32:
Chain = CurDAG->getCopyToReg(Chain, PPC::R3, Val);
break;
}
if (N->getNumOperands() > 2) {
assert(N->getOperand(1).getValueType() == MVT::i32 &&
N->getOperand(2).getValueType() == MVT::i32 &&
N->getNumOperands() == 2 && "Unknown two-register ret value!");
Val = Select(N->getOperand(2));
Chain = CurDAG->getCopyToReg(Chain, PPC::R4, Val);
}
}
// Finally, select this to a blr (return) instruction.
CurDAG->SelectNodeTo(N, MVT::Other, PPC::BLR, Chain);
break;
}
}
return SDOperand(N, 0);
}
/// createPPC32ISelDag - This pass converts a legalized DAG into a
/// PowerPC-specific DAG, ready for instruction scheduling.
///
FunctionPass *llvm::createPPC32ISelDag(TargetMachine &TM) {
return new PPC32DAGToDAGISel(TM);
}