a4dc02c0e7
After #128718 lands there will be two ways of performing a reversed widened memory access, either by performing a consecutive unit-stride access and a reverse, or a strided access with a negative stride. Even though both produce a reversed vector, only the former needs VPReverseVectorPointerRecipe which computes a pointer to the last element of each part. A strided reverse still needs a pointer to the first element of each part so it will use VPVectorPointerRecipe. This renames VPReverseVectorPointerRecipe to VPVectorEndPointerRecipe to clarify that a reversed access may not necessarily need a pointer to the last element.
428 lines
14 KiB
C++
428 lines
14 KiB
C++
//===-- VPlanVerifier.cpp -------------------------------------------------===//
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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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/// \file
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/// This file defines the class VPlanVerifier, which contains utility functions
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/// to check the consistency and invariants of a VPlan.
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///
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//===----------------------------------------------------------------------===//
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#include "VPlanVerifier.h"
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#include "VPlan.h"
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#include "VPlanCFG.h"
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#include "VPlanDominatorTree.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/TypeSwitch.h"
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#define DEBUG_TYPE "loop-vectorize"
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using namespace llvm;
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namespace {
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class VPlanVerifier {
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const VPDominatorTree &VPDT;
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VPTypeAnalysis &TypeInfo;
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SmallPtrSet<BasicBlock *, 8> WrappedIRBBs;
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// Verify that phi-like recipes are at the beginning of \p VPBB, with no
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// other recipes in between. Also check that only header blocks contain
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// VPHeaderPHIRecipes.
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bool verifyPhiRecipes(const VPBasicBlock *VPBB);
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/// Verify that \p EVL is used correctly. The user must be either in
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/// EVL-based recipes as a last operand or VPInstruction::Add which is
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/// incoming value into EVL's recipe.
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bool verifyEVLRecipe(const VPInstruction &EVL) const;
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bool verifyVPBasicBlock(const VPBasicBlock *VPBB);
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bool verifyBlock(const VPBlockBase *VPB);
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/// Helper function that verifies the CFG invariants of the VPBlockBases
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/// within
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/// \p Region. Checks in this function are generic for VPBlockBases. They are
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/// not specific for VPBasicBlocks or VPRegionBlocks.
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bool verifyBlocksInRegion(const VPRegionBlock *Region);
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/// Verify the CFG invariants of VPRegionBlock \p Region and its nested
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/// VPBlockBases. Do not recurse inside nested VPRegionBlocks.
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bool verifyRegion(const VPRegionBlock *Region);
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/// Verify the CFG invariants of VPRegionBlock \p Region and its nested
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/// VPBlockBases. Recurse inside nested VPRegionBlocks.
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bool verifyRegionRec(const VPRegionBlock *Region);
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public:
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VPlanVerifier(VPDominatorTree &VPDT, VPTypeAnalysis &TypeInfo)
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: VPDT(VPDT), TypeInfo(TypeInfo) {}
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bool verify(const VPlan &Plan);
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};
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} // namespace
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bool VPlanVerifier::verifyPhiRecipes(const VPBasicBlock *VPBB) {
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auto RecipeI = VPBB->begin();
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auto End = VPBB->end();
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unsigned NumActiveLaneMaskPhiRecipes = 0;
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const VPRegionBlock *ParentR = VPBB->getParent();
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bool IsHeaderVPBB = ParentR && !ParentR->isReplicator() &&
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ParentR->getEntryBasicBlock() == VPBB;
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while (RecipeI != End && RecipeI->isPhi()) {
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if (isa<VPActiveLaneMaskPHIRecipe>(RecipeI))
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NumActiveLaneMaskPhiRecipes++;
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if (IsHeaderVPBB && !isa<VPHeaderPHIRecipe, VPWidenPHIRecipe>(*RecipeI) &&
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!isa<VPInstruction>(*RecipeI) &&
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cast<VPInstruction>(RecipeI)->getOpcode() == Instruction::PHI) {
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errs() << "Found non-header PHI recipe in header VPBB";
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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errs() << ": ";
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RecipeI->dump();
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#endif
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return false;
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}
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if (!IsHeaderVPBB && isa<VPHeaderPHIRecipe>(*RecipeI)) {
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errs() << "Found header PHI recipe in non-header VPBB";
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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errs() << ": ";
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RecipeI->dump();
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#endif
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return false;
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}
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RecipeI++;
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}
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if (NumActiveLaneMaskPhiRecipes > 1) {
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errs() << "There should be no more than one VPActiveLaneMaskPHIRecipe";
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return false;
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}
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while (RecipeI != End) {
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if (RecipeI->isPhi() && !isa<VPBlendRecipe>(&*RecipeI)) {
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errs() << "Found phi-like recipe after non-phi recipe";
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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errs() << ": ";
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RecipeI->dump();
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errs() << "after\n";
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std::prev(RecipeI)->dump();
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#endif
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return false;
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}
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RecipeI++;
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}
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return true;
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}
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bool VPlanVerifier::verifyEVLRecipe(const VPInstruction &EVL) const {
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if (EVL.getOpcode() != VPInstruction::ExplicitVectorLength) {
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errs() << "verifyEVLRecipe should only be called on "
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"VPInstruction::ExplicitVectorLength\n";
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return false;
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}
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auto VerifyEVLUse = [&](const VPRecipeBase &R,
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const unsigned ExpectedIdx) -> bool {
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SmallVector<const VPValue *> Ops(R.operands());
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unsigned UseCount = count(Ops, &EVL);
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if (UseCount != 1 || Ops[ExpectedIdx] != &EVL) {
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errs() << "EVL is used as non-last operand in EVL-based recipe\n";
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return false;
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}
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return true;
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};
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return all_of(EVL.users(), [&VerifyEVLUse](VPUser *U) {
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return TypeSwitch<const VPUser *, bool>(U)
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.Case<VPWidenIntrinsicRecipe>([&](const VPWidenIntrinsicRecipe *S) {
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return VerifyEVLUse(*S, S->getNumOperands() - 1);
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})
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.Case<VPWidenStoreEVLRecipe, VPReductionEVLRecipe>(
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[&](const VPRecipeBase *S) { return VerifyEVLUse(*S, 2); })
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.Case<VPWidenLoadEVLRecipe, VPVectorEndPointerRecipe>(
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[&](const VPRecipeBase *R) { return VerifyEVLUse(*R, 1); })
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.Case<VPScalarCastRecipe>(
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[&](const VPScalarCastRecipe *S) { return VerifyEVLUse(*S, 0); })
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.Case<VPInstruction>([&](const VPInstruction *I) {
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if (I->getOpcode() == Instruction::PHI)
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return VerifyEVLUse(*I, 1);
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if (I->getOpcode() != Instruction::Add) {
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errs() << "EVL is used as an operand in non-VPInstruction::Add\n";
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return false;
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}
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if (I->getNumUsers() != 1) {
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errs() << "EVL is used in VPInstruction:Add with multiple "
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"users\n";
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return false;
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}
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if (!isa<VPEVLBasedIVPHIRecipe>(*I->users().begin())) {
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errs() << "Result of VPInstruction::Add with EVL operand is "
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"not used by VPEVLBasedIVPHIRecipe\n";
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return false;
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}
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return true;
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})
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.Default([&](const VPUser *U) {
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errs() << "EVL has unexpected user\n";
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return false;
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});
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});
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}
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bool VPlanVerifier::verifyVPBasicBlock(const VPBasicBlock *VPBB) {
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if (!verifyPhiRecipes(VPBB))
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return false;
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// Verify that defs in VPBB dominate all their uses. The current
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// implementation is still incomplete.
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DenseMap<const VPRecipeBase *, unsigned> RecipeNumbering;
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unsigned Cnt = 0;
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for (const VPRecipeBase &R : *VPBB)
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RecipeNumbering[&R] = Cnt++;
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for (const VPRecipeBase &R : *VPBB) {
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if (isa<VPIRInstruction>(&R) && !isa<VPIRBasicBlock>(VPBB)) {
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errs() << "VPIRInstructions ";
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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R.dump();
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errs() << " ";
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#endif
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errs() << "not in a VPIRBasicBlock!\n";
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return false;
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}
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for (const VPValue *V : R.definedValues()) {
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// Verify that we can infer a scalar type for each defined value. With
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// assertions enabled, inferScalarType will perform some consistency
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// checks during type inference.
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if (!TypeInfo.inferScalarType(V)) {
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errs() << "Failed to infer scalar type!\n";
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return false;
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}
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for (const VPUser *U : V->users()) {
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auto *UI = cast<VPRecipeBase>(U);
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// TODO: check dominance of incoming values for phis properly.
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if (!UI ||
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isa<VPHeaderPHIRecipe, VPWidenPHIRecipe, VPPredInstPHIRecipe>(UI) ||
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(isa<VPIRInstruction>(UI) &&
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isa<PHINode>(cast<VPIRInstruction>(UI)->getInstruction())) ||
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(isa<VPInstruction>(UI) &&
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cast<VPInstruction>(UI)->getOpcode() == Instruction::PHI))
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continue;
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// If the user is in the same block, check it comes after R in the
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// block.
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if (UI->getParent() == VPBB) {
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if (RecipeNumbering[UI] < RecipeNumbering[&R]) {
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errs() << "Use before def!\n";
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return false;
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}
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continue;
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}
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if (!VPDT.dominates(VPBB, UI->getParent())) {
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errs() << "Use before def!\n";
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return false;
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}
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}
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}
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if (const auto *EVL = dyn_cast<VPInstruction>(&R)) {
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if (EVL->getOpcode() == VPInstruction::ExplicitVectorLength &&
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!verifyEVLRecipe(*EVL)) {
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errs() << "EVL VPValue is not used correctly\n";
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return false;
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}
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}
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}
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auto *IRBB = dyn_cast<VPIRBasicBlock>(VPBB);
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if (!IRBB)
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return true;
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if (!WrappedIRBBs.insert(IRBB->getIRBasicBlock()).second) {
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errs() << "Same IR basic block used by multiple wrapper blocks!\n";
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return false;
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}
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return true;
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}
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/// Utility function that checks whether \p VPBlockVec has duplicate
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/// VPBlockBases.
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static bool hasDuplicates(const SmallVectorImpl<VPBlockBase *> &VPBlockVec) {
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SmallDenseSet<const VPBlockBase *, 8> VPBlockSet;
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for (const auto *Block : VPBlockVec) {
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if (!VPBlockSet.insert(Block).second)
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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 VPlanVerifier::verifyBlock(const VPBlockBase *VPB) {
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auto *VPBB = dyn_cast<VPBasicBlock>(VPB);
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// Check block's condition bit.
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if (VPB->getNumSuccessors() > 1 ||
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(VPBB && VPBB->getParent() && VPBB->isExiting() &&
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!VPBB->getParent()->isReplicator())) {
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if (!VPBB || !VPBB->getTerminator()) {
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errs() << "Block has multiple successors but doesn't "
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"have a proper branch recipe!\n";
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return false;
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}
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} else {
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if (VPBB && VPBB->getTerminator()) {
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errs() << "Unexpected branch recipe!\n";
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return false;
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}
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}
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// Check block's successors.
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const auto &Successors = VPB->getSuccessors();
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// There must be only one instance of a successor in block's successor list.
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// TODO: This won't work for switch statements.
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if (hasDuplicates(Successors)) {
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errs() << "Multiple instances of the same successor.\n";
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return false;
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}
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for (const VPBlockBase *Succ : Successors) {
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// There must be a bi-directional link between block and successor.
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const auto &SuccPreds = Succ->getPredecessors();
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if (!is_contained(SuccPreds, VPB)) {
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errs() << "Missing predecessor link.\n";
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return false;
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}
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}
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// Check block's predecessors.
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const auto &Predecessors = VPB->getPredecessors();
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// There must be only one instance of a predecessor in block's predecessor
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// list.
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// TODO: This won't work for switch statements.
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if (hasDuplicates(Predecessors)) {
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errs() << "Multiple instances of the same predecessor.\n";
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return false;
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}
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for (const VPBlockBase *Pred : Predecessors) {
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// Block and predecessor must be inside the same region.
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if (Pred->getParent() != VPB->getParent()) {
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errs() << "Predecessor is not in the same region.\n";
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return false;
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}
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// There must be a bi-directional link between block and predecessor.
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const auto &PredSuccs = Pred->getSuccessors();
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if (!is_contained(PredSuccs, VPB)) {
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errs() << "Missing successor link.\n";
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return false;
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}
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}
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return !VPBB || verifyVPBasicBlock(VPBB);
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}
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bool VPlanVerifier::verifyBlocksInRegion(const VPRegionBlock *Region) {
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for (const VPBlockBase *VPB : vp_depth_first_shallow(Region->getEntry())) {
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// Check block's parent.
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if (VPB->getParent() != Region) {
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errs() << "VPBlockBase has wrong parent\n";
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return false;
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}
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if (!verifyBlock(VPB))
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return false;
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}
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return true;
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}
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bool VPlanVerifier::verifyRegion(const VPRegionBlock *Region) {
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const VPBlockBase *Entry = Region->getEntry();
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const VPBlockBase *Exiting = Region->getExiting();
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// Entry and Exiting shouldn't have any predecessor/successor, respectively.
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if (Entry->getNumPredecessors() != 0) {
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errs() << "region entry block has predecessors\n";
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return false;
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}
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if (Exiting->getNumSuccessors() != 0) {
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errs() << "region exiting block has successors\n";
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return false;
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}
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return verifyBlocksInRegion(Region);
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}
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bool VPlanVerifier::verifyRegionRec(const VPRegionBlock *Region) {
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// Recurse inside nested regions and check all blocks inside the region.
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return verifyRegion(Region) &&
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all_of(vp_depth_first_shallow(Region->getEntry()),
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[this](const VPBlockBase *VPB) {
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const auto *SubRegion = dyn_cast<VPRegionBlock>(VPB);
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return !SubRegion || verifyRegionRec(SubRegion);
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});
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}
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bool VPlanVerifier::verify(const VPlan &Plan) {
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if (any_of(vp_depth_first_shallow(Plan.getEntry()),
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[this](const VPBlockBase *VPB) { return !verifyBlock(VPB); }))
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return false;
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const VPRegionBlock *TopRegion = Plan.getVectorLoopRegion();
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if (!verifyRegionRec(TopRegion))
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return false;
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if (TopRegion->getParent()) {
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errs() << "VPlan Top Region should have no parent.\n";
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return false;
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}
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const VPBasicBlock *Entry = dyn_cast<VPBasicBlock>(TopRegion->getEntry());
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if (!Entry) {
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errs() << "VPlan entry block is not a VPBasicBlock\n";
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return false;
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}
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if (!isa<VPCanonicalIVPHIRecipe>(&*Entry->begin())) {
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errs() << "VPlan vector loop header does not start with a "
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"VPCanonicalIVPHIRecipe\n";
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return false;
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}
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const VPBasicBlock *Exiting = dyn_cast<VPBasicBlock>(TopRegion->getExiting());
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if (!Exiting) {
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errs() << "VPlan exiting block is not a VPBasicBlock\n";
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return false;
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}
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if (Exiting->empty()) {
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errs() << "VPlan vector loop exiting block must end with BranchOnCount or "
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"BranchOnCond VPInstruction but is empty\n";
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return false;
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}
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auto *LastInst = dyn_cast<VPInstruction>(std::prev(Exiting->end()));
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if (!LastInst || (LastInst->getOpcode() != VPInstruction::BranchOnCount &&
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LastInst->getOpcode() != VPInstruction::BranchOnCond)) {
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errs() << "VPlan vector loop exit must end with BranchOnCount or "
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"BranchOnCond VPInstruction\n";
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return false;
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}
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return true;
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}
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bool llvm::verifyVPlanIsValid(const VPlan &Plan) {
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VPDominatorTree VPDT;
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VPDT.recalculate(const_cast<VPlan &>(Plan));
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VPTypeAnalysis TypeInfo(
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const_cast<VPlan &>(Plan).getCanonicalIV()->getScalarType());
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VPlanVerifier Verifier(VPDT, TypeInfo);
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return Verifier.verify(Plan);
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}
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