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Implement a small optimization. In test/Regression/CodeGen/X86/select.ll, we now generate this for foldSel3: foldSel3: mov %AL, BYTE PTR [%ESP + 4] fld DWORD PTR [%ESP + 8] fld DWORD PTR [%ESP + 12] mov %EAX, DWORD PTR [%ESP + 16] mov %ECX, DWORD PTR [%ESP + 20] cmp %EAX, %ECX fxch %ST(1) fcmovae %ST(0), %ST(1) *** fstp %ST(1) ret Instead of: foldSel3: mov %AL, BYTE PTR [%ESP + 4] fld DWORD PTR [%ESP + 8] fld DWORD PTR [%ESP + 12] mov %EAX, DWORD PTR [%ESP + 16] mov %ECX, DWORD PTR [%ESP + 20] cmp %EAX, %ECX fxch %ST(1) fcmovae %ST(0), %ST(1) *** fxch %ST(1) *** fstp %ST(0) ret In practice, this only effects code size: performance should be basically unaffected. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12588 91177308-0d34-0410-b5e6-96231b3b80d8
726 lines
26 KiB
C++
726 lines
26 KiB
C++
//===-- FloatingPoint.cpp - Floating point Reg -> Stack converter ---------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the pass which converts floating point instructions from
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// virtual registers into register stack instructions. This pass uses live
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// variable information to indicate where the FPn registers are used and their
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// lifetimes.
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//
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// This pass is hampered by the lack of decent CFG manipulation routines for
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// machine code. In particular, this wants to be able to split critical edges
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// as necessary, traverse the machine basic block CFG in depth-first order, and
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// allow there to be multiple machine basic blocks for each LLVM basicblock
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// (needed for critical edge splitting).
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//
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// In particular, this pass currently barfs on critical edges. Because of this,
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// it requires the instruction selector to insert FP_REG_KILL instructions on
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// the exits of any basic block that has critical edges going from it, or which
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// branch to a critical basic block.
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//
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// FIXME: this is not implemented yet. The stackifier pass only works on local
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// basic blocks.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "fp"
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#include "X86.h"
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#include "X86InstrInfo.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/LiveVariables.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Function.h" // FIXME: remove when using MBB CFG!
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#include "llvm/Support/CFG.h" // FIXME: remove when using MBB CFG!
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#include "Support/Debug.h"
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#include "Support/DepthFirstIterator.h"
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#include "Support/Statistic.h"
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#include "Support/STLExtras.h"
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#include <algorithm>
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#include <set>
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using namespace llvm;
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namespace {
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Statistic<> NumFXCH("x86-codegen", "Number of fxch instructions inserted");
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Statistic<> NumFP ("x86-codegen", "Number of floating point instructions");
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struct FPS : public MachineFunctionPass {
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virtual bool runOnMachineFunction(MachineFunction &MF);
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virtual const char *getPassName() const { return "X86 FP Stackifier"; }
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<LiveVariables>();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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private:
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LiveVariables *LV; // Live variable info for current function...
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MachineBasicBlock *MBB; // Current basic block
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unsigned Stack[8]; // FP<n> Registers in each stack slot...
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unsigned RegMap[8]; // Track which stack slot contains each register
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unsigned StackTop; // The current top of the FP stack.
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void dumpStack() const {
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std::cerr << "Stack contents:";
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for (unsigned i = 0; i != StackTop; ++i) {
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std::cerr << " FP" << Stack[i];
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assert(RegMap[Stack[i]] == i && "Stack[] doesn't match RegMap[]!");
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}
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std::cerr << "\n";
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}
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private:
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// getSlot - Return the stack slot number a particular register number is
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// in...
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unsigned getSlot(unsigned RegNo) const {
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assert(RegNo < 8 && "Regno out of range!");
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return RegMap[RegNo];
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}
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// getStackEntry - Return the X86::FP<n> register in register ST(i)
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unsigned getStackEntry(unsigned STi) const {
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assert(STi < StackTop && "Access past stack top!");
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return Stack[StackTop-1-STi];
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}
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// getSTReg - Return the X86::ST(i) register which contains the specified
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// FP<RegNo> register
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unsigned getSTReg(unsigned RegNo) const {
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return StackTop - 1 - getSlot(RegNo) + llvm::X86::ST0;
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}
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// pushReg - Push the specified FP<n> register onto the stack
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void pushReg(unsigned Reg) {
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assert(Reg < 8 && "Register number out of range!");
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assert(StackTop < 8 && "Stack overflow!");
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Stack[StackTop] = Reg;
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RegMap[Reg] = StackTop++;
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}
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bool isAtTop(unsigned RegNo) const { return getSlot(RegNo) == StackTop-1; }
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void moveToTop(unsigned RegNo, MachineBasicBlock::iterator &I) {
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if (!isAtTop(RegNo)) {
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unsigned Slot = getSlot(RegNo);
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unsigned STReg = getSTReg(RegNo);
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unsigned RegOnTop = getStackEntry(0);
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// Swap the slots the regs are in
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std::swap(RegMap[RegNo], RegMap[RegOnTop]);
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// Swap stack slot contents
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assert(RegMap[RegOnTop] < StackTop);
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std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
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// Emit an fxch to update the runtime processors version of the state
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BuildMI(*MBB, I, X86::FXCH, 1).addReg(STReg);
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NumFXCH++;
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}
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}
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void duplicateToTop(unsigned RegNo, unsigned AsReg, MachineInstr *I) {
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unsigned STReg = getSTReg(RegNo);
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pushReg(AsReg); // New register on top of stack
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BuildMI(*MBB, I, X86::FLDrr, 1).addReg(STReg);
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}
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// popStackAfter - Pop the current value off of the top of the FP stack
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// after the specified instruction.
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void popStackAfter(MachineBasicBlock::iterator &I);
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// freeStackSlotAfter - Free the specified register from the register stack,
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// so that it is no longer in a register. If the register is currently at
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// the top of the stack, we just pop the current instruction, otherwise we
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// store the current top-of-stack into the specified slot, then pop the top
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// of stack.
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void freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned Reg);
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bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB);
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void handleZeroArgFP(MachineBasicBlock::iterator &I);
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void handleOneArgFP(MachineBasicBlock::iterator &I);
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void handleOneArgFPRW(MachineBasicBlock::iterator &I);
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void handleTwoArgFP(MachineBasicBlock::iterator &I);
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void handleCondMovFP(MachineBasicBlock::iterator &I);
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void handleSpecialFP(MachineBasicBlock::iterator &I);
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};
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}
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FunctionPass *llvm::createX86FloatingPointStackifierPass() { return new FPS(); }
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/// runOnMachineFunction - Loop over all of the basic blocks, transforming FP
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/// register references into FP stack references.
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///
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bool FPS::runOnMachineFunction(MachineFunction &MF) {
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LV = &getAnalysis<LiveVariables>();
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StackTop = 0;
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// Figure out the mapping of MBB's to BB's.
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//
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// FIXME: Eventually we should be able to traverse the MBB CFG directly, and
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// we will need to extend this when one llvm basic block can codegen to
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// multiple MBBs.
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//
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// FIXME again: Just use the mapping established by LiveVariables!
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//
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std::map<const BasicBlock*, MachineBasicBlock *> MBBMap;
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for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
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MBBMap[I->getBasicBlock()] = I;
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// Process the function in depth first order so that we process at least one
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// of the predecessors for every reachable block in the function.
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std::set<const BasicBlock*> Processed;
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const BasicBlock *Entry = MF.getFunction()->begin();
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bool Changed = false;
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for (df_ext_iterator<const BasicBlock*, std::set<const BasicBlock*> >
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I = df_ext_begin(Entry, Processed), E = df_ext_end(Entry, Processed);
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I != E; ++I)
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Changed |= processBasicBlock(MF, *MBBMap[*I]);
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assert(MBBMap.size() == Processed.size() &&
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"Doesn't handle unreachable code yet!");
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return Changed;
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}
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/// processBasicBlock - Loop over all of the instructions in the basic block,
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/// transforming FP instructions into their stack form.
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///
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bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
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const TargetInstrInfo &TII = MF.getTarget().getInstrInfo();
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bool Changed = false;
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MBB = &BB;
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for (MachineBasicBlock::iterator I = BB.begin(); I != BB.end(); ++I) {
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MachineInstr *MI = I;
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unsigned Flags = TII.get(MI->getOpcode()).TSFlags;
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if ((Flags & X86II::FPTypeMask) == X86II::NotFP)
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continue; // Efficiently ignore non-fp insts!
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MachineInstr *PrevMI = 0;
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if (I != BB.begin())
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PrevMI = prior(I);
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++NumFP; // Keep track of # of pseudo instrs
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DEBUG(std::cerr << "\nFPInst:\t";
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MI->print(std::cerr, MF.getTarget()));
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// Get dead variables list now because the MI pointer may be deleted as part
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// of processing!
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LiveVariables::killed_iterator IB = LV->dead_begin(MI);
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LiveVariables::killed_iterator IE = LV->dead_end(MI);
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DEBUG(const MRegisterInfo *MRI = MF.getTarget().getRegisterInfo();
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LiveVariables::killed_iterator I = LV->killed_begin(MI);
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LiveVariables::killed_iterator E = LV->killed_end(MI);
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if (I != E) {
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std::cerr << "Killed Operands:";
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for (; I != E; ++I)
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std::cerr << " %" << MRI->getName(I->second);
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std::cerr << "\n";
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});
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switch (Flags & X86II::FPTypeMask) {
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case X86II::ZeroArgFP: handleZeroArgFP(I); break;
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case X86II::OneArgFP: handleOneArgFP(I); break; // fstp ST(0)
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case X86II::OneArgFPRW: handleOneArgFPRW(I); break; // ST(0) = fsqrt(ST(0))
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case X86II::TwoArgFP: handleTwoArgFP(I); break;
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case X86II::CondMovFP: handleCondMovFP(I); break;
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case X86II::SpecialFP: handleSpecialFP(I); break;
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default: assert(0 && "Unknown FP Type!");
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}
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// Check to see if any of the values defined by this instruction are dead
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// after definition. If so, pop them.
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for (; IB != IE; ++IB) {
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unsigned Reg = IB->second;
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if (Reg >= X86::FP0 && Reg <= X86::FP6) {
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DEBUG(std::cerr << "Register FP#" << Reg-X86::FP0 << " is dead!\n");
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++I; // Insert fxch AFTER the instruction
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moveToTop(Reg-X86::FP0, I); // Insert fxch if necessary
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--I; // Move to fxch or old instruction
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popStackAfter(I); // Pop the top of the stack, killing value
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}
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}
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// Print out all of the instructions expanded to if -debug
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DEBUG(
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MachineBasicBlock::iterator PrevI(PrevMI);
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if (I == PrevI) {
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std::cerr << "Just deleted pseudo instruction\n";
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} else {
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MachineBasicBlock::iterator Start = I;
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// Rewind to first instruction newly inserted.
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while (Start != BB.begin() && prior(Start) != PrevI) --Start;
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std::cerr << "Inserted instructions:\n\t";
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Start->print(std::cerr, MF.getTarget());
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while (++Start != next(I));
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}
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dumpStack();
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);
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Changed = true;
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}
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assert(StackTop == 0 && "Stack not empty at end of basic block?");
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return Changed;
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}
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//===----------------------------------------------------------------------===//
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// Efficient Lookup Table Support
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//===----------------------------------------------------------------------===//
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namespace {
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struct TableEntry {
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unsigned from;
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unsigned to;
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bool operator<(const TableEntry &TE) const { return from < TE.from; }
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bool operator<(unsigned V) const { return from < V; }
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};
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}
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static bool TableIsSorted(const TableEntry *Table, unsigned NumEntries) {
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for (unsigned i = 0; i != NumEntries-1; ++i)
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if (!(Table[i] < Table[i+1])) return false;
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return true;
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}
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static int Lookup(const TableEntry *Table, unsigned N, unsigned Opcode) {
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const TableEntry *I = std::lower_bound(Table, Table+N, Opcode);
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if (I != Table+N && I->from == Opcode)
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return I->to;
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return -1;
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}
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#define ARRAY_SIZE(TABLE) \
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(sizeof(TABLE)/sizeof(TABLE[0]))
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#ifdef NDEBUG
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#define ASSERT_SORTED(TABLE)
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#else
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#define ASSERT_SORTED(TABLE) \
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{ static bool TABLE##Checked = false; \
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if (!TABLE##Checked) \
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assert(TableIsSorted(TABLE, ARRAY_SIZE(TABLE)) && \
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"All lookup tables must be sorted for efficient access!"); \
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}
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#endif
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//===----------------------------------------------------------------------===//
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// Helper Methods
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//===----------------------------------------------------------------------===//
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// PopTable - Sorted map of instructions to their popping version. The first
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// element is an instruction, the second is the version which pops.
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//
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static const TableEntry PopTable[] = {
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{ X86::FADDrST0 , X86::FADDPrST0 },
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{ X86::FDIVRrST0, X86::FDIVRPrST0 },
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{ X86::FDIVrST0 , X86::FDIVPrST0 },
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{ X86::FIST16m , X86::FISTP16m },
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{ X86::FIST32m , X86::FISTP32m },
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{ X86::FMULrST0 , X86::FMULPrST0 },
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{ X86::FST32m , X86::FSTP32m },
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{ X86::FST64m , X86::FSTP64m },
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{ X86::FSTrr , X86::FSTPrr },
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{ X86::FSUBRrST0, X86::FSUBRPrST0 },
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{ X86::FSUBrST0 , X86::FSUBPrST0 },
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{ X86::FUCOMPr , X86::FUCOMPPr },
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{ X86::FUCOMr , X86::FUCOMPr },
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};
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/// popStackAfter - Pop the current value off of the top of the FP stack after
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/// the specified instruction. This attempts to be sneaky and combine the pop
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/// into the instruction itself if possible. The iterator is left pointing to
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/// the last instruction, be it a new pop instruction inserted, or the old
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/// instruction if it was modified in place.
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///
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void FPS::popStackAfter(MachineBasicBlock::iterator &I) {
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ASSERT_SORTED(PopTable);
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assert(StackTop > 0 && "Cannot pop empty stack!");
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RegMap[Stack[--StackTop]] = ~0; // Update state
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// Check to see if there is a popping version of this instruction...
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int Opcode = Lookup(PopTable, ARRAY_SIZE(PopTable), I->getOpcode());
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if (Opcode != -1) {
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I->setOpcode(Opcode);
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if (Opcode == X86::FUCOMPPr)
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I->RemoveOperand(0);
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} else { // Insert an explicit pop
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I = BuildMI(*MBB, ++I, X86::FSTPrr, 1).addReg(X86::ST0);
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}
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}
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/// freeStackSlotAfter - Free the specified register from the register stack, so
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/// that it is no longer in a register. If the register is currently at the top
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/// of the stack, we just pop the current instruction, otherwise we store the
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/// current top-of-stack into the specified slot, then pop the top of stack.
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void FPS::freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned FPRegNo) {
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if (getStackEntry(0) == FPRegNo) { // already at the top of stack? easy.
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popStackAfter(I);
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return;
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}
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// Otherwise, store the top of stack into the dead slot, killing the operand
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// without having to add in an explicit xchg then pop.
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//
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unsigned STReg = getSTReg(FPRegNo);
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unsigned OldSlot = getSlot(FPRegNo);
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unsigned TopReg = Stack[StackTop-1];
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Stack[OldSlot] = TopReg;
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RegMap[TopReg] = OldSlot;
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RegMap[FPRegNo] = ~0;
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Stack[--StackTop] = ~0;
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I = BuildMI(*MBB, ++I, X86::FSTPrr, 1).addReg(STReg);
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}
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static unsigned getFPReg(const MachineOperand &MO) {
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assert(MO.isRegister() && "Expected an FP register!");
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unsigned Reg = MO.getReg();
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assert(Reg >= X86::FP0 && Reg <= X86::FP6 && "Expected FP register!");
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return Reg - X86::FP0;
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}
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//===----------------------------------------------------------------------===//
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// Instruction transformation implementation
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//===----------------------------------------------------------------------===//
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/// handleZeroArgFP - ST(0) = fld0 ST(0) = flds <mem>
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///
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void FPS::handleZeroArgFP(MachineBasicBlock::iterator &I) {
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MachineInstr *MI = I;
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unsigned DestReg = getFPReg(MI->getOperand(0));
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MI->RemoveOperand(0); // Remove the explicit ST(0) operand
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// Result gets pushed on the stack...
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pushReg(DestReg);
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}
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/// handleOneArgFP - fst <mem>, ST(0)
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///
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void FPS::handleOneArgFP(MachineBasicBlock::iterator &I) {
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MachineInstr *MI = I;
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assert((MI->getNumOperands() == 5 || MI->getNumOperands() == 1) &&
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"Can only handle fst* & ftst instructions!");
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// Is this the last use of the source register?
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unsigned Reg = getFPReg(MI->getOperand(MI->getNumOperands()-1));
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bool KillsSrc = false;
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for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
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E = LV->killed_end(MI); KI != E; ++KI)
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KillsSrc |= KI->second == X86::FP0+Reg;
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// FSTP80r and FISTP64r are strange because there are no non-popping versions.
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// If we have one _and_ we don't want to pop the operand, duplicate the value
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// on the stack instead of moving it. This ensure that popping the value is
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// always ok.
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//
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if ((MI->getOpcode() == X86::FSTP80m ||
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MI->getOpcode() == X86::FISTP64m) && !KillsSrc) {
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duplicateToTop(Reg, 7 /*temp register*/, I);
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} else {
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moveToTop(Reg, I); // Move to the top of the stack...
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}
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MI->RemoveOperand(MI->getNumOperands()-1); // Remove explicit ST(0) operand
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if (MI->getOpcode() == X86::FSTP80m || MI->getOpcode() == X86::FISTP64m) {
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assert(StackTop > 0 && "Stack empty??");
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--StackTop;
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} else if (KillsSrc) { // Last use of operand?
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popStackAfter(I);
|
|
}
|
|
}
|
|
|
|
|
|
/// handleOneArgFPRW - fchs - ST(0) = -ST(0)
|
|
///
|
|
void FPS::handleOneArgFPRW(MachineBasicBlock::iterator &I) {
|
|
MachineInstr *MI = I;
|
|
assert(MI->getNumOperands() == 2 && "Can only handle fst* instructions!");
|
|
|
|
// Is this the last use of the source register?
|
|
unsigned Reg = getFPReg(MI->getOperand(1));
|
|
bool KillsSrc = false;
|
|
for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
|
|
E = LV->killed_end(MI); KI != E; ++KI)
|
|
KillsSrc |= KI->second == 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);
|
|
}
|
|
|
|
MI->RemoveOperand(1); // Drop the source operand.
|
|
MI->RemoveOperand(0); // Drop the destination operand.
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// 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::FpADD, X86::FADDST0r },
|
|
{ X86::FpDIV, X86::FDIVST0r },
|
|
{ X86::FpMUL, X86::FMULST0r },
|
|
{ X86::FpSUB, X86::FSUBST0r },
|
|
{ X86::FpUCOM, X86::FUCOMr },
|
|
};
|
|
|
|
// ReverseST0Table - Map: A = B op C into: ST(0) = ST(i) op ST(0)
|
|
static const TableEntry ReverseST0Table[] = {
|
|
{ X86::FpADD, X86::FADDST0r }, // commutative
|
|
{ X86::FpDIV, X86::FDIVRST0r },
|
|
{ X86::FpMUL, X86::FMULST0r }, // commutative
|
|
{ X86::FpSUB, X86::FSUBRST0r },
|
|
{ X86::FpUCOM, ~0 },
|
|
};
|
|
|
|
// ForwardSTiTable - Map: A = B op C into: ST(i) = ST(0) op ST(i)
|
|
static const TableEntry ForwardSTiTable[] = {
|
|
{ X86::FpADD, X86::FADDrST0 }, // commutative
|
|
{ X86::FpDIV, X86::FDIVRrST0 },
|
|
{ X86::FpMUL, X86::FMULrST0 }, // commutative
|
|
{ X86::FpSUB, X86::FSUBRrST0 },
|
|
{ X86::FpUCOM, X86::FUCOMr },
|
|
};
|
|
|
|
// ReverseSTiTable - Map: A = B op C into: ST(i) = ST(i) op ST(0)
|
|
static const TableEntry ReverseSTiTable[] = {
|
|
{ X86::FpADD, X86::FADDrST0 },
|
|
{ X86::FpDIV, X86::FDIVrST0 },
|
|
{ X86::FpMUL, X86::FMULrST0 },
|
|
{ X86::FpSUB, X86::FSUBrST0 },
|
|
{ X86::FpUCOM, ~0 },
|
|
};
|
|
|
|
|
|
/// 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)
|
|
///
|
|
/// In addition to three address instructions, this also handles the FpUCOM
|
|
/// instruction which only has two operands, but no destination. This
|
|
/// instruction is also annoying because there is no "reverse" form of it
|
|
/// available.
|
|
///
|
|
void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) {
|
|
ASSERT_SORTED(ForwardST0Table); ASSERT_SORTED(ReverseST0Table);
|
|
ASSERT_SORTED(ForwardSTiTable); ASSERT_SORTED(ReverseSTiTable);
|
|
MachineInstr *MI = I;
|
|
|
|
unsigned NumOperands = MI->getNumOperands();
|
|
assert(NumOperands == 3 ||
|
|
(NumOperands == 2 && MI->getOpcode() == X86::FpUCOM) &&
|
|
"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 = false, KillsOp1 = false;
|
|
|
|
for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
|
|
E = LV->killed_end(MI); KI != E; ++KI) {
|
|
KillsOp0 |= (KI->second == X86::FP0+Op0);
|
|
KillsOp1 |= (KI->second == X86::FP0+Op1);
|
|
}
|
|
|
|
// If this is an FpUCOM instruction, we must make sure the first operand is on
|
|
// the top of stack, the other one can be anywhere...
|
|
if (MI->getOpcode() == X86::FpUCOM)
|
|
moveToTop(Op0, I);
|
|
|
|
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 && MI->getOpcode() != X86::FpUCOM) {
|
|
// 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 || MI->getOpcode() == X86::FpUCOM) &&
|
|
"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_SIZE(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, Opcode, 1).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
|
|
}
|
|
|
|
// Insert an explicit pop of the "updated" operand for FUCOM
|
|
if (MI->getOpcode() == X86::FpUCOM) {
|
|
if (KillsOp0 && !KillsOp1)
|
|
popStackAfter(I); // If we kill the first operand, pop it!
|
|
else if (KillsOp1 && Op0 != Op1)
|
|
freeStackSlotAfter(I, Op1);
|
|
}
|
|
|
|
// Update stack information so that we know the destination register is now on
|
|
// the stack.
|
|
if (MI->getOpcode() != X86::FpUCOM) {
|
|
unsigned UpdatedSlot = getSlot(updateST0 ? TOS : NotTOS);
|
|
assert(UpdatedSlot < StackTop && Dest < 7);
|
|
Stack[UpdatedSlot] = Dest;
|
|
RegMap[Dest] = UpdatedSlot;
|
|
}
|
|
delete MI; // Remove the old instruction
|
|
}
|
|
|
|
/// 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(1));
|
|
|
|
// 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.
|
|
MI->RemoveOperand(0);
|
|
MI->getOperand(0).setReg(getSTReg(Op1));
|
|
|
|
// If we kill the second operand, make sure to pop it from the stack.
|
|
for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
|
|
E = LV->killed_end(MI); KI != E; ++KI)
|
|
if (KI->second == X86::FP0+Op1) {
|
|
// Get this value off of the register stack.
|
|
freeStackSlotAfter(I, Op1);
|
|
break;
|
|
}
|
|
}
|
|
|
|
|
|
/// 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::FpGETRESULT: // 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::FpSETRESULT:
|
|
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::FpMOV: {
|
|
unsigned SrcReg = getFPReg(MI->getOperand(1));
|
|
unsigned DestReg = getFPReg(MI->getOperand(0));
|
|
bool KillsSrc = false;
|
|
for (LiveVariables::killed_iterator KI = LV->killed_begin(MI),
|
|
E = LV->killed_end(MI); KI != E; ++KI)
|
|
KillsSrc |= KI->second == X86::FP0+SrcReg;
|
|
|
|
if (KillsSrc) {
|
|
// 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;
|
|
}
|
|
}
|
|
|
|
I = MBB->erase(I); // Remove the pseudo instruction
|
|
--I;
|
|
}
|