8e70273509
As part of the "RemoveDIs" project, BasicBlock::iterator now carries a debug-info bit that's needed when getFirstNonPHI and similar feed into instruction insertion positions. Call-sites where that's necessary were updated a year ago; but to ensure some type safety however, we'd like to have all calls to moveBefore use iterators. This patch adds a (guaranteed dereferenceable) iterator-taking moveBefore, and changes a bunch of call-sites where it's obviously safe to change to use it by just calling getIterator() on an instruction pointer. A follow-up patch will contain less-obviously-safe changes. We'll eventually deprecate and remove the instruction-pointer insertBefore, but not before adding concise documentation of what considerations are needed (very few).
70 lines
2.1 KiB
C++
70 lines
2.1 KiB
C++
//===-- AllocaHoisting.cpp - Hoist allocas to the entry block --*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Hoist the alloca instructions in the non-entry blocks to the entry blocks.
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//
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//===----------------------------------------------------------------------===//
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#include "NVPTXAllocaHoisting.h"
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#include "llvm/CodeGen/StackProtector.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Instructions.h"
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using namespace llvm;
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namespace {
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// Hoisting the alloca instructions in the non-entry blocks to the entry
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// block.
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class NVPTXAllocaHoisting : public FunctionPass {
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public:
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static char ID; // Pass ID
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NVPTXAllocaHoisting() : FunctionPass(ID) {}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addPreserved<StackProtector>();
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}
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StringRef getPassName() const override {
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return "NVPTX specific alloca hoisting";
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}
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bool runOnFunction(Function &function) override;
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};
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} // namespace
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bool NVPTXAllocaHoisting::runOnFunction(Function &function) {
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bool functionModified = false;
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Function::iterator I = function.begin();
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Instruction *firstTerminatorInst = (I++)->getTerminator();
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for (Function::iterator E = function.end(); I != E; ++I) {
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for (BasicBlock::iterator BI = I->begin(), BE = I->end(); BI != BE;) {
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AllocaInst *allocaInst = dyn_cast<AllocaInst>(BI++);
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if (allocaInst && isa<ConstantInt>(allocaInst->getArraySize())) {
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allocaInst->moveBefore(firstTerminatorInst->getIterator());
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functionModified = true;
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}
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}
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}
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return functionModified;
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}
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char NVPTXAllocaHoisting::ID = 0;
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namespace llvm {
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void initializeNVPTXAllocaHoistingPass(PassRegistry &);
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}
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INITIALIZE_PASS(
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NVPTXAllocaHoisting, "alloca-hoisting",
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"Hoisting alloca instructions in non-entry blocks to the entry block",
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false, false)
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FunctionPass *llvm::createAllocaHoisting() { return new NVPTXAllocaHoisting; }
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