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//===-- AllocaHoisting.cpp - Hoist allocas to the entry block --*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Hoist the alloca instructions in the non-entry blocks to the entry blocks.
//
//===----------------------------------------------------------------------===//
#include "NVPTXAllocaHoisting.h"
#include "llvm/CodeGen/StackProtector.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
using namespace llvm;
namespace {
// Hoisting the alloca instructions in the non-entry blocks to the entry
// block.
class NVPTXAllocaHoisting : public FunctionPass {
public:
static char ID; // Pass ID
NVPTXAllocaHoisting() : FunctionPass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addPreserved<StackProtector>();
}
StringRef getPassName() const override {
return "NVPTX specific alloca hoisting";
}
bool runOnFunction(Function &function) override;
};
} // namespace
bool NVPTXAllocaHoisting::runOnFunction(Function &function) {
bool functionModified = false;
Function::iterator I = function.begin();
Instruction *firstTerminatorInst = (I++)->getTerminator();
for (Function::iterator E = function.end(); I != E; ++I) {
for (BasicBlock::iterator BI = I->begin(), BE = I->end(); BI != BE;) {
AllocaInst *allocaInst = dyn_cast<AllocaInst>(BI++);
if (allocaInst && isa<ConstantInt>(allocaInst->getArraySize())) {
allocaInst->moveBefore(firstTerminatorInst);
functionModified = true;
}
}
}
return functionModified;
}
char NVPTXAllocaHoisting::ID = 0;
namespace llvm {
void initializeNVPTXAllocaHoistingPass(PassRegistry &);
}
INITIALIZE_PASS(
NVPTXAllocaHoisting, "alloca-hoisting",
"Hoisting alloca instructions in non-entry blocks to the entry block",
false, false)
FunctionPass *llvm::createAllocaHoisting() { return new NVPTXAllocaHoisting; }
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