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| 1 | +//===- ConstantArgumentGlobalisation.cpp ----------------------------------===// |
| 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-exception |
| 6 | +// |
| 7 | +//===----------------------------------------------------------------------===// |
| 8 | + |
| 9 | +#include "flang/Optimizer/Builder/FIRBuilder.h" |
| 10 | +#include "flang/Optimizer/Dialect/FIRDialect.h" |
| 11 | +#include "flang/Optimizer/Dialect/FIROps.h" |
| 12 | +#include "flang/Optimizer/Dialect/FIRType.h" |
| 13 | +#include "flang/Optimizer/Transforms/Passes.h" |
| 14 | +#include "mlir/Dialect/Func/IR/FuncOps.h" |
| 15 | +#include "mlir/IR/Diagnostics.h" |
| 16 | +#include "mlir/IR/Dominance.h" |
| 17 | +#include "mlir/Pass/Pass.h" |
| 18 | +#include "mlir/Transforms/GreedyPatternRewriteDriver.h" |
| 19 | + |
| 20 | +namespace fir { |
| 21 | +#define GEN_PASS_DEF_CONSTANTARGUMENTGLOBALISATIONOPT |
| 22 | +#include "flang/Optimizer/Transforms/Passes.h.inc" |
| 23 | +} // namespace fir |
| 24 | + |
| 25 | +#define DEBUG_TYPE "flang-constant-argument-globalisation-opt" |
| 26 | + |
| 27 | +namespace { |
| 28 | +unsigned uniqueLitId = 1; |
| 29 | + |
| 30 | +class CallOpRewriter : public mlir::OpRewritePattern<fir::CallOp> { |
| 31 | +protected: |
| 32 | + const mlir::DominanceInfo &di; |
| 33 | + |
| 34 | +public: |
| 35 | + using OpRewritePattern::OpRewritePattern; |
| 36 | + |
| 37 | + CallOpRewriter(mlir::MLIRContext *ctx, const mlir::DominanceInfo &_di) |
| 38 | + : OpRewritePattern(ctx), di(_di) {} |
| 39 | + |
| 40 | + mlir::LogicalResult |
| 41 | + matchAndRewrite(fir::CallOp callOp, |
| 42 | + mlir::PatternRewriter &rewriter) const override { |
| 43 | + LLVM_DEBUG(llvm::dbgs() << "Processing call op: " << callOp << "\n"); |
| 44 | + auto module = callOp->getParentOfType<mlir::ModuleOp>(); |
| 45 | + bool needUpdate = false; |
| 46 | + fir::FirOpBuilder builder(rewriter, module); |
| 47 | + llvm::SmallVector<mlir::Value> newOperands; |
| 48 | + llvm::SmallVector<std::pair<mlir::Operation *, mlir::Operation *>> allocas; |
| 49 | + for (const mlir::Value &a : callOp.getArgs()) { |
| 50 | + auto alloca = mlir::dyn_cast_or_null<fir::AllocaOp>(a.getDefiningOp()); |
| 51 | + // We can convert arguments that are alloca, and that has |
| 52 | + // the value by reference attribute. All else is just added |
| 53 | + // to the argument list. |
| 54 | + if (!alloca || !alloca->hasAttr(fir::getAdaptToByRefAttrName())) { |
| 55 | + newOperands.push_back(a); |
| 56 | + continue; |
| 57 | + } |
| 58 | + |
| 59 | + mlir::Type varTy = alloca.getInType(); |
| 60 | + assert(!fir::hasDynamicSize(varTy) && |
| 61 | + "only expect statically sized scalars to be by value"); |
| 62 | + |
| 63 | + // Find immediate store with const argument |
| 64 | + mlir::Operation *store = nullptr; |
| 65 | + for (mlir::Operation *s : alloca->getUsers()) { |
| 66 | + if (mlir::isa<fir::StoreOp>(s) && di.dominates(s, callOp)) { |
| 67 | + // We can only deal with ONE store - if already found one, |
| 68 | + // set to nullptr and exit the loop. |
| 69 | + if (store) { |
| 70 | + store = nullptr; |
| 71 | + break; |
| 72 | + } |
| 73 | + store = s; |
| 74 | + } |
| 75 | + } |
| 76 | + |
| 77 | + // If we didn't find any store, or multiple stores, add argument as is |
| 78 | + // and move on. |
| 79 | + if (!store) { |
| 80 | + newOperands.push_back(a); |
| 81 | + continue; |
| 82 | + } |
| 83 | + |
| 84 | + LLVM_DEBUG(llvm::dbgs() << " found store " << *store << "\n"); |
| 85 | + |
| 86 | + mlir::Operation *definingOp = store->getOperand(0).getDefiningOp(); |
| 87 | + // If not a constant, add to operands and move on. |
| 88 | + if (!mlir::isa<mlir::arith::ConstantOp>(definingOp)) { |
| 89 | + // Unable to remove alloca arg |
| 90 | + newOperands.push_back(a); |
| 91 | + continue; |
| 92 | + } |
| 93 | + |
| 94 | + LLVM_DEBUG(llvm::dbgs() << " found define " << *definingOp << "\n"); |
| 95 | + |
| 96 | + std::string globalName = |
| 97 | + "_global_const_." + std::to_string(uniqueLitId++); |
| 98 | + assert(!builder.getNamedGlobal(globalName) && |
| 99 | + "We should have a unique name here"); |
| 100 | + |
| 101 | + if (std::find_if(allocas.begin(), allocas.end(), [alloca](auto x) { |
| 102 | + return x.first == alloca; |
| 103 | + }) == allocas.end()) { |
| 104 | + allocas.push_back(std::make_pair(alloca, store)); |
| 105 | + } |
| 106 | + |
| 107 | + auto loc = callOp.getLoc(); |
| 108 | + fir::GlobalOp global = builder.createGlobalConstant( |
| 109 | + loc, varTy, globalName, |
| 110 | + [&](fir::FirOpBuilder &builder) { |
| 111 | + mlir::Operation *cln = definingOp->clone(); |
| 112 | + builder.insert(cln); |
| 113 | + mlir::Value val = |
| 114 | + builder.createConvert(loc, varTy, cln->getResult(0)); |
| 115 | + builder.create<fir::HasValueOp>(loc, val); |
| 116 | + }, |
| 117 | + builder.createInternalLinkage()); |
| 118 | + mlir::Value addr = builder.create<fir::AddrOfOp>(loc, global.resultType(), |
| 119 | + global.getSymbol()); |
| 120 | + newOperands.push_back(addr); |
| 121 | + needUpdate = true; |
| 122 | + } |
| 123 | + |
| 124 | + if (needUpdate) { |
| 125 | + auto loc = callOp.getLoc(); |
| 126 | + llvm::SmallVector<mlir::Type> newResultTypes; |
| 127 | + newResultTypes.append(callOp.getResultTypes().begin(), |
| 128 | + callOp.getResultTypes().end()); |
| 129 | + fir::CallOp newOp = builder.create<fir::CallOp>( |
| 130 | + loc, newResultTypes, |
| 131 | + callOp.getCallee().has_value() ? callOp.getCallee().value() |
| 132 | + : mlir::SymbolRefAttr{}, |
| 133 | + newOperands); |
| 134 | + // Copy all the attributes from the old to new op. |
| 135 | + newOp->setAttrs(callOp->getAttrs()); |
| 136 | + rewriter.replaceOp(callOp, newOp); |
| 137 | + |
| 138 | + for (auto a : allocas) { |
| 139 | + if (a.first->hasOneUse()) { |
| 140 | + // If the alloca is only used for a store and the call operand, the |
| 141 | + // store is no longer required. |
| 142 | + rewriter.eraseOp(a.second); |
| 143 | + rewriter.eraseOp(a.first); |
| 144 | + } |
| 145 | + } |
| 146 | + LLVM_DEBUG(llvm::dbgs() << "global constant for " << callOp << " as " |
| 147 | + << newOp << '\n'); |
| 148 | + return mlir::success(); |
| 149 | + } |
| 150 | + |
| 151 | + // Failure here just means "we couldn't do the conversion", which is |
| 152 | + // perfectly acceptable to the upper layers of this function. |
| 153 | + return mlir::failure(); |
| 154 | + } |
| 155 | +}; |
| 156 | + |
| 157 | +// this pass attempts to convert immediate scalar literals in function calls |
| 158 | +// to global constants to allow transformations such as Dead Argument |
| 159 | +// Elimination |
| 160 | +class ConstantArgumentGlobalisationOpt |
| 161 | + : public fir::impl::ConstantArgumentGlobalisationOptBase< |
| 162 | + ConstantArgumentGlobalisationOpt> { |
| 163 | +public: |
| 164 | + ConstantArgumentGlobalisationOpt() = default; |
| 165 | + |
| 166 | + void runOnOperation() override { |
| 167 | + mlir::ModuleOp mod = getOperation(); |
| 168 | + mlir::DominanceInfo *di = &getAnalysis<mlir::DominanceInfo>(); |
| 169 | + auto *context = &getContext(); |
| 170 | + mlir::RewritePatternSet patterns(context); |
| 171 | + mlir::GreedyRewriteConfig config; |
| 172 | + config.enableRegionSimplification = |
| 173 | + mlir::GreedySimplifyRegionLevel::Disabled; |
| 174 | + config.strictMode = mlir::GreedyRewriteStrictness::ExistingOps; |
| 175 | + |
| 176 | + patterns.insert<CallOpRewriter>(context, *di); |
| 177 | + if (mlir::failed(mlir::applyPatternsAndFoldGreedily( |
| 178 | + mod, std::move(patterns), config))) { |
| 179 | + mlir::emitError(mod.getLoc(), |
| 180 | + "error in constant globalisation optimization\n"); |
| 181 | + signalPassFailure(); |
| 182 | + } |
| 183 | + } |
| 184 | +}; |
| 185 | +} // namespace |
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