c992690179
This seems to cause asserts in our builds: llvm/include/llvm/Support/GenericDomTreeConstruction.h:927: static void llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<BasicBlock, false>>::DeleteEdge(DomTreeT &, const BatchUpdatePtr, const NodePtr, const NodePtr) [DomTreeT = llvm::DominatorTreeBase<BasicBlock, false>]: Assertion `!IsSuccessor(To, From) && "Deleted edge still exists in the CFG!"' failed. and llvm/lib/Analysis/FunctionPropertiesAnalysis.cpp:390: DominatorTree &llvm::FunctionPropertiesUpdater::getUpdatedDominatorTree(FunctionAnalysisManager &) const: Assertion `DT.getNode(BB)' failed. See comment on the PR. > We need the dominator tree analysis for loop info analysis, which we need to get features like most nested loop and number of top level loops. Invalidating and recomputing these from scratch after each successful inlining can sometimes lead to lengthy compile times. We don't need to recompute from scratch, though, since we have some boundary information about where the changes to the CFG happen; moreover, for dom tree, the API supports incrementally updating the analysis result. > > This change addresses the dom tree part. The loop info is still recomputed from scratch. This does reduce the compile time quite significantly already, though (~5x in a specific case) > > The loop info change might be more involved and would follow in a subsequent PR. This reverts commit a2a5508bdae7d115b6c3ace461beb7a987a44407 and the follow-up commit cdd11d694a406a98a16d6265168ee2fbe1b6a87c.
440 lines
16 KiB
C++
440 lines
16 KiB
C++
//===- FunctionPropertiesAnalysis.cpp - Function Properties Analysis ------===//
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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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// This file defines the FunctionPropertiesInfo and FunctionPropertiesAnalysis
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// classes used to extract function properties.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/FunctionPropertiesAnalysis.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/IR/CFG.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/IntrinsicInst.h"
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#include "llvm/Support/CommandLine.h"
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#include <deque>
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using namespace llvm;
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namespace llvm {
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cl::opt<bool> EnableDetailedFunctionProperties(
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"enable-detailed-function-properties", cl::Hidden, cl::init(false),
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cl::desc("Whether or not to compute detailed function properties."));
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cl::opt<unsigned> BigBasicBlockInstructionThreshold(
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"big-basic-block-instruction-threshold", cl::Hidden, cl::init(500),
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cl::desc("The minimum number of instructions a basic block should contain "
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"before being considered big."));
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cl::opt<unsigned> MediumBasicBlockInstructionThreshold(
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"medium-basic-block-instruction-threshold", cl::Hidden, cl::init(15),
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cl::desc("The minimum number of instructions a basic block should contain "
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"before being considered medium-sized."));
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} // namespace llvm
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static cl::opt<unsigned> CallWithManyArgumentsThreshold(
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"call-with-many-arguments-threshold", cl::Hidden, cl::init(4),
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cl::desc("The minimum number of arguments a function call must have before "
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"it is considered having many arguments."));
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namespace {
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int64_t getNrBlocksFromCond(const BasicBlock &BB) {
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int64_t Ret = 0;
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if (const auto *BI = dyn_cast<BranchInst>(BB.getTerminator())) {
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if (BI->isConditional())
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Ret += BI->getNumSuccessors();
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} else if (const auto *SI = dyn_cast<SwitchInst>(BB.getTerminator())) {
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Ret += (SI->getNumCases() + (nullptr != SI->getDefaultDest()));
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}
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return Ret;
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}
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int64_t getUses(const Function &F) {
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return ((!F.hasLocalLinkage()) ? 1 : 0) + F.getNumUses();
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}
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} // namespace
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void FunctionPropertiesInfo::reIncludeBB(const BasicBlock &BB) {
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updateForBB(BB, +1);
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}
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void FunctionPropertiesInfo::updateForBB(const BasicBlock &BB,
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int64_t Direction) {
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assert(Direction == 1 || Direction == -1);
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BasicBlockCount += Direction;
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BlocksReachedFromConditionalInstruction +=
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(Direction * getNrBlocksFromCond(BB));
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for (const auto &I : BB) {
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if (auto *CS = dyn_cast<CallBase>(&I)) {
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const auto *Callee = CS->getCalledFunction();
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if (Callee && !Callee->isIntrinsic() && !Callee->isDeclaration())
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DirectCallsToDefinedFunctions += Direction;
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}
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if (I.getOpcode() == Instruction::Load) {
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LoadInstCount += Direction;
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} else if (I.getOpcode() == Instruction::Store) {
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StoreInstCount += Direction;
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}
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}
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TotalInstructionCount += Direction * BB.sizeWithoutDebug();
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if (EnableDetailedFunctionProperties) {
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unsigned SuccessorCount = succ_size(&BB);
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if (SuccessorCount == 1)
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BasicBlocksWithSingleSuccessor += Direction;
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else if (SuccessorCount == 2)
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BasicBlocksWithTwoSuccessors += Direction;
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else if (SuccessorCount > 2)
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BasicBlocksWithMoreThanTwoSuccessors += Direction;
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unsigned PredecessorCount = pred_size(&BB);
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if (PredecessorCount == 1)
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BasicBlocksWithSinglePredecessor += Direction;
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else if (PredecessorCount == 2)
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BasicBlocksWithTwoPredecessors += Direction;
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else if (PredecessorCount > 2)
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BasicBlocksWithMoreThanTwoPredecessors += Direction;
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if (TotalInstructionCount > BigBasicBlockInstructionThreshold)
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BigBasicBlocks += Direction;
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else if (TotalInstructionCount > MediumBasicBlockInstructionThreshold)
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MediumBasicBlocks += Direction;
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else
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SmallBasicBlocks += Direction;
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// Calculate critical edges by looking through all successors of a basic
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// block that has multiple successors and finding ones that have multiple
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// predecessors, which represent critical edges.
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if (SuccessorCount > 1) {
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for (const auto *Successor : successors(&BB)) {
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if (pred_size(Successor) > 1)
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CriticalEdgeCount += Direction;
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}
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}
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ControlFlowEdgeCount += Direction * SuccessorCount;
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if (const auto *BI = dyn_cast<BranchInst>(BB.getTerminator())) {
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if (!BI->isConditional())
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UnconditionalBranchCount += Direction;
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}
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for (const Instruction &I : BB.instructionsWithoutDebug()) {
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if (I.isCast())
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CastInstructionCount += Direction;
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if (I.getType()->isFloatTy())
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FloatingPointInstructionCount += Direction;
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else if (I.getType()->isIntegerTy())
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IntegerInstructionCount += Direction;
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if (isa<IntrinsicInst>(I))
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++IntrinsicCount;
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if (const auto *Call = dyn_cast<CallInst>(&I)) {
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if (Call->isIndirectCall())
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IndirectCallCount += Direction;
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else
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DirectCallCount += Direction;
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if (Call->getType()->isIntegerTy())
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CallReturnsIntegerCount += Direction;
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else if (Call->getType()->isFloatingPointTy())
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CallReturnsFloatCount += Direction;
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else if (Call->getType()->isPointerTy())
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CallReturnsPointerCount += Direction;
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else if (Call->getType()->isVectorTy()) {
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if (Call->getType()->getScalarType()->isIntegerTy())
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CallReturnsVectorIntCount += Direction;
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else if (Call->getType()->getScalarType()->isFloatingPointTy())
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CallReturnsVectorFloatCount += Direction;
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else if (Call->getType()->getScalarType()->isPointerTy())
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CallReturnsVectorPointerCount += Direction;
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}
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if (Call->arg_size() > CallWithManyArgumentsThreshold)
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CallWithManyArgumentsCount += Direction;
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for (const auto &Arg : Call->args()) {
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if (Arg->getType()->isPointerTy()) {
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CallWithPointerArgumentCount += Direction;
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break;
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}
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}
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}
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#define COUNT_OPERAND(OPTYPE) \
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if (isa<OPTYPE>(Operand)) { \
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OPTYPE##OperandCount += Direction; \
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continue; \
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}
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for (unsigned int OperandIndex = 0; OperandIndex < I.getNumOperands();
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++OperandIndex) {
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Value *Operand = I.getOperand(OperandIndex);
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COUNT_OPERAND(GlobalValue)
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COUNT_OPERAND(ConstantInt)
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COUNT_OPERAND(ConstantFP)
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COUNT_OPERAND(Constant)
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COUNT_OPERAND(Instruction)
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COUNT_OPERAND(BasicBlock)
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COUNT_OPERAND(InlineAsm)
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COUNT_OPERAND(Argument)
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// We only get to this point if we haven't matched any of the other
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// operand types.
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UnknownOperandCount += Direction;
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}
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#undef CHECK_OPERAND
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}
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}
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}
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void FunctionPropertiesInfo::updateAggregateStats(const Function &F,
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const LoopInfo &LI) {
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Uses = getUses(F);
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TopLevelLoopCount = llvm::size(LI);
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MaxLoopDepth = 0;
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std::deque<const Loop *> Worklist;
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llvm::append_range(Worklist, LI);
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while (!Worklist.empty()) {
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const auto *L = Worklist.front();
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MaxLoopDepth =
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std::max(MaxLoopDepth, static_cast<int64_t>(L->getLoopDepth()));
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Worklist.pop_front();
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llvm::append_range(Worklist, L->getSubLoops());
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}
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}
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FunctionPropertiesInfo FunctionPropertiesInfo::getFunctionPropertiesInfo(
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Function &F, FunctionAnalysisManager &FAM) {
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return getFunctionPropertiesInfo(F, FAM.getResult<DominatorTreeAnalysis>(F),
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FAM.getResult<LoopAnalysis>(F));
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}
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FunctionPropertiesInfo FunctionPropertiesInfo::getFunctionPropertiesInfo(
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const Function &F, const DominatorTree &DT, const LoopInfo &LI) {
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FunctionPropertiesInfo FPI;
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for (const auto &BB : F)
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if (DT.isReachableFromEntry(&BB))
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FPI.reIncludeBB(BB);
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FPI.updateAggregateStats(F, LI);
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return FPI;
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}
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void FunctionPropertiesInfo::print(raw_ostream &OS) const {
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#define PRINT_PROPERTY(PROP_NAME) OS << #PROP_NAME ": " << PROP_NAME << "\n";
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PRINT_PROPERTY(BasicBlockCount)
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PRINT_PROPERTY(BlocksReachedFromConditionalInstruction)
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PRINT_PROPERTY(Uses)
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PRINT_PROPERTY(DirectCallsToDefinedFunctions)
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PRINT_PROPERTY(LoadInstCount)
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PRINT_PROPERTY(StoreInstCount)
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PRINT_PROPERTY(MaxLoopDepth)
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PRINT_PROPERTY(TopLevelLoopCount)
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PRINT_PROPERTY(TotalInstructionCount)
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if (EnableDetailedFunctionProperties) {
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PRINT_PROPERTY(BasicBlocksWithSingleSuccessor)
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PRINT_PROPERTY(BasicBlocksWithTwoSuccessors)
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PRINT_PROPERTY(BasicBlocksWithMoreThanTwoSuccessors)
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PRINT_PROPERTY(BasicBlocksWithSinglePredecessor)
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PRINT_PROPERTY(BasicBlocksWithTwoPredecessors)
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PRINT_PROPERTY(BasicBlocksWithMoreThanTwoPredecessors)
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PRINT_PROPERTY(BigBasicBlocks)
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PRINT_PROPERTY(MediumBasicBlocks)
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PRINT_PROPERTY(SmallBasicBlocks)
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PRINT_PROPERTY(CastInstructionCount)
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PRINT_PROPERTY(FloatingPointInstructionCount)
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PRINT_PROPERTY(IntegerInstructionCount)
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PRINT_PROPERTY(ConstantIntOperandCount)
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PRINT_PROPERTY(ConstantFPOperandCount)
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PRINT_PROPERTY(ConstantOperandCount)
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PRINT_PROPERTY(InstructionOperandCount)
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PRINT_PROPERTY(BasicBlockOperandCount)
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PRINT_PROPERTY(GlobalValueOperandCount)
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PRINT_PROPERTY(InlineAsmOperandCount)
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PRINT_PROPERTY(ArgumentOperandCount)
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PRINT_PROPERTY(UnknownOperandCount)
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PRINT_PROPERTY(CriticalEdgeCount)
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PRINT_PROPERTY(ControlFlowEdgeCount)
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PRINT_PROPERTY(UnconditionalBranchCount)
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PRINT_PROPERTY(IntrinsicCount)
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PRINT_PROPERTY(DirectCallCount)
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PRINT_PROPERTY(IndirectCallCount)
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PRINT_PROPERTY(CallReturnsIntegerCount)
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PRINT_PROPERTY(CallReturnsFloatCount)
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PRINT_PROPERTY(CallReturnsPointerCount)
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PRINT_PROPERTY(CallReturnsVectorIntCount)
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PRINT_PROPERTY(CallReturnsVectorFloatCount)
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PRINT_PROPERTY(CallReturnsVectorPointerCount)
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PRINT_PROPERTY(CallWithManyArgumentsCount)
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PRINT_PROPERTY(CallWithPointerArgumentCount)
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}
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#undef PRINT_PROPERTY
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OS << "\n";
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}
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AnalysisKey FunctionPropertiesAnalysis::Key;
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FunctionPropertiesInfo
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FunctionPropertiesAnalysis::run(Function &F, FunctionAnalysisManager &FAM) {
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return FunctionPropertiesInfo::getFunctionPropertiesInfo(F, FAM);
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}
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PreservedAnalyses
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FunctionPropertiesPrinterPass::run(Function &F, FunctionAnalysisManager &AM) {
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OS << "Printing analysis results of CFA for function "
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<< "'" << F.getName() << "':"
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<< "\n";
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AM.getResult<FunctionPropertiesAnalysis>(F).print(OS);
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return PreservedAnalyses::all();
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}
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FunctionPropertiesUpdater::FunctionPropertiesUpdater(
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FunctionPropertiesInfo &FPI, CallBase &CB)
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: FPI(FPI), CallSiteBB(*CB.getParent()), Caller(*CallSiteBB.getParent()) {
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assert(isa<CallInst>(CB) || isa<InvokeInst>(CB));
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// For BBs that are likely to change, we subtract from feature totals their
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// contribution. Some features, like max loop counts or depths, are left
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// invalid, as they will be updated post-inlining.
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SmallPtrSet<const BasicBlock *, 4> LikelyToChangeBBs;
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// The CB BB will change - it'll either be split or the callee's body (single
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// BB) will be pasted in.
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LikelyToChangeBBs.insert(&CallSiteBB);
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// The caller's entry BB may change due to new alloca instructions.
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LikelyToChangeBBs.insert(&*Caller.begin());
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// The successors may become unreachable in the case of `invoke` inlining.
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// We track successors separately, too, because they form a boundary, together
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// with the CB BB ('Entry') between which the inlined callee will be pasted.
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Successors.insert(succ_begin(&CallSiteBB), succ_end(&CallSiteBB));
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// Inlining only handles invoke and calls. If this is an invoke, and inlining
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// it pulls another invoke, the original landing pad may get split, so as to
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// share its content with other potential users. So the edge up to which we
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// need to invalidate and then re-account BB data is the successors of the
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// current landing pad. We can leave the current lp, too - if it doesn't get
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// split, then it will be the place traversal stops. Either way, the
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// discounted BBs will be checked if reachable and re-added.
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if (const auto *II = dyn_cast<InvokeInst>(&CB)) {
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const auto *UnwindDest = II->getUnwindDest();
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Successors.insert(succ_begin(UnwindDest), succ_end(UnwindDest));
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}
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// Exclude the CallSiteBB, if it happens to be its own successor (1-BB loop).
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// We are only interested in BBs the graph moves past the callsite BB to
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// define the frontier past which we don't want to re-process BBs. Including
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// the callsite BB in this case would prematurely stop the traversal in
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// finish().
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Successors.erase(&CallSiteBB);
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for (const auto *BB : Successors)
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LikelyToChangeBBs.insert(BB);
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// Commit the change. While some of the BBs accounted for above may play dual
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// role - e.g. caller's entry BB may be the same as the callsite BB - set
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// insertion semantics make sure we account them once. This needs to be
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// followed in `finish`, too.
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for (const auto *BB : LikelyToChangeBBs)
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FPI.updateForBB(*BB, -1);
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}
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void FunctionPropertiesUpdater::finish(FunctionAnalysisManager &FAM) const {
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// Update feature values from the BBs that were copied from the callee, or
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// might have been modified because of inlining. The latter have been
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// subtracted in the FunctionPropertiesUpdater ctor.
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// There could be successors that were reached before but now are only
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// reachable from elsewhere in the CFG.
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// One example is the following diamond CFG (lines are arrows pointing down):
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// A
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// / \
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// B C
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// | |
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// | D
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// | |
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// | E
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// \ /
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// F
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// There's a call site in C that is inlined. Upon doing that, it turns out
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// it expands to
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// call void @llvm.trap()
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// unreachable
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// F isn't reachable from C anymore, but we did discount it when we set up
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// FunctionPropertiesUpdater, so we need to re-include it here.
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// At the same time, D and E were reachable before, but now are not anymore,
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// so we need to leave D out (we discounted it at setup), and explicitly
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// remove E.
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SetVector<const BasicBlock *> Reinclude;
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SetVector<const BasicBlock *> Unreachable;
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const auto &DT =
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FAM.getResult<DominatorTreeAnalysis>(const_cast<Function &>(Caller));
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if (&CallSiteBB != &*Caller.begin())
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Reinclude.insert(&*Caller.begin());
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// Distribute the successors to the 2 buckets.
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for (const auto *Succ : Successors)
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if (DT.isReachableFromEntry(Succ))
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Reinclude.insert(Succ);
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else
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Unreachable.insert(Succ);
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// For reinclusion, we want to stop at the reachable successors, who are at
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// the beginning of the worklist; but, starting from the callsite bb and
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// ending at those successors, we also want to perform a traversal.
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// IncludeSuccessorsMark is the index after which we include successors.
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const auto IncludeSuccessorsMark = Reinclude.size();
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bool CSInsertion = Reinclude.insert(&CallSiteBB);
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(void)CSInsertion;
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assert(CSInsertion);
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for (size_t I = 0; I < Reinclude.size(); ++I) {
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const auto *BB = Reinclude[I];
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FPI.reIncludeBB(*BB);
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if (I >= IncludeSuccessorsMark)
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Reinclude.insert(succ_begin(BB), succ_end(BB));
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}
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// For exclusion, we don't need to exclude the set of BBs that were successors
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// before and are now unreachable, because we already did that at setup. For
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// the rest, as long as a successor is unreachable, we want to explicitly
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// exclude it.
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const auto AlreadyExcludedMark = Unreachable.size();
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for (size_t I = 0; I < Unreachable.size(); ++I) {
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const auto *U = Unreachable[I];
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if (I >= AlreadyExcludedMark)
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FPI.updateForBB(*U, -1);
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for (const auto *Succ : successors(U))
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if (!DT.isReachableFromEntry(Succ))
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Unreachable.insert(Succ);
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}
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const auto &LI = FAM.getResult<LoopAnalysis>(const_cast<Function &>(Caller));
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FPI.updateAggregateStats(Caller, LI);
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}
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bool FunctionPropertiesUpdater::isUpdateValid(Function &F,
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const FunctionPropertiesInfo &FPI,
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FunctionAnalysisManager &FAM) {
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DominatorTree DT(F);
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LoopInfo LI(DT);
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auto Fresh = FunctionPropertiesInfo::getFunctionPropertiesInfo(F, DT, LI);
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return FPI == Fresh;
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}
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