Files
clang-p2996/mlir/lib/Dialect/MemRef/Transforms/NormalizeMemRefs.cpp
Uday Bondhugula 80625c16f0 [MLIR][Affine] Fix memref replacement in affine-data-copy-generate (#139016)
Fixes: https://github.com/llvm/llvm-project/issues/130257

Fix affine-data-copy-generate in certain cases that involved users in
multiple blocks. Perform the memref replacement correctly during copy
generation.

Improve/clean up memref affine use replacement API. Instead of
supporting dominance and post dominance filters (which aren't adequate
in most cases) and computing dominance info expensively each time in
RAMUW, provide a user filter callback, i.e., force users to compute
dominance if needed.
2025-06-28 10:27:11 +05:30

557 lines
25 KiB
C++

//===- NormalizeMemRefs.cpp -----------------------------------------------===//
//
// 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 an interprocedural pass to normalize memrefs to have
// identity layout maps.
//
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/Affine/IR/AffineOps.h"
#include "mlir/Dialect/Affine/Utils.h"
#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/Dialect/MemRef/Transforms/Passes.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/Support/Debug.h"
namespace mlir {
namespace memref {
#define GEN_PASS_DEF_NORMALIZEMEMREFSPASS
#include "mlir/Dialect/MemRef/Transforms/Passes.h.inc"
} // namespace memref
} // namespace mlir
#define DEBUG_TYPE "normalize-memrefs"
using namespace mlir;
using namespace mlir::affine;
using namespace mlir::memref;
namespace {
/// All memrefs passed across functions with non-trivial layout maps are
/// converted to ones with trivial identity layout ones.
/// If all the memref types/uses in a function are normalizable, we treat
/// such functions as normalizable. Also, if a normalizable function is known
/// to call a non-normalizable function, we treat that function as
/// non-normalizable as well. We assume external functions to be normalizable.
struct NormalizeMemRefs
: public memref::impl::NormalizeMemRefsPassBase<NormalizeMemRefs> {
void runOnOperation() override;
void normalizeFuncOpMemRefs(func::FuncOp funcOp, ModuleOp moduleOp);
bool areMemRefsNormalizable(func::FuncOp funcOp);
void updateFunctionSignature(func::FuncOp funcOp, ModuleOp moduleOp);
void setCalleesAndCallersNonNormalizable(
func::FuncOp funcOp, ModuleOp moduleOp,
DenseSet<func::FuncOp> &normalizableFuncs);
Operation *createOpResultsNormalized(func::FuncOp funcOp, Operation *oldOp);
};
} // namespace
void NormalizeMemRefs::runOnOperation() {
LLVM_DEBUG(llvm::dbgs() << "Normalizing Memrefs...\n");
ModuleOp moduleOp = getOperation();
// We maintain all normalizable FuncOps in a DenseSet. It is initialized
// with all the functions within a module and then functions which are not
// normalizable are removed from this set.
// TODO: Change this to work on FuncLikeOp once there is an operation
// interface for it.
DenseSet<func::FuncOp> normalizableFuncs;
// Initialize `normalizableFuncs` with all the functions within a module.
moduleOp.walk([&](func::FuncOp funcOp) { normalizableFuncs.insert(funcOp); });
// Traverse through all the functions applying a filter which determines
// whether that function is normalizable or not. All callers/callees of
// a non-normalizable function will also become non-normalizable even if
// they aren't passing any or specific non-normalizable memrefs. So,
// functions which calls or get called by a non-normalizable becomes non-
// normalizable functions themselves.
moduleOp.walk([&](func::FuncOp funcOp) {
if (normalizableFuncs.contains(funcOp)) {
if (!areMemRefsNormalizable(funcOp)) {
LLVM_DEBUG(llvm::dbgs()
<< "@" << funcOp.getName()
<< " contains ops that cannot normalize MemRefs\n");
// Since this function is not normalizable, we set all the caller
// functions and the callees of this function as not normalizable.
// TODO: Drop this conservative assumption in the future.
setCalleesAndCallersNonNormalizable(funcOp, moduleOp,
normalizableFuncs);
}
}
});
LLVM_DEBUG(llvm::dbgs() << "Normalizing " << normalizableFuncs.size()
<< " functions\n");
// Those functions which can be normalized are subjected to normalization.
for (func::FuncOp &funcOp : normalizableFuncs)
normalizeFuncOpMemRefs(funcOp, moduleOp);
}
/// Check whether all the uses of oldMemRef are either dereferencing uses or the
/// op is of type : DeallocOp, CallOp or ReturnOp. Only if these constraints
/// are satisfied will the value become a candidate for replacement.
/// TODO: Extend this for DimOps.
static bool isMemRefNormalizable(Value::user_range opUsers) {
return llvm::all_of(opUsers, [](Operation *op) {
return op->hasTrait<OpTrait::MemRefsNormalizable>();
});
}
/// Set all the calling functions and the callees of the function as not
/// normalizable.
void NormalizeMemRefs::setCalleesAndCallersNonNormalizable(
func::FuncOp funcOp, ModuleOp moduleOp,
DenseSet<func::FuncOp> &normalizableFuncs) {
if (!normalizableFuncs.contains(funcOp))
return;
LLVM_DEBUG(
llvm::dbgs() << "@" << funcOp.getName()
<< " calls or is called by non-normalizable function\n");
normalizableFuncs.erase(funcOp);
// Caller of the function.
std::optional<SymbolTable::UseRange> symbolUses =
funcOp.getSymbolUses(moduleOp);
for (SymbolTable::SymbolUse symbolUse : *symbolUses) {
// TODO: Extend this for ops that are FunctionOpInterface. This would
// require creating an OpInterface for FunctionOpInterface ops.
func::FuncOp parentFuncOp =
symbolUse.getUser()->getParentOfType<func::FuncOp>();
for (func::FuncOp &funcOp : normalizableFuncs) {
if (parentFuncOp == funcOp) {
setCalleesAndCallersNonNormalizable(funcOp, moduleOp,
normalizableFuncs);
break;
}
}
}
// Functions called by this function.
funcOp.walk([&](func::CallOp callOp) {
StringAttr callee = callOp.getCalleeAttr().getAttr();
for (func::FuncOp &funcOp : normalizableFuncs) {
// We compare func::FuncOp and callee's name.
if (callee == funcOp.getNameAttr()) {
setCalleesAndCallersNonNormalizable(funcOp, moduleOp,
normalizableFuncs);
break;
}
}
});
}
/// Check whether all the uses of AllocOps, AllocaOps, CallOps and function
/// arguments of a function are either of dereferencing type or are uses in:
/// DeallocOp, CallOp or ReturnOp. Only if these constraints are satisfied will
/// the function become a candidate for normalization. When the uses of a memref
/// are non-normalizable and the memref map layout is trivial (identity), we can
/// still label the entire function as normalizable. We assume external
/// functions to be normalizable.
bool NormalizeMemRefs::areMemRefsNormalizable(func::FuncOp funcOp) {
// We assume external functions to be normalizable.
if (funcOp.isExternal())
return true;
if (funcOp
.walk([&](AllocOp allocOp) -> WalkResult {
Value oldMemRef = allocOp.getResult();
if (!allocOp.getType().getLayout().isIdentity() &&
!isMemRefNormalizable(oldMemRef.getUsers()))
return WalkResult::interrupt();
return WalkResult::advance();
})
.wasInterrupted())
return false;
if (funcOp
.walk([&](AllocaOp allocaOp) -> WalkResult {
Value oldMemRef = allocaOp.getResult();
if (!allocaOp.getType().getLayout().isIdentity() &&
!isMemRefNormalizable(oldMemRef.getUsers()))
return WalkResult::interrupt();
return WalkResult::advance();
})
.wasInterrupted())
return false;
if (funcOp
.walk([&](func::CallOp callOp) -> WalkResult {
for (unsigned resIndex :
llvm::seq<unsigned>(0, callOp.getNumResults())) {
Value oldMemRef = callOp.getResult(resIndex);
if (auto oldMemRefType =
dyn_cast<MemRefType>(oldMemRef.getType()))
if (!oldMemRefType.getLayout().isIdentity() &&
!isMemRefNormalizable(oldMemRef.getUsers()))
return WalkResult::interrupt();
}
return WalkResult::advance();
})
.wasInterrupted())
return false;
for (unsigned argIndex : llvm::seq<unsigned>(0, funcOp.getNumArguments())) {
BlockArgument oldMemRef = funcOp.getArgument(argIndex);
if (auto oldMemRefType = dyn_cast<MemRefType>(oldMemRef.getType()))
if (!oldMemRefType.getLayout().isIdentity() &&
!isMemRefNormalizable(oldMemRef.getUsers()))
return false;
}
return true;
}
/// Fetch the updated argument list and result of the function and update the
/// function signature. This updates the function's return type at the caller
/// site and in case the return type is a normalized memref then it updates
/// the calling function's signature.
/// TODO: An update to the calling function signature is required only if the
/// returned value is in turn used in ReturnOp of the calling function.
void NormalizeMemRefs::updateFunctionSignature(func::FuncOp funcOp,
ModuleOp moduleOp) {
FunctionType functionType = funcOp.getFunctionType();
SmallVector<Type, 4> resultTypes;
FunctionType newFuncType;
resultTypes = llvm::to_vector<4>(functionType.getResults());
// External function's signature was already updated in
// 'normalizeFuncOpMemRefs()'.
if (!funcOp.isExternal()) {
SmallVector<Type, 8> argTypes;
for (const auto &argEn : llvm::enumerate(funcOp.getArguments()))
argTypes.push_back(argEn.value().getType());
// Traverse ReturnOps to check if an update to the return type in the
// function signature is required.
funcOp.walk([&](func::ReturnOp returnOp) {
for (const auto &operandEn : llvm::enumerate(returnOp.getOperands())) {
Type opType = operandEn.value().getType();
MemRefType memrefType = dyn_cast<MemRefType>(opType);
// If type is not memref or if the memref type is same as that in
// function's return signature then no update is required.
if (!memrefType || memrefType == resultTypes[operandEn.index()])
continue;
// Update function's return type signature.
// Return type gets normalized either as a result of function argument
// normalization, AllocOp normalization or an update made at CallOp.
// There can be many call flows inside a function and an update to a
// specific ReturnOp has not yet been made. So we check that the result
// memref type is normalized.
// TODO: When selective normalization is implemented, handle multiple
// results case where some are normalized, some aren't.
if (memrefType.getLayout().isIdentity())
resultTypes[operandEn.index()] = memrefType;
}
});
// We create a new function type and modify the function signature with this
// new type.
newFuncType = FunctionType::get(&getContext(), /*inputs=*/argTypes,
/*results=*/resultTypes);
}
// Since we update the function signature, it might affect the result types at
// the caller site. Since this result might even be used by the caller
// function in ReturnOps, the caller function's signature will also change.
// Hence we record the caller function in 'funcOpsToUpdate' to update their
// signature as well.
llvm::SmallDenseSet<func::FuncOp, 8> funcOpsToUpdate;
// We iterate over all symbolic uses of the function and update the return
// type at the caller site.
std::optional<SymbolTable::UseRange> symbolUses =
funcOp.getSymbolUses(moduleOp);
for (SymbolTable::SymbolUse symbolUse : *symbolUses) {
Operation *userOp = symbolUse.getUser();
OpBuilder builder(userOp);
// When `userOp` can not be casted to `CallOp`, it is skipped. This assumes
// that the non-CallOp has no memrefs to be replaced.
// TODO: Handle cases where a non-CallOp symbol use of a function deals with
// memrefs.
auto callOp = dyn_cast<func::CallOp>(userOp);
if (!callOp)
continue;
Operation *newCallOp =
builder.create<func::CallOp>(userOp->getLoc(), callOp.getCalleeAttr(),
resultTypes, userOp->getOperands());
bool replacingMemRefUsesFailed = false;
bool returnTypeChanged = false;
for (unsigned resIndex : llvm::seq<unsigned>(0, userOp->getNumResults())) {
OpResult oldResult = userOp->getResult(resIndex);
OpResult newResult = newCallOp->getResult(resIndex);
// This condition ensures that if the result is not of type memref or if
// the resulting memref was already having a trivial map layout then we
// need not perform any use replacement here.
if (oldResult.getType() == newResult.getType())
continue;
AffineMap layoutMap =
cast<MemRefType>(oldResult.getType()).getLayout().getAffineMap();
if (failed(replaceAllMemRefUsesWith(oldResult, /*newMemRef=*/newResult,
/*extraIndices=*/{},
/*indexRemap=*/layoutMap,
/*extraOperands=*/{},
/*symbolOperands=*/{},
/*userFilterFn=*/nullptr,
/*allowNonDereferencingOps=*/true,
/*replaceInDeallocOp=*/true))) {
// If it failed (due to escapes for example), bail out.
// It should never hit this part of the code because it is called by
// only those functions which are normalizable.
newCallOp->erase();
replacingMemRefUsesFailed = true;
break;
}
returnTypeChanged = true;
}
if (replacingMemRefUsesFailed)
continue;
// Replace all uses for other non-memref result types.
userOp->replaceAllUsesWith(newCallOp);
userOp->erase();
if (returnTypeChanged) {
// Since the return type changed it might lead to a change in function's
// signature.
// TODO: If funcOp doesn't return any memref type then no need to update
// signature.
// TODO: Further optimization - Check if the memref is indeed part of
// ReturnOp at the parentFuncOp and only then updation of signature is
// required.
// TODO: Extend this for ops that are FunctionOpInterface. This would
// require creating an OpInterface for FunctionOpInterface ops.
func::FuncOp parentFuncOp = newCallOp->getParentOfType<func::FuncOp>();
funcOpsToUpdate.insert(parentFuncOp);
}
}
// Because external function's signature is already updated in
// 'normalizeFuncOpMemRefs()', we don't need to update it here again.
if (!funcOp.isExternal())
funcOp.setType(newFuncType);
// Updating the signature type of those functions which call the current
// function. Only if the return type of the current function has a normalized
// memref will the caller function become a candidate for signature update.
for (func::FuncOp parentFuncOp : funcOpsToUpdate)
updateFunctionSignature(parentFuncOp, moduleOp);
}
/// Normalizes the memrefs within a function which includes those arising as a
/// result of AllocOps, AllocaOps, CallOps, ReinterpretCastOps and function's
/// argument. The ModuleOp argument is used to help update function's signature
/// after normalization.
void NormalizeMemRefs::normalizeFuncOpMemRefs(func::FuncOp funcOp,
ModuleOp moduleOp) {
// Turn memrefs' non-identity layouts maps into ones with identity. Collect
// alloc, alloca ops and reinterpret_cast ops first and then process since
// normalizeMemRef replaces/erases ops during memref rewriting.
SmallVector<AllocOp, 4> allocOps;
SmallVector<AllocaOp> allocaOps;
SmallVector<ReinterpretCastOp> reinterpretCastOps;
funcOp.walk([&](Operation *op) {
if (auto allocOp = dyn_cast<AllocOp>(op))
allocOps.push_back(allocOp);
else if (auto allocaOp = dyn_cast<AllocaOp>(op))
allocaOps.push_back(allocaOp);
else if (auto reinterpretCastOp = dyn_cast<ReinterpretCastOp>(op))
reinterpretCastOps.push_back(reinterpretCastOp);
});
for (AllocOp allocOp : allocOps)
(void)normalizeMemRef(allocOp);
for (AllocaOp allocaOp : allocaOps)
(void)normalizeMemRef(allocaOp);
for (ReinterpretCastOp reinterpretCastOp : reinterpretCastOps)
(void)normalizeMemRef(reinterpretCastOp);
// We use this OpBuilder to create new memref layout later.
OpBuilder b(funcOp);
FunctionType functionType = funcOp.getFunctionType();
SmallVector<Location> functionArgLocs(llvm::map_range(
funcOp.getArguments(), [](BlockArgument arg) { return arg.getLoc(); }));
SmallVector<Type, 8> inputTypes;
// Walk over each argument of a function to perform memref normalization (if
for (unsigned argIndex :
llvm::seq<unsigned>(0, functionType.getNumInputs())) {
Type argType = functionType.getInput(argIndex);
MemRefType memrefType = dyn_cast<MemRefType>(argType);
// Check whether argument is of MemRef type. Any other argument type can
// simply be part of the final function signature.
if (!memrefType) {
inputTypes.push_back(argType);
continue;
}
// Fetch a new memref type after normalizing the old memref to have an
// identity map layout.
MemRefType newMemRefType = normalizeMemRefType(memrefType);
if (newMemRefType == memrefType || funcOp.isExternal()) {
// Either memrefType already had an identity map or the map couldn't be
// transformed to an identity map.
inputTypes.push_back(newMemRefType);
continue;
}
// Insert a new temporary argument with the new memref type.
BlockArgument newMemRef = funcOp.front().insertArgument(
argIndex, newMemRefType, functionArgLocs[argIndex]);
BlockArgument oldMemRef = funcOp.getArgument(argIndex + 1);
AffineMap layoutMap = memrefType.getLayout().getAffineMap();
// Replace all uses of the old memref.
if (failed(replaceAllMemRefUsesWith(oldMemRef, /*newMemRef=*/newMemRef,
/*extraIndices=*/{},
/*indexRemap=*/layoutMap,
/*extraOperands=*/{},
/*symbolOperands=*/{},
/*userFilterFn=*/nullptr,
/*allowNonDereferencingOps=*/true,
/*replaceInDeallocOp=*/true))) {
// If it failed (due to escapes for example), bail out. Removing the
// temporary argument inserted previously.
funcOp.front().eraseArgument(argIndex);
continue;
}
// All uses for the argument with old memref type were replaced
// successfully. So we remove the old argument now.
funcOp.front().eraseArgument(argIndex + 1);
}
// Walk over normalizable operations to normalize memrefs of the operation
// results. When `op` has memrefs with affine map in the operation results,
// new operation containin normalized memrefs is created. Then, the memrefs
// are replaced. `CallOp` is skipped here because it is handled in
// `updateFunctionSignature()`.
funcOp.walk([&](Operation *op) {
if (op->hasTrait<OpTrait::MemRefsNormalizable>() &&
op->getNumResults() > 0 && !isa<func::CallOp>(op) &&
!funcOp.isExternal()) {
// Create newOp containing normalized memref in the operation result.
Operation *newOp = createOpResultsNormalized(funcOp, op);
// When all of the operation results have no memrefs or memrefs without
// affine map, `newOp` is the same with `op` and following process is
// skipped.
if (op != newOp) {
bool replacingMemRefUsesFailed = false;
for (unsigned resIndex : llvm::seq<unsigned>(0, op->getNumResults())) {
// Replace all uses of the old memrefs.
Value oldMemRef = op->getResult(resIndex);
Value newMemRef = newOp->getResult(resIndex);
MemRefType oldMemRefType = dyn_cast<MemRefType>(oldMemRef.getType());
// Check whether the operation result is MemRef type.
if (!oldMemRefType)
continue;
MemRefType newMemRefType = cast<MemRefType>(newMemRef.getType());
if (oldMemRefType == newMemRefType)
continue;
// TODO: Assume single layout map. Multiple maps not supported.
AffineMap layoutMap = oldMemRefType.getLayout().getAffineMap();
if (failed(replaceAllMemRefUsesWith(oldMemRef,
/*newMemRef=*/newMemRef,
/*extraIndices=*/{},
/*indexRemap=*/layoutMap,
/*extraOperands=*/{},
/*symbolOperands=*/{},
/*userFilterFn=*/nullptr,
/*allowNonDereferencingOps=*/true,
/*replaceInDeallocOp=*/true))) {
newOp->erase();
replacingMemRefUsesFailed = true;
continue;
}
}
if (!replacingMemRefUsesFailed) {
// Replace other ops with new op and delete the old op when the
// replacement succeeded.
op->replaceAllUsesWith(newOp);
op->erase();
}
}
}
});
// In a normal function, memrefs in the return type signature gets normalized
// as a result of normalization of functions arguments, AllocOps or CallOps'
// result types. Since an external function doesn't have a body, memrefs in
// the return type signature can only get normalized by iterating over the
// individual return types.
if (funcOp.isExternal()) {
SmallVector<Type, 4> resultTypes;
for (unsigned resIndex :
llvm::seq<unsigned>(0, functionType.getNumResults())) {
Type resType = functionType.getResult(resIndex);
MemRefType memrefType = dyn_cast<MemRefType>(resType);
// Check whether result is of MemRef type. Any other argument type can
// simply be part of the final function signature.
if (!memrefType) {
resultTypes.push_back(resType);
continue;
}
// Computing a new memref type after normalizing the old memref to have an
// identity map layout.
MemRefType newMemRefType = normalizeMemRefType(memrefType);
resultTypes.push_back(newMemRefType);
}
FunctionType newFuncType =
FunctionType::get(&getContext(), /*inputs=*/inputTypes,
/*results=*/resultTypes);
// Setting the new function signature for this external function.
funcOp.setType(newFuncType);
}
updateFunctionSignature(funcOp, moduleOp);
}
/// Create an operation containing normalized memrefs in the operation results.
/// When the results of `oldOp` have memrefs with affine map, the memrefs are
/// normalized, and new operation containing them in the operation results is
/// returned. If all of the results of `oldOp` have no memrefs or memrefs
/// without affine map, `oldOp` is returned without modification.
Operation *NormalizeMemRefs::createOpResultsNormalized(func::FuncOp funcOp,
Operation *oldOp) {
// Prepare OperationState to create newOp containing normalized memref in
// the operation results.
OperationState result(oldOp->getLoc(), oldOp->getName());
result.addOperands(oldOp->getOperands());
result.addAttributes(oldOp->getAttrs());
// Add normalized MemRefType to the OperationState.
SmallVector<Type, 4> resultTypes;
OpBuilder b(funcOp);
bool resultTypeNormalized = false;
for (unsigned resIndex : llvm::seq<unsigned>(0, oldOp->getNumResults())) {
auto resultType = oldOp->getResult(resIndex).getType();
MemRefType memrefType = dyn_cast<MemRefType>(resultType);
// Check whether the operation result is MemRef type.
if (!memrefType) {
resultTypes.push_back(resultType);
continue;
}
// Fetch a new memref type after normalizing the old memref.
MemRefType newMemRefType = normalizeMemRefType(memrefType);
if (newMemRefType == memrefType) {
// Either memrefType already had an identity map or the map couldn't
// be transformed to an identity map.
resultTypes.push_back(memrefType);
continue;
}
resultTypes.push_back(newMemRefType);
resultTypeNormalized = true;
}
result.addTypes(resultTypes);
// When all of the results of `oldOp` have no memrefs or memrefs without
// affine map, `oldOp` is returned without modification.
if (resultTypeNormalized) {
OpBuilder bb(oldOp);
for (auto &oldRegion : oldOp->getRegions()) {
Region *newRegion = result.addRegion();
newRegion->takeBody(oldRegion);
}
return bb.create(result);
}
return oldOp;
}