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//===- TestMemRefDependenceCheck.cpp - Test dep analysis ------------------===//
//
// 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 run pair-wise memref access dependence checks.
//
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/Affine/Analysis/AffineAnalysis.h"
#include "mlir/Dialect/Affine/Analysis/AffineStructures.h"
#include "mlir/Dialect/Affine/Analysis/Utils.h"
#include "mlir/Dialect/Affine/IR/AffineOps.h"
#include "mlir/IR/Builders.h"
#include "mlir/Pass/Pass.h"
#include "llvm/Support/Debug.h"
#define DEBUG_TYPE "test-memref-dependence-check"
using namespace mlir;
using namespace mlir::affine;
namespace {
// TODO: Add common surrounding loop depth-wise dependence checks.
/// Checks dependences between all pairs of memref accesses in a Function.
struct TestMemRefDependenceCheck
: public PassWrapper<TestMemRefDependenceCheck, OperationPass<>> {
MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID(TestMemRefDependenceCheck)
StringRef getArgument() const final { return "test-memref-dependence-check"; }
StringRef getDescription() const final {
return "Checks dependences between all pairs of memref accesses.";
}
SmallVector<Operation *, 4> loadsAndStores;
void runOnOperation() override;
};
} // namespace
// Returns a result string which represents the direction vector (if there was
// a dependence), returns the string "false" otherwise.
static std::string
getDirectionVectorStr(bool ret, unsigned numCommonLoops, unsigned loopNestDepth,
ArrayRef<DependenceComponent> dependenceComponents) {
if (!ret)
return "false";
if (dependenceComponents.empty() || loopNestDepth > numCommonLoops)
return "true";
std::string result;
for (const auto &dependenceComponent : dependenceComponents) {
std::string lbStr = "-inf";
if (dependenceComponent.lb.has_value() &&
*dependenceComponent.lb != std::numeric_limits<int64_t>::min())
lbStr = std::to_string(*dependenceComponent.lb);
std::string ubStr = "+inf";
if (dependenceComponent.ub.has_value() &&
*dependenceComponent.ub != std::numeric_limits<int64_t>::max())
ubStr = std::to_string(*dependenceComponent.ub);
result += "[" + lbStr + ", " + ubStr + "]";
}
return result;
}
// For each access in 'loadsAndStores', runs a dependence check between this
// "source" access and all subsequent "destination" accesses in
// 'loadsAndStores'. Emits the result of the dependence check as a note with
// the source access.
static void checkDependences(ArrayRef<Operation *> loadsAndStores) {
for (unsigned i = 0, e = loadsAndStores.size(); i < e; ++i) {
auto *srcOpInst = loadsAndStores[i];
MemRefAccess srcAccess(srcOpInst);
for (unsigned j = 0; j < e; ++j) {
auto *dstOpInst = loadsAndStores[j];
MemRefAccess dstAccess(dstOpInst);
unsigned numCommonLoops =
getNumCommonSurroundingLoops(*srcOpInst, *dstOpInst);
for (unsigned d = 1; d <= numCommonLoops + 1; ++d) {
SmallVector<DependenceComponent, 2> dependenceComponents;
DependenceResult result = checkMemrefAccessDependence(
srcAccess, dstAccess, d, /*dependenceConstraints=*/nullptr,
&dependenceComponents);
if (result.value == DependenceResult::Failure) {
srcOpInst->emitError("dependence check failed");
} else {
bool ret = hasDependence(result);
// TODO: Print dependence type (i.e. RAW, etc) and print
// distance vectors as: ([2, 3], [0, 10]). Also, shorten distance
// vectors from ([1, 1], [3, 3]) to (1, 3).
srcOpInst->emitRemark("dependence from ")
<< i << " to " << j << " at depth " << d << " = "
<< getDirectionVectorStr(ret, numCommonLoops, d,
dependenceComponents);
}
}
}
}
}
/// Walks the operation adding load and store ops to 'loadsAndStores'. Runs
/// pair-wise dependence checks.
void TestMemRefDependenceCheck::runOnOperation() {
// Collect the loads and stores within the function.
loadsAndStores.clear();
getOperation()->walk([&](Operation *op) {
if (isa<AffineLoadOp, AffineStoreOp>(op))
loadsAndStores.push_back(op);
});
checkDependences(loadsAndStores);
}
namespace mlir {
namespace test {
void registerTestMemRefDependenceCheck() {
PassRegistration<TestMemRefDependenceCheck>();
}
} // namespace test
} // namespace mlir
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