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https://github.com/c64scene-ar/llvm-6502.git
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e9d3c6b919
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9310 91177308-0d34-0410-b5e6-96231b3b80d8
235 lines
8.2 KiB
C++
235 lines
8.2 KiB
C++
//===-- BBLiveVar.cpp - Live Variable Analysis for a BasicBlock -----------===//
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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 is a wrapper class for BasicBlock which is used by live var analysis.
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//
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//===----------------------------------------------------------------------===//
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#include "BBLiveVar.h"
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#include "llvm/CodeGen/FunctionLiveVarInfo.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/Support/CFG.h"
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#include "Support/SetOperations.h"
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/// BROKEN: Should not include sparc stuff directly into here
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#include "../../Target/Sparc/SparcInternals.h" // Only for PHI defn
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BBLiveVar::BBLiveVar(const BasicBlock &bb, MachineBasicBlock &mbb, unsigned id)
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: BB(bb), MBB(mbb), POID(id) {
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InSetChanged = OutSetChanged = false;
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calcDefUseSets();
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}
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//-----------------------------------------------------------------------------
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// calculates def and use sets for each BB
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// There are two passes over operands of a machine instruction. This is
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// because, we can have instructions like V = V + 1, since we no longer
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// assume single definition.
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//-----------------------------------------------------------------------------
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void BBLiveVar::calcDefUseSets() {
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// iterate over all the machine instructions in BB
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for (MachineBasicBlock::const_reverse_iterator MII = MBB.rbegin(),
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MIE = MBB.rend(); MII != MIE; ++MII) {
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const MachineInstr *MI = *MII;
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if (DEBUG_LV >= LV_DEBUG_Verbose) {
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std::cerr << " *Iterating over machine instr ";
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MI->dump();
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std::cerr << "\n";
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}
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// iterate over MI operands to find defs
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for (MachineInstr::const_val_op_iterator OpI = MI->begin(), OpE = MI->end();
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OpI != OpE; ++OpI)
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if (OpI.isDefOnly() || OpI.isDefAndUse()) // add to Defs if this operand is a def
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addDef(*OpI);
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// do for implicit operands as well
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for (unsigned i = 0; i < MI->getNumImplicitRefs(); ++i)
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if (MI->getImplicitOp(i).opIsDefOnly() || MI->getImplicitOp(i).opIsDefAndUse())
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addDef(MI->getImplicitRef(i));
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// iterate over MI operands to find uses
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for (MachineInstr::const_val_op_iterator OpI = MI->begin(), OpE = MI->end();
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OpI != OpE; ++OpI) {
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const Value *Op = *OpI;
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if (isa<BasicBlock>(Op))
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continue; // don't process labels
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if (OpI.isUseOnly() || OpI.isDefAndUse()) {
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// add to Uses only if this operand is a use
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//
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// *** WARNING: The following code for handling dummy PHI machine
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// instructions is untested. The previous code was broken and I
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// fixed it, but it turned out to be unused as long as Phi
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// elimination is performed during instruction selection.
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//
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// Put Phi operands in UseSet for the incoming edge, not node.
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// They must not "hide" later defs, and must be handled specially
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// during set propagation over the CFG.
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if (MI->getOpCode() == V9::PHI) { // for a phi node
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const Value *ArgVal = Op;
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const BasicBlock *PredBB = cast<BasicBlock>(*++OpI); // next ptr is BB
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PredToEdgeInSetMap[PredBB].insert(ArgVal);
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if (DEBUG_LV >= LV_DEBUG_Verbose)
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std::cerr << " - phi operand " << RAV(ArgVal) << " came from BB "
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<< RAV(PredBB) << "\n";
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} // if( IsPhi )
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else {
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// It is not a Phi use: add to regular use set and remove later defs.
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addUse(Op);
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}
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} // if a use
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} // for all operands
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// do for implicit operands as well
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for (unsigned i = 0; i < MI->getNumImplicitRefs(); ++i) {
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assert(MI->getOpCode() != V9::PHI && "Phi cannot have implicit operands");
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const Value *Op = MI->getImplicitRef(i);
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if (Op->getType() == Type::LabelTy) // don't process labels
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continue;
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if (MI->getImplicitOp(i).opIsUse() || MI->getImplicitOp(i).opIsDefAndUse())
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addUse(Op);
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}
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} // for all machine instructions
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}
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//-----------------------------------------------------------------------------
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// To add an operand which is a def
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//-----------------------------------------------------------------------------
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void BBLiveVar::addDef(const Value *Op) {
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DefSet.insert(Op); // operand is a def - so add to def set
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InSet.erase(Op); // this definition kills any later uses
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InSetChanged = true;
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if (DEBUG_LV >= LV_DEBUG_Verbose) std::cerr << " +Def: " << RAV(Op) << "\n";
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}
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//-----------------------------------------------------------------------------
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// To add an operand which is a use
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//-----------------------------------------------------------------------------
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void BBLiveVar::addUse(const Value *Op) {
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InSet.insert(Op); // An operand is a use - so add to use set
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DefSet.erase(Op); // remove if there is a def below this use
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InSetChanged = true;
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if (DEBUG_LV >= LV_DEBUG_Verbose) std::cerr << " Use: " << RAV(Op) << "\n";
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}
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//-----------------------------------------------------------------------------
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// Applies the transfer function to a basic block to produce the InSet using
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// the OutSet.
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//-----------------------------------------------------------------------------
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bool BBLiveVar::applyTransferFunc() {
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// IMPORTANT: caller should check whether the OutSet changed
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// (else no point in calling)
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ValueSet OutMinusDef = set_difference(OutSet, DefSet);
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InSetChanged = set_union(InSet, OutMinusDef);
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OutSetChanged = false; // no change to OutSet since transf func applied
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return InSetChanged;
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}
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//-----------------------------------------------------------------------------
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// calculates Out set using In sets of the successors
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//-----------------------------------------------------------------------------
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bool BBLiveVar::setPropagate(ValueSet *OutSet, const ValueSet *InSet,
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const BasicBlock *PredBB) {
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bool Changed = false;
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// merge all members of InSet into OutSet of the predecessor
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for (ValueSet::const_iterator InIt = InSet->begin(), InE = InSet->end();
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InIt != InE; ++InIt)
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if ((OutSet->insert(*InIt)).second)
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Changed = true;
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//
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//**** WARNING: The following code for handling dummy PHI machine
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// instructions is untested. See explanation above.
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//
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// then merge all members of the EdgeInSet for the predecessor into the OutSet
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const ValueSet& EdgeInSet = PredToEdgeInSetMap[PredBB];
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for (ValueSet::const_iterator InIt = EdgeInSet.begin(), InE = EdgeInSet.end();
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InIt != InE; ++InIt)
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if ((OutSet->insert(*InIt)).second)
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Changed = true;
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//
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//****
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return Changed;
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}
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//-----------------------------------------------------------------------------
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// propagates in set to OutSets of PREDECESSORs
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//-----------------------------------------------------------------------------
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bool BBLiveVar::applyFlowFunc(hash_map<const BasicBlock*,
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BBLiveVar*> &BBLiveVarInfo) {
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// IMPORTANT: caller should check whether inset changed
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// (else no point in calling)
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// If this BB changed any OutSets of preds whose POID is lower, than we need
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// another iteration...
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//
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bool needAnotherIt = false;
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for (pred_const_iterator PI = pred_begin(&BB), PE = pred_end(&BB);
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PI != PE ; ++PI) {
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BBLiveVar *PredLVBB = BBLiveVarInfo[*PI];
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// do set union
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if (setPropagate(&PredLVBB->OutSet, &InSet, *PI)) {
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PredLVBB->OutSetChanged = true;
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// if the predec POID is lower than mine
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if (PredLVBB->getPOId() <= POID)
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needAnotherIt = true;
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}
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} // for
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return needAnotherIt;
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}
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// ----------------- Methods For Debugging (Printing) -----------------
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void BBLiveVar::printAllSets() const {
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std::cerr << " Defs: "; printSet(DefSet); std::cerr << "\n";
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std::cerr << " In: "; printSet(InSet); std::cerr << "\n";
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std::cerr << " Out: "; printSet(OutSet); std::cerr << "\n";
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}
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void BBLiveVar::printInOutSets() const {
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std::cerr << " In: "; printSet(InSet); std::cerr << "\n";
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std::cerr << " Out: "; printSet(OutSet); std::cerr << "\n";
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}
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