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| 1 | +//===--- MoveFunctionCanonicalization.cpp ---------------------------------===// |
| 2 | +// |
| 3 | +// This source file is part of the Swift.org open source project |
| 4 | +// |
| 5 | +// Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors |
| 6 | +// Licensed under Apache License v2.0 with Runtime Library Exception |
| 7 | +// |
| 8 | +// See https://swift.org/LICENSE.txt for license information |
| 9 | +// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors |
| 10 | +// |
| 11 | +//===----------------------------------------------------------------------===// |
| 12 | + |
| 13 | +#define DEBUG_TYPE "sil-move-function-canonicalization" |
| 14 | + |
| 15 | +#include "swift/AST/DiagnosticsSIL.h" |
| 16 | +#include "swift/Basic/Defer.h" |
| 17 | +#include "swift/Basic/FrozenMultiMap.h" |
| 18 | +#include "swift/SIL/BasicBlockBits.h" |
| 19 | +#include "swift/SIL/BasicBlockDatastructures.h" |
| 20 | +#include "swift/SIL/Consumption.h" |
| 21 | +#include "swift/SIL/DebugUtils.h" |
| 22 | +#include "swift/SIL/InstructionUtils.h" |
| 23 | +#include "swift/SIL/MemAccessUtils.h" |
| 24 | +#include "swift/SIL/OwnershipUtils.h" |
| 25 | +#include "swift/SIL/SILArgument.h" |
| 26 | +#include "swift/SIL/SILBuilder.h" |
| 27 | +#include "swift/SIL/SILFunction.h" |
| 28 | +#include "swift/SIL/SILInstruction.h" |
| 29 | +#include "swift/SIL/SILUndef.h" |
| 30 | +#include "swift/SILOptimizer/Analysis/ClosureScope.h" |
| 31 | +#include "swift/SILOptimizer/PassManager/Transforms.h" |
| 32 | +#include "swift/SILOptimizer/Utils/CanonicalOSSALifetime.h" |
| 33 | +#include "llvm/ADT/PointerEmbeddedInt.h" |
| 34 | +#include "llvm/ADT/PointerSumType.h" |
| 35 | + |
| 36 | +using namespace swift; |
| 37 | + |
| 38 | +//===----------------------------------------------------------------------===// |
| 39 | +// Utility |
| 40 | +//===----------------------------------------------------------------------===// |
| 41 | + |
| 42 | +/// Attempts to perform several small optimizations to setup both the address |
| 43 | +/// and object checkers. Returns true if we made a change to the IR. |
| 44 | +static bool tryConvertSimpleMoveFromAllocStackTemporary( |
| 45 | + MarkUnresolvedMoveAddrInst *markMoveAddr, AliasAnalysis *aa) { |
| 46 | + LLVM_DEBUG(llvm::dbgs() << "Trying to fix up: " << *markMoveAddr); |
| 47 | + |
| 48 | + // We need a non-lexical alloc_stack as our source. |
| 49 | + auto *asi = dyn_cast<AllocStackInst>(markMoveAddr-> getSrc()); |
| 50 | + if (!asi || asi->isLexical()) { |
| 51 | + LLVM_DEBUG(llvm::dbgs() |
| 52 | + << " Source isnt an alloc_stack or is lexical... Bailing!\n"); |
| 53 | + return false; |
| 54 | + } |
| 55 | + |
| 56 | + DestroyAddrInst *dai = nullptr; |
| 57 | + CopyAddrInst *cai = nullptr; |
| 58 | + StoreInst *si = nullptr; |
| 59 | + for (auto *use : asi->getUses()) { |
| 60 | + auto *user = use->getUser(); |
| 61 | + LLVM_DEBUG(llvm::dbgs() << " Visiting User: " << *user); |
| 62 | + |
| 63 | + // If we find our own instruction or a dealloc stack, just skip. |
| 64 | + if (user == markMoveAddr || isa<DeallocStackInst>(user)) { |
| 65 | + LLVM_DEBUG( |
| 66 | + llvm::dbgs() |
| 67 | + << " Found our original inst or a dealloc stack... Ok!\n"); |
| 68 | + continue; |
| 69 | + } |
| 70 | + |
| 71 | + if (auto *destroyAddrInst = dyn_cast<DestroyAddrInst>(user)) { |
| 72 | + if (dai) |
| 73 | + return false; |
| 74 | + dai = destroyAddrInst; |
| 75 | + continue; |
| 76 | + } |
| 77 | + |
| 78 | + if (auto *newCAI = dyn_cast<CopyAddrInst>(user)) { |
| 79 | + LLVM_DEBUG(llvm::dbgs() |
| 80 | + << " Found copy_addr... checking if legal...\n"); |
| 81 | + // We require that our copy_addr be an init into our temp and in the same |
| 82 | + // block as markMoveAddr. |
| 83 | + if (newCAI->getDest() == asi && bool(newCAI->isInitializationOfDest()) && |
| 84 | + !bool(newCAI->isTakeOfSrc()) && |
| 85 | + newCAI->getParent() == markMoveAddr->getParent()) { |
| 86 | + if (cai || si) |
| 87 | + return false; |
| 88 | + cai = newCAI; |
| 89 | + continue; |
| 90 | + } |
| 91 | + } |
| 92 | + |
| 93 | + if (auto *newSI = dyn_cast<StoreInst>(user)) { |
| 94 | + LLVM_DEBUG(llvm::dbgs() |
| 95 | + << " Found store... checking if legal...\n"); |
| 96 | + // We require that our copy_addr be an init into our temp and in the same |
| 97 | + // block as markMoveAddr. |
| 98 | + if (newSI->getDest() == asi && |
| 99 | + newSI->getOwnershipQualifier() == StoreOwnershipQualifier::Init && |
| 100 | + newSI->getParent() == markMoveAddr->getParent()) { |
| 101 | + if (cai || si) |
| 102 | + return false; |
| 103 | + si = newSI; |
| 104 | + continue; |
| 105 | + } |
| 106 | + } |
| 107 | + |
| 108 | + // If we do not find an instruction that we know about, return we can't |
| 109 | + // optimize. |
| 110 | + LLVM_DEBUG( |
| 111 | + llvm::dbgs() |
| 112 | + << " Found instruction we did not understand! Bailing!\n"); |
| 113 | + return false; |
| 114 | + } |
| 115 | + |
| 116 | + // If we did not find an (init | store) or destroy_addr, just bail. |
| 117 | + if (!(cai || si) || !dai) { |
| 118 | + LLVM_DEBUG(llvm::dbgs() |
| 119 | + << " Did not find a single init! Bailing!\n"); |
| 120 | + return false; |
| 121 | + } |
| 122 | + |
| 123 | + assert(bool(cai) != bool(si)); |
| 124 | + |
| 125 | + // Otherwise, lets walk from cai to markMoveAddr and make sure there aren't |
| 126 | + // any side-effect having instructions in between them. |
| 127 | + // |
| 128 | + // NOTE: We know that cai must be before the markMoveAddr in the block since |
| 129 | + // otherwise we would be moving from uninitialized memory. |
| 130 | + SILInstruction *init = nullptr; |
| 131 | + if (cai) |
| 132 | + init = cai; |
| 133 | + else |
| 134 | + init = si; |
| 135 | + |
| 136 | + auto range = llvm::make_range(std::next(init->getIterator()), |
| 137 | + markMoveAddr->getIterator()); |
| 138 | + if (llvm::any_of(range, [&](SILInstruction &iter) { |
| 139 | + if (!iter.mayHaveSideEffects()) { |
| 140 | + return false; |
| 141 | + } |
| 142 | + |
| 143 | + if (auto *dvi = dyn_cast<DestroyAddrInst>(&iter)) { |
| 144 | + if (aa->isNoAlias(dvi->getOperand(), asi)) { |
| 145 | + // We are going to be extending the lifetime of our |
| 146 | + // underlying value, not shrinking it so we can ignore |
| 147 | + // destroy_addr on other non-aliasing values. |
| 148 | + return false; |
| 149 | + } |
| 150 | + } |
| 151 | + |
| 152 | + // Ignore end of scope markers with side-effects. |
| 153 | + if (isEndOfScopeMarker(&iter)) { |
| 154 | + return false; |
| 155 | + } |
| 156 | + |
| 157 | + LLVM_DEBUG(llvm::dbgs() |
| 158 | + << " Found side-effect inst... Bailing!: " << iter); |
| 159 | + return true; |
| 160 | + })) |
| 161 | + return false; |
| 162 | + |
| 163 | + LLVM_DEBUG(llvm::dbgs() << " Success! Performing optimization!\n"); |
| 164 | + // Ok, we can perform our optimization! Change move_addr's source to be the |
| 165 | + // original copy_addr's src and add add uses of the stack location to an |
| 166 | + // instruction deleter. We will eliminate them later. |
| 167 | + if (cai) { |
| 168 | + markMoveAddr->setSrc(cai->getSrc()); |
| 169 | + return true; |
| 170 | + } |
| 171 | + |
| 172 | + // If we have a store [init], see if our src is a load [copy] from an |
| 173 | + // alloc_stack that is lexical var. In this case, we want to move our |
| 174 | + // mark_unresolved_move_addr onto that lexical var. This pattern occurs due to |
| 175 | + // SILGen always loading loadable values from memory when retrieving an |
| 176 | + // RValue. Calling _move then since _move is generic forces the value to be |
| 177 | + // re-materialized into an alloc_stack. In this example remembering that |
| 178 | + // mark_unresolved_move_addr is a copy_addr [init], we try to move the MUMA |
| 179 | + // onto the original lexical alloc_stack. |
| 180 | + // |
| 181 | + // TODO: Implement. |
| 182 | + |
| 183 | + // If we do not have a load [copy], transform this mark_resolved_move_addr |
| 184 | + // into a move_value [diagnostic] + store [init]. Predictable mem opts is |
| 185 | + // smart enough to handle this case and promote away loads from the |
| 186 | + // allocation. This runs before the value move checker runs. |
| 187 | + SILBuilderWithScope builder(si); |
| 188 | + auto *newValue = builder.createMoveValue(si->getLoc(), si->getSrc()); |
| 189 | + newValue->setAllowsDiagnostics(true); |
| 190 | + si->setSrc(newValue); |
| 191 | + markMoveAddr->eraseFromParent(); |
| 192 | + return true; |
| 193 | +} |
| 194 | + |
| 195 | +//===----------------------------------------------------------------------===// |
| 196 | +// Top Level Entrypoint |
| 197 | +//===----------------------------------------------------------------------===// |
| 198 | + |
| 199 | +namespace { |
| 200 | + |
| 201 | +class MoveFunctionCanonicalization : public SILFunctionTransform { |
| 202 | + void run() override { |
| 203 | + auto *fn = getFunction(); |
| 204 | + |
| 205 | + // If we do not have experimental move only enabled, do not emit |
| 206 | + // diagnostics. |
| 207 | + if (!astContext.LangOpts.EnableExperimentalMoveOnly) |
| 208 | + return; |
| 209 | + |
| 210 | + // Don't rerun diagnostics on deserialized functions. |
| 211 | + if (getFunction()->wasDeserializedCanonical()) |
| 212 | + return; |
| 213 | + |
| 214 | + bool madeChange = false; |
| 215 | + |
| 216 | + assert(fn->getModule().getStage() == SILStage::Raw && |
| 217 | + "Should only run on Raw SIL"); |
| 218 | + |
| 219 | + auto *aa = getAnalysis<AliasAnalysis>(fn); |
| 220 | + |
| 221 | + for (auto &block : *fn) { |
| 222 | + for (auto ii = block.begin(), ie = block.end(); ii != ie;) { |
| 223 | + auto *inst = &*ii; |
| 224 | + ++ii; |
| 225 | + |
| 226 | + // See if we see a mark_unresolved_move_addr inst from a simple |
| 227 | + // temporary and move it onto the temporary's source. This ensures that |
| 228 | + // the mark_unresolved_move_addr is always on the operand regardless if |
| 229 | + // in the caller we materalized the address into a temporary. |
| 230 | + if (auto *markMoveAddr = dyn_cast<MarkUnresolvedMoveAddrInst>(inst)) { |
| 231 | + madeChange |= |
| 232 | + tryConvertSimpleMoveFromAllocStackTemporary(markMoveAddr, aa); |
| 233 | + continue; |
| 234 | + } |
| 235 | + } |
| 236 | + } |
| 237 | + |
| 238 | + if (madeChange) { |
| 239 | + invalidateAnalysis(SILAnalysis::InvalidationKind::Instructions); |
| 240 | + } |
| 241 | + } |
| 242 | +}; |
| 243 | + |
| 244 | +} // anonymous namespace |
| 245 | + |
| 246 | +SILTransform *swift::createMoveFunctionCanonicalization() { |
| 247 | + return new MoveFunctionCanonicalization(); |
| 248 | +} |
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