// | | |
// B4 B5 B?
//
-// This simplification cannot be applied for loop headers, as they
-// contain a suspend check.
+// Note that individual edges can be redirected (for example B2->B3
+// can be redirected as B2->B5) without applying this optimization
+// to other incoming edges.
+//
+// This simplification cannot be applied to catch blocks, because
+// exception handler edges do not represent normal control flow.
+// Though in theory this could still apply to normal control flow
+// going directly to a catch block, we cannot support it at the
+// moment because the catch Phi's inputs do not correspond to the
+// catch block's predecessors, so we cannot identify which
+// predecessor corresponds to a given statically evaluated input.
+//
+// We do not apply this optimization to loop headers as this could
+// create irreducible loops. We rely on the suspend check in the
+// loop header to prevent the pattern match.
//
// Note that we rely on the dead code elimination to get rid of B3.
bool HDeadCodeElimination::SimplifyIfs() {
for (HBasicBlock* block : graph_->GetReversePostOrder()) {
HInstruction* last = block->GetLastInstruction();
HInstruction* first = block->GetFirstInstruction();
- if (last->IsIf() &&
+ if (!block->IsCatchBlock() &&
+ last->IsIf() &&
block->HasSinglePhi() &&
block->GetFirstPhi()->HasOnlyOneNonEnvironmentUse()) {
bool has_only_phi_and_if = (last == first) && (last->InputAt(0) == block->GetFirstPhi());
--- /dev/null
+Regression test for the SimplifyIfs() graph simplification erroneously trying
+to redirect exception handler edges.
\ No newline at end of file
--- /dev/null
+# Copyright (C) 2016 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.
+
+.class public LTest;
+
+.super Ljava/lang/Object;
+
+.method public static test([I)I
+ .locals 2
+ const/4 v0, 0
+ :try1_begin
+ array-length v1, p0
+ :try1_end
+ add-int/lit8 v0, v1, -1
+ :try2_begin
+ aget v0, p0, v0
+ :try2_end
+ :end
+ return v0
+
+ :catch_all
+ # Regression test for bug 32545860:
+ # SimplifyIfs() would have redirected exception handler edges leading here.
+ # Note: There is no move-exception here to prevent matching the SimplifyIfs() pattern.
+ if-eqz v0, :is_zero
+ const/4 v0, -1
+ goto :end
+ :is_zero
+ const/4 v0, -2
+ goto :end
+
+ .catchall {:try1_begin .. :try1_end } :catch_all
+ .catchall {:try2_begin .. :try2_end } :catch_all
+.end method
+
+.method public static test2([II)I
+ .locals 3
+ move v0, p1
+ :try_begin
+ array-length v1, p0
+ add-int/lit8 v1, v1, -1
+ add-int/lit8 v0, v0, 1
+ aget v1, p0, v1
+ const/4 v0, 2
+ aget v2, p0, p1
+ const/4 v0, 3
+ :try_end
+ :end
+ return v0
+
+ :catch_all
+ # Regression test for bug 32546110:
+ # SimplifyIfs() would have looked at predecessors of this block based on the indexes
+ # of the catch Phi's inputs. For catch blocks these two arrays are unrelated, so
+ # this caused out-of-range access triggering a DCHECK() in dchecked_vector<>.
+ # Note: There is no move-exception here to prevent matching the SimplifyIfs() pattern.
+ if-eqz v0, :is_zero
+ const/4 v0, -1
+ goto :end
+ :is_zero
+ const/4 v0, -2
+ goto :end
+
+ .catchall {:try_begin .. :try_end } :catch_all
+.end method
--- /dev/null
+/*
+ * Copyright (C) 2016 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.
+ */
+
+import java.lang.reflect.Method;
+import java.lang.reflect.InvocationTargetException;
+
+public class Main {
+ public static void main(String[] args) throws Exception {
+ Class<?> c = Class.forName("Test");
+ Method test = c.getDeclaredMethod("test", int[].class);
+ assertIntEquals(-2, (int)test.invoke(null, new Object[] { null }));
+ assertIntEquals(-1, (int)test.invoke(null, new Object[] { new int[0] }));
+ assertIntEquals(42, (int)test.invoke(null, new Object[] { new int[] { 42 } }));
+
+ Method test2 = c.getDeclaredMethod("test2", int[].class, int.class);
+ assertIntEquals(-2, (int)test2.invoke(null, new Object[] { null, 0 }));
+ assertIntEquals(-1, (int)test2.invoke(null, new Object[] { new int[0], 0 }));
+ assertIntEquals(-1, (int)test2.invoke(null, new Object[] { new int[0], 1 }));
+ assertIntEquals(3, (int)test2.invoke(null, new Object[] { new int[] { 42 }, 0 }));
+ }
+
+ public static void assertIntEquals(int expected, int result) {
+ if (expected != result) {
+ throw new Error("Expected: " + expected + ", found: " + result);
+ }
+ }
+
+ // Workaround for non-zero field ids offset in dex file with no fields. Bug: 18051191
+ static final boolean dummy = false;
+}
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