6042c2eb9e
This is important to ensure that tags end up in the same trees that were created in the FIR TBAA pass. If they are in different trees then everything in one tree will be assumed to MayAlias with everything in the other tree. This leads to poor performance. @vzakhari requested that the old (not-per-function) trees are maintained so I left the old test intact. PR: https://github.com/llvm/llvm-project/pull/68437
135 lines
5.0 KiB
C++
135 lines
5.0 KiB
C++
//===-- TBAABuilder.cpp -- TBAA builder definitions -----------------------===//
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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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// Coding style: https://mlir.llvm.org/getting_started/DeveloperGuide/
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//
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//===----------------------------------------------------------------------===//
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#include "flang/Optimizer/CodeGen/TBAABuilder.h"
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#include "flang/Optimizer/Dialect/FIRType.h"
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#include "llvm/ADT/TypeSwitch.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include <mlir/Dialect/LLVMIR/LLVMAttrs.h>
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#include <mlir/Dialect/LLVMIR/LLVMDialect.h>
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#include <mlir/Dialect/LLVMIR/LLVMTypes.h>
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#define DEBUG_TYPE "flang-tbaa-builder"
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using namespace mlir;
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using namespace mlir::LLVM;
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static llvm::cl::opt<bool> disableTBAA(
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"disable-tbaa",
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llvm::cl::desc("disable attaching TBAA tags to memory accessing operations "
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"to override default Flang behavior"),
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llvm::cl::init(false));
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// disabling this will play badly with the FIR TBAA pass, leading to worse
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// performance
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static llvm::cl::opt<bool> perFunctionTBAATrees(
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"per-function-tbaa-trees",
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llvm::cl::desc("Give each function an independent TBAA tree (default)"),
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llvm::cl::init(true), llvm::cl::Hidden);
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// tagAttachmentLimit is a debugging option that allows limiting
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// the number of TBAA access tag attributes attached to operations.
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// It is set to kTagAttachmentUnlimited by default denoting "no limit".
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static constexpr unsigned kTagAttachmentUnlimited =
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std::numeric_limits<unsigned>::max();
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static llvm::cl::opt<unsigned>
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tagAttachmentLimit("tbaa-attach-tag-max", llvm::cl::desc(""),
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llvm::cl::init(kTagAttachmentUnlimited));
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namespace fir {
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TBAABuilder::TBAABuilder(MLIRContext *context, bool applyTBAA,
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bool forceUnifiedTree)
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: enableTBAA(applyTBAA && !disableTBAA),
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trees(/*separatePerFunction=*/perFunctionTBAATrees && !forceUnifiedTree) {
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if (!enableTBAA)
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return;
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}
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TBAATagAttr TBAABuilder::getAccessTag(TBAATypeDescriptorAttr baseTypeDesc,
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TBAATypeDescriptorAttr accessTypeDesc,
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int64_t offset) {
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TBAATagAttr &tag = tagsMap[{baseTypeDesc, accessTypeDesc, offset}];
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if (tag)
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return tag;
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// Initialize new tag.
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tag = TBAATagAttr::get(baseTypeDesc, accessTypeDesc, offset);
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return tag;
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}
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TBAATagAttr TBAABuilder::getAnyBoxAccessTag(mlir::LLVM::LLVMFuncOp func) {
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TBAATypeDescriptorAttr boxMemberTypeDesc = trees[func].boxMemberTypeDesc;
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return getAccessTag(boxMemberTypeDesc, boxMemberTypeDesc, /*offset=*/0);
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}
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TBAATagAttr TBAABuilder::getBoxAccessTag(Type baseFIRType, Type accessFIRType,
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GEPOp gep,
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mlir::LLVM::LLVMFuncOp func) {
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return getAnyBoxAccessTag(func);
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}
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TBAATagAttr TBAABuilder::getAnyDataAccessTag(mlir::LLVM::LLVMFuncOp func) {
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TBAATypeDescriptorAttr anyDataAccessTypeDesc = trees[func].anyDataTypeDesc;
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return getAccessTag(anyDataAccessTypeDesc, anyDataAccessTypeDesc,
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/*offset=*/0);
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}
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TBAATagAttr TBAABuilder::getDataAccessTag(Type baseFIRType, Type accessFIRType,
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GEPOp gep,
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mlir::LLVM::LLVMFuncOp func) {
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return getAnyDataAccessTag(func);
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}
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TBAATagAttr TBAABuilder::getAnyAccessTag(mlir::LLVM::LLVMFuncOp func) {
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TBAATypeDescriptorAttr anyAccessTypeDesc = trees[func].anyAccessDesc;
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return getAccessTag(anyAccessTypeDesc, anyAccessTypeDesc, /*offset=*/0);
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}
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void TBAABuilder::attachTBAATag(AliasAnalysisOpInterface op, Type baseFIRType,
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Type accessFIRType, GEPOp gep) {
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if (!enableTBAA)
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return;
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mlir::LLVM::LLVMFuncOp func = op->getParentOfType<mlir::LLVM::LLVMFuncOp>();
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assert(func && "func.func should have already been converted to llvm.func");
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++tagAttachmentCounter;
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if (tagAttachmentLimit != kTagAttachmentUnlimited &&
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tagAttachmentCounter > tagAttachmentLimit)
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return;
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LLVM_DEBUG(llvm::dbgs() << "Attaching TBAA tag #" << tagAttachmentCounter
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<< "\n");
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TBAATagAttr tbaaTagSym;
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if (fir::isRecordWithDescriptorMember(baseFIRType)) {
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// A memory access that addresses an aggregate that contains
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// a mix of data members and descriptor members may alias
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// with both data and descriptor accesses.
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// Conservatively set any-access tag if there is any descriptor member.
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tbaaTagSym = getAnyAccessTag(func);
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} else if (baseFIRType.isa<fir::BaseBoxType>()) {
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tbaaTagSym = getBoxAccessTag(baseFIRType, accessFIRType, gep, func);
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} else {
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tbaaTagSym = getDataAccessTag(baseFIRType, accessFIRType, gep, func);
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}
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if (!tbaaTagSym)
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return;
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op.setTBAATags(ArrayAttr::get(op->getContext(), tbaaTagSym));
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}
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} // namespace fir
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