[SILOptimizer] Added MandatoryCombiner.

include/swift/SILOptimizer/PassManager/Passes.def

@@ -36,7 +36,7 @@
 ///   This macro follows the same conventions as PASS(Id, Tag, Description),
 ///   but is used for IRGen passes which are built outside of the
 ///   SILOptimizer library.
-///   
+///
 ///   An IRGen pass is created by IRGen and needs to be registered with the pass
 ///   manager dynamically.
 #ifndef IRGEN_PASS
@@ -312,6 +312,8 @@ PASS(SerializeSILPass, "serialize-sil",
 PASS(YieldOnceCheck, "yield-once-check",
     "Check correct usage of yields in yield-once coroutines")
 PASS(OSLogOptimization, "os-log-optimization", "Optimize os log calls")
+PASS(MandatoryCombiner, "mandatory-combiner",
+    "Perform mandatory peephole combines")
 PASS(BugReducerTester, "bug-reducer-tester",
      "sil-bug-reducer Tool Testing by Asserting on a Sentinel Function")
 PASS_RANGE(AllPasses, AADumper, BugReducerTester)

lib/SILOptimizer/Mandatory/CMakeLists.txt

@@ -21,5 +21,6 @@ silopt_register_sources(
   SemanticARCOpts.cpp
   SILGenCleanup.cpp
   YieldOnceCheck.cpp
+  MandatoryCombiner.cpp
   OSLogOptimization.cpp
 )

lib/SILOptimizer/Mandatory/MandatoryCombiner.cpp

@@ -0,0 +1,174 @@
+//===------- MandatoryCombiner.cpp ----------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+///
+///  \file
+///
+///  Defines the MandatoryCombiner function transform.  The pass contains basic
+///  instruction combines to be performed at the begining of both the Onone and
+///  also the performance pass pipelines, after the diagnostics passes have been
+///  run.  It is intended to be run before and to be independent of other
+///  transforms.
+///
+///  The intention of this pass is to be a place for mandatory peepholes that
+///  are not needed for diagnostics. Please put any such peepholes here instead
+///  of in the diagnostic passes.
+///
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "sil-mandatory-combiner"
+#include "swift/SIL/SILVisitor.h"
+#include "swift/SILOptimizer/PassManager/Passes.h"
+#include "swift/SILOptimizer/PassManager/Transforms.h"
+#include "swift/SILOptimizer/Utils/Local.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <vector>
+
+using namespace swift;
+
+/// \returns whether all the values are of trivial type in the provided
+///          function.
+template <typename Values>
+static bool areAllValuesTrivial(Values values, SILFunction &function) {
+  return llvm::all_of(values, [&](SILValue value) -> bool {
+    return value->getType().isTrivial(function);
+  });
+}
+
+/// Replaces all full applies of the specified partial apply with full applies
+/// of the underlying function ref and attempts to delete the partial apply.
+///
+/// The transformation of the full applies only takes place if all the arguments
+/// to the full applies are trivial.
+///
+/// TODO: Apply this transformation to partial applies not all of whose
+/// arguments are trivial.
+///
+/// \param pai the partial apply to attempt to delete
+///
+/// \returns a pair of bools.  The first bool indicates whether the a full apply
+///          of the partial apply was deleted, meaning that analyses must be
+///          invalidated.  The second bool indicates that the provided partial
+///          apply instruction itself was deleted, with consequences for the
+///          iterator.
+static std::pair<bool, bool> processPartialApply(PartialApplyInst *pai) {
+  auto callee = pai->getCallee();
+  LLVM_DEBUG(llvm::dbgs() << "Callee: " << *callee);
+
+  // Apply this pass only to partial applies all of whose arguments are
+  // trivial.
+  auto *function = pai->getReferencedFunctionOrNull();
+  if (!function) {
+    return {false, false};
+  }
+
+  auto paiArgs = ApplySite(pai).getArguments();
+  if (!areAllValuesTrivial(paiArgs, *function)) {
+    return {false, false};
+  }
+
+  bool erasedFullApply = false;
+  for (auto *use : pai->getUses()) {
+    auto fas = FullApplySite::isa(use->getUser());
+    if (!fas) {
+      continue;
+    }
+    LLVM_DEBUG(llvm::dbgs() << "Partial Apply: " << *pai);
+    LLVM_DEBUG(llvm::dbgs() << "Full Apply Site: " << *fas.getInstruction());
+    auto *fasi = dyn_cast<ApplyInst>(fas.getInstruction());
+    if (!fasi) {
+      continue;
+    }
+
+    auto fasArgs = fas.getArguments();
+    if (!areAllValuesTrivial(fasArgs, *function)) {
+      continue;
+    }
+
+    SmallVector<SILValue, 8> argsVec;
+    llvm::copy(paiArgs, std::back_inserter(argsVec));
+    llvm::copy(fasArgs, std::back_inserter(argsVec));
+
+    SILBuilderWithScope builder(fasi);
+    ApplyInst *appInst = builder.createApply(
+        /*Loc=*/fasi->getDebugLocation().getLocation(), /*Fn=*/callee,
+        /*Subs=*/pai->getSubstitutionMap(),
+        /*Args*/ argsVec,
+        /*isNonThrowing=*/fasi->isNonThrowing(),
+        /*SpecializationInfo=*/pai->getSpecializationInfo());
+    fasi->replaceAllUsesWith(appInst);
+    fasi->eraseFromParent();
+    erasedFullApply = true;
+  }
+  bool deletedDeadClosure = tryDeleteDeadClosure(pai);
+  return {erasedFullApply, deletedDeadClosure};
+}
+
+//===----------------------------------------------------------------------===//
+//                            Top Level Entrypoint
+//===----------------------------------------------------------------------===//
+
+namespace {
+
+struct MandatoryCombiner : SILFunctionTransform {
+  void run() override {
+    bool madeChange = false;
+    auto *f = getFunction();
+    for (auto &block : *f) {
+      for (auto ii = block.begin(), ie = block.end(); ii != ie;) {
+        auto *inst = &*ii;
+        // If any action is taken, the current instruction will be deleted.
+        // That instruction would be the definition of a partial apply.  Because
+        // the definition dominates all its uses, the previous instruction will
+        // be unaffected by the removal of the instruction and its uses.  So
+        // move the iterator back a step.  If no action is taken, it will be
+        // advanced twice.  If an action is taken, it will be advanced once to a
+        // new instruction (since the current one will have been deleted).
+        ii = prev_or_default(ii, block.begin(), block.end());
+
+        bool deleted = false;
+        if (auto *pai = dyn_cast<PartialApplyInst>(inst)) {
+          auto result = processPartialApply(pai);
+          deleted = result.second;
+          madeChange |= result.first || result.second;
+        }
+
+        if (deleted) {
+          // The deletion succeeded.  The iterator has already been moved back
+          // a step so as to avoid invalidation.  Advancing it one step will
+          // not advance it to the current instruction since that has been
+          // deleted.  Instead, it will advance it to the next *remaining*
+          // instruction after the previous instruction as desired.
+          ii = next_or_default(ii, /*end*/block.end(), /*defaultIter*/block.begin());
+          continue;
+        }
+
+        // No action was taken.  The iterator has already been moved back a
+        // step.  Consequently it is insufficient to advance it once--it must
+        // be advanced twice.
+        ii = next_or_default(ii, /*end*/block.end(), /*defaultIter*/block.begin());
+        ++ii;
+      }
+    }
+
+    if (madeChange) {
+      invalidateAnalysis(SILAnalysis::InvalidationKind::Instructions);
+    }
+  }
+};
+
+} // end anonymous namespace
+
+SILTransform *swift::createMandatoryCombiner() {
+  return new MandatoryCombiner();
+}