-// $Id$ -*-c++-*-
-//***************************************************************************
-// File:
-// InstrSelection.cpp
+//===- InstrSelection.cpp - Machine Independent Inst Selection Driver -----===//
//
-// Purpose:
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Machine-independent driver file for instruction selection. This file
+// constructs a forest of BURG instruction trees and then uses the
+// BURG-generated tree grammar (BURM) to find the optimal instruction sequences
+// for a given machine.
//
-// History:
-// 7/02/01 - Vikram Adve - Created
-//**************************************************************************/
-
-
-//************************** System Include Files ***************************/
-
-
-//*************************** User Include Files ***************************/
+//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/InstrSelection.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Type.h"
-#include "llvm/iMemory.h"
-#include "llvm/Instruction.h"
-#include "llvm/BasicBlock.h"
-#include "llvm/Method.h"
-#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/InstrSelectionSupport.h"
+#include "llvm/CodeGen/InstrForest.h"
+#include "llvm/CodeGen/MachineCodeForInstruction.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/Target/TargetRegInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Function.h"
+#include "llvm/iPHINode.h"
+#include "llvm/Pass.h"
+#include "Support/CommandLine.h"
+#include "Support/LeakDetector.h"
+using std::vector;
+std::vector<MachineInstr*>
+FixConstantOperandsForInstr(Instruction* vmInstr, MachineInstr* minstr,
+ TargetMachine& target);
-//************************* Forward Declarations ***************************/
+namespace {
+ //===--------------------------------------------------------------------===//
+ // SelectDebugLevel - Allow command line control over debugging.
+ //
+ enum SelectDebugLevel_t {
+ Select_NoDebugInfo,
+ Select_PrintMachineCode,
+ Select_DebugInstTrees,
+ Select_DebugBurgTrees,
+ };
+
+ // Enable Debug Options to be specified on the command line
+ cl::opt<SelectDebugLevel_t>
+ SelectDebugLevel("dselect", cl::Hidden,
+ cl::desc("enable instruction selection debug information"),
+ cl::values(
+ clEnumValN(Select_NoDebugInfo, "n", "disable debug output"),
+ clEnumValN(Select_PrintMachineCode, "y", "print generated machine code"),
+ clEnumValN(Select_DebugInstTrees, "i",
+ "print debugging info for instruction selection"),
+ clEnumValN(Select_DebugBurgTrees, "b", "print burg trees"),
+ 0));
-static bool SelectInstructionsForTree(BasicTreeNode* treeRoot,
- int goalnt,
- TargetMachine &Target);
+ //===--------------------------------------------------------------------===//
+ // InstructionSelection Pass
+ //
+ // This is the actual pass object that drives the instruction selection
+ // process.
+ //
+ class InstructionSelection : public FunctionPass {
+ TargetMachine &Target;
+ void InsertCodeForPhis(Function &F);
+ void InsertPhiElimInstructions(BasicBlock *BB,
+ const vector<MachineInstr*>& CpVec);
+ void SelectInstructionsForTree(InstrTreeNode* treeRoot, int goalnt);
+ void PostprocessMachineCodeForTree(InstructionNode* instrNode,
+ int ruleForNode, short* nts);
+ public:
+ InstructionSelection(TargetMachine &T) : Target(T) {}
-//************************* Internal Data Types *****************************/
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ }
+
+ bool runOnFunction(Function &F);
+ virtual const char *getPassName() const { return "Instruction Selection"; }
+ };
+}
-enum SelectDebugLevel_t {
- Select_NoDebugInfo,
- Select_PrintMachineCode,
- Select_DebugInstTrees,
- Select_DebugBurgTrees,
-};
+TmpInstruction::TmpInstruction(MachineCodeForInstruction& mcfi,
+ Value *s1, Value *s2, const std::string &name)
+ : Instruction(s1->getType(), Instruction::UserOp1, name)
+{
+ mcfi.addTemp(this);
-// Enable Debug Options to be specified on the command line
-cl::Enum<enum SelectDebugLevel_t> SelectDebugLevel("dselect", cl::NoFlags, // cl::Hidden
- "enable instruction selection debugging information",
- clEnumValN(Select_NoDebugInfo, "n", "disable debug output"),
- clEnumValN(Select_PrintMachineCode, "y", "print generated machine code"),
- clEnumValN(Select_DebugInstTrees, "i", "print instr. selection debugging info"),
- clEnumValN(Select_DebugBurgTrees, "b", "print burg trees"), 0);
+ Operands.push_back(Use(s1, this)); // s1 must be non-null
+ if (s2) {
+ Operands.push_back(Use(s2, this));
+ }
+ // TmpInstructions should not be garbage checked.
+ LeakDetector::removeGarbageObject(this);
+}
+
+// Constructor that requires the type of the temporary to be specified.
+// Both S1 and S2 may be NULL.(
+TmpInstruction::TmpInstruction(MachineCodeForInstruction& mcfi,
+ const Type *Ty, Value *s1, Value* s2,
+ const std::string &name)
+ : Instruction(Ty, Instruction::UserOp1, name)
+{
+ mcfi.addTemp(this);
-//************************** External Functions ****************************/
+ if (s1) { Operands.push_back(Use(s1, this)); }
+ if (s2) { Operands.push_back(Use(s2, this)); }
+ // TmpInstructions should not be garbage checked.
+ LeakDetector::removeGarbageObject(this);
+}
-//---------------------------------------------------------------------------
-// Entry point for instruction selection using BURG.
-// Returns true if instruction selection failed, false otherwise.
-//---------------------------------------------------------------------------
-bool
-SelectInstructionsForMethod(Method* method,
- TargetMachine &Target)
+bool InstructionSelection::runOnFunction(Function &F)
{
- bool failed = false;
-
//
// Build the instruction trees to be given as inputs to BURG.
//
- InstrForest instrForest;
- instrForest.buildTreesForMethod(method);
+ InstrForest instrForest(&F);
if (SelectDebugLevel >= Select_DebugInstTrees)
{
- cout << "\n\n*** Instruction trees for method "
- << (method->hasName()? method->getName() : "")
- << endl << endl;
+ std::cerr << "\n\n*** Input to instruction selection for function "
+ << F.getName() << "\n\n" << F
+ << "\n\n*** Instruction trees for function "
+ << F.getName() << "\n\n";
instrForest.dump();
}
//
// Invoke BURG instruction selection for each tree
//
- const hash_set<InstructionNode*> &treeRoots = instrForest.getRootSet();
- for (hash_set<InstructionNode*>::const_iterator
- treeRootIter = treeRoots.begin();
- treeRootIter != treeRoots.end();
- ++treeRootIter)
+ for (InstrForest::const_root_iterator RI = instrForest.roots_begin();
+ RI != instrForest.roots_end(); ++RI)
{
- BasicTreeNode* basicNode = (*treeRootIter)->getBasicNode();
+ InstructionNode* basicNode = *RI;
+ assert(basicNode->parent() == NULL && "A `root' node has a parent?");
// Invoke BURM to label each tree node with a state
- (void) burm_label(basicNode);
+ burm_label(basicNode);
if (SelectDebugLevel >= Select_DebugBurgTrees)
{
printcover(basicNode, 1, 0);
- cerr << "\nCover cost == " << treecost(basicNode, 1, 0) << "\n\n";
+ std::cerr << "\nCover cost == " << treecost(basicNode, 1, 0) <<"\n\n";
printMatches(basicNode);
}
// Then recursively walk the tree to select instructions
- if (SelectInstructionsForTree(basicNode, /*goalnt*/1, Target))
- {
- failed = true;
- break;
- }
+ SelectInstructionsForTree(basicNode, /*goalnt*/1);
}
//
- // Record instructions in the vector for each basic block
+ // Create the MachineBasicBlock records and add all of the MachineInstrs
+ // defined in the MachineCodeForInstruction objects to also live in the
+ // MachineBasicBlock objects.
//
- for (Method::iterator BI = method->begin(); BI != method->end(); ++BI)
- {
- MachineCodeForBasicBlock& bbMvec = (*BI)->getMachineInstrVec();
- for (BasicBlock::iterator II = (*BI)->begin(); II != (*BI)->end(); ++II)
- {
- MachineCodeForVMInstr& mvec = (*II)->getMachineInstrVec();
- for (unsigned i=0; i < mvec.size(); i++)
- bbMvec.push_back(mvec[i]);
- }
+ MachineFunction &MF = MachineFunction::get(&F);
+ for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
+ MachineBasicBlock *MCBB = new MachineBasicBlock(BI);
+ MF.getBasicBlockList().push_back(MCBB);
+
+ for (BasicBlock::iterator II = BI->begin(); II != BI->end(); ++II) {
+ MachineCodeForInstruction &mvec = MachineCodeForInstruction::get(II);
+ MCBB->insert(MCBB->end(), mvec.begin(), mvec.end());
}
+ }
+
+ // Insert phi elimination code
+ InsertCodeForPhis(F);
if (SelectDebugLevel >= Select_PrintMachineCode)
{
- cout << endl << "*** Machine instructions after INSTRUCTION SELECTION" << endl;
- PrintMachineInstructions(method);
+ std::cerr << "\n*** Machine instructions after INSTRUCTION SELECTION\n";
+ MachineFunction::get(&F).dump();
}
- return false;
+ return true;
}
-//---------------------------------------------------------------------------
-// Function: FoldGetElemChain
-//
-// Purpose:
-// Fold a chain of GetElementPtr instructions into an equivalent
-// (Pointer, IndexVector) pair. Returns the pointer Value, and
-// stores the resulting IndexVector in argument chainIdxVec.
-//---------------------------------------------------------------------------
+//-------------------------------------------------------------------------
+// This method inserts phi elimination code for all BBs in a method
+//-------------------------------------------------------------------------
-Value*
-FoldGetElemChain(const InstructionNode* getElemInstrNode,
- vector<ConstPoolVal*>& chainIdxVec)
+void
+InstructionSelection::InsertCodeForPhis(Function &F)
{
- MemAccessInst* getElemInst = (MemAccessInst*)
- getElemInstrNode->getInstruction();
-
- // Initialize return values from the incoming instruction
- Value* ptrVal = getElemInst->getPtrOperand();
- chainIdxVec = getElemInst->getIndexVec(); // copies index vector values
-
- // Now chase the chain of getElementInstr instructions, if any
- InstrTreeNode* ptrChild = getElemInstrNode->leftChild();
- while (ptrChild->getOpLabel() == Instruction::GetElementPtr ||
- ptrChild->getOpLabel() == GetElemPtrIdx)
- {
- // Child is a GetElemPtr instruction
- getElemInst = (MemAccessInst*)
- ((InstructionNode*) ptrChild)->getInstruction();
- const vector<ConstPoolVal*>& idxVec = getElemInst->getIndexVec();
-
- // Get the pointer value out of ptrChild and *prepend* its index vector
- ptrVal = getElemInst->getPtrOperand();
- chainIdxVec.insert(chainIdxVec.begin(), idxVec.begin(), idxVec.end());
+ // for all basic blocks in function
+ //
+ MachineFunction &MF = MachineFunction::get(&F);
+ for (MachineFunction::iterator BB = MF.begin(); BB != MF.end(); ++BB) {
+ for (BasicBlock::const_iterator IIt = BB->getBasicBlock()->begin();
+ const PHINode *PN = dyn_cast<PHINode>(IIt); ++IIt) {
+ // FIXME: This is probably wrong...
+ Value *PhiCpRes = new PHINode(PN->getType(), "PhiCp:");
+
+ // The leak detector shouldn't track these nodes. They are not garbage,
+ // even though their parent field is never filled in.
+ //
+ LeakDetector::removeGarbageObject(PhiCpRes);
+
+ // for each incoming value of the phi, insert phi elimination
+ //
+ for (unsigned i = 0; i < PN->getNumIncomingValues(); ++i) {
+ // insert the copy instruction to the predecessor BB
+ vector<MachineInstr*> mvec, CpVec;
+ Target.getRegInfo().cpValue2Value(PN->getIncomingValue(i), PhiCpRes,
+ mvec);
+ for (vector<MachineInstr*>::iterator MI=mvec.begin();
+ MI != mvec.end(); ++MI) {
+ vector<MachineInstr*> CpVec2 =
+ FixConstantOperandsForInstr(const_cast<PHINode*>(PN), *MI, Target);
+ CpVec2.push_back(*MI);
+ CpVec.insert(CpVec.end(), CpVec2.begin(), CpVec2.end());
+ }
+
+ InsertPhiElimInstructions(PN->getIncomingBlock(i), CpVec);
+ }
- ptrChild = ptrChild->leftChild();
- }
-
- return ptrVal;
+ vector<MachineInstr*> mvec;
+ Target.getRegInfo().cpValue2Value(PhiCpRes, const_cast<PHINode*>(PN),
+ mvec);
+ BB->insert(BB->begin(), mvec.begin(), mvec.end());
+ } // for each Phi Instr in BB
+ } // for all BBs in function
}
+//-------------------------------------------------------------------------
+// Thid method inserts a copy instruction to a predecessor BB as a result
+// of phi elimination.
+//-------------------------------------------------------------------------
+
+void
+InstructionSelection::InsertPhiElimInstructions(BasicBlock *BB,
+ const vector<MachineInstr*>& CpVec)
+{
+ Instruction *TermInst = (Instruction*)BB->getTerminator();
+ MachineCodeForInstruction &MC4Term = MachineCodeForInstruction::get(TermInst);
+ MachineInstr *FirstMIOfTerm = MC4Term.front();
+ assert (FirstMIOfTerm && "No Machine Instrs for terminator");
+
+ MachineFunction &MF = MachineFunction::get(BB->getParent());
-//*********************** Private Functions *****************************/
+ // FIXME: if PHI instructions existed in the machine code, this would be
+ // unnecessary.
+ MachineBasicBlock *MBB = 0;
+ for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
+ if (I->getBasicBlock() == BB) {
+ MBB = I;
+ break;
+ }
+
+ // find the position of first machine instruction generated by the
+ // terminator of this BB
+ MachineBasicBlock::iterator MCIt =
+ std::find(MBB->begin(), MBB->end(), FirstMIOfTerm);
+
+ assert(MCIt != MBB->end() && "Start inst of terminator not found");
+
+ // insert the copy instructions just before the first machine instruction
+ // generated for the terminator
+ MBB->insert(MCIt, CpVec.begin(), CpVec.end());
+}
//---------------------------------------------------------------------------
// may be used by multiple instructions).
//---------------------------------------------------------------------------
-bool
-SelectInstructionsForTree(BasicTreeNode* treeRoot,
- int goalnt,
- TargetMachine &Target)
+void
+InstructionSelection::SelectInstructionsForTree(InstrTreeNode* treeRoot,
+ int goalnt)
{
- // Use a static vector to avoid allocating a new one per VM instruction
- static MachineInstr* minstrVec[MAX_INSTR_PER_VMINSTR];
-
// Get the rule that matches this node.
//
int ruleForNode = burm_rule(treeRoot->state, goalnt);
- if (ruleForNode == 0)
- {
- cerr << "Could not match instruction tree for instr selection" << endl;
- return true;
- }
+ if (ruleForNode == 0) {
+ std::cerr << "Could not match instruction tree for instr selection\n";
+ abort();
+ }
// Get this rule's non-terminals and the corresponding child nodes (if any)
//
short *nts = burm_nts[ruleForNode];
-
// First, select instructions for the current node and rule.
// (If this is a list node, not an instruction, then skip this step).
// This function is specific to the target architecture.
//
if (treeRoot->opLabel != VRegListOp)
{
- InstructionNode* instrNode = (InstructionNode*) MainTreeNode(treeRoot);
+ vector<MachineInstr*> minstrVec;
+
+ InstructionNode* instrNode = (InstructionNode*)treeRoot;
assert(instrNode->getNodeType() == InstrTreeNode::NTInstructionNode);
- unsigned N = GetInstructionsByRule(instrNode, ruleForNode, nts, Target,
- minstrVec);
- assert(N <= MAX_INSTR_PER_VMINSTR);
- for (unsigned i=0; i < N; i++)
- {
- assert(minstrVec[i] != NULL);
- instrNode->getInstruction()->addMachineInstruction(minstrVec[i]);
- }
+ GetInstructionsByRule(instrNode, ruleForNode, nts, Target, minstrVec);
+
+ MachineCodeForInstruction &mvec =
+ MachineCodeForInstruction::get(instrNode->getInstruction());
+ mvec.insert(mvec.end(), minstrVec.begin(), minstrVec.end());
}
// Then, recursively compile the child nodes, if any.
//
if (nts[0])
{ // i.e., there is at least one kid
-
- BasicTreeNode* kids[2];
+ InstrTreeNode* kids[2];
int currentRule = ruleForNode;
burm_kids(treeRoot, currentRule, kids);
-
+
// First skip over any chain rules so that we don't visit
// the current node again.
//
// Now we have the first non-chain rule so we have found
// the actual child nodes. Recursively compile them.
//
- for (int i = 0; nts[i]; i++)
+ for (unsigned i = 0; nts[i]; i++)
{
assert(i < 2);
- InstrTreeNode::InstrTreeNodeType
- nodeType = MainTreeNode(kids[i])->getNodeType();
+ InstrTreeNode::InstrTreeNodeType nodeType = kids[i]->getNodeType();
if (nodeType == InstrTreeNode::NTVRegListNode ||
nodeType == InstrTreeNode::NTInstructionNode)
- {
- if (SelectInstructionsForTree(kids[i], nts[i], Target))
- return true; // failure
- }
+ SelectInstructionsForTree(kids[i], nts[i]);
}
}
- return false; // success
+ // Finally, do any post-processing on this node after its children
+ // have been translated
+ //
+ if (treeRoot->opLabel != VRegListOp)
+ PostprocessMachineCodeForTree((InstructionNode*)treeRoot, ruleForNode, nts);
+}
+
+//---------------------------------------------------------------------------
+// Function PostprocessMachineCodeForTree
+//
+// Apply any final cleanups to machine code for the root of a subtree
+// after selection for all its children has been completed.
+//
+void
+InstructionSelection::PostprocessMachineCodeForTree(InstructionNode* instrNode,
+ int ruleForNode,
+ short* nts)
+{
+ // Fix up any constant operands in the machine instructions to either
+ // use an immediate field or to load the constant into a register
+ // Walk backwards and use direct indexes to allow insertion before current
+ //
+ Instruction* vmInstr = instrNode->getInstruction();
+ MachineCodeForInstruction &mvec = MachineCodeForInstruction::get(vmInstr);
+ for (unsigned i = mvec.size(); i != 0; --i)
+ {
+ vector<MachineInstr*> loadConstVec =
+ FixConstantOperandsForInstr(vmInstr, mvec[i-1], Target);
+
+ mvec.insert(mvec.begin()+i-1, loadConstVec.begin(), loadConstVec.end());
+ }
}
+
+
+//===----------------------------------------------------------------------===//
+// createInstructionSelectionPass - Public entrypoint for instruction selection
+// and this file as a whole...
+//
+FunctionPass *createInstructionSelectionPass(TargetMachine &T) {
+ return new InstructionSelection(T);
+}
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