// Optimization.
//
+bool HLoopOptimization::CanRemoveCycle() {
+ for (HInstruction* i : *iset_) {
+ // We can never remove instructions that have environment
+ // uses when we compile 'debuggable'.
+ if (i->HasEnvironmentUses() && graph_->IsDebuggable()) {
+ return false;
+ }
+ // A deoptimization should never have an environment input removed.
+ for (const HUseListNode<HEnvironment*>& use : i->GetEnvUses()) {
+ if (use.GetUser()->GetHolder()->IsDeoptimize()) {
+ return false;
+ }
+ }
+ }
+ return true;
+}
+
void HLoopOptimization::SimplifyInduction(LoopNode* node) {
HBasicBlock* header = node->loop_info->GetHeader();
HBasicBlock* preheader = node->loop_info->GetPreHeader();
iset_->clear(); // prepare phi induction
if (TrySetPhiInduction(phi, /*restrict_uses*/ true) &&
TryAssignLastValue(node->loop_info, phi, preheader, /*collect_loop_uses*/ false)) {
- for (HInstruction* i : *iset_) {
- RemoveFromCycle(i);
+ // Note that it's ok to have replaced uses after the loop with the last value, without
+ // being able to remove the cycle. Environment uses (which are the reason we may not be
+ // able to remove the cycle) within the loop will still hold the right value.
+ if (CanRemoveCycle()) {
+ for (HInstruction* i : *iset_) {
+ RemoveFromCycle(i);
+ }
+ simplified_ = true;
}
- simplified_ = true;
}
}
}
return true;
}
-bool HLoopOptimization::TryReplaceWithLastValue(HInstruction* instruction, HBasicBlock* block) {
- // Try to replace outside uses with the last value. Environment uses can consume this
- // value too, since any first true use is outside the loop (although this may imply
- // that de-opting may look "ahead" a bit on the phi value). If there are only environment
- // uses, the value is dropped altogether, since the computations have no effect.
+bool HLoopOptimization::TryReplaceWithLastValue(HLoopInformation* loop_info,
+ HInstruction* instruction,
+ HBasicBlock* block) {
+ // Try to replace outside uses with the last value.
if (induction_range_.CanGenerateLastValue(instruction)) {
HInstruction* replacement = induction_range_.GenerateLastValue(instruction, graph_, block);
const HUseList<HInstruction*>& uses = instruction->GetUses();
size_t index = it->GetIndex();
++it; // increment before replacing
if (iset_->find(user) == iset_->end()) { // not excluded?
+ if (kIsDebugBuild) {
+ // We have checked earlier in 'IsOnlyUsedAfterLoop' that the use is after the loop.
+ HLoopInformation* other_loop_info = user->GetBlock()->GetLoopInformation();
+ CHECK(other_loop_info == nullptr || !other_loop_info->IsIn(*loop_info));
+ }
user->ReplaceInput(replacement, index);
induction_range_.Replace(user, instruction, replacement); // update induction
}
size_t index = it->GetIndex();
++it; // increment before replacing
if (iset_->find(user->GetHolder()) == iset_->end()) { // not excluded?
- user->RemoveAsUserOfInput(index);
- user->SetRawEnvAt(index, replacement);
- replacement->AddEnvUseAt(user, index);
+ HLoopInformation* other_loop_info = user->GetHolder()->GetBlock()->GetLoopInformation();
+ // Only update environment uses after the loop.
+ if (other_loop_info == nullptr || !other_loop_info->IsIn(*loop_info)) {
+ user->RemoveAsUserOfInput(index);
+ user->SetRawEnvAt(index, replacement);
+ replacement->AddEnvUseAt(user, index);
+ }
}
}
induction_simplication_count_++;
int32_t use_count = 0;
return IsOnlyUsedAfterLoop(loop_info, instruction, collect_loop_uses, &use_count) &&
(use_count == 0 ||
- (!IsEarlyExit(loop_info) && TryReplaceWithLastValue(instruction, block)));
+ (!IsEarlyExit(loop_info) && TryReplaceWithLastValue(loop_info, instruction, block)));
}
void HLoopOptimization::RemoveDeadInstructions(const HInstructionList& list) {
/*out*/ int32_t* use_count);
bool IsUsedOutsideLoop(HLoopInformation* loop_info,
HInstruction* instruction);
- bool TryReplaceWithLastValue(HInstruction* instruction, HBasicBlock* block);
+ bool TryReplaceWithLastValue(HLoopInformation* loop_info,
+ HInstruction* instruction,
+ HBasicBlock* block);
bool TryAssignLastValue(HLoopInformation* loop_info,
HInstruction* instruction,
HBasicBlock* block,
bool collect_loop_uses);
void RemoveDeadInstructions(const HInstructionList& list);
+ bool CanRemoveCycle(); // Whether the current 'iset_' is removable.
// Compiler driver (to query ISA features).
const CompilerDriver* compiler_driver_;
--- /dev/null
+JNI_OnLoad called
--- /dev/null
+Regression test for the compiler, whose loop optimization used to wrongly
+remove environment uses of HDeoptimize instructions.
--- /dev/null
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public class Main {
+ public static void main(String[] args) throws Exception {
+ System.loadLibrary(args[0]);
+
+ $noinline$intUpdate(new Main());
+ ensureJitCompiled(Main.class, "$noinline$intUpdate");
+ $noinline$intUpdate(new SubMain());
+ if (myIntStatic != 5000) {
+ throw new Error("Expected 5000, got " + myIntStatic);
+ }
+
+ $noinline$objectUpdate(new Main());
+ ensureJitCompiled(Main.class, "$noinline$objectUpdate");
+ $noinline$objectUpdate(new SubMain());
+
+ $noinline$loopIncrement(new Main());
+ ensureJitCompiled(Main.class, "$noinline$loopIncrement");
+ $noinline$loopIncrement(new SubMain());
+ }
+
+ public boolean doCheck() {
+ return false;
+ }
+
+ public static void $noinline$intUpdate(Main m) {
+ int a = 0;
+ // We used to kill 'a' when the inline cache of 'doCheck' only
+ // contains 'Main' (which makes the only branch using 'a' dead).
+ // So the deoptimization at the inline cache was incorrectly assuming
+ // 'a' was dead.
+ for (int i = 0; i < 5000; i++) {
+ if (m.doCheck()) {
+ a++;
+ // We make this branch the only true user of the 'a' phi. All other uses
+ // of 'a' are phi updates.
+ myIntStatic = a;
+ } else if (myIntStatic == 42) {
+ a = 1;
+ }
+ }
+ }
+
+ public static void $noinline$objectUpdate(Main m) {
+ Object o = new Object();
+ // We used to kill 'o' when the inline cache of 'doCheck' only
+ // contains 'Main' (which makes the only branch using 'a' dead).
+ // So the deoptimization at the inline cache was incorrectly assuming
+ // 'o' was dead.
+ // This lead to a NPE on the 'toString' call just after deoptimizing.
+ for (int i = 0; i < 5000; i++) {
+ if (m.doCheck()) {
+ // We make this branch the only true user of the 'o' phi. All other uses
+ // of 'o' are phi updates.
+ o.toString();
+ } else if (myIntStatic == 42) {
+ o = m;
+ }
+ }
+ }
+
+ public static void $noinline$loopIncrement(Main m) {
+ int k = 0;
+ // We used to kill 'k' and replace it with 5000 when the inline cache
+ // of 'doCheck' only contains 'Main'.
+ // So the deoptimization at the inline cache was incorrectly assuming
+ // 'k' was 5000.
+ for (int i = 0; i < 5000; i++, k++) {
+ if (m.doCheck()) {
+ // We make this branch the only true user of the 'a' phi. All other uses
+ // of 'a' are phi updates.
+ myIntStatic = k;
+ }
+ }
+ if (k != 5000) {
+ throw new Error("Expected 5000, got " + k);
+ }
+ }
+
+ public static int myIntStatic = 0;
+
+ public static native void ensureJitCompiled(Class<?> itf, String name);
+}
+
+class SubMain extends Main {
+ public boolean doCheck() {
+ return true;
+ }
+}
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