mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-28 06:29:45 +00:00
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76702 91177308-0d34-0410-b5e6-96231b3b80d8
192 lines
6.7 KiB
C++
192 lines
6.7 KiB
C++
//===-- PartialSpecialization.cpp - Specialize for common constants--------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This pass finds function arguments that are often a common constant and
|
|
// specializes a version of the called function for that constant.
|
|
//
|
|
// This pass simply does the cloning for functions it specializes. It depends
|
|
// on IPSCCP and DAE to clean up the results.
|
|
//
|
|
// The initial heuristic favors constant arguments that are used in control
|
|
// flow.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "partialspecialization"
|
|
#include "llvm/Transforms/IPO.h"
|
|
#include "llvm/Constant.h"
|
|
#include "llvm/Instructions.h"
|
|
#include "llvm/Module.h"
|
|
#include "llvm/Pass.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/Transforms/Utils/Cloning.h"
|
|
#include "llvm/Support/CallSite.h"
|
|
#include "llvm/Support/Compiler.h"
|
|
#include "llvm/ADT/DenseSet.h"
|
|
#include <map>
|
|
using namespace llvm;
|
|
|
|
STATISTIC(numSpecialized, "Number of specialized functions created");
|
|
|
|
// Call must be used at least occasionally
|
|
static const int CallsMin = 5;
|
|
|
|
// Must have 10% of calls having the same constant to specialize on
|
|
static const double ConstValPercent = .1;
|
|
|
|
namespace {
|
|
class VISIBILITY_HIDDEN PartSpec : public ModulePass {
|
|
void scanForInterest(Function&, SmallVector<int, 6>&);
|
|
int scanDistribution(Function&, int, std::map<Constant*, int>&);
|
|
public :
|
|
static char ID; // Pass identification, replacement for typeid
|
|
PartSpec() : ModulePass(&ID) {}
|
|
bool runOnModule(Module &M);
|
|
};
|
|
}
|
|
|
|
char PartSpec::ID = 0;
|
|
static RegisterPass<PartSpec>
|
|
X("partialspecialization", "Partial Specialization");
|
|
|
|
// Specialize F by replacing the arguments (keys) in replacements with the
|
|
// constants (values). Replace all calls to F with those constants with
|
|
// a call to the specialized function. Returns the specialized function
|
|
static Function*
|
|
SpecializeFunction(Function* F,
|
|
DenseMap<const Value*, Value*>& replacements) {
|
|
// arg numbers of deleted arguments
|
|
DenseSet<unsigned> deleted;
|
|
for (DenseMap<const Value*, Value*>::iterator
|
|
repb = replacements.begin(), repe = replacements.end();
|
|
repb != repe; ++repb)
|
|
deleted.insert(cast<Argument>(repb->first)->getArgNo());
|
|
|
|
Function* NF = CloneFunction(F, replacements);
|
|
NF->setLinkage(GlobalValue::InternalLinkage);
|
|
F->getParent()->getFunctionList().push_back(NF);
|
|
|
|
for (Value::use_iterator ii = F->use_begin(), ee = F->use_end();
|
|
ii != ee; ) {
|
|
Value::use_iterator i = ii;
|
|
++ii;
|
|
if (isa<CallInst>(i) || isa<InvokeInst>(i)) {
|
|
CallSite CS(cast<Instruction>(i));
|
|
if (CS.getCalledFunction() == F) {
|
|
|
|
SmallVector<Value*, 6> args;
|
|
for (unsigned x = 0; x < CS.arg_size(); ++x)
|
|
if (!deleted.count(x))
|
|
args.push_back(CS.getArgument(x));
|
|
Value* NCall;
|
|
if (CallInst *CI = dyn_cast<CallInst>(i)) {
|
|
NCall = CallInst::Create(NF, args.begin(), args.end(),
|
|
CI->getName(), CI);
|
|
cast<CallInst>(NCall)->setTailCall(CI->isTailCall());
|
|
cast<CallInst>(NCall)->setCallingConv(CI->getCallingConv());
|
|
} else {
|
|
InvokeInst *II = cast<InvokeInst>(i);
|
|
NCall = InvokeInst::Create(NF, II->getNormalDest(),
|
|
II->getUnwindDest(),
|
|
args.begin(), args.end(),
|
|
II->getName(), II);
|
|
cast<InvokeInst>(NCall)->setCallingConv(II->getCallingConv());
|
|
}
|
|
CS.getInstruction()->replaceAllUsesWith(NCall);
|
|
CS.getInstruction()->eraseFromParent();
|
|
}
|
|
}
|
|
}
|
|
return NF;
|
|
}
|
|
|
|
|
|
bool PartSpec::runOnModule(Module &M) {
|
|
bool Changed = false;
|
|
for (Module::iterator I = M.begin(); I != M.end(); ++I) {
|
|
Function &F = *I;
|
|
if (F.isDeclaration() || F.mayBeOverridden()) continue;
|
|
SmallVector<int, 6> interestingArgs;
|
|
scanForInterest(F, interestingArgs);
|
|
|
|
// Find the first interesting Argument that we can specialize on
|
|
// If there are multiple interesting Arguments, then those will be found
|
|
// when processing the cloned function.
|
|
bool breakOuter = false;
|
|
for (unsigned int x = 0; !breakOuter && x < interestingArgs.size(); ++x) {
|
|
std::map<Constant*, int> distribution;
|
|
int total = scanDistribution(F, interestingArgs[x], distribution);
|
|
if (total > CallsMin)
|
|
for (std::map<Constant*, int>::iterator ii = distribution.begin(),
|
|
ee = distribution.end(); ii != ee; ++ii)
|
|
if (total > ii->second && ii->first &&
|
|
ii->second > total * ConstValPercent) {
|
|
DenseMap<const Value*, Value*> m;
|
|
Function::arg_iterator arg = F.arg_begin();
|
|
for (int y = 0; y < interestingArgs[x]; ++y)
|
|
++arg;
|
|
m[&*arg] = ii->first;
|
|
SpecializeFunction(&F, m);
|
|
++numSpecialized;
|
|
breakOuter = true;
|
|
Changed = true;
|
|
}
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|
|
|
|
/// scanForInterest - This function decides which arguments would be worth
|
|
/// specializing on.
|
|
void PartSpec::scanForInterest(Function& F, SmallVector<int, 6>& args) {
|
|
for(Function::arg_iterator ii = F.arg_begin(), ee = F.arg_end();
|
|
ii != ee; ++ii) {
|
|
for(Value::use_iterator ui = ii->use_begin(), ue = ii->use_end();
|
|
ui != ue; ++ui) {
|
|
|
|
bool interesting = false;
|
|
|
|
if (isa<CmpInst>(ui)) interesting = true;
|
|
else if (isa<CallInst>(ui))
|
|
interesting = ui->getOperand(0) == ii;
|
|
else if (isa<InvokeInst>(ui))
|
|
interesting = ui->getOperand(0) == ii;
|
|
else if (isa<SwitchInst>(ui)) interesting = true;
|
|
else if (isa<BranchInst>(ui)) interesting = true;
|
|
|
|
if (interesting) {
|
|
args.push_back(std::distance(F.arg_begin(), ii));
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// scanDistribution - Construct a histogram of constants for arg of F at arg.
|
|
int PartSpec::scanDistribution(Function& F, int arg,
|
|
std::map<Constant*, int>& dist) {
|
|
bool hasIndirect = false;
|
|
int total = 0;
|
|
for(Value::use_iterator ii = F.use_begin(), ee = F.use_end();
|
|
ii != ee; ++ii)
|
|
if ((isa<CallInst>(ii) || isa<InvokeInst>(ii))
|
|
&& ii->getOperand(0) == &F) {
|
|
++dist[dyn_cast<Constant>(ii->getOperand(arg + 1))];
|
|
++total;
|
|
} else
|
|
hasIndirect = true;
|
|
|
|
// Preserve the original address taken function even if all other uses
|
|
// will be specialized.
|
|
if (hasIndirect) ++total;
|
|
return total;
|
|
}
|
|
|
|
ModulePass* llvm::createPartialSpecializationPass() { return new PartSpec(); }
|