================ @@ -0,0 +1,147 @@ +//===----------------------------------------------------------------------===// +// +// 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 pass that canonicalizes CIR operations, eliminating +// redundant branches, empty scopes, and other unnecessary operations. +// +//===----------------------------------------------------------------------===// + +#include "PassDetail.h" +#include "mlir/Dialect/Func/IR/FuncOps.h" +#include "mlir/IR/Block.h" +#include "mlir/IR/Operation.h" +#include "mlir/IR/PatternMatch.h" +#include "mlir/IR/Region.h" +#include "mlir/Support/LogicalResult.h" +#include "mlir/Transforms/GreedyPatternRewriteDriver.h" +#include "clang/CIR/Dialect/IR/CIRDialect.h" +#include "clang/CIR/Dialect/Passes.h" +#include "clang/CIR/MissingFeatures.h" + +using namespace mlir; +using namespace cir; + +namespace { + +/// Removes branches between two blocks if it is the only branch. +/// +/// From: +/// ^bb0: +/// cir.br ^bb1 +/// ^bb1: // pred: ^bb0 +/// cir.return +/// +/// To: +/// ^bb0: +/// cir.return +struct RemoveRedundantBranches : public OpRewritePattern<BrOp> { + using OpRewritePattern<BrOp>::OpRewritePattern; + + LogicalResult matchAndRewrite(BrOp op, + PatternRewriter &rewriter) const final { + Block *block = op.getOperation()->getBlock(); + Block *dest = op.getDest(); + + assert(!cir::MissingFeatures::labelOp()); + + // Single edge between blocks: merge it. + if (block->getNumSuccessors() == 1 && + dest->getSinglePredecessor() == block) { + rewriter.eraseOp(op); + rewriter.mergeBlocks(dest, block); + return success(); + } + + return failure(); + } +}; + +struct RemoveEmptyScope + : public OpRewritePattern<ScopeOp>::SplitMatchAndRewrite { + using SplitMatchAndRewrite::SplitMatchAndRewrite; + + LogicalResult match(ScopeOp op) const final { + // TODO: Remove this logic once CIR uses MLIR infrastructure to remove + // trivially dead operations + if (op.isEmpty()) { + return success(); + } + + Region *region = &(op.getScopeRegion()); // getRegions().front(); ---------------- erichkeane wrote:
This is VERY suspicious. Address-of a thing resulting in nullptr? I think we'd better ensure that there IS a scope region, then make `region` here a reference instead. https://github.com/llvm/llvm-project/pull/131891 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
