Fix StringBuilder append assumptions.

Do not rely on use ordering, it can be different because of
SimplifyReturnThis(); just use HBackwardInstructionIterator.
Instead of checking that we find a StringBuilder.toString(),
check that it is the invoke we're trying to simplify.

Add regression test 699-checker-string-append2.

Test: testrunner.py --host --jvm -t 699-checker-string-append2
Bug: 19575890
Bug: 146014745
Change-Id: I7b16f376c16ba5a4107e9718e0acf17d82280f54

4 files changed, 205 insertions, 0 deletions

diff --git a/test/699-checker-string-append2/expected.txt b/test/699-checker-string-append2/expected.txt
new file mode 100644
index 0000000000..b0aad4deb5
--- /dev/null
+++ b/test/699-checker-string-append2/expected.txt
@@ -0,0 +1 @@
+passed
diff --git a/test/699-checker-string-append2/info.txt b/test/699-checker-string-append2/info.txt
new file mode 100644
index 0000000000..1bd4a1a297
--- /dev/null
+++ b/test/699-checker-string-append2/info.txt
@@ -0,0 +1 @@
+Regression tests for String append pattern recognition bugs. b/146014745
diff --git a/test/699-checker-string-append2/smali/B146014745.smali b/test/699-checker-string-append2/smali/B146014745.smali
new file mode 100644
index 0000000000..0a20b41a68
--- /dev/null
+++ b/test/699-checker-string-append2/smali/B146014745.smali
@@ -0,0 +1,163 @@
+# Copyright (C) 2019 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 LB146014745;
+.super Ljava/lang/Object;
+
+## CHECK-START: java.lang.String B146014745.$noinline$testAppend1(java.lang.String, int) instruction_simplifier (before)
+## CHECK-NOT:                  StringBuilderAppend
+
+## CHECK-START: java.lang.String B146014745.$noinline$testAppend1(java.lang.String, int) instruction_simplifier (after)
+## CHECK:                      StringBuilderAppend
+
+.method public static $noinline$testAppend1(Ljava/lang/String;I)Ljava/lang/String;
+    .registers 4
+# StringBuilder sb = new StringBuilder();
+    new-instance v0, Ljava/lang/StringBuilder;
+    invoke-direct {v0}, Ljava/lang/StringBuilder;-><init>()V
+# sb.append(s).append(i);
+    invoke-virtual {v0, p0}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+    move-result-object v1
+    invoke-virtual {v1, p1}, Ljava/lang/StringBuilder;->append(I)Ljava/lang/StringBuilder;
+# return sb.append(s).append(i).toString();
+    invoke-virtual {v0, p0}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+    move-result-object v1
+    invoke-virtual {v1, p1}, Ljava/lang/StringBuilder;->append(I)Ljava/lang/StringBuilder;
+    move-result-object v1
+    invoke-virtual {v1}, Ljava/lang/StringBuilder;->toString()Ljava/lang/String;
+    move-result-object v1
+    return-object v1
+.end method
+
+## CHECK-START: java.lang.String B146014745.$noinline$testAppend2(java.lang.String, int) instruction_simplifier (after)
+## CHECK-NOT:                  StringBuilderAppend
+
+.method public static $noinline$testAppend2(Ljava/lang/String;I)Ljava/lang/String;
+    .registers 4
+# StringBuilder sb = new StringBuilder();
+    new-instance v0, Ljava/lang/StringBuilder;
+    invoke-direct {v0}, Ljava/lang/StringBuilder;-><init>()V
+# String s2 = sb.append(s).append(i).toString();
+    invoke-virtual {v0, p0}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+    move-result-object v1
+    invoke-virtual {v1, p1}, Ljava/lang/StringBuilder;->append(I)Ljava/lang/StringBuilder;
+    move-result-object v1
+    invoke-virtual {v1}, Ljava/lang/StringBuilder;->toString()Ljava/lang/String;
+    move-result-object v1
+# return sb.append(s2).toString();
+    invoke-virtual {v0, v1}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+    move-result-object v1
+    invoke-virtual {v1}, Ljava/lang/StringBuilder;->toString()Ljava/lang/String;
+    move-result-object v1
+    return-object v1
+.end method
+
+## CHECK-START: java.lang.String B146014745.$noinline$testAppend3(java.lang.String, int) instruction_simplifier (after)
+## CHECK-NOT:                  StringBuilderAppend
+
+.method public static $noinline$testAppend3(Ljava/lang/String;I)Ljava/lang/String;
+    .registers 5
+# StringBuilder sb = new StringBuilder();
+    new-instance v0, Ljava/lang/StringBuilder;
+    invoke-direct {v0}, Ljava/lang/StringBuilder;-><init>()V
+# String s2 = sb.append(s).toString();
+    invoke-virtual {v0, p0}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+    move-result-object v2
+    invoke-virtual {v2}, Ljava/lang/StringBuilder;->toString()Ljava/lang/String;
+    move-result-object v2
+# return sb.append(i).append(s2).append(i);
+    invoke-virtual {v0, p1}, Ljava/lang/StringBuilder;->append(I)Ljava/lang/StringBuilder;
+    move-result-object v1
+    invoke-virtual {v1, v2}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+    move-result-object v1
+    invoke-virtual {v1, p1}, Ljava/lang/StringBuilder;->append(I)Ljava/lang/StringBuilder;
+# return sb.toString();
+    invoke-virtual {v0}, Ljava/lang/StringBuilder;->toString()Ljava/lang/String;
+    move-result-object v1
+    return-object v1
+.end method
+
+# The following is a jasmin version.
+# Unfortunately, this would be translated without the required move-result-object,
+# instead using the register initialized by new-instance for subsequent calls.
+
+#.class public B146014745
+#.super java/lang/Object
+
+#.method public static $noinline$testAppend1(Ljava/lang/String;I)Ljava/lang/String;
+#    .limit stack 3
+#    .limit locals 2
+#; StringBuilder sb = new StringBuilder();
+#    new java/lang/StringBuilder
+#    dup
+#    invokespecial java.lang.StringBuilder.<init>()V
+#; sb.append(s).append(i);
+#    dup
+#    aload_0
+#    invokevirtual java.lang.StringBuilder.append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+#    iload_1
+#    invokevirtual java.lang.StringBuilder.append(I)Ljava/lang/StringBuilder;
+#    pop
+#; return sb.append(s).append(i).toString();
+#    aload_0
+#    invokevirtual java.lang.StringBuilder.append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+#    iload_1
+#    invokevirtual java.lang.StringBuilder.append(I)Ljava/lang/StringBuilder;
+#    invokevirtual java.lang.StringBuilder.toString()Ljava/lang/String;
+#    areturn
+#.end method
+
+#.method public static $noinline$testAppend2(Ljava/lang/String;I)Ljava/lang/String;
+#    .limit stack 3
+#    .limit locals 2
+#; StringBuilder sb = new StringBuilder();
+#    new java/lang/StringBuilder
+#    dup
+#    invokespecial java.lang.StringBuilder.<init>()V
+#; String s2 = sb.append(s).append(i).toString();
+#    dup
+#    aload_0
+#    invokevirtual java.lang.StringBuilder.append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+#    iload_1
+#    invokevirtual java.lang.StringBuilder.append(I)Ljava/lang/StringBuilder;
+#    invokevirtual java.lang.StringBuilder.toString()Ljava/lang/String;
+#; return sb.append(s2).toString();
+#    invokevirtual java.lang.StringBuilder.append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+#    invokevirtual java.lang.StringBuilder.toString()Ljava/lang/String;
+#    areturn
+#.end method
+
+#.method public static $noinline$testAppend3(Ljava/lang/String;I)Ljava/lang/String;
+#    .limit stack 3
+#    .limit locals 3
+#; StringBuilder sb = new StringBuilder();
+#    new java/lang/StringBuilder
+#    dup
+#    invokespecial java.lang.StringBuilder.<init>()V
+#; String s2 = sb.append(s).toString();
+#    dup
+#    aload_0
+#    invokevirtual java.lang.StringBuilder.append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+#    invokevirtual java.lang.StringBuilder.toString()Ljava/lang/String;
+#    astore_2
+#; return sb.append(i).append(s2).append(i);
+#    iload_1
+#    invokevirtual java.lang.StringBuilder.append(I)Ljava/lang/StringBuilder;
+#    aload_2
+#    invokevirtual java.lang.StringBuilder.append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+#    iload_1
+#    invokevirtual java.lang.StringBuilder.append(I)Ljava/lang/StringBuilder;
+#    invokevirtual java.lang.StringBuilder.toString()Ljava/lang/String;
+#    areturn
+#.end method
diff --git a/test/699-checker-string-append2/src/Main.java b/test/699-checker-string-append2/src/Main.java
new file mode 100644
index 0000000000..3753af603b
--- /dev/null
+++ b/test/699-checker-string-append2/src/Main.java
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2019 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;
+
+public class Main {
+    public static void main(String[] args) throws Exception {
+        Class<?> c = Class.forName("B146014745");
+        Method m1 = c.getDeclaredMethod("$noinline$testAppend1", String.class, int.class);
+        String b146014745_result1 = (String) m1.invoke(null, "x", 42);
+        assertEquals("x42x42", b146014745_result1);
+        Method m2 = c.getDeclaredMethod("$noinline$testAppend2", String.class, int.class);
+        String b146014745_result2 = (String) m2.invoke(null, "x", 42);
+        assertEquals("x42x42", b146014745_result2);
+        Method m3 = c.getDeclaredMethod("$noinline$testAppend3", String.class, int.class);
+        String b146014745_result3 = (String) m3.invoke(null, "x", 42);
+        assertEquals("x42x42", b146014745_result3);
+
+        System.out.println("passed");
+    }
+
+    public static void assertEquals(String expected, String actual) {
+        if (!expected.equals(actual)) {
+            throw new AssertionError("Expected: " + expected + ", actual: " + actual);
+        }
+    }
+}