91 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "PassDetail.h"10#include "mlir/Dialect/Func/IR/FuncOps.h"11#include "mlir/IR/PatternMatch.h"12#include "mlir/Support/LogicalResult.h"13#include "mlir/Transforms/DialectConversion.h"14#include "mlir/Transforms/GreedyPatternRewriteDriver.h"15#include "clang/CIR/Dialect/IR/CIRDialect.h"16#include "clang/CIR/Dialect/Passes.h"17#include "clang/CIR/MissingFeatures.h"18#include "llvm/Support/TimeProfiler.h"19 20using namespace mlir;21using namespace cir;22 23namespace mlir {24#define GEN_PASS_DEF_HOISTALLOCAS25#include "clang/CIR/Dialect/Passes.h.inc"26} // namespace mlir27 28namespace {29 30struct HoistAllocasPass : public impl::HoistAllocasBase<HoistAllocasPass> {31 32 HoistAllocasPass() = default;33 void runOnOperation() override;34};35 36static void process(mlir::ModuleOp mod, cir::FuncOp func) {37 if (func.getRegion().empty())38 return;39 40 // Hoist all static allocas to the entry block.41 mlir::Block &entryBlock = func.getRegion().front();42 mlir::Operation *insertPoint = &*entryBlock.begin();43 44 // Post-order is the default, but the code below requires it, so45 // let's not depend on the default staying that way.46 func.getBody().walk<mlir::WalkOrder::PostOrder>([&](cir::AllocaOp alloca) {47 if (alloca->getBlock() == &entryBlock)48 return;49 // Don't hoist allocas with dynamic alloca size.50 if (alloca.getDynAllocSize())51 return;52 53 // Hoist allocas into the entry block.54 55 // Preserving the `const` attribute on hoisted allocas can cause LLVM to56 // incorrectly introduce invariant group metadata in some circumstances.57 // The incubator performs some analysis to determine whether the attribute58 // can be preserved, but it only runs this analysis when optimizations are59 // enabled. Until we start tracking the optimization level, we can just60 // always remove the `const` attribute.61 assert(!cir::MissingFeatures::optInfoAttr());62 if (alloca.getConstant())63 alloca.setConstant(false);64 65 alloca->moveBefore(insertPoint);66 });67}68 69void HoistAllocasPass::runOnOperation() {70 llvm::TimeTraceScope scope("Hoist Allocas");71 llvm::SmallVector<Operation *, 16> ops;72 73 Operation *op = getOperation();74 auto mod = mlir::dyn_cast<mlir::ModuleOp>(op);75 if (!mod)76 mod = op->getParentOfType<mlir::ModuleOp>();77 78 // If we ever introduce nested cir.function ops, we'll need to make this79 // walk in post-order and recurse into nested functions.80 getOperation()->walk<mlir::WalkOrder::PreOrder>([&](cir::FuncOp op) {81 process(mod, op);82 return mlir::WalkResult::skip();83 });84}85 86} // namespace87 88std::unique_ptr<Pass> mlir::createHoistAllocasPass() {89 return std::make_unique<HoistAllocasPass>();90}91