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Add some comments sketching out how this is to work eventually.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11026 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner
parent
79b13735ad
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847df25e7d
@ -8,7 +8,23 @@
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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.
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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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@ -21,10 +37,13 @@
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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 <algorithm>
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#include <iostream>
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#include <set>
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using namespace llvm;
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namespace {
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@ -135,9 +154,32 @@ bool FPS::runOnMachineFunction(MachineFunction &MF) {
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LV = &getAnalysis<LiveVariables>();
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StackTop = 0;
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bool Changed = false;
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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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Changed |= processBasicBlock(MF, *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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@ -151,10 +193,11 @@ bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &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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MachineInstr *PrevMI = I == BB.begin() ? 0 : *(I-1);
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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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if ((Flags & X86II::FPTypeMask) == 0) continue; // Ignore non-fp insts!
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MachineInstr *PrevMI = I == BB.begin() ? 0 : *(I-1);
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++NumFP; // Keep track of # of pseudo instrs
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DEBUG(std::cerr << "\nFPInst:\t";
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@ -8,7 +8,23 @@
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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.
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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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@ -21,10 +37,13 @@
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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 <algorithm>
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#include <iostream>
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#include <set>
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using namespace llvm;
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namespace {
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@ -135,9 +154,32 @@ bool FPS::runOnMachineFunction(MachineFunction &MF) {
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LV = &getAnalysis<LiveVariables>();
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StackTop = 0;
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bool Changed = false;
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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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Changed |= processBasicBlock(MF, *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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@ -151,10 +193,11 @@ bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &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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MachineInstr *PrevMI = I == BB.begin() ? 0 : *(I-1);
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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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if ((Flags & X86II::FPTypeMask) == 0) continue; // Ignore non-fp insts!
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MachineInstr *PrevMI = I == BB.begin() ? 0 : *(I-1);
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++NumFP; // Keep track of # of pseudo instrs
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DEBUG(std::cerr << "\nFPInst:\t";
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