| //===- Verifier.cpp - MLIR Verifier Implementation ------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the verify() methods on the various IR types, performing |
| // (potentially expensive) checks on the holistic structure of the code. This |
| // can be used for detecting bugs in compiler transformations and hand written |
| // .mlir files. |
| // |
| // The checks in this file are only for things that can occur as part of IR |
| // transformations: e.g. violation of dominance information, malformed operation |
| // attributes, etc. MLIR supports transformations moving IR through locally |
| // invalid states (e.g. unlinking an operation from a block before re-inserting |
| // it in a new place), but each transformation must complete with the IR in a |
| // valid form. |
| // |
| // This should not check for things that are always wrong by construction (e.g. |
| // attributes or other immutable structures that are incorrect), because those |
| // are not mutable and can be checked at time of construction. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "mlir/IR/Verifier.h" |
| #include "mlir/IR/Attributes.h" |
| #include "mlir/IR/Dialect.h" |
| #include "mlir/IR/Dominance.h" |
| #include "mlir/IR/Operation.h" |
| #include "mlir/IR/RegionKindInterface.h" |
| #include "llvm/ADT/StringMap.h" |
| #include "llvm/Support/FormatVariadic.h" |
| #include "llvm/Support/PrettyStackTrace.h" |
| #include "llvm/Support/Regex.h" |
| |
| using namespace mlir; |
| |
| namespace { |
| /// This class encapsulates all the state used to verify an operation region. |
| class OperationVerifier { |
| public: |
| explicit OperationVerifier(MLIRContext *ctx) : ctx(ctx) {} |
| |
| /// Verify the given operation. |
| LogicalResult verify(Operation &op); |
| |
| private: |
| /// Verify the given potentially nested region or block. |
| LogicalResult verifyRegion(Region ®ion); |
| LogicalResult verifyBlock(Block &block); |
| LogicalResult verifyOperation(Operation &op); |
| |
| /// Verify the dominance property of operations within the given Region. |
| LogicalResult verifyDominance(Region ®ion); |
| |
| /// Verify the dominance property of regions contained within the given |
| /// Operation. |
| LogicalResult verifyDominanceOfContainedRegions(Operation &op); |
| |
| /// Emit an error for the given block. |
| InFlightDiagnostic emitError(Block &bb, const Twine &message) { |
| // Take the location information for the first operation in the block. |
| if (!bb.empty()) |
| return bb.front().emitError(message); |
| |
| // Worst case, fall back to using the parent's location. |
| return mlir::emitError(bb.getParent()->getLoc(), message); |
| } |
| |
| /// The current context for the verifier. |
| MLIRContext *ctx; |
| |
| /// Dominance information for this operation, when checking dominance. |
| DominanceInfo *domInfo = nullptr; |
| }; |
| } // end anonymous namespace |
| |
| /// Verify the given operation. |
| LogicalResult OperationVerifier::verify(Operation &op) { |
| // Verify the operation first. |
| if (failed(verifyOperation(op))) |
| return failure(); |
| |
| // Since everything looks structurally ok to this point, we do a dominance |
| // check for any nested regions. We do this as a second pass since malformed |
| // CFG's can cause dominator analysis constructure to crash and we want the |
| // verifier to be resilient to malformed code. |
| DominanceInfo theDomInfo(&op); |
| domInfo = &theDomInfo; |
| if (failed(verifyDominanceOfContainedRegions(op))) |
| return failure(); |
| |
| domInfo = nullptr; |
| return success(); |
| } |
| |
| LogicalResult OperationVerifier::verifyRegion(Region ®ion) { |
| if (region.empty()) |
| return success(); |
| |
| // Verify the first block has no predecessors. |
| auto *firstBB = ®ion.front(); |
| if (!firstBB->hasNoPredecessors()) |
| return mlir::emitError(region.getLoc(), |
| "entry block of region may not have predecessors"); |
| |
| // Verify each of the blocks within the region. |
| for (Block &block : region) |
| if (failed(verifyBlock(block))) |
| return failure(); |
| return success(); |
| } |
| |
| /// Returns true if this block may be valid without terminator. That is if: |
| /// - it does not have a parent region. |
| /// - Or the parent region have a single block and: |
| /// - This region does not have a parent op. |
| /// - Or the parent op is unregistered. |
| /// - Or the parent op has the NoTerminator trait. |
| static bool mayNotHaveTerminator(Block *block) { |
| if (!block->getParent()) |
| return true; |
| if (!llvm::hasSingleElement(*block->getParent())) |
| return false; |
| Operation *op = block->getParentOp(); |
| return !op || op->mightHaveTrait<OpTrait::NoTerminator>(); |
| } |
| |
| LogicalResult OperationVerifier::verifyBlock(Block &block) { |
| for (auto arg : block.getArguments()) |
| if (arg.getOwner() != &block) |
| return emitError(block, "block argument not owned by block"); |
| |
| // Verify that this block has a terminator. |
| |
| if (block.empty()) { |
| if (mayNotHaveTerminator(&block)) |
| return success(); |
| return emitError(block, "empty block: expect at least a terminator"); |
| } |
| |
| // Verify the non-terminator operations separately so that we can verify |
| // they have no successors. |
| for (auto &op : llvm::make_range(block.begin(), std::prev(block.end()))) { |
| if (op.getNumSuccessors() != 0) |
| return op.emitError( |
| "operation with block successors must terminate its parent block"); |
| |
| if (failed(verifyOperation(op))) |
| return failure(); |
| } |
| |
| // Verify the terminator. |
| Operation &terminator = block.back(); |
| if (failed(verifyOperation(terminator))) |
| return failure(); |
| |
| if (mayNotHaveTerminator(&block)) |
| return success(); |
| |
| if (!terminator.mightHaveTrait<OpTrait::IsTerminator>()) |
| return block.back().emitError("block with no terminator, has ") |
| << terminator; |
| |
| // Verify that this block is not branching to a block of a different |
| // region. |
| for (Block *successor : block.getSuccessors()) |
| if (successor->getParent() != block.getParent()) |
| return block.back().emitOpError( |
| "branching to block of a different region"); |
| |
| return success(); |
| } |
| |
| LogicalResult OperationVerifier::verifyOperation(Operation &op) { |
| // Check that operands are non-nil and structurally ok. |
| for (auto operand : op.getOperands()) |
| if (!operand) |
| return op.emitError("null operand found"); |
| |
| /// Verify that all of the attributes are okay. |
| for (auto attr : op.getAttrs()) { |
| // Check for any optional dialect specific attributes. |
| if (auto *dialect = attr.first.getDialect()) |
| if (failed(dialect->verifyOperationAttribute(&op, attr))) |
| return failure(); |
| } |
| |
| // If we can get operation info for this, check the custom hook. |
| OperationName opName = op.getName(); |
| auto *opInfo = opName.getAbstractOperation(); |
| if (opInfo && failed(opInfo->verifyInvariants(&op))) |
| return failure(); |
| |
| auto kindInterface = dyn_cast<mlir::RegionKindInterface>(op); |
| |
| // Verify that all child regions are ok. |
| unsigned numRegions = op.getNumRegions(); |
| for (unsigned i = 0; i < numRegions; i++) { |
| Region ®ion = op.getRegion(i); |
| RegionKind kind = |
| kindInterface ? kindInterface.getRegionKind(i) : RegionKind::SSACFG; |
| // Check that Graph Regions only have a single basic block. This is |
| // similar to the code in SingleBlockImplicitTerminator, but doesn't |
| // require the trait to be specified. This arbitrary limitation is |
| // designed to limit the number of cases that have to be handled by |
| // transforms and conversions until the concept stabilizes. |
| if (op.isRegistered() && kind == RegionKind::Graph) { |
| // Empty regions are fine. |
| if (region.empty()) |
| continue; |
| |
| // Non-empty regions must contain a single basic block. |
| if (std::next(region.begin()) != region.end()) |
| return op.emitOpError("expects graph region #") |
| << i << " to have 0 or 1 blocks"; |
| } |
| if (failed(verifyRegion(region))) |
| return failure(); |
| } |
| |
| // If this is a registered operation, there is nothing left to do. |
| if (opInfo) |
| return success(); |
| |
| // Otherwise, verify that the parent dialect allows un-registered operations. |
| Dialect *dialect = opName.getDialect(); |
| if (!dialect) { |
| if (!ctx->allowsUnregisteredDialects()) { |
| return op.emitOpError() |
| << "created with unregistered dialect. If this is " |
| "intended, please call allowUnregisteredDialects() on the " |
| "MLIRContext, or use -allow-unregistered-dialect with " |
| "mlir-opt"; |
| } |
| return success(); |
| } |
| |
| if (!dialect->allowsUnknownOperations()) { |
| return op.emitError("unregistered operation '") |
| << op.getName() << "' found in dialect ('" << dialect->getNamespace() |
| << "') that does not allow unknown operations"; |
| } |
| |
| return success(); |
| } |
| |
| /// Attach a note to an in-flight diagnostic that provide more information about |
| /// where an op operand is defined. |
| static void attachNoteForOperandDefinition(InFlightDiagnostic &diag, |
| Operation &op, Value operand) { |
| if (auto *useOp = operand.getDefiningOp()) { |
| Diagnostic ¬e = diag.attachNote(useOp->getLoc()); |
| note << "operand defined here"; |
| Block *block1 = op.getBlock(); |
| Block *block2 = useOp->getBlock(); |
| Region *region1 = block1->getParent(); |
| Region *region2 = block2->getParent(); |
| if (block1 == block2) |
| note << " (op in the same block)"; |
| else if (region1 == region2) |
| note << " (op in the same region)"; |
| else if (region2->isProperAncestor(region1)) |
| note << " (op in a parent region)"; |
| else if (region1->isProperAncestor(region2)) |
| note << " (op in a child region)"; |
| else |
| note << " (op is neither in a parent nor in a child region)"; |
| return; |
| } |
| // Block argument case. |
| Block *block1 = op.getBlock(); |
| Block *block2 = operand.cast<BlockArgument>().getOwner(); |
| Region *region1 = block1->getParent(); |
| Region *region2 = block2->getParent(); |
| Location loc = UnknownLoc::get(op.getContext()); |
| if (block2->getParentOp()) |
| loc = block2->getParentOp()->getLoc(); |
| Diagnostic ¬e = diag.attachNote(loc); |
| if (!region2) { |
| note << " (block without parent)"; |
| return; |
| } |
| if (block1 == block2) |
| llvm::report_fatal_error("Internal error in dominance verification"); |
| int index = std::distance(region2->begin(), block2->getIterator()); |
| note << "operand defined as a block argument (block #" << index; |
| if (region1 == region2) |
| note << " in the same region)"; |
| else if (region2->isProperAncestor(region1)) |
| note << " in a parent region)"; |
| else if (region1->isProperAncestor(region2)) |
| note << " in a child region)"; |
| else |
| note << " neither in a parent nor in a child region)"; |
| } |
| |
| LogicalResult OperationVerifier::verifyDominance(Region ®ion) { |
| // Verify the dominance of each of the held operations. |
| for (Block &block : region) { |
| // Dominance is only meaningful inside reachable blocks. |
| if (domInfo->isReachableFromEntry(&block)) |
| for (Operation &op : block) |
| // Check that operands properly dominate this use. |
| for (unsigned operandNo = 0, e = op.getNumOperands(); operandNo != e; |
| ++operandNo) { |
| Value operand = op.getOperand(operandNo); |
| if (domInfo->properlyDominates(operand, &op)) |
| continue; |
| |
| InFlightDiagnostic diag = op.emitError("operand #") |
| << operandNo |
| << " does not dominate this use"; |
| attachNoteForOperandDefinition(diag, op, operand); |
| return failure(); |
| } |
| // Recursively verify dominance within each operation in the |
| // block, even if the block itself is not reachable, or we are in |
| // a region which doesn't respect dominance. |
| for (Operation &op : block) |
| if (failed(verifyDominanceOfContainedRegions(op))) |
| return failure(); |
| } |
| return success(); |
| } |
| |
| /// Verify the dominance of each of the nested blocks within the given operation |
| LogicalResult |
| OperationVerifier::verifyDominanceOfContainedRegions(Operation &op) { |
| for (Region ®ion : op.getRegions()) { |
| if (failed(verifyDominance(region))) |
| return failure(); |
| } |
| return success(); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Entrypoint |
| //===----------------------------------------------------------------------===// |
| |
| /// Perform (potentially expensive) checks of invariants, used to detect |
| /// compiler bugs. On error, this reports the error through the MLIRContext and |
| /// returns failure. |
| LogicalResult mlir::verify(Operation *op) { |
| return OperationVerifier(op->getContext()).verify(*op); |
| } |