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llvm-mirror/lib/Target/X86/X86FloatingPoint.cpp
Dan Gohman 30c5ce1b7d Switch the MachineOperand accessors back to the short names like 
isReg, etc., from isRegister, etc.

llvm-svn: 57006
2008-10-03 15:45:36 +00:00

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//===-- X86FloatingPoint.cpp - Floating point Reg -> Stack converter ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the pass which converts floating point instructions from
// virtual registers into register stack instructions. This pass uses live
// variable information to indicate where the FPn registers are used and their
// lifetimes.
//
// This pass is hampered by the lack of decent CFG manipulation routines for
// machine code. In particular, this wants to be able to split critical edges
// as necessary, traverse the machine basic block CFG in depth-first order, and
// allow there to be multiple machine basic blocks for each LLVM basicblock
// (needed for critical edge splitting).
//
// In particular, this pass currently barfs on critical edges. Because of this,
// it requires the instruction selector to insert FP_REG_KILL instructions on
// the exits of any basic block that has critical edges going from it, or which
// branch to a critical basic block.
//
// FIXME: this is not implemented yet. The stackifier pass only works on local
// basic blocks.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "x86-codegen"
#include "X86.h"
#include "X86InstrInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include <algorithm>
using namespace llvm;
STATISTIC(NumFXCH, "Number of fxch instructions inserted");
STATISTIC(NumFP , "Number of floating point instructions");
namespace {
struct VISIBILITY_HIDDEN FPS : public MachineFunctionPass {
static char ID;
FPS() : MachineFunctionPass(&ID) {}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual const char *getPassName() const { return "X86 FP Stackifier"; }
private:
const TargetInstrInfo *TII; // Machine instruction info.
MachineBasicBlock *MBB; // Current basic block
unsigned Stack[8]; // FP<n> Registers in each stack slot...
unsigned RegMap[8]; // Track which stack slot contains each register
unsigned StackTop; // The current top of the FP stack.
void dumpStack() const {
cerr << "Stack contents:";
for (unsigned i = 0; i != StackTop; ++i) {
cerr << " FP" << Stack[i];
assert(RegMap[Stack[i]] == i && "Stack[] doesn't match RegMap[]!");
}
cerr << "\n";
}
private:
/// isStackEmpty - Return true if the FP stack is empty.
bool isStackEmpty() const {
return StackTop == 0;
}
// getSlot - Return the stack slot number a particular register number is
// in.
unsigned getSlot(unsigned RegNo) const {
assert(RegNo < 8 && "Regno out of range!");
return RegMap[RegNo];
}
// getStackEntry - Return the X86::FP<n> register in register ST(i).
unsigned getStackEntry(unsigned STi) const {
assert(STi < StackTop && "Access past stack top!");
return Stack[StackTop-1-STi];
}
// getSTReg - Return the X86::ST(i) register which contains the specified
// FP<RegNo> register.
unsigned getSTReg(unsigned RegNo) const {
return StackTop - 1 - getSlot(RegNo) + llvm::X86::ST0;
}
// pushReg - Push the specified FP<n> register onto the stack.
void pushReg(unsigned Reg) {
assert(Reg < 8 && "Register number out of range!");
assert(StackTop < 8 && "Stack overflow!");
Stack[StackTop] = Reg;
RegMap[Reg] = StackTop++;
}
bool isAtTop(unsigned RegNo) const { return getSlot(RegNo) == StackTop-1; }
void moveToTop(unsigned RegNo, MachineBasicBlock::iterator I) {
if (isAtTop(RegNo)) return;
unsigned STReg = getSTReg(RegNo);
unsigned RegOnTop = getStackEntry(0);
// Swap the slots the regs are in.
std::swap(RegMap[RegNo], RegMap[RegOnTop]);
// Swap stack slot contents.
assert(RegMap[RegOnTop] < StackTop);
std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
// Emit an fxch to update the runtime processors version of the state.
BuildMI(*MBB, I, TII->get(X86::XCH_F)).addReg(STReg);
NumFXCH++;
}
void duplicateToTop(unsigned RegNo, unsigned AsReg, MachineInstr *I) {
unsigned STReg = getSTReg(RegNo);
pushReg(AsReg); // New register on top of stack
BuildMI(*MBB, I, TII->get(X86::LD_Frr)).addReg(STReg);
}
// popStackAfter - Pop the current value off of the top of the FP stack
// after the specified instruction.
void popStackAfter(MachineBasicBlock::iterator &I);
// freeStackSlotAfter - Free the specified register from the register stack,
// so that it is no longer in a register. If the register is currently at
// the top of the stack, we just pop the current instruction, otherwise we
// store the current top-of-stack into the specified slot, then pop the top
// of stack.
void freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned Reg);
bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB);
void handleZeroArgFP(MachineBasicBlock::iterator &I);
void handleOneArgFP(MachineBasicBlock::iterator &I);
void handleOneArgFPRW(MachineBasicBlock::iterator &I);
void handleTwoArgFP(MachineBasicBlock::iterator &I);
void handleCompareFP(MachineBasicBlock::iterator &I);
void handleCondMovFP(MachineBasicBlock::iterator &I);
void handleSpecialFP(MachineBasicBlock::iterator &I);
};
char FPS::ID = 0;
}
FunctionPass *llvm::createX86FloatingPointStackifierPass() { return new FPS(); }
/// getFPReg - Return the X86::FPx register number for the specified operand.
/// For example, this returns 3 for X86::FP3.
static unsigned getFPReg(const MachineOperand &MO) {
assert(MO.isReg() && "Expected an FP register!");
unsigned Reg = MO.getReg();
assert(Reg >= X86::FP0 && Reg <= X86::FP6 && "Expected FP register!");
return Reg - X86::FP0;
}
/// runOnMachineFunction - Loop over all of the basic blocks, transforming FP
/// register references into FP stack references.
///
bool FPS::runOnMachineFunction(MachineFunction &MF) {
// We only need to run this pass if there are any FP registers used in this
// function. If it is all integer, there is nothing for us to do!
bool FPIsUsed = false;
assert(X86::FP6 == X86::FP0+6 && "Register enums aren't sorted right!");
for (unsigned i = 0; i <= 6; ++i)
if (MF.getRegInfo().isPhysRegUsed(X86::FP0+i)) {
FPIsUsed = true;
break;
}
// Early exit.
if (!FPIsUsed) return false;
TII = MF.getTarget().getInstrInfo();
StackTop = 0;
// Process the function in depth first order so that we process at least one
// of the predecessors for every reachable block in the function.
SmallPtrSet<MachineBasicBlock*, 8> Processed;
MachineBasicBlock *Entry = MF.begin();
bool Changed = false;
for (df_ext_iterator<MachineBasicBlock*, SmallPtrSet<MachineBasicBlock*, 8> >
I = df_ext_begin(Entry, Processed), E = df_ext_end(Entry, Processed);
I != E; ++I)
Changed |= processBasicBlock(MF, **I);
return Changed;
}
/// processBasicBlock - Loop over all of the instructions in the basic block,
/// transforming FP instructions into their stack form.
///
bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
bool Changed = false;
MBB = &BB;
for (MachineBasicBlock::iterator I = BB.begin(); I != BB.end(); ++I) {
MachineInstr *MI = I;
unsigned Flags = MI->getDesc().TSFlags;
unsigned FPInstClass = Flags & X86II::FPTypeMask;
if (MI->getOpcode() == TargetInstrInfo::INLINEASM)
FPInstClass = X86II::SpecialFP;
if (FPInstClass == X86II::NotFP)
continue; // Efficiently ignore non-fp insts!
MachineInstr *PrevMI = 0;
if (I != BB.begin())
PrevMI = prior(I);
++NumFP; // Keep track of # of pseudo instrs
DOUT << "\nFPInst:\t" << *MI;
// Get dead variables list now because the MI pointer may be deleted as part
// of processing!
SmallVector<unsigned, 8> DeadRegs;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
if (MO.isReg() && MO.isDead())
DeadRegs.push_back(MO.getReg());
}
switch (FPInstClass) {
case X86II::ZeroArgFP: handleZeroArgFP(I); break;
case X86II::OneArgFP: handleOneArgFP(I); break; // fstp ST(0)
case X86II::OneArgFPRW: handleOneArgFPRW(I); break; // ST(0) = fsqrt(ST(0))
case X86II::TwoArgFP: handleTwoArgFP(I); break;
case X86II::CompareFP: handleCompareFP(I); break;
case X86II::CondMovFP: handleCondMovFP(I); break;
case X86II::SpecialFP: handleSpecialFP(I); break;
default: assert(0 && "Unknown FP Type!");
}
// Check to see if any of the values defined by this instruction are dead
// after definition. If so, pop them.
for (unsigned i = 0, e = DeadRegs.size(); i != e; ++i) {
unsigned Reg = DeadRegs[i];
if (Reg >= X86::FP0 && Reg <= X86::FP6) {
DOUT << "Register FP#" << Reg-X86::FP0 << " is dead!\n";
freeStackSlotAfter(I, Reg-X86::FP0);
}
}
// Print out all of the instructions expanded to if -debug
DEBUG(
MachineBasicBlock::iterator PrevI(PrevMI);
if (I == PrevI) {
cerr << "Just deleted pseudo instruction\n";
} else {
MachineBasicBlock::iterator Start = I;
// Rewind to first instruction newly inserted.
while (Start != BB.begin() && prior(Start) != PrevI) --Start;
cerr << "Inserted instructions:\n\t";
Start->print(*cerr.stream(), &MF.getTarget());
while (++Start != next(I)) {}
}
dumpStack();
);
Changed = true;
}
assert(isStackEmpty() && "Stack not empty at end of basic block?");
return Changed;
}
//===----------------------------------------------------------------------===//
// Efficient Lookup Table Support
//===----------------------------------------------------------------------===//
namespace {
struct TableEntry {
unsigned from;
unsigned to;
bool operator<(const TableEntry &TE) const { return from < TE.from; }
friend bool operator<(const TableEntry &TE, unsigned V) {
return TE.from < V;
}
friend bool operator<(unsigned V, const TableEntry &TE) {
return V < TE.from;
}
};
}
#ifndef NDEBUG
static bool TableIsSorted(const TableEntry *Table, unsigned NumEntries) {
for (unsigned i = 0; i != NumEntries-1; ++i)
if (!(Table[i] < Table[i+1])) return false;
return true;
}
#endif
static int Lookup(const TableEntry *Table, unsigned N, unsigned Opcode) {
const TableEntry *I = std::lower_bound(Table, Table+N, Opcode);
if (I != Table+N && I->from == Opcode)
return I->to;
return -1;
}
#ifdef NDEBUG
#define ASSERT_SORTED(TABLE)
#else
#define ASSERT_SORTED(TABLE) \
{ static bool TABLE##Checked = false; \
if (!TABLE##Checked) { \
assert(TableIsSorted(TABLE, array_lengthof(TABLE)) && \
"All lookup tables must be sorted for efficient access!"); \
TABLE##Checked = true; \
} \
}
#endif
//===----------------------------------------------------------------------===//
// Register File -> Register Stack Mapping Methods
//===----------------------------------------------------------------------===//
// OpcodeTable - Sorted map of register instructions to their stack version.
// The first element is an register file pseudo instruction, the second is the
// concrete X86 instruction which uses the register stack.
//
static const TableEntry OpcodeTable[] = {
{ X86::ABS_Fp32 , X86::ABS_F },
{ X86::ABS_Fp64 , X86::ABS_F },
{ X86::ABS_Fp80 , X86::ABS_F },
{ X86::ADD_Fp32m , X86::ADD_F32m },
{ X86::ADD_Fp64m , X86::ADD_F64m },
{ X86::ADD_Fp64m32 , X86::ADD_F32m },
{ X86::ADD_Fp80m32 , X86::ADD_F32m },
{ X86::ADD_Fp80m64 , X86::ADD_F64m },
{ X86::ADD_FpI16m32 , X86::ADD_FI16m },
{ X86::ADD_FpI16m64 , X86::ADD_FI16m },
{ X86::ADD_FpI16m80 , X86::ADD_FI16m },
{ X86::ADD_FpI32m32 , X86::ADD_FI32m },
{ X86::ADD_FpI32m64 , X86::ADD_FI32m },
{ X86::ADD_FpI32m80 , X86::ADD_FI32m },
{ X86::CHS_Fp32 , X86::CHS_F },
{ X86::CHS_Fp64 , X86::CHS_F },
{ X86::CHS_Fp80 , X86::CHS_F },
{ X86::CMOVBE_Fp32 , X86::CMOVBE_F },
{ X86::CMOVBE_Fp64 , X86::CMOVBE_F },
{ X86::CMOVBE_Fp80 , X86::CMOVBE_F },
{ X86::CMOVB_Fp32 , X86::CMOVB_F },
{ X86::CMOVB_Fp64 , X86::CMOVB_F },
{ X86::CMOVB_Fp80 , X86::CMOVB_F },
{ X86::CMOVE_Fp32 , X86::CMOVE_F },
{ X86::CMOVE_Fp64 , X86::CMOVE_F },
{ X86::CMOVE_Fp80 , X86::CMOVE_F },
{ X86::CMOVNBE_Fp32 , X86::CMOVNBE_F },
{ X86::CMOVNBE_Fp64 , X86::CMOVNBE_F },
{ X86::CMOVNBE_Fp80 , X86::CMOVNBE_F },
{ X86::CMOVNB_Fp32 , X86::CMOVNB_F },
{ X86::CMOVNB_Fp64 , X86::CMOVNB_F },
{ X86::CMOVNB_Fp80 , X86::CMOVNB_F },
{ X86::CMOVNE_Fp32 , X86::CMOVNE_F },
{ X86::CMOVNE_Fp64 , X86::CMOVNE_F },
{ X86::CMOVNE_Fp80 , X86::CMOVNE_F },
{ X86::CMOVNP_Fp32 , X86::CMOVNP_F },
{ X86::CMOVNP_Fp64 , X86::CMOVNP_F },
{ X86::CMOVNP_Fp80 , X86::CMOVNP_F },
{ X86::CMOVP_Fp32 , X86::CMOVP_F },
{ X86::CMOVP_Fp64 , X86::CMOVP_F },
{ X86::CMOVP_Fp80 , X86::CMOVP_F },
{ X86::COS_Fp32 , X86::COS_F },
{ X86::COS_Fp64 , X86::COS_F },
{ X86::COS_Fp80 , X86::COS_F },
{ X86::DIVR_Fp32m , X86::DIVR_F32m },
{ X86::DIVR_Fp64m , X86::DIVR_F64m },
{ X86::DIVR_Fp64m32 , X86::DIVR_F32m },
{ X86::DIVR_Fp80m32 , X86::DIVR_F32m },
{ X86::DIVR_Fp80m64 , X86::DIVR_F64m },
{ X86::DIVR_FpI16m32, X86::DIVR_FI16m},
{ X86::DIVR_FpI16m64, X86::DIVR_FI16m},
{ X86::DIVR_FpI16m80, X86::DIVR_FI16m},
{ X86::DIVR_FpI32m32, X86::DIVR_FI32m},
{ X86::DIVR_FpI32m64, X86::DIVR_FI32m},
{ X86::DIVR_FpI32m80, X86::DIVR_FI32m},
{ X86::DIV_Fp32m , X86::DIV_F32m },
{ X86::DIV_Fp64m , X86::DIV_F64m },
{ X86::DIV_Fp64m32 , X86::DIV_F32m },
{ X86::DIV_Fp80m32 , X86::DIV_F32m },
{ X86::DIV_Fp80m64 , X86::DIV_F64m },
{ X86::DIV_FpI16m32 , X86::DIV_FI16m },
{ X86::DIV_FpI16m64 , X86::DIV_FI16m },
{ X86::DIV_FpI16m80 , X86::DIV_FI16m },
{ X86::DIV_FpI32m32 , X86::DIV_FI32m },
{ X86::DIV_FpI32m64 , X86::DIV_FI32m },
{ X86::DIV_FpI32m80 , X86::DIV_FI32m },
{ X86::ILD_Fp16m32 , X86::ILD_F16m },
{ X86::ILD_Fp16m64 , X86::ILD_F16m },
{ X86::ILD_Fp16m80 , X86::ILD_F16m },
{ X86::ILD_Fp32m32 , X86::ILD_F32m },
{ X86::ILD_Fp32m64 , X86::ILD_F32m },
{ X86::ILD_Fp32m80 , X86::ILD_F32m },
{ X86::ILD_Fp64m32 , X86::ILD_F64m },
{ X86::ILD_Fp64m64 , X86::ILD_F64m },
{ X86::ILD_Fp64m80 , X86::ILD_F64m },
{ X86::ISTT_Fp16m32 , X86::ISTT_FP16m},
{ X86::ISTT_Fp16m64 , X86::ISTT_FP16m},
{ X86::ISTT_Fp16m80 , X86::ISTT_FP16m},
{ X86::ISTT_Fp32m32 , X86::ISTT_FP32m},
{ X86::ISTT_Fp32m64 , X86::ISTT_FP32m},
{ X86::ISTT_Fp32m80 , X86::ISTT_FP32m},
{ X86::ISTT_Fp64m32 , X86::ISTT_FP64m},
{ X86::ISTT_Fp64m64 , X86::ISTT_FP64m},
{ X86::ISTT_Fp64m80 , X86::ISTT_FP64m},
{ X86::IST_Fp16m32 , X86::IST_F16m },
{ X86::IST_Fp16m64 , X86::IST_F16m },
{ X86::IST_Fp16m80 , X86::IST_F16m },
{ X86::IST_Fp32m32 , X86::IST_F32m },
{ X86::IST_Fp32m64 , X86::IST_F32m },
{ X86::IST_Fp32m80 , X86::IST_F32m },
{ X86::IST_Fp64m32 , X86::IST_FP64m },
{ X86::IST_Fp64m64 , X86::IST_FP64m },
{ X86::IST_Fp64m80 , X86::IST_FP64m },
{ X86::LD_Fp032 , X86::LD_F0 },
{ X86::LD_Fp064 , X86::LD_F0 },
{ X86::LD_Fp080 , X86::LD_F0 },
{ X86::LD_Fp132 , X86::LD_F1 },
{ X86::LD_Fp164 , X86::LD_F1 },
{ X86::LD_Fp180 , X86::LD_F1 },
{ X86::LD_Fp32m , X86::LD_F32m },
{ X86::LD_Fp32m64 , X86::LD_F32m },
{ X86::LD_Fp32m80 , X86::LD_F32m },
{ X86::LD_Fp64m , X86::LD_F64m },
{ X86::LD_Fp64m80 , X86::LD_F64m },
{ X86::LD_Fp80m , X86::LD_F80m },
{ X86::MUL_Fp32m , X86::MUL_F32m },
{ X86::MUL_Fp64m , X86::MUL_F64m },
{ X86::MUL_Fp64m32 , X86::MUL_F32m },
{ X86::MUL_Fp80m32 , X86::MUL_F32m },
{ X86::MUL_Fp80m64 , X86::MUL_F64m },
{ X86::MUL_FpI16m32 , X86::MUL_FI16m },
{ X86::MUL_FpI16m64 , X86::MUL_FI16m },
{ X86::MUL_FpI16m80 , X86::MUL_FI16m },
{ X86::MUL_FpI32m32 , X86::MUL_FI32m },
{ X86::MUL_FpI32m64 , X86::MUL_FI32m },
{ X86::MUL_FpI32m80 , X86::MUL_FI32m },
{ X86::SIN_Fp32 , X86::SIN_F },
{ X86::SIN_Fp64 , X86::SIN_F },
{ X86::SIN_Fp80 , X86::SIN_F },
{ X86::SQRT_Fp32 , X86::SQRT_F },
{ X86::SQRT_Fp64 , X86::SQRT_F },
{ X86::SQRT_Fp80 , X86::SQRT_F },
{ X86::ST_Fp32m , X86::ST_F32m },
{ X86::ST_Fp64m , X86::ST_F64m },
{ X86::ST_Fp64m32 , X86::ST_F32m },
{ X86::ST_Fp80m32 , X86::ST_F32m },
{ X86::ST_Fp80m64 , X86::ST_F64m },
{ X86::ST_FpP80m , X86::ST_FP80m },
{ X86::SUBR_Fp32m , X86::SUBR_F32m },
{ X86::SUBR_Fp64m , X86::SUBR_F64m },
{ X86::SUBR_Fp64m32 , X86::SUBR_F32m },
{ X86::SUBR_Fp80m32 , X86::SUBR_F32m },
{ X86::SUBR_Fp80m64 , X86::SUBR_F64m },
{ X86::SUBR_FpI16m32, X86::SUBR_FI16m},
{ X86::SUBR_FpI16m64, X86::SUBR_FI16m},
{ X86::SUBR_FpI16m80, X86::SUBR_FI16m},
{ X86::SUBR_FpI32m32, X86::SUBR_FI32m},
{ X86::SUBR_FpI32m64, X86::SUBR_FI32m},
{ X86::SUBR_FpI32m80, X86::SUBR_FI32m},
{ X86::SUB_Fp32m , X86::SUB_F32m },
{ X86::SUB_Fp64m , X86::SUB_F64m },
{ X86::SUB_Fp64m32 , X86::SUB_F32m },
{ X86::SUB_Fp80m32 , X86::SUB_F32m },
{ X86::SUB_Fp80m64 , X86::SUB_F64m },
{ X86::SUB_FpI16m32 , X86::SUB_FI16m },
{ X86::SUB_FpI16m64 , X86::SUB_FI16m },
{ X86::SUB_FpI16m80 , X86::SUB_FI16m },
{ X86::SUB_FpI32m32 , X86::SUB_FI32m },
{ X86::SUB_FpI32m64 , X86::SUB_FI32m },
{ X86::SUB_FpI32m80 , X86::SUB_FI32m },
{ X86::TST_Fp32 , X86::TST_F },
{ X86::TST_Fp64 , X86::TST_F },
{ X86::TST_Fp80 , X86::TST_F },
{ X86::UCOM_FpIr32 , X86::UCOM_FIr },
{ X86::UCOM_FpIr64 , X86::UCOM_FIr },
{ X86::UCOM_FpIr80 , X86::UCOM_FIr },
{ X86::UCOM_Fpr32 , X86::UCOM_Fr },
{ X86::UCOM_Fpr64 , X86::UCOM_Fr },
{ X86::UCOM_Fpr80 , X86::UCOM_Fr },
};
static unsigned getConcreteOpcode(unsigned Opcode) {
ASSERT_SORTED(OpcodeTable);
int Opc = Lookup(OpcodeTable, array_lengthof(OpcodeTable), Opcode);
assert(Opc != -1 && "FP Stack instruction not in OpcodeTable!");
return Opc;
}
//===----------------------------------------------------------------------===//
// Helper Methods
//===----------------------------------------------------------------------===//
// PopTable - Sorted map of instructions to their popping version. The first
// element is an instruction, the second is the version which pops.
//
static const TableEntry PopTable[] = {
{ X86::ADD_FrST0 , X86::ADD_FPrST0 },
{ X86::DIVR_FrST0, X86::DIVR_FPrST0 },
{ X86::DIV_FrST0 , X86::DIV_FPrST0 },
{ X86::IST_F16m , X86::IST_FP16m },
{ X86::IST_F32m , X86::IST_FP32m },
{ X86::MUL_FrST0 , X86::MUL_FPrST0 },
{ X86::ST_F32m , X86::ST_FP32m },
{ X86::ST_F64m , X86::ST_FP64m },
{ X86::ST_Frr , X86::ST_FPrr },
{ X86::SUBR_FrST0, X86::SUBR_FPrST0 },
{ X86::SUB_FrST0 , X86::SUB_FPrST0 },
{ X86::UCOM_FIr , X86::UCOM_FIPr },
{ X86::UCOM_FPr , X86::UCOM_FPPr },
{ X86::UCOM_Fr , X86::UCOM_FPr },
};
/// popStackAfter - Pop the current value off of the top of the FP stack after
/// the specified instruction. This attempts to be sneaky and combine the pop
/// into the instruction itself if possible. The iterator is left pointing to
/// the last instruction, be it a new pop instruction inserted, or the old
/// instruction if it was modified in place.
///
void FPS::popStackAfter(MachineBasicBlock::iterator &I) {
ASSERT_SORTED(PopTable);
assert(StackTop > 0 && "Cannot pop empty stack!");
RegMap[Stack[--StackTop]] = ~0; // Update state
// Check to see if there is a popping version of this instruction...
int Opcode = Lookup(PopTable, array_lengthof(PopTable), I->getOpcode());
if (Opcode != -1) {
I->setDesc(TII->get(Opcode));
if (Opcode == X86::UCOM_FPPr)
I->RemoveOperand(0);
} else { // Insert an explicit pop
I = BuildMI(*MBB, ++I, TII->get(X86::ST_FPrr)).addReg(X86::ST0);
}
}
/// freeStackSlotAfter - Free the specified register from the register stack, so
/// that it is no longer in a register. If the register is currently at the top
/// of the stack, we just pop the current instruction, otherwise we store the
/// current top-of-stack into the specified slot, then pop the top of stack.
void FPS::freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned FPRegNo) {
if (getStackEntry(0) == FPRegNo) { // already at the top of stack? easy.
popStackAfter(I);
return;
}
// Otherwise, store the top of stack into the dead slot, killing the operand
// without having to add in an explicit xchg then pop.
//
unsigned STReg = getSTReg(FPRegNo);
unsigned OldSlot = getSlot(FPRegNo);
unsigned TopReg = Stack[StackTop-1];
Stack[OldSlot] = TopReg;
RegMap[TopReg] = OldSlot;
RegMap[FPRegNo] = ~0;
Stack[--StackTop] = ~0;
I = BuildMI(*MBB, ++I, TII->get(X86::ST_FPrr)).addReg(STReg);
}
//===----------------------------------------------------------------------===//
// Instruction transformation implementation
//===----------------------------------------------------------------------===//
/// handleZeroArgFP - ST(0) = fld0 ST(0) = flds <mem>
///
void FPS::handleZeroArgFP(MachineBasicBlock::iterator &I) {
MachineInstr *MI = I;
unsigned DestReg = getFPReg(MI->getOperand(0));
// Change from the pseudo instruction to the concrete instruction.
MI->RemoveOperand(0); // Remove the explicit ST(0) operand
MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
// Result gets pushed on the stack.
pushReg(DestReg);
}
/// handleOneArgFP - fst <mem>, ST(0)
///
void FPS::handleOneArgFP(MachineBasicBlock::iterator &I) {
MachineInstr *MI = I;
unsigned NumOps = MI->getDesc().getNumOperands();
assert((NumOps == 5 || NumOps == 1) &&
"Can only handle fst* & ftst instructions!");
// Is this the last use of the source register?
unsigned Reg = getFPReg(MI->getOperand(NumOps-1));
bool KillsSrc = MI->killsRegister(X86::FP0+Reg);
// FISTP64m is strange because there isn't a non-popping versions.
// If we have one _and_ we don't want to pop the operand, duplicate the value
// on the stack instead of moving it. This ensure that popping the value is
// always ok.
// Ditto FISTTP16m, FISTTP32m, FISTTP64m, ST_FpP80m.
//
if (!KillsSrc &&
(MI->getOpcode() == X86::IST_Fp64m32 ||
MI->getOpcode() == X86::ISTT_Fp16m32 ||
MI->getOpcode() == X86::ISTT_Fp32m32 ||
MI->getOpcode() == X86::ISTT_Fp64m32 ||
MI->getOpcode() == X86::IST_Fp64m64 ||
MI->getOpcode() == X86::ISTT_Fp16m64 ||
MI->getOpcode() == X86::ISTT_Fp32m64 ||
MI->getOpcode() == X86::ISTT_Fp64m64 ||
MI->getOpcode() == X86::IST_Fp64m80 ||
MI->getOpcode() == X86::ISTT_Fp16m80 ||
MI->getOpcode() == X86::ISTT_Fp32m80 ||
MI->getOpcode() == X86::ISTT_Fp64m80 ||
MI->getOpcode() == X86::ST_FpP80m)) {
duplicateToTop(Reg, 7 /*temp register*/, I);
} else {
moveToTop(Reg, I); // Move to the top of the stack...
}
// Convert from the pseudo instruction to the concrete instruction.
MI->RemoveOperand(NumOps-1); // Remove explicit ST(0) operand
MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
if (MI->getOpcode() == X86::IST_FP64m ||
MI->getOpcode() == X86::ISTT_FP16m ||
MI->getOpcode() == X86::ISTT_FP32m ||
MI->getOpcode() == X86::ISTT_FP64m ||
MI->getOpcode() == X86::ST_FP80m) {
assert(StackTop > 0 && "Stack empty??");
--StackTop;
} else if (KillsSrc) { // Last use of operand?
popStackAfter(I);
}
}
/// handleOneArgFPRW: Handle instructions that read from the top of stack and
/// replace the value with a newly computed value. These instructions may have
/// non-fp operands after their FP operands.
///
/// Examples:
/// R1 = fchs R2
/// R1 = fadd R2, [mem]
///
void FPS::handleOneArgFPRW(MachineBasicBlock::iterator &I) {
MachineInstr *MI = I;
#ifndef NDEBUG
unsigned NumOps = MI->getDesc().getNumOperands();
assert(NumOps >= 2 && "FPRW instructions must have 2 ops!!");
#endif
// Is this the last use of the source register?
unsigned Reg = getFPReg(MI->getOperand(1));
bool KillsSrc = MI->killsRegister(X86::FP0+Reg);
if (KillsSrc) {
// If this is the last use of the source register, just make sure it's on
// the top of the stack.
moveToTop(Reg, I);
assert(StackTop > 0 && "Stack cannot be empty!");
--StackTop;
pushReg(getFPReg(MI->getOperand(0)));
} else {
// If this is not the last use of the source register, _copy_ it to the top
// of the stack.
duplicateToTop(Reg, getFPReg(MI->getOperand(0)), I);
}
// Change from the pseudo instruction to the concrete instruction.
MI->RemoveOperand(1); // Drop the source operand.
MI->RemoveOperand(0); // Drop the destination operand.
MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
}
//===----------------------------------------------------------------------===//
// Define tables of various ways to map pseudo instructions
//
// ForwardST0Table - Map: A = B op C into: ST(0) = ST(0) op ST(i)
static const TableEntry ForwardST0Table[] = {
{ X86::ADD_Fp32 , X86::ADD_FST0r },
{ X86::ADD_Fp64 , X86::ADD_FST0r },
{ X86::ADD_Fp80 , X86::ADD_FST0r },
{ X86::DIV_Fp32 , X86::DIV_FST0r },
{ X86::DIV_Fp64 , X86::DIV_FST0r },
{ X86::DIV_Fp80 , X86::DIV_FST0r },
{ X86::MUL_Fp32 , X86::MUL_FST0r },
{ X86::MUL_Fp64 , X86::MUL_FST0r },
{ X86::MUL_Fp80 , X86::MUL_FST0r },
{ X86::SUB_Fp32 , X86::SUB_FST0r },
{ X86::SUB_Fp64 , X86::SUB_FST0r },
{ X86::SUB_Fp80 , X86::SUB_FST0r },
};
// ReverseST0Table - Map: A = B op C into: ST(0) = ST(i) op ST(0)
static const TableEntry ReverseST0Table[] = {
{ X86::ADD_Fp32 , X86::ADD_FST0r }, // commutative
{ X86::ADD_Fp64 , X86::ADD_FST0r }, // commutative
{ X86::ADD_Fp80 , X86::ADD_FST0r }, // commutative
{ X86::DIV_Fp32 , X86::DIVR_FST0r },
{ X86::DIV_Fp64 , X86::DIVR_FST0r },
{ X86::DIV_Fp80 , X86::DIVR_FST0r },
{ X86::MUL_Fp32 , X86::MUL_FST0r }, // commutative
{ X86::MUL_Fp64 , X86::MUL_FST0r }, // commutative
{ X86::MUL_Fp80 , X86::MUL_FST0r }, // commutative
{ X86::SUB_Fp32 , X86::SUBR_FST0r },
{ X86::SUB_Fp64 , X86::SUBR_FST0r },
{ X86::SUB_Fp80 , X86::SUBR_FST0r },
};
// ForwardSTiTable - Map: A = B op C into: ST(i) = ST(0) op ST(i)
static const TableEntry ForwardSTiTable[] = {
{ X86::ADD_Fp32 , X86::ADD_FrST0 }, // commutative
{ X86::ADD_Fp64 , X86::ADD_FrST0 }, // commutative
{ X86::ADD_Fp80 , X86::ADD_FrST0 }, // commutative
{ X86::DIV_Fp32 , X86::DIVR_FrST0 },
{ X86::DIV_Fp64 , X86::DIVR_FrST0 },
{ X86::DIV_Fp80 , X86::DIVR_FrST0 },
{ X86::MUL_Fp32 , X86::MUL_FrST0 }, // commutative
{ X86::MUL_Fp64 , X86::MUL_FrST0 }, // commutative
{ X86::MUL_Fp80 , X86::MUL_FrST0 }, // commutative
{ X86::SUB_Fp32 , X86::SUBR_FrST0 },
{ X86::SUB_Fp64 , X86::SUBR_FrST0 },
{ X86::SUB_Fp80 , X86::SUBR_FrST0 },
};
// ReverseSTiTable - Map: A = B op C into: ST(i) = ST(i) op ST(0)
static const TableEntry ReverseSTiTable[] = {
{ X86::ADD_Fp32 , X86::ADD_FrST0 },
{ X86::ADD_Fp64 , X86::ADD_FrST0 },
{ X86::ADD_Fp80 , X86::ADD_FrST0 },
{ X86::DIV_Fp32 , X86::DIV_FrST0 },
{ X86::DIV_Fp64 , X86::DIV_FrST0 },
{ X86::DIV_Fp80 , X86::DIV_FrST0 },
{ X86::MUL_Fp32 , X86::MUL_FrST0 },
{ X86::MUL_Fp64 , X86::MUL_FrST0 },
{ X86::MUL_Fp80 , X86::MUL_FrST0 },
{ X86::SUB_Fp32 , X86::SUB_FrST0 },
{ X86::SUB_Fp64 , X86::SUB_FrST0 },
{ X86::SUB_Fp80 , X86::SUB_FrST0 },
};
/// handleTwoArgFP - Handle instructions like FADD and friends which are virtual
/// instructions which need to be simplified and possibly transformed.
///
/// Result: ST(0) = fsub ST(0), ST(i)
/// ST(i) = fsub ST(0), ST(i)
/// ST(0) = fsubr ST(0), ST(i)
/// ST(i) = fsubr ST(0), ST(i)
///
void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) {
ASSERT_SORTED(ForwardST0Table); ASSERT_SORTED(ReverseST0Table);
ASSERT_SORTED(ForwardSTiTable); ASSERT_SORTED(ReverseSTiTable);
MachineInstr *MI = I;
unsigned NumOperands = MI->getDesc().getNumOperands();
assert(NumOperands == 3 && "Illegal TwoArgFP instruction!");
unsigned Dest = getFPReg(MI->getOperand(0));
unsigned Op0 = getFPReg(MI->getOperand(NumOperands-2));
unsigned Op1 = getFPReg(MI->getOperand(NumOperands-1));
bool KillsOp0 = MI->killsRegister(X86::FP0+Op0);
bool KillsOp1 = MI->killsRegister(X86::FP0+Op1);
unsigned TOS = getStackEntry(0);
// One of our operands must be on the top of the stack. If neither is yet, we
// need to move one.
if (Op0 != TOS && Op1 != TOS) { // No operand at TOS?
// We can choose to move either operand to the top of the stack. If one of
// the operands is killed by this instruction, we want that one so that we
// can update right on top of the old version.
if (KillsOp0) {
moveToTop(Op0, I); // Move dead operand to TOS.
TOS = Op0;
} else if (KillsOp1) {
moveToTop(Op1, I);
TOS = Op1;
} else {
// All of the operands are live after this instruction executes, so we
// cannot update on top of any operand. Because of this, we must
// duplicate one of the stack elements to the top. It doesn't matter
// which one we pick.
//
duplicateToTop(Op0, Dest, I);
Op0 = TOS = Dest;
KillsOp0 = true;
}
} else if (!KillsOp0 && !KillsOp1) {
// If we DO have one of our operands at the top of the stack, but we don't
// have a dead operand, we must duplicate one of the operands to a new slot
// on the stack.
duplicateToTop(Op0, Dest, I);
Op0 = TOS = Dest;
KillsOp0 = true;
}
// Now we know that one of our operands is on the top of the stack, and at
// least one of our operands is killed by this instruction.
assert((TOS == Op0 || TOS == Op1) && (KillsOp0 || KillsOp1) &&
"Stack conditions not set up right!");
// We decide which form to use based on what is on the top of the stack, and
// which operand is killed by this instruction.
const TableEntry *InstTable;
bool isForward = TOS == Op0;
bool updateST0 = (TOS == Op0 && !KillsOp1) || (TOS == Op1 && !KillsOp0);
if (updateST0) {
if (isForward)
InstTable = ForwardST0Table;
else
InstTable = ReverseST0Table;
} else {
if (isForward)
InstTable = ForwardSTiTable;
else
InstTable = ReverseSTiTable;
}
int Opcode = Lookup(InstTable, array_lengthof(ForwardST0Table),
MI->getOpcode());
assert(Opcode != -1 && "Unknown TwoArgFP pseudo instruction!");
// NotTOS - The register which is not on the top of stack...
unsigned NotTOS = (TOS == Op0) ? Op1 : Op0;
// Replace the old instruction with a new instruction
MBB->remove(I++);
I = BuildMI(*MBB, I, TII->get(Opcode)).addReg(getSTReg(NotTOS));
// If both operands are killed, pop one off of the stack in addition to
// overwriting the other one.
if (KillsOp0 && KillsOp1 && Op0 != Op1) {
assert(!updateST0 && "Should have updated other operand!");
popStackAfter(I); // Pop the top of stack
}
// Update stack information so that we know the destination register is now on
// the stack.
unsigned UpdatedSlot = getSlot(updateST0 ? TOS : NotTOS);
assert(UpdatedSlot < StackTop && Dest < 7);
Stack[UpdatedSlot] = Dest;
RegMap[Dest] = UpdatedSlot;
MBB->getParent()->DeleteMachineInstr(MI); // Remove the old instruction
}
/// handleCompareFP - Handle FUCOM and FUCOMI instructions, which have two FP
/// register arguments and no explicit destinations.
///
void FPS::handleCompareFP(MachineBasicBlock::iterator &I) {
ASSERT_SORTED(ForwardST0Table); ASSERT_SORTED(ReverseST0Table);
ASSERT_SORTED(ForwardSTiTable); ASSERT_SORTED(ReverseSTiTable);
MachineInstr *MI = I;
unsigned NumOperands = MI->getDesc().getNumOperands();
assert(NumOperands == 2 && "Illegal FUCOM* instruction!");
unsigned Op0 = getFPReg(MI->getOperand(NumOperands-2));
unsigned Op1 = getFPReg(MI->getOperand(NumOperands-1));
bool KillsOp0 = MI->killsRegister(X86::FP0+Op0);
bool KillsOp1 = MI->killsRegister(X86::FP0+Op1);
// Make sure the first operand is on the top of stack, the other one can be
// anywhere.
moveToTop(Op0, I);
// Change from the pseudo instruction to the concrete instruction.
MI->getOperand(0).setReg(getSTReg(Op1));
MI->RemoveOperand(1);
MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
// If any of the operands are killed by this instruction, free them.
if (KillsOp0) freeStackSlotAfter(I, Op0);
if (KillsOp1 && Op0 != Op1) freeStackSlotAfter(I, Op1);
}
/// handleCondMovFP - Handle two address conditional move instructions. These
/// instructions move a st(i) register to st(0) iff a condition is true. These
/// instructions require that the first operand is at the top of the stack, but
/// otherwise don't modify the stack at all.
void FPS::handleCondMovFP(MachineBasicBlock::iterator &I) {
MachineInstr *MI = I;
unsigned Op0 = getFPReg(MI->getOperand(0));
unsigned Op1 = getFPReg(MI->getOperand(2));
bool KillsOp1 = MI->killsRegister(X86::FP0+Op1);
// The first operand *must* be on the top of the stack.
moveToTop(Op0, I);
// Change the second operand to the stack register that the operand is in.
// Change from the pseudo instruction to the concrete instruction.
MI->RemoveOperand(0);
MI->RemoveOperand(1);
MI->getOperand(0).setReg(getSTReg(Op1));
MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
// If we kill the second operand, make sure to pop it from the stack.
if (Op0 != Op1 && KillsOp1) {
// Get this value off of the register stack.
freeStackSlotAfter(I, Op1);
}
}
/// handleSpecialFP - Handle special instructions which behave unlike other
/// floating point instructions. This is primarily intended for use by pseudo
/// instructions.
///
void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
MachineInstr *MI = I;
switch (MI->getOpcode()) {
default: assert(0 && "Unknown SpecialFP instruction!");
case X86::FpGET_ST0_32:// Appears immediately after a call returning FP type!
case X86::FpGET_ST0_64:// Appears immediately after a call returning FP type!
case X86::FpGET_ST0_80:// Appears immediately after a call returning FP type!
assert(StackTop == 0 && "Stack should be empty after a call!");
pushReg(getFPReg(MI->getOperand(0)));
break;
case X86::FpGET_ST1_32:// Appears immediately after a call returning FP type!
case X86::FpGET_ST1_64:// Appears immediately after a call returning FP type!
case X86::FpGET_ST1_80:{// Appears immediately after a call returning FP type!
// FpGET_ST1 should occur right after a FpGET_ST0 for a call or inline asm.
// The pattern we expect is:
// CALL
// FP1 = FpGET_ST0
// FP4 = FpGET_ST1
//
// At this point, we've pushed FP1 on the top of stack, so it should be
// present if it isn't dead. If it was dead, we already emitted a pop to
// remove it from the stack and StackTop = 0.
// Push FP4 as top of stack next.
pushReg(getFPReg(MI->getOperand(0)));
// If StackTop was 0 before we pushed our operand, then ST(0) must have been
// dead. In this case, the ST(1) value is the only thing that is live, so
// it should be on the TOS (after the pop that was emitted) and is. Just
// continue in this case.
if (StackTop == 1)
break;
// Because pushReg just pushed ST(1) as TOS, we now have to swap the two top
// elements so that our accounting is correct.
unsigned RegOnTop = getStackEntry(0);
unsigned RegNo = getStackEntry(1);
// Swap the slots the regs are in.
std::swap(RegMap[RegNo], RegMap[RegOnTop]);
// Swap stack slot contents.
assert(RegMap[RegOnTop] < StackTop);
std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
break;
}
case X86::FpSET_ST0_32:
case X86::FpSET_ST0_64:
case X86::FpSET_ST0_80:
assert(StackTop == 1 && "Stack should have one element on it to return!");
--StackTop; // "Forget" we have something on the top of stack!
break;
case X86::MOV_Fp3232:
case X86::MOV_Fp3264:
case X86::MOV_Fp6432:
case X86::MOV_Fp6464:
case X86::MOV_Fp3280:
case X86::MOV_Fp6480:
case X86::MOV_Fp8032:
case X86::MOV_Fp8064:
case X86::MOV_Fp8080: {
unsigned SrcReg = getFPReg(MI->getOperand(1));
unsigned DestReg = getFPReg(MI->getOperand(0));
if (MI->killsRegister(X86::FP0+SrcReg)) {
// If the input operand is killed, we can just change the owner of the
// incoming stack slot into the result.
unsigned Slot = getSlot(SrcReg);
assert(Slot < 7 && DestReg < 7 && "FpMOV operands invalid!");
Stack[Slot] = DestReg;
RegMap[DestReg] = Slot;
} else {
// For FMOV we just duplicate the specified value to a new stack slot.
// This could be made better, but would require substantial changes.
duplicateToTop(SrcReg, DestReg, I);
}
}
break;
case TargetInstrInfo::INLINEASM: {
// The inline asm MachineInstr currently only *uses* FP registers for the
// 'f' constraint. These should be turned into the current ST(x) register
// in the machine instr. Also, any kills should be explicitly popped after
// the inline asm.
unsigned Kills[7];
unsigned NumKills = 0;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &Op = MI->getOperand(i);
if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
continue;
assert(Op.isUse() && "Only handle inline asm uses right now");
unsigned FPReg = getFPReg(Op);
Op.setReg(getSTReg(FPReg));
// If we kill this operand, make sure to pop it from the stack after the
// asm. We just remember it for now, and pop them all off at the end in
// a batch.
if (Op.isKill())
Kills[NumKills++] = FPReg;
}
// If this asm kills any FP registers (is the last use of them) we must
// explicitly emit pop instructions for them. Do this now after the asm has
// executed so that the ST(x) numbers are not off (which would happen if we
// did this inline with operand rewriting).
//
// Note: this might be a non-optimal pop sequence. We might be able to do
// better by trying to pop in stack order or something.
MachineBasicBlock::iterator InsertPt = MI;
while (NumKills)
freeStackSlotAfter(InsertPt, Kills[--NumKills]);
// Don't delete the inline asm!
return;
}
case X86::RET:
case X86::RETI:
// If RET has an FP register use operand, pass the first one in ST(0) and
// the second one in ST(1).
if (isStackEmpty()) return; // Quick check to see if any are possible.
// Find the register operands.
unsigned FirstFPRegOp = ~0U, SecondFPRegOp = ~0U;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &Op = MI->getOperand(i);
if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
continue;
// FP Register uses must be kills unless there are two uses of the same
// register, in which case only one will be a kill.
assert(Op.isUse() &&
(Op.isKill() || // Marked kill.
getFPReg(Op) == FirstFPRegOp || // Second instance.
MI->killsRegister(Op.getReg())) && // Later use is marked kill.
"Ret only defs operands, and values aren't live beyond it");
if (FirstFPRegOp == ~0U)
FirstFPRegOp = getFPReg(Op);
else {
assert(SecondFPRegOp == ~0U && "More than two fp operands!");
SecondFPRegOp = getFPReg(Op);
}
// Remove the operand so that later passes don't see it.
MI->RemoveOperand(i);
--i, --e;
}
// There are only four possibilities here:
// 1) we are returning a single FP value. In this case, it has to be in
// ST(0) already, so just declare success by removing the value from the
// FP Stack.
if (SecondFPRegOp == ~0U) {
// Assert that the top of stack contains the right FP register.
assert(StackTop == 1 && FirstFPRegOp == getStackEntry(0) &&
"Top of stack not the right register for RET!");
// Ok, everything is good, mark the value as not being on the stack
// anymore so that our assertion about the stack being empty at end of
// block doesn't fire.
StackTop = 0;
return;
}
// Otherwise, we are returning two values:
// 2) If returning the same value for both, we only have one thing in the FP
// stack. Consider: RET FP1, FP1
if (StackTop == 1) {
assert(FirstFPRegOp == SecondFPRegOp && FirstFPRegOp == getStackEntry(0)&&
"Stack misconfiguration for RET!");
// Duplicate the TOS so that we return it twice. Just pick some other FPx
// register to hold it.
unsigned NewReg = (FirstFPRegOp+1)%7;
duplicateToTop(FirstFPRegOp, NewReg, MI);
FirstFPRegOp = NewReg;
}
/// Okay we know we have two different FPx operands now:
assert(StackTop == 2 && "Must have two values live!");
/// 3) If SecondFPRegOp is currently in ST(0) and FirstFPRegOp is currently
/// in ST(1). In this case, emit an fxch.
if (getStackEntry(0) == SecondFPRegOp) {
assert(getStackEntry(1) == FirstFPRegOp && "Unknown regs live");
moveToTop(FirstFPRegOp, MI);
}
/// 4) Finally, FirstFPRegOp must be in ST(0) and SecondFPRegOp must be in
/// ST(1). Just remove both from our understanding of the stack and return.
assert(getStackEntry(0) == FirstFPRegOp && "Unknown regs live");
assert(getStackEntry(1) == SecondFPRegOp && "Unknown regs live");
StackTop = 0;
return;
}
I = MBB->erase(I); // Remove the pseudo instruction
--I;
}
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