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https://github.com/c64scene-ar/llvm-6502.git
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9311f5b6fe
This patch refactors the definition of common utility function "isInductionPHI" to LoopUtils.cpp. This fixes compilation error when configured with -DBUILD_SHARED_LIBS=ON git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235577 91177308-0d34-0410-b5e6-96231b3b80d8
500 lines
18 KiB
C++
500 lines
18 KiB
C++
//===-- LoopUtils.cpp - Loop Utility functions -------------------------===//
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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 file defines common loop utility functions.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/IR/ValueHandle.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/ScalarEvolutionExpressions.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Transforms/Utils/LoopUtils.h"
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using namespace llvm;
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using namespace llvm::PatternMatch;
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#define DEBUG_TYPE "loop-utils"
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bool ReductionDescriptor::areAllUsesIn(Instruction *I,
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SmallPtrSetImpl<Instruction *> &Set) {
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for (User::op_iterator Use = I->op_begin(), E = I->op_end(); Use != E; ++Use)
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if (!Set.count(dyn_cast<Instruction>(*Use)))
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return false;
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return true;
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}
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bool ReductionDescriptor::AddReductionVar(PHINode *Phi, ReductionKind Kind,
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Loop *TheLoop, bool HasFunNoNaNAttr,
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ReductionDescriptor &RedDes) {
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if (Phi->getNumIncomingValues() != 2)
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return false;
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// Reduction variables are only found in the loop header block.
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if (Phi->getParent() != TheLoop->getHeader())
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return false;
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// Obtain the reduction start value from the value that comes from the loop
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// preheader.
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Value *RdxStart = Phi->getIncomingValueForBlock(TheLoop->getLoopPreheader());
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// ExitInstruction is the single value which is used outside the loop.
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// We only allow for a single reduction value to be used outside the loop.
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// This includes users of the reduction, variables (which form a cycle
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// which ends in the phi node).
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Instruction *ExitInstruction = nullptr;
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// Indicates that we found a reduction operation in our scan.
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bool FoundReduxOp = false;
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// We start with the PHI node and scan for all of the users of this
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// instruction. All users must be instructions that can be used as reduction
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// variables (such as ADD). We must have a single out-of-block user. The cycle
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// must include the original PHI.
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bool FoundStartPHI = false;
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// To recognize min/max patterns formed by a icmp select sequence, we store
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// the number of instruction we saw from the recognized min/max pattern,
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// to make sure we only see exactly the two instructions.
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unsigned NumCmpSelectPatternInst = 0;
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ReductionInstDesc ReduxDesc(false, nullptr);
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SmallPtrSet<Instruction *, 8> VisitedInsts;
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SmallVector<Instruction *, 8> Worklist;
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Worklist.push_back(Phi);
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VisitedInsts.insert(Phi);
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// A value in the reduction can be used:
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// - By the reduction:
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// - Reduction operation:
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// - One use of reduction value (safe).
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// - Multiple use of reduction value (not safe).
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// - PHI:
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// - All uses of the PHI must be the reduction (safe).
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// - Otherwise, not safe.
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// - By one instruction outside of the loop (safe).
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// - By further instructions outside of the loop (not safe).
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// - By an instruction that is not part of the reduction (not safe).
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// This is either:
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// * An instruction type other than PHI or the reduction operation.
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// * A PHI in the header other than the initial PHI.
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while (!Worklist.empty()) {
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Instruction *Cur = Worklist.back();
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Worklist.pop_back();
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// No Users.
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// If the instruction has no users then this is a broken chain and can't be
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// a reduction variable.
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if (Cur->use_empty())
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return false;
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bool IsAPhi = isa<PHINode>(Cur);
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// A header PHI use other than the original PHI.
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if (Cur != Phi && IsAPhi && Cur->getParent() == Phi->getParent())
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return false;
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// Reductions of instructions such as Div, and Sub is only possible if the
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// LHS is the reduction variable.
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if (!Cur->isCommutative() && !IsAPhi && !isa<SelectInst>(Cur) &&
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!isa<ICmpInst>(Cur) && !isa<FCmpInst>(Cur) &&
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!VisitedInsts.count(dyn_cast<Instruction>(Cur->getOperand(0))))
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return false;
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// Any reduction instruction must be of one of the allowed kinds.
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ReduxDesc = isReductionInstr(Cur, Kind, ReduxDesc, HasFunNoNaNAttr);
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if (!ReduxDesc.isReduction())
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return false;
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// A reduction operation must only have one use of the reduction value.
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if (!IsAPhi && Kind != RK_IntegerMinMax && Kind != RK_FloatMinMax &&
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hasMultipleUsesOf(Cur, VisitedInsts))
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return false;
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// All inputs to a PHI node must be a reduction value.
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if (IsAPhi && Cur != Phi && !areAllUsesIn(Cur, VisitedInsts))
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return false;
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if (Kind == RK_IntegerMinMax &&
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(isa<ICmpInst>(Cur) || isa<SelectInst>(Cur)))
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++NumCmpSelectPatternInst;
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if (Kind == RK_FloatMinMax && (isa<FCmpInst>(Cur) || isa<SelectInst>(Cur)))
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++NumCmpSelectPatternInst;
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// Check whether we found a reduction operator.
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FoundReduxOp |= !IsAPhi;
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// Process users of current instruction. Push non-PHI nodes after PHI nodes
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// onto the stack. This way we are going to have seen all inputs to PHI
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// nodes once we get to them.
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SmallVector<Instruction *, 8> NonPHIs;
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SmallVector<Instruction *, 8> PHIs;
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for (User *U : Cur->users()) {
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Instruction *UI = cast<Instruction>(U);
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// Check if we found the exit user.
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BasicBlock *Parent = UI->getParent();
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if (!TheLoop->contains(Parent)) {
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// Exit if you find multiple outside users or if the header phi node is
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// being used. In this case the user uses the value of the previous
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// iteration, in which case we would loose "VF-1" iterations of the
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// reduction operation if we vectorize.
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if (ExitInstruction != nullptr || Cur == Phi)
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return false;
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// The instruction used by an outside user must be the last instruction
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// before we feed back to the reduction phi. Otherwise, we loose VF-1
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// operations on the value.
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if (std::find(Phi->op_begin(), Phi->op_end(), Cur) == Phi->op_end())
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return false;
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ExitInstruction = Cur;
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continue;
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}
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// Process instructions only once (termination). Each reduction cycle
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// value must only be used once, except by phi nodes and min/max
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// reductions which are represented as a cmp followed by a select.
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ReductionInstDesc IgnoredVal(false, nullptr);
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if (VisitedInsts.insert(UI).second) {
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if (isa<PHINode>(UI))
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PHIs.push_back(UI);
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else
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NonPHIs.push_back(UI);
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} else if (!isa<PHINode>(UI) &&
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((!isa<FCmpInst>(UI) && !isa<ICmpInst>(UI) &&
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!isa<SelectInst>(UI)) ||
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!isMinMaxSelectCmpPattern(UI, IgnoredVal).isReduction()))
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return false;
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// Remember that we completed the cycle.
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if (UI == Phi)
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FoundStartPHI = true;
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}
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Worklist.append(PHIs.begin(), PHIs.end());
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Worklist.append(NonPHIs.begin(), NonPHIs.end());
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}
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// This means we have seen one but not the other instruction of the
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// pattern or more than just a select and cmp.
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if ((Kind == RK_IntegerMinMax || Kind == RK_FloatMinMax) &&
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NumCmpSelectPatternInst != 2)
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return false;
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if (!FoundStartPHI || !FoundReduxOp || !ExitInstruction)
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return false;
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// We found a reduction var if we have reached the original phi node and we
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// only have a single instruction with out-of-loop users.
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// The ExitInstruction(Instruction which is allowed to have out-of-loop users)
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// is saved as part of the ReductionDescriptor.
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// Save the description of this reduction variable.
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ReductionDescriptor RD(RdxStart, ExitInstruction, Kind,
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ReduxDesc.getMinMaxKind());
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RedDes = RD;
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return true;
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}
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/// Returns true if the instruction is a Select(ICmp(X, Y), X, Y) instruction
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/// pattern corresponding to a min(X, Y) or max(X, Y).
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ReductionInstDesc
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ReductionDescriptor::isMinMaxSelectCmpPattern(Instruction *I,
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ReductionInstDesc &Prev) {
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assert((isa<ICmpInst>(I) || isa<FCmpInst>(I) || isa<SelectInst>(I)) &&
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"Expect a select instruction");
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Instruction *Cmp = nullptr;
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SelectInst *Select = nullptr;
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// We must handle the select(cmp()) as a single instruction. Advance to the
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// select.
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if ((Cmp = dyn_cast<ICmpInst>(I)) || (Cmp = dyn_cast<FCmpInst>(I))) {
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if (!Cmp->hasOneUse() || !(Select = dyn_cast<SelectInst>(*I->user_begin())))
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return ReductionInstDesc(false, I);
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return ReductionInstDesc(Select, Prev.getMinMaxKind());
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}
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// Only handle single use cases for now.
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if (!(Select = dyn_cast<SelectInst>(I)))
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return ReductionInstDesc(false, I);
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if (!(Cmp = dyn_cast<ICmpInst>(I->getOperand(0))) &&
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!(Cmp = dyn_cast<FCmpInst>(I->getOperand(0))))
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return ReductionInstDesc(false, I);
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if (!Cmp->hasOneUse())
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return ReductionInstDesc(false, I);
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Value *CmpLeft;
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Value *CmpRight;
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// Look for a min/max pattern.
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if (m_UMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
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return ReductionInstDesc(Select, ReductionInstDesc::MRK_UIntMin);
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else if (m_UMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
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return ReductionInstDesc(Select, ReductionInstDesc::MRK_UIntMax);
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else if (m_SMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
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return ReductionInstDesc(Select, ReductionInstDesc::MRK_SIntMax);
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else if (m_SMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
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return ReductionInstDesc(Select, ReductionInstDesc::MRK_SIntMin);
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else if (m_OrdFMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
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return ReductionInstDesc(Select, ReductionInstDesc::MRK_FloatMin);
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else if (m_OrdFMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
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return ReductionInstDesc(Select, ReductionInstDesc::MRK_FloatMax);
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else if (m_UnordFMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
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return ReductionInstDesc(Select, ReductionInstDesc::MRK_FloatMin);
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else if (m_UnordFMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
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return ReductionInstDesc(Select, ReductionInstDesc::MRK_FloatMax);
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return ReductionInstDesc(false, I);
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}
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ReductionInstDesc ReductionDescriptor::isReductionInstr(Instruction *I,
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ReductionKind Kind,
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ReductionInstDesc &Prev,
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bool HasFunNoNaNAttr) {
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bool FP = I->getType()->isFloatingPointTy();
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bool FastMath = FP && I->hasUnsafeAlgebra();
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switch (I->getOpcode()) {
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default:
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return ReductionInstDesc(false, I);
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case Instruction::PHI:
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if (FP &&
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(Kind != RK_FloatMult && Kind != RK_FloatAdd && Kind != RK_FloatMinMax))
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return ReductionInstDesc(false, I);
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return ReductionInstDesc(I, Prev.getMinMaxKind());
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case Instruction::Sub:
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case Instruction::Add:
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return ReductionInstDesc(Kind == RK_IntegerAdd, I);
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case Instruction::Mul:
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return ReductionInstDesc(Kind == RK_IntegerMult, I);
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case Instruction::And:
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return ReductionInstDesc(Kind == RK_IntegerAnd, I);
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case Instruction::Or:
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return ReductionInstDesc(Kind == RK_IntegerOr, I);
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case Instruction::Xor:
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return ReductionInstDesc(Kind == RK_IntegerXor, I);
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case Instruction::FMul:
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return ReductionInstDesc(Kind == RK_FloatMult && FastMath, I);
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case Instruction::FSub:
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case Instruction::FAdd:
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return ReductionInstDesc(Kind == RK_FloatAdd && FastMath, I);
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case Instruction::FCmp:
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case Instruction::ICmp:
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case Instruction::Select:
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if (Kind != RK_IntegerMinMax &&
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(!HasFunNoNaNAttr || Kind != RK_FloatMinMax))
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return ReductionInstDesc(false, I);
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return isMinMaxSelectCmpPattern(I, Prev);
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}
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}
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bool ReductionDescriptor::hasMultipleUsesOf(
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Instruction *I, SmallPtrSetImpl<Instruction *> &Insts) {
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unsigned NumUses = 0;
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for (User::op_iterator Use = I->op_begin(), E = I->op_end(); Use != E;
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++Use) {
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if (Insts.count(dyn_cast<Instruction>(*Use)))
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++NumUses;
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if (NumUses > 1)
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return true;
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}
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return false;
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}
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bool ReductionDescriptor::isReductionPHI(PHINode *Phi, Loop *TheLoop,
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ReductionDescriptor &RedDes) {
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bool HasFunNoNaNAttr = false;
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BasicBlock *Header = TheLoop->getHeader();
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Function &F = *Header->getParent();
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if (F.hasFnAttribute("no-nans-fp-math"))
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HasFunNoNaNAttr =
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F.getFnAttribute("no-nans-fp-math").getValueAsString() == "true";
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if (AddReductionVar(Phi, RK_IntegerAdd, TheLoop, HasFunNoNaNAttr, RedDes)) {
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DEBUG(dbgs() << "Found an ADD reduction PHI." << *Phi << "\n");
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return true;
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}
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if (AddReductionVar(Phi, RK_IntegerMult, TheLoop, HasFunNoNaNAttr, RedDes)) {
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DEBUG(dbgs() << "Found a MUL reduction PHI." << *Phi << "\n");
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return true;
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}
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if (AddReductionVar(Phi, RK_IntegerOr, TheLoop, HasFunNoNaNAttr, RedDes)) {
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DEBUG(dbgs() << "Found an OR reduction PHI." << *Phi << "\n");
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return true;
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}
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if (AddReductionVar(Phi, RK_IntegerAnd, TheLoop, HasFunNoNaNAttr, RedDes)) {
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DEBUG(dbgs() << "Found an AND reduction PHI." << *Phi << "\n");
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return true;
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}
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if (AddReductionVar(Phi, RK_IntegerXor, TheLoop, HasFunNoNaNAttr, RedDes)) {
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DEBUG(dbgs() << "Found a XOR reduction PHI." << *Phi << "\n");
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return true;
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}
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if (AddReductionVar(Phi, RK_IntegerMinMax, TheLoop, HasFunNoNaNAttr,
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RedDes)) {
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DEBUG(dbgs() << "Found a MINMAX reduction PHI." << *Phi << "\n");
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return true;
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}
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if (AddReductionVar(Phi, RK_FloatMult, TheLoop, HasFunNoNaNAttr, RedDes)) {
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DEBUG(dbgs() << "Found an FMult reduction PHI." << *Phi << "\n");
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return true;
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}
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if (AddReductionVar(Phi, RK_FloatAdd, TheLoop, HasFunNoNaNAttr, RedDes)) {
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DEBUG(dbgs() << "Found an FAdd reduction PHI." << *Phi << "\n");
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return true;
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}
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if (AddReductionVar(Phi, RK_FloatMinMax, TheLoop, HasFunNoNaNAttr, RedDes)) {
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DEBUG(dbgs() << "Found an float MINMAX reduction PHI." << *Phi << "\n");
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return true;
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}
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// Not a reduction of known type.
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return false;
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}
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/// This function returns the identity element (or neutral element) for
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/// the operation K.
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Constant *ReductionDescriptor::getReductionIdentity(ReductionKind K, Type *Tp) {
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switch (K) {
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case RK_IntegerXor:
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case RK_IntegerAdd:
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case RK_IntegerOr:
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// Adding, Xoring, Oring zero to a number does not change it.
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return ConstantInt::get(Tp, 0);
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case RK_IntegerMult:
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// Multiplying a number by 1 does not change it.
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return ConstantInt::get(Tp, 1);
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case RK_IntegerAnd:
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// AND-ing a number with an all-1 value does not change it.
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return ConstantInt::get(Tp, -1, true);
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case RK_FloatMult:
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// Multiplying a number by 1 does not change it.
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return ConstantFP::get(Tp, 1.0L);
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case RK_FloatAdd:
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// Adding zero to a number does not change it.
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return ConstantFP::get(Tp, 0.0L);
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default:
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llvm_unreachable("Unknown reduction kind");
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}
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}
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/// This function translates the reduction kind to an LLVM binary operator.
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unsigned ReductionDescriptor::getReductionBinOp(ReductionKind Kind) {
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switch (Kind) {
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case RK_IntegerAdd:
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return Instruction::Add;
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case RK_IntegerMult:
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return Instruction::Mul;
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case RK_IntegerOr:
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return Instruction::Or;
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case RK_IntegerAnd:
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return Instruction::And;
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case RK_IntegerXor:
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return Instruction::Xor;
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case RK_FloatMult:
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return Instruction::FMul;
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case RK_FloatAdd:
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return Instruction::FAdd;
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case RK_IntegerMinMax:
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return Instruction::ICmp;
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case RK_FloatMinMax:
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return Instruction::FCmp;
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default:
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llvm_unreachable("Unknown reduction operation");
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}
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}
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Value *
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ReductionDescriptor::createMinMaxOp(IRBuilder<> &Builder,
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ReductionInstDesc::MinMaxReductionKind RK,
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Value *Left, Value *Right) {
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CmpInst::Predicate P = CmpInst::ICMP_NE;
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switch (RK) {
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default:
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llvm_unreachable("Unknown min/max reduction kind");
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case ReductionInstDesc::MRK_UIntMin:
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P = CmpInst::ICMP_ULT;
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break;
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case ReductionInstDesc::MRK_UIntMax:
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P = CmpInst::ICMP_UGT;
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break;
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case ReductionInstDesc::MRK_SIntMin:
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P = CmpInst::ICMP_SLT;
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break;
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case ReductionInstDesc::MRK_SIntMax:
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P = CmpInst::ICMP_SGT;
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break;
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case ReductionInstDesc::MRK_FloatMin:
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P = CmpInst::FCMP_OLT;
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break;
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case ReductionInstDesc::MRK_FloatMax:
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P = CmpInst::FCMP_OGT;
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break;
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}
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Value *Cmp;
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if (RK == ReductionInstDesc::MRK_FloatMin ||
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RK == ReductionInstDesc::MRK_FloatMax)
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Cmp = Builder.CreateFCmp(P, Left, Right, "rdx.minmax.cmp");
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else
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Cmp = Builder.CreateICmp(P, Left, Right, "rdx.minmax.cmp");
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Value *Select = Builder.CreateSelect(Cmp, Left, Right, "rdx.minmax.select");
|
|
return Select;
|
|
}
|
|
|
|
bool llvm::isInductionPHI(PHINode *Phi, ScalarEvolution *SE,
|
|
ConstantInt *&StepValue) {
|
|
Type *PhiTy = Phi->getType();
|
|
// We only handle integer and pointer inductions variables.
|
|
if (!PhiTy->isIntegerTy() && !PhiTy->isPointerTy())
|
|
return false;
|
|
|
|
// Check that the PHI is consecutive.
|
|
const SCEV *PhiScev = SE->getSCEV(Phi);
|
|
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PhiScev);
|
|
if (!AR) {
|
|
DEBUG(dbgs() << "LV: PHI is not a poly recurrence.\n");
|
|
return false;
|
|
}
|
|
|
|
const SCEV *Step = AR->getStepRecurrence(*SE);
|
|
// Calculate the pointer stride and check if it is consecutive.
|
|
const SCEVConstant *C = dyn_cast<SCEVConstant>(Step);
|
|
if (!C)
|
|
return false;
|
|
|
|
ConstantInt *CV = C->getValue();
|
|
if (PhiTy->isIntegerTy()) {
|
|
StepValue = CV;
|
|
return true;
|
|
}
|
|
|
|
assert(PhiTy->isPointerTy() && "The PHI must be a pointer");
|
|
Type *PointerElementType = PhiTy->getPointerElementType();
|
|
// The pointer stride cannot be determined if the pointer element type is not
|
|
// sized.
|
|
if (!PointerElementType->isSized())
|
|
return false;
|
|
|
|
const DataLayout &DL = Phi->getModule()->getDataLayout();
|
|
int64_t Size = static_cast<int64_t>(DL.getTypeAllocSize(PointerElementType));
|
|
int64_t CVSize = CV->getSExtValue();
|
|
if (CVSize % Size)
|
|
return false;
|
|
StepValue = ConstantInt::getSigned(CV->getType(), CVSize / Size);
|
|
return true;
|
|
}
|