llvm-6502/lib/Target/SparcV9/InstrSelection/InstrSelection.cpp
2001-07-30 18:48:43 +00:00

284 lines
8.5 KiB
C++

// $Id$ -*-c++-*-
//***************************************************************************
// File:
// InstrSelection.h
//
// Purpose:
//
// History:
// 7/02/01 - Vikram Adve - Created
//***************************************************************************
#include "llvm/CodeGen/InstrSelection.h"
#include "llvm/Method.h"
#include "llvm/BasicBlock.h"
#include "llvm/Type.h"
#include "llvm/iMemory.h"
#include "llvm/Instruction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/Support/CommandLine.h"
enum DebugLev {
NoDebugInfo,
DebugInstTrees,
DebugBurgTrees,
};
// Enable Debug Options to be specified on the command line
cl::Enum<enum DebugLev> DebugLevel("debug_select", cl::NoFlags, // cl::Hidden
"enable instruction selection debugging information",
clEnumVal(NoDebugInfo , "disable debug output"),
clEnumVal(DebugInstTrees, "print instruction trees"),
clEnumVal(DebugBurgTrees, "print burg trees"), 0);
//************************* Forward Declarations ***************************/
static bool SelectInstructionsForTree(BasicTreeNode* treeRoot, int goalnt,
TargetMachine &Target);
//******************* Externally Visible Functions *************************/
//---------------------------------------------------------------------------
// Entry point for instruction selection using BURG.
// Returns true if instruction selection failed, false otherwise.
//---------------------------------------------------------------------------
bool SelectInstructionsForMethod(Method* method, TargetMachine &Target) {
bool failed = false;
InstrForest instrForest;
instrForest.buildTreesForMethod(method);
const hash_set<InstructionNode*> &treeRoots = instrForest.getRootSet();
//
// Invoke BURG instruction selection for each tree
//
for (hash_set<InstructionNode*>::const_iterator
treeRootIter = treeRoots.begin();
treeRootIter != treeRoots.end();
++treeRootIter)
{
BasicTreeNode* basicNode = (*treeRootIter)->getBasicNode();
// Invoke BURM to label each tree node with a state
(void) burm_label(basicNode);
if (DebugLevel >= DebugBurgTrees)
{
printcover(basicNode, 1, 0);
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;
}
}
if (!failed)
{
if (DebugLevel >= DebugInstTrees)
{
cout << "\n\n*** Instruction trees for method "
<< (method->hasName()? method->getName() : "")
<< endl << endl;
instrForest.dump();
}
if (DebugLevel > NoDebugInfo)
PrintMachineInstructions(method);
}
//
// Record instructions in the vector for each basic block
//
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]);
}
}
return false;
}
//---------------------------------------------------------------------------
// 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.
//---------------------------------------------------------------------------
Value*
FoldGetElemChain(const InstructionNode* getElemInstrNode,
vector<ConstPoolVal*>& chainIdxVec)
{
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());
ptrChild = ptrChild->leftChild();
}
return ptrVal;
}
void PrintMachineInstructions(Method* method) {
cout << "\n" << method->getReturnType()
<< " \"" << method->getName() << "\"" << endl;
for (Method::const_iterator bbIter = method->begin();
bbIter != method->end();
++bbIter)
{
BasicBlock* bb = *bbIter;
cout << "\n"
<< (bb->hasName()? bb->getName() : "Label")
<< " (" << bb << ")" << ":"
<< endl;
for (BasicBlock::const_iterator instrIter = bb->begin();
instrIter != bb->end();
++instrIter)
{
Instruction *instr = *instrIter;
const MachineCodeForVMInstr& minstrVec = instr->getMachineInstrVec();
for (unsigned i=0, N=minstrVec.size(); i < N; i++)
cout << "\t" << *minstrVec[i] << endl;
}
}
}
//*********************** Private Functions *****************************/
//---------------------------------------------------------------------------
// Function SelectInstructionsForTree
//
// Recursively walk the tree to select instructions.
// Do this top-down so that child instructions can exploit decisions
// made at the child instructions.
//
// E.g., if br(setle(reg,const)) decides the constant is 0 and uses
// a branch-on-integer-register instruction, then the setle node
// can use that information to avoid generating the SUBcc instruction.
//
// Note that this cannot be done bottom-up because setle must do this
// only if it is a child of the branch (otherwise, the result of setle
// may be used by multiple instructions).
//---------------------------------------------------------------------------
bool
SelectInstructionsForTree(BasicTreeNode* treeRoot,
int goalnt,
TargetMachine &Target)
{
// 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;
}
// 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);
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]);
}
}
// Then, recursively compile the child nodes, if any.
//
if (nts[0])
{ // i.e., there is at least one kid
BasicTreeNode* 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.
//
while (ThisIsAChainRule(currentRule))
{
currentRule = burm_rule(treeRoot->state, nts[0]);
nts = burm_nts[currentRule];
burm_kids(treeRoot, currentRule, kids);
}
// 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++)
{
assert(i < 2);
InstrTreeNode::InstrTreeNodeType
nodeType = MainTreeNode(kids[i])->getNodeType();
if (nodeType == InstrTreeNode::NTVRegListNode ||
nodeType == InstrTreeNode::NTInstructionNode)
{
if (SelectInstructionsForTree(kids[i], nts[i], Target))
return true; // failure
}
}
}
return false; // success
}