// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
void RecursionElimination::ReplaceParameters() {
// As it is now, the function still uses the parameters
// in SSA form directly, but now it should use
// the 'phi' instructions from the old entry block.
// We use a dictionary to map from parameter to 'phi' result.
Dictionary<Parameter*, Operand*> paramToPhi;
DebugValidator::AreEqual(funct_->ParameterCount(),
parameterPhis_.Count());
for(int i = 0; i < funct_->ParameterCount(); i++) {
paramToPhi.Add(funct_->GetParameter(i),
parameterPhis_[i]->ResultOp());
}
// Scan all instructions and do the replacements.
auto oldEntryBlock = oldEntryBlock_;
funct_->ForEachInstruction([¶mToPhi, oldEntryBlock]
(Instruction* instr) -> bool {
if(instr->IsPhi() && (instr->ParentBlock() == oldEntryBlock)) {
// The 'phi's int the old entry block
// shouldn't have their operands changed.
return true;
}
for(int i = 0; i < instr->SourceOpCount(); i++) {
if(auto parameter = instr->GetSourceOp(i)->As<Parameter>()) {
DebugValidator::IsTrue(paramToPhi.ContainsKey(parameter));
instr->ReplaceSourceOp(i, paramToPhi[parameter]);
}
}
return true;
});
}
void SimpleDeadCodeElimination::Execute(Function* function) {
StaticList<Instruction*, 512> worklist;
Dictionary<Instruction*, bool> inWorklist; // If an instruction is in the worklist.
// Try to remove 'store' instructions that have no effect.
// The algorithm is really simple, but should catch cases like
// arrays initialized with constants that were propagated already.
RemoveDeadStores(function);
// Try to remove copy/set operations that are unused,
// because the aggregates they target are never referenced.
RemoveDeadCopyOperations(function);
// We process the blocks from last to first, and the instructions in the block
// from last to first too; this allows removing more instructions on each
// iteration that the usual first-last order.
for(auto block = function->LastBlock(); block; block = block->PreviousBlock()) {
// If the block is unreachable we remove all instructions from it,
// but don't remove the block; this will be handled by the CFG Simplifier,
// which knows how to repair the Dominator Tree.
if(block->IsUnreachable() && (block->IsEmpty() == false)) {
CleanUnreachableBlock(block);
continue;
}
for(auto instr = block->LastInstruction(); instr;
instr = instr->PreviousInstruction()) {
if(GetSafetyInfo()->IsDefinitelyDead(instr)) {
worklist.Add(instr);
inWorklist.Add(instr, true);
}
}
}
// Process while we have instructions in the worklist.
while(worklist.IsNotEmpty()) {
auto instr = worklist.RemoveLast();
inWorklist.Remove(instr);
// Remove the instruction if it's dead.
if(GetSafetyInfo()->IsDefinitelyDead(instr)) {
// All the instructions that where used by this one
// may be dead now, add them to the worklist.
for(int i = 0; i < instr->SourceOpCount(); i++) {
auto sourceOp = instr->GetSourceOp(i);
// Make sure we don't add an instruction in the worklist twice.
if(auto definingInstr = sourceOp->DefiningInstruction()) {
if(inWorklist.ContainsKey(definingInstr) == false) {
worklist.Add(definingInstr);
inWorklist.Add(definingInstr, true);
}
}
}
InstructionRemoved(instr);
instr->RemoveFromBlock(true /* free */);
}
}
// If there were removed stored we may now have variables
// that are not used by any instruction.
RemoveDeadVariables(function);
}
bool WasInstructionProcessed(Instruction* instr) {
return processedInstrs_.ContainsKey(instr);
}
// Sets the number of volatile operations for the specified function.
void SetVolatileCount(Function* function, int value) {
if(volatileCount_.ContainsKey(function)) {
volatileCount_[function] = value;
}
else volatileCount_.Add(function, value);
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Returns the number of volatile operations from the specified function.
int GetVolatileCount(Function* function) {
if(volatileCount_.ContainsKey(function)) {
return volatileCount_[function];
}
else return 0;
}
