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8383a7b7a6
such as those in PR2235. Right now the pass is not very effective. :) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50000 91177308-0d34-0410-b5e6-96231b3b80d8
53 lines
1.8 KiB
C++
53 lines
1.8 KiB
C++
//===- JumpThreading.cpp - Thread control through conditional blocks ------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass performs 'jump threading', which looks at blocks that have multiple
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// predecessors and multiple successors. If one or more of the predecessors of
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// the block can be proven to always jump to one of the successors, we forward
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// the edge from the predecessor to the successor by duplicating the contents of
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// this block.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "jump-threading"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Pass.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Compiler.h"
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using namespace llvm;
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//STATISTIC(NumThreads, "Number of jumps threaded");
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namespace {
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cl::opt<unsigned>
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Threshold("jump-threading-threshold",
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cl::desc("Max block size to duplicate for jump threading"),
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cl::init(6), cl::Hidden);
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class VISIBILITY_HIDDEN JumpThreading : public FunctionPass {
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public:
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static char ID; // Pass identification
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JumpThreading() : FunctionPass((intptr_t)&ID) {}
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bool runOnFunction(Function &F);
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};
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char JumpThreading::ID = 0;
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RegisterPass<JumpThreading> X("jump-threading", "Jump Threading");
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}
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// Public interface to the Jump Threading pass
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FunctionPass *llvm::createJumpThreadingPass() { return new JumpThreading(); }
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/// runOnFunction - Top level algorithm.
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///
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bool JumpThreading::runOnFunction(Function &F) {
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bool Changed = false;
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return Changed;
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}
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