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can be used by both the new pass manager and the old. This removes it from any of the virtual mess of the pass interfaces and lets it derive cleanly from the DominatorTreeBase<> template. In turn, tons of boilerplate interface can be nuked and it turns into a very straightforward extension of the base DominatorTree interface. The old analysis pass is now a simple wrapper. The names and style of this split should match the split between CallGraph and CallGraphWrapperPass. All of the users of DominatorTree have been updated to match using many of the same tricks as with CallGraph. The goal is that the common type remains the resulting DominatorTree rather than the pass. This will make subsequent work toward the new pass manager significantly easier. Also in numerous places things became cleaner because I switched from re-running the pass (!!! mid way through some other passes run!!!) to directly recomputing the domtree. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199104 91177308-0d34-0410-b5e6-96231b3b80d8
332 lines
9.5 KiB
C++
332 lines
9.5 KiB
C++
//===-- SIAnnotateControlFlow.cpp - ------------------===//
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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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/// \file
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/// Annotates the control flow with hardware specific intrinsics.
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//
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//===----------------------------------------------------------------------===//
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#include "AMDGPU.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/SSAUpdater.h"
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using namespace llvm;
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namespace {
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// Complex types used in this pass
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typedef std::pair<BasicBlock *, Value *> StackEntry;
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typedef SmallVector<StackEntry, 16> StackVector;
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// Intrinsic names the control flow is annotated with
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static const char *const IfIntrinsic = "llvm.SI.if";
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static const char *const ElseIntrinsic = "llvm.SI.else";
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static const char *const BreakIntrinsic = "llvm.SI.break";
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static const char *const IfBreakIntrinsic = "llvm.SI.if.break";
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static const char *const ElseBreakIntrinsic = "llvm.SI.else.break";
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static const char *const LoopIntrinsic = "llvm.SI.loop";
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static const char *const EndCfIntrinsic = "llvm.SI.end.cf";
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class SIAnnotateControlFlow : public FunctionPass {
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static char ID;
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Type *Boolean;
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Type *Void;
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Type *Int64;
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Type *ReturnStruct;
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ConstantInt *BoolTrue;
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ConstantInt *BoolFalse;
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UndefValue *BoolUndef;
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Constant *Int64Zero;
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Constant *If;
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Constant *Else;
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Constant *Break;
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Constant *IfBreak;
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Constant *ElseBreak;
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Constant *Loop;
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Constant *EndCf;
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DominatorTree *DT;
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StackVector Stack;
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SSAUpdater PhiInserter;
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bool isTopOfStack(BasicBlock *BB);
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Value *popSaved();
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void push(BasicBlock *BB, Value *Saved);
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bool isElse(PHINode *Phi);
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void eraseIfUnused(PHINode *Phi);
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void openIf(BranchInst *Term);
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void insertElse(BranchInst *Term);
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void handleLoopCondition(Value *Cond);
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void handleLoop(BranchInst *Term);
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void closeControlFlow(BasicBlock *BB);
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public:
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SIAnnotateControlFlow():
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FunctionPass(ID) { }
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virtual bool doInitialization(Module &M);
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virtual bool runOnFunction(Function &F);
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virtual const char *getPassName() const {
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return "SI annotate control flow";
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}
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<DominatorTreeWrapperPass>();
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AU.addPreserved<DominatorTreeWrapperPass>();
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FunctionPass::getAnalysisUsage(AU);
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}
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};
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} // end anonymous namespace
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char SIAnnotateControlFlow::ID = 0;
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/// \brief Initialize all the types and constants used in the pass
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bool SIAnnotateControlFlow::doInitialization(Module &M) {
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LLVMContext &Context = M.getContext();
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Void = Type::getVoidTy(Context);
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Boolean = Type::getInt1Ty(Context);
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Int64 = Type::getInt64Ty(Context);
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ReturnStruct = StructType::get(Boolean, Int64, (Type *)0);
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BoolTrue = ConstantInt::getTrue(Context);
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BoolFalse = ConstantInt::getFalse(Context);
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BoolUndef = UndefValue::get(Boolean);
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Int64Zero = ConstantInt::get(Int64, 0);
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If = M.getOrInsertFunction(
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IfIntrinsic, ReturnStruct, Boolean, (Type *)0);
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Else = M.getOrInsertFunction(
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ElseIntrinsic, ReturnStruct, Int64, (Type *)0);
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Break = M.getOrInsertFunction(
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BreakIntrinsic, Int64, Int64, (Type *)0);
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IfBreak = M.getOrInsertFunction(
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IfBreakIntrinsic, Int64, Boolean, Int64, (Type *)0);
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ElseBreak = M.getOrInsertFunction(
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ElseBreakIntrinsic, Int64, Int64, Int64, (Type *)0);
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Loop = M.getOrInsertFunction(
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LoopIntrinsic, Boolean, Int64, (Type *)0);
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EndCf = M.getOrInsertFunction(
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EndCfIntrinsic, Void, Int64, (Type *)0);
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return false;
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}
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/// \brief Is BB the last block saved on the stack ?
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bool SIAnnotateControlFlow::isTopOfStack(BasicBlock *BB) {
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return !Stack.empty() && Stack.back().first == BB;
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}
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/// \brief Pop the last saved value from the control flow stack
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Value *SIAnnotateControlFlow::popSaved() {
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return Stack.pop_back_val().second;
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}
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/// \brief Push a BB and saved value to the control flow stack
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void SIAnnotateControlFlow::push(BasicBlock *BB, Value *Saved) {
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Stack.push_back(std::make_pair(BB, Saved));
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}
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/// \brief Can the condition represented by this PHI node treated like
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/// an "Else" block?
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bool SIAnnotateControlFlow::isElse(PHINode *Phi) {
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BasicBlock *IDom = DT->getNode(Phi->getParent())->getIDom()->getBlock();
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for (unsigned i = 0, e = Phi->getNumIncomingValues(); i != e; ++i) {
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if (Phi->getIncomingBlock(i) == IDom) {
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if (Phi->getIncomingValue(i) != BoolTrue)
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return false;
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} else {
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if (Phi->getIncomingValue(i) != BoolFalse)
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return false;
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}
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}
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return true;
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}
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// \brief Erase "Phi" if it is not used any more
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void SIAnnotateControlFlow::eraseIfUnused(PHINode *Phi) {
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if (!Phi->hasNUsesOrMore(1))
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Phi->eraseFromParent();
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}
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/// \brief Open a new "If" block
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void SIAnnotateControlFlow::openIf(BranchInst *Term) {
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Value *Ret = CallInst::Create(If, Term->getCondition(), "", Term);
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Term->setCondition(ExtractValueInst::Create(Ret, 0, "", Term));
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push(Term->getSuccessor(1), ExtractValueInst::Create(Ret, 1, "", Term));
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}
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/// \brief Close the last "If" block and open a new "Else" block
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void SIAnnotateControlFlow::insertElse(BranchInst *Term) {
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Value *Ret = CallInst::Create(Else, popSaved(), "", Term);
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Term->setCondition(ExtractValueInst::Create(Ret, 0, "", Term));
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push(Term->getSuccessor(1), ExtractValueInst::Create(Ret, 1, "", Term));
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}
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/// \brief Recursively handle the condition leading to a loop
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void SIAnnotateControlFlow::handleLoopCondition(Value *Cond) {
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if (PHINode *Phi = dyn_cast<PHINode>(Cond)) {
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// Handle all non-constant incoming values first
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for (unsigned i = 0, e = Phi->getNumIncomingValues(); i != e; ++i) {
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Value *Incoming = Phi->getIncomingValue(i);
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if (isa<ConstantInt>(Incoming))
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continue;
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Phi->setIncomingValue(i, BoolFalse);
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handleLoopCondition(Incoming);
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}
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BasicBlock *Parent = Phi->getParent();
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BasicBlock *IDom = DT->getNode(Parent)->getIDom()->getBlock();
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for (unsigned i = 0, e = Phi->getNumIncomingValues(); i != e; ++i) {
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Value *Incoming = Phi->getIncomingValue(i);
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if (Incoming != BoolTrue)
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continue;
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BasicBlock *From = Phi->getIncomingBlock(i);
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if (From == IDom) {
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CallInst *OldEnd = dyn_cast<CallInst>(Parent->getFirstInsertionPt());
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if (OldEnd && OldEnd->getCalledFunction() == EndCf) {
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Value *Args[] = {
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OldEnd->getArgOperand(0),
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PhiInserter.GetValueAtEndOfBlock(Parent)
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};
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Value *Ret = CallInst::Create(ElseBreak, Args, "", OldEnd);
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PhiInserter.AddAvailableValue(Parent, Ret);
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continue;
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}
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}
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TerminatorInst *Insert = From->getTerminator();
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Value *Arg = PhiInserter.GetValueAtEndOfBlock(From);
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Value *Ret = CallInst::Create(Break, Arg, "", Insert);
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PhiInserter.AddAvailableValue(From, Ret);
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}
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eraseIfUnused(Phi);
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} else if (Instruction *Inst = dyn_cast<Instruction>(Cond)) {
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BasicBlock *Parent = Inst->getParent();
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TerminatorInst *Insert = Parent->getTerminator();
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Value *Args[] = { Cond, PhiInserter.GetValueAtEndOfBlock(Parent) };
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Value *Ret = CallInst::Create(IfBreak, Args, "", Insert);
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PhiInserter.AddAvailableValue(Parent, Ret);
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} else {
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llvm_unreachable("Unhandled loop condition!");
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}
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}
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/// \brief Handle a back edge (loop)
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void SIAnnotateControlFlow::handleLoop(BranchInst *Term) {
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BasicBlock *Target = Term->getSuccessor(1);
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PHINode *Broken = PHINode::Create(Int64, 0, "", &Target->front());
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PhiInserter.Initialize(Int64, "");
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PhiInserter.AddAvailableValue(Target, Broken);
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Value *Cond = Term->getCondition();
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Term->setCondition(BoolTrue);
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handleLoopCondition(Cond);
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BasicBlock *BB = Term->getParent();
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Value *Arg = PhiInserter.GetValueAtEndOfBlock(BB);
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for (pred_iterator PI = pred_begin(Target), PE = pred_end(Target);
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PI != PE; ++PI) {
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Broken->addIncoming(*PI == BB ? Arg : Int64Zero, *PI);
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}
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Term->setCondition(CallInst::Create(Loop, Arg, "", Term));
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push(Term->getSuccessor(0), Arg);
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}
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/// \brief Close the last opened control flow
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void SIAnnotateControlFlow::closeControlFlow(BasicBlock *BB) {
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CallInst::Create(EndCf, popSaved(), "", BB->getFirstInsertionPt());
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}
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/// \brief Annotate the control flow with intrinsics so the backend can
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/// recognize if/then/else and loops.
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bool SIAnnotateControlFlow::runOnFunction(Function &F) {
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DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
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for (df_iterator<BasicBlock *> I = df_begin(&F.getEntryBlock()),
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E = df_end(&F.getEntryBlock()); I != E; ++I) {
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BranchInst *Term = dyn_cast<BranchInst>((*I)->getTerminator());
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if (!Term || Term->isUnconditional()) {
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if (isTopOfStack(*I))
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closeControlFlow(*I);
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continue;
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}
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if (I.nodeVisited(Term->getSuccessor(1))) {
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if (isTopOfStack(*I))
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closeControlFlow(*I);
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handleLoop(Term);
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continue;
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}
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if (isTopOfStack(*I)) {
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PHINode *Phi = dyn_cast<PHINode>(Term->getCondition());
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if (Phi && Phi->getParent() == *I && isElse(Phi)) {
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insertElse(Term);
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eraseIfUnused(Phi);
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continue;
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}
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closeControlFlow(*I);
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}
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openIf(Term);
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}
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assert(Stack.empty());
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return true;
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}
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/// \brief Create the annotation pass
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FunctionPass *llvm::createSIAnnotateControlFlowPass() {
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return new SIAnnotateControlFlow();
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}
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