Add a test for UsedDeclVisitor

This test is reduced from mlir/lib/Transforms/AffineDataCopyGeneration.cpp
to make sure there is no assertion due to UsedDeclVisitor.

Author: yxsamliu

clang/test/CodeGenCXX/used-decl-visitor.cpp

@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -triple x86_64 -emit-llvm -o %t %s
+
+// Make sure there is no assertion due to UsedDeclVisitor.
+
+struct A {
+  int a;
+};
+
+static A a;
+
+struct B {
+  B(int b = a.a) {}
+};
+
+
+void foo() {
+  B();
+}

mlir/lib/Transforms/AffineDataCopyGeneration.cpp

@@ -1,268 +1,14 @@
-//===- AffineDataCopyGeneration.cpp - Explicit memref copying pass ------*-===//
-//
-// 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 a pass to automatically promote accessed memref regions
-// to buffers in a faster memory space that is explicitly managed, with the
-// necessary data movement operations performed through either regular
-// point-wise load/store's or DMAs. Such explicit copying (also referred to as
-// array packing/unpacking in the literature), when done on arrays that exhibit
-// reuse, results in near elimination of conflict misses, TLB misses, reduced
-// use of hardware prefetch streams, and reduced false sharing. It is also
-// necessary for hardware that explicitly managed levels in the memory
-// hierarchy, and where DMAs may have to be used. This optimization is often
-// performed on already tiled code.
-//
-//===----------------------------------------------------------------------===//
-
-#include "mlir/Analysis/Utils.h"
-#include "mlir/Dialect/AffineOps/AffineOps.h"
-#include "mlir/IR/Builders.h"
-#include "mlir/Pass/Pass.h"
-#include "mlir/Transforms/LoopUtils.h"
-#include "mlir/Transforms/Passes.h"
-#include "mlir/Transforms/Utils.h"
-#include "llvm/ADT/MapVector.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Debug.h"
-#include <algorithm>
-
-#define DEBUG_TYPE "affine-data-copy-generate"
-
-using namespace mlir;
-
-static llvm::cl::OptionCategory clOptionsCategory(DEBUG_TYPE " options");
-
-static llvm::cl::opt<unsigned long long> clFastMemoryCapacity(
-    "affine-data-copy-generate-fast-mem-capacity",
-    llvm::cl::desc(
-        "Set fast memory space capacity in KiB (default: unlimited)"),
-    llvm::cl::cat(clOptionsCategory));
-
-static llvm::cl::opt<bool>
-    clDma("affine-data-copy-generate-dma",
-          llvm::cl::desc("Generate DMA instead of point-wise copy"),
-          llvm::cl::cat(clOptionsCategory), llvm::cl::init(true));
-
-static llvm::cl::opt<unsigned> clFastMemorySpace(
-    "affine-data-copy-generate-fast-mem-space", llvm::cl::init(1),
-    llvm::cl::desc(
-        "Fast memory space identifier for copy generation (default: 1)"),
-    llvm::cl::cat(clOptionsCategory));
-
-static llvm::cl::opt<bool> clSkipNonUnitStrideLoop(
-    "affine-data-copy-generate-skip-non-unit-stride-loops", llvm::cl::Hidden,
-    llvm::cl::init(false),
-    llvm::cl::desc("Testing purposes: avoid non-unit stride loop choice depths "
-                   "for copy placement"),
-    llvm::cl::cat(clOptionsCategory));
-
-namespace {
-
-/// Replaces all loads and stores on memref's living in 'slowMemorySpace' by
-/// introducing copy operations to transfer data into `fastMemorySpace` and
-/// rewriting the original load's/store's to instead load/store from the
-/// allocated fast memory buffers. Additional options specify the identifier
-/// corresponding to the fast memory space and the amount of fast memory space
-/// available. The pass traverses through the nesting structure, recursing to
-/// inner levels if necessary to determine at what depth copies need to be
-/// placed so that the allocated buffers fit within the memory capacity
-/// provided.
-// TODO(bondhugula): We currently can't generate copies correctly when stores
-// are strided. Check for strided stores.
-struct AffineDataCopyGeneration
-    : public FunctionPass<AffineDataCopyGeneration> {
-  explicit AffineDataCopyGeneration(
-      unsigned slowMemorySpace = 0,
-      unsigned fastMemorySpace = clFastMemorySpace, unsigned tagMemorySpace = 0,
-      int minDmaTransferSize = 1024,
-      uint64_t fastMemCapacityBytes =
-          (clFastMemoryCapacity.getNumOccurrences() > 0
-               ? clFastMemoryCapacity * 1024 // cl-provided size is in KiB
-               : std::numeric_limits<uint64_t>::max()),
-      bool generateDma = clDma,
-      bool skipNonUnitStrideLoops = clSkipNonUnitStrideLoop)
-      : slowMemorySpace(slowMemorySpace), fastMemorySpace(fastMemorySpace),
-        tagMemorySpace(tagMemorySpace), minDmaTransferSize(minDmaTransferSize),
-        fastMemCapacityBytes(fastMemCapacityBytes), generateDma(generateDma),
-        skipNonUnitStrideLoops(skipNonUnitStrideLoops) {}
-
-  explicit AffineDataCopyGeneration(const AffineDataCopyGeneration &other)
-      : slowMemorySpace(other.slowMemorySpace),
-        fastMemorySpace(other.fastMemorySpace),
-        tagMemorySpace(other.tagMemorySpace),
-        minDmaTransferSize(other.minDmaTransferSize),
-        fastMemCapacityBytes(other.fastMemCapacityBytes),
-        generateDma(other.generateDma),
-        skipNonUnitStrideLoops(other.skipNonUnitStrideLoops) {}
-
-  void runOnFunction() override;
-  LogicalResult runOnBlock(Block *block, DenseSet<Operation *> &copyNests);
-
-  // Slow memory space associated with copies.
-  const unsigned slowMemorySpace;
-  // Fast memory space associated with copies.
-  unsigned fastMemorySpace;
-  // Memory space associated with DMA tags.
-  unsigned tagMemorySpace;
-  // Minimum DMA transfer size supported by the target in bytes.
-  const int minDmaTransferSize;
-  // Capacity of the faster memory space.
-  uint64_t fastMemCapacityBytes;
-
-  // If set, generate DMA operations instead of read/write.
-  bool generateDma;
-
-  // If set, ignore loops with steps other than 1.
-  bool skipNonUnitStrideLoops;
-
-  // Constant zero index to avoid too many duplicates.
-  Value zeroIndex = nullptr;
+struct A {
+  int a;
 };
 
-} // end anonymous namespace
+static A a;
 
-/// Generates copies for memref's living in 'slowMemorySpace' into newly created
-/// buffers in 'fastMemorySpace', and replaces memory operations to the former
-/// by the latter. Only load op's handled for now.
-/// TODO(bondhugula): extend this to store op's.
-std::unique_ptr<OpPassBase<FuncOp>> mlir::createAffineDataCopyGenerationPass(
-    unsigned slowMemorySpace, unsigned fastMemorySpace, unsigned tagMemorySpace,
-    int minDmaTransferSize, uint64_t fastMemCapacityBytes) {
-  return std::make_unique<AffineDataCopyGeneration>(
-      slowMemorySpace, fastMemorySpace, tagMemorySpace, minDmaTransferSize,
-      fastMemCapacityBytes);
-}
-
-/// Generate copies for this block. The block is partitioned into separate
-/// ranges: each range is either a sequence of one or more operations starting
-/// and ending with an affine load or store op, or just an affine.forop (which
-/// could have other affine for op's nested within).
-LogicalResult
-AffineDataCopyGeneration::runOnBlock(Block *block,
-                                     DenseSet<Operation *> &copyNests) {
-  if (block->empty())
-    return success();
-
-  AffineCopyOptions copyOptions = {generateDma, slowMemorySpace,
-                                   fastMemorySpace, tagMemorySpace,
-                                   fastMemCapacityBytes};
-
-  // Every affine.forop in the block starts and ends a block range for copying;
-  // in addition, a contiguous sequence of operations starting with a
-  // load/store op but not including any copy nests themselves is also
-  // identified as a copy block range. Straightline code (a contiguous chunk of
-  // operations excluding AffineForOp's) are always assumed to not exhaust
-  // memory. As a result, this approach is conservative in some cases at the
-  // moment; we do a check later and report an error with location info.
-  // TODO(bondhugula): An 'affine.if' operation is being treated similar to an
-  // operation. 'affine.if''s could have 'affine.for's in them;
-  // treat them separately.
-
-  // Get to the first load, store, or for op (that is not a copy nest itself).
-  auto curBegin =
-      std::find_if(block->begin(), block->end(), [&](Operation &op) {
-        return (isa<AffineLoadOp>(op) || isa<AffineStoreOp>(op) ||
-                isa<AffineForOp>(op)) &&
-               copyNests.count(&op) == 0;
-      });
-
-  // Create [begin, end) ranges.
-  auto it = curBegin;
-  while (it != block->end()) {
-    AffineForOp forOp;
-    // If you hit a non-copy for loop, we will split there.
-    if ((forOp = dyn_cast<AffineForOp>(&*it)) && copyNests.count(forOp) == 0) {
-      // Perform the copying up unti this 'for' op first.
-      affineDataCopyGenerate(/*begin=*/curBegin, /*end=*/it, copyOptions,
-                             /*filterMemRef=*/llvm::None, copyNests);
-
-      // Returns true if the footprint is known to exceed capacity.
-      auto exceedsCapacity = [&](AffineForOp forOp) {
-        Optional<int64_t> footprint =
-            getMemoryFootprintBytes(forOp,
-                                    /*memorySpace=*/0);
-        return (footprint.hasValue() &&
-                static_cast<uint64_t>(footprint.getValue()) >
-                    fastMemCapacityBytes);
-      };
-
-      // If the memory footprint of the 'affine.for' loop is higher than fast
-      // memory capacity (when provided), we recurse to copy at an inner level
-      // until we find a depth at which footprint fits in fast mem capacity. If
-      // the footprint can't be calculated, we assume for now it fits. Recurse
-      // inside if footprint for 'forOp' exceeds capacity, or when
-      // skipNonUnitStrideLoops is set and the step size is not one.
-      bool recurseInner = skipNonUnitStrideLoops ? forOp.getStep() != 1
-                                                 : exceedsCapacity(forOp);
-      if (recurseInner) {
-        // We'll recurse and do the copies at an inner level for 'forInst'.
-        // Recurse onto the body of this loop.
-        runOnBlock(forOp.getBody(), copyNests);
-      } else {
-        // We have enough capacity, i.e., copies will be computed for the
-        // portion of the block until 'it', and for 'it', which is 'forOp'. Note
-        // that for the latter, the copies are placed just before this loop (for
-        // incoming copies) and right after (for outgoing ones).
-
-        // Inner loop copies have their own scope - we don't thus update
-        // consumed capacity. The footprint check above guarantees this inner
-        // loop's footprint fits.
-        affineDataCopyGenerate(/*begin=*/it, /*end=*/std::next(it), copyOptions,
-                               /*filterMemRef=*/llvm::None, copyNests);
-      }
-      // Get to the next load or store op after 'forOp'.
-      curBegin = std::find_if(std::next(it), block->end(), [&](Operation &op) {
-        return (isa<AffineLoadOp>(op) || isa<AffineStoreOp>(op) ||
-                isa<AffineForOp>(op)) &&
-               copyNests.count(&op) == 0;
-      });
-      it = curBegin;
-    } else {
-      assert(copyNests.count(&*it) == 0 &&
-             "all copy nests generated should have been skipped above");
-      // We simply include this op in the current range and continue for more.
-      ++it;
-    }
-  }
-
-  // Generate the copy for the final block range.
-  if (curBegin != block->end()) {
-    // Can't be a terminator because it would have been skipped above.
-    assert(!curBegin->isKnownTerminator() && "can't be a terminator");
-    // Exclude the affine terminator - hence, the std::prev.
-    affineDataCopyGenerate(/*begin=*/curBegin, /*end=*/std::prev(block->end()),
-                           copyOptions, /*filterMemRef=*/llvm::None, copyNests);
-  }
-
-  return success();
-}
-
-void AffineDataCopyGeneration::runOnFunction() {
-  FuncOp f = getFunction();
-  OpBuilder topBuilder(f.getBody());
-  zeroIndex = topBuilder.create<ConstantIndexOp>(f.getLoc(), 0);
-
-  // Nests that are copy-in's or copy-out's; the root AffineForOps of those
-  // nests are stored herein.
-  DenseSet<Operation *> copyNests;
-
-  // Clear recorded copy nests.
-  copyNests.clear();
+struct B {
+  B(int b = a.a) {}
+};
 
-  for (auto &block : f)
-    runOnBlock(&block, copyNests);
 
-  // Promote any single iteration loops in the copy nests.
-  for (auto nest : copyNests) {
-    nest->walk([](AffineForOp forOp) { promoteIfSingleIteration(forOp); });
-  }
+void foo() {
+  B();
 }
-
-static PassRegistration<AffineDataCopyGeneration>
-    pass("affine-data-copy-generate",
-         "Generate explicit copying for memory operations");