mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-07-24 23:29:41 +00:00
8a261e44f7
to declare that they preserve other passes without needing to pull in additional header file or library dependencies. Convert MachineFunctionPass and CodeGenLICM to make use of this. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83555 91177308-0d34-0410-b5e6-96231b3b80d8
113 lines
3.8 KiB
C++
113 lines
3.8 KiB
C++
//===- CodeGenLICM.cpp - LICM a function for code generation --------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This function performs late LICM, hoisting constants out of loops that
|
|
// are not valid immediates. It should not be followed by instcombine,
|
|
// because instcombine would quickly stuff the constants back into the loop.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "codegen-licm"
|
|
#include "llvm/Transforms/Scalar.h"
|
|
#include "llvm/Constants.h"
|
|
#include "llvm/DerivedTypes.h"
|
|
#include "llvm/Instructions.h"
|
|
#include "llvm/IntrinsicInst.h"
|
|
#include "llvm/LLVMContext.h"
|
|
#include "llvm/Analysis/LoopPass.h"
|
|
#include "llvm/Analysis/AliasAnalysis.h"
|
|
#include "llvm/ADT/DenseMap.h"
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
class CodeGenLICM : public LoopPass {
|
|
virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
|
|
public:
|
|
static char ID; // Pass identification, replacement for typeid
|
|
explicit CodeGenLICM() : LoopPass(&ID) {}
|
|
};
|
|
}
|
|
|
|
char CodeGenLICM::ID = 0;
|
|
static RegisterPass<CodeGenLICM> X("codegen-licm",
|
|
"hoist constants out of loops");
|
|
|
|
Pass *llvm::createCodeGenLICMPass() {
|
|
return new CodeGenLICM();
|
|
}
|
|
|
|
bool CodeGenLICM::runOnLoop(Loop *L, LPPassManager &) {
|
|
bool Changed = false;
|
|
|
|
// Only visit outermost loops.
|
|
if (L->getParentLoop()) return Changed;
|
|
|
|
Instruction *PreheaderTerm = L->getLoopPreheader()->getTerminator();
|
|
DenseMap<Constant *, BitCastInst *> HoistedConstants;
|
|
|
|
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
|
|
I != E; ++I) {
|
|
BasicBlock *BB = *I;
|
|
for (BasicBlock::iterator BBI = BB->begin(), BBE = BB->end();
|
|
BBI != BBE; ++BBI) {
|
|
Instruction *I = BBI;
|
|
// TODO: For now, skip all intrinsic instructions, because some of them
|
|
// can require their operands to be constants, and we don't want to
|
|
// break that.
|
|
if (isa<IntrinsicInst>(I))
|
|
continue;
|
|
// LLVM represents fneg as -0.0-x; don't hoist the -0.0 out.
|
|
if (BinaryOperator::isFNeg(I) ||
|
|
BinaryOperator::isNeg(I) ||
|
|
BinaryOperator::isNot(I))
|
|
continue;
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
|
|
// Don't hoist out switch case constants.
|
|
if (isa<SwitchInst>(I) && i == 1)
|
|
break;
|
|
// Don't hoist out shuffle masks.
|
|
if (isa<ShuffleVectorInst>(I) && i == 2)
|
|
break;
|
|
Value *Op = I->getOperand(i);
|
|
Constant *C = dyn_cast<Constant>(Op);
|
|
if (!C) continue;
|
|
// TODO: Ask the target which constants are legal. This would allow
|
|
// us to add support for hoisting ConstantInts and GlobalValues too.
|
|
if (isa<ConstantFP>(C) ||
|
|
isa<ConstantVector>(C) ||
|
|
isa<ConstantAggregateZero>(C)) {
|
|
BitCastInst *&BC = HoistedConstants[C];
|
|
if (!BC)
|
|
BC = new BitCastInst(C, C->getType(), "hoist", PreheaderTerm);
|
|
I->setOperand(i, BC);
|
|
Changed = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
void CodeGenLICM::getAnalysisUsage(AnalysisUsage &AU) const {
|
|
// This pass preserves just about everything. List some popular things here.
|
|
AU.setPreservesCFG();
|
|
AU.addPreservedID(LoopSimplifyID);
|
|
AU.addPreserved<LoopInfo>();
|
|
AU.addPreserved<AliasAnalysis>();
|
|
AU.addPreserved("scalar-evolution");
|
|
AU.addPreserved("iv-users");
|
|
AU.addPreserved("lda");
|
|
AU.addPreserved("live-values");
|
|
|
|
// Hoisting requires a loop preheader.
|
|
AU.addRequiredID(LoopSimplifyID);
|
|
}
|