Fixed bug in relying on precise FP in periodic sequence.
Rationale:
FP arithmetic is not always precise, so relying on FP
period sequences to "compute back" precisely is not
valid; when all values in the period are "fetches"
however, the rotation is precise.
Bug found by fuzz testing. With regression test.
Bug: 62196559
Test: test-art-host
Change-Id: Ie8f6b965b1921ff2762b90eebb8c20503c44c6bb
diff --git a/compiler/optimizing/induction_var_range.cc b/compiler/optimizing/induction_var_range.cc
index 7c833cf..c0ec58f 100644
--- a/compiler/optimizing/induction_var_range.cc
+++ b/compiler/optimizing/induction_var_range.cc
@@ -1132,11 +1132,27 @@
/*out*/bool* needs_taken_test) const {
DCHECK(info != nullptr);
DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kPeriodic);
- // Count period.
+ // Count period and detect all-invariants.
int64_t period = 1;
- for (HInductionVarAnalysis::InductionInfo* p = info;
- p->induction_class == HInductionVarAnalysis::kPeriodic;
- p = p->op_b, ++period) {}
+ bool all_invariants = true;
+ HInductionVarAnalysis::InductionInfo* p = info;
+ for (; p->induction_class == HInductionVarAnalysis::kPeriodic; p = p->op_b, ++period) {
+ DCHECK_EQ(p->op_a->induction_class, HInductionVarAnalysis::kInvariant);
+ if (p->op_a->operation != HInductionVarAnalysis::kFetch) {
+ all_invariants = false;
+ }
+ }
+ DCHECK_EQ(p->induction_class, HInductionVarAnalysis::kInvariant);
+ if (p->operation != HInductionVarAnalysis::kFetch) {
+ all_invariants = false;
+ }
+ // Don't rely on FP arithmetic to be precise, unless the full period
+ // consist of pre-computed expressions only.
+ if (info->type == Primitive::kPrimFloat || info->type == Primitive::kPrimDouble) {
+ if (!all_invariants) {
+ return false;
+ }
+ }
// Handle any periodic(x, periodic(.., y)) for known maximum index value m.
int64_t m = 0;
if (IsConstant(trip->op_a, kExact, &m) && m >= 1) {
diff --git a/test/654-checker-periodic/expected.txt b/test/654-checker-periodic/expected.txt
new file mode 100644
index 0000000..b0aad4d
--- /dev/null
+++ b/test/654-checker-periodic/expected.txt
@@ -0,0 +1 @@
+passed
diff --git a/test/654-checker-periodic/info.txt b/test/654-checker-periodic/info.txt
new file mode 100644
index 0000000..7c8a777
--- /dev/null
+++ b/test/654-checker-periodic/info.txt
@@ -0,0 +1 @@
+Periodic sequence on integer and floating-point.
diff --git a/test/654-checker-periodic/src/Main.java b/test/654-checker-periodic/src/Main.java
new file mode 100644
index 0000000..7a0c98c
--- /dev/null
+++ b/test/654-checker-periodic/src/Main.java
@@ -0,0 +1,173 @@
+/*
+ * 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.
+ */
+
+/**
+ * Tests for last value of a few periodic sequences
+ * (found by fuzz testing).
+ */
+public class Main {
+
+ /// CHECK-START: int Main.doitUpInt(int) loop_optimization (before)
+ /// CHECK-DAG: <<Phi:i\d+>> Phi loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: Phi loop:<<Loop>> outer_loop:none
+ //
+ /// CHECK-START: int Main.doitUpInt(int) loop_optimization (after)
+ /// CHECK-NOT: Phi
+ static int doitUpInt(int n) {
+ // Complete loop is replaced by last-value.
+ int lI = 1;
+ for (int i1 = 0; i1 < n; i1++) {
+ lI = (1486662021 - lI);
+ }
+ return lI;
+ }
+
+ /// CHECK-START: int Main.doitDownInt(int) loop_optimization (before)
+ /// CHECK-DAG: <<Phi:i\d+>> Phi loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: Phi loop:<<Loop>> outer_loop:none
+ //
+ /// CHECK-START: int Main.doitDownInt(int) loop_optimization (after)
+ /// CHECK-NOT: Phi
+ static int doitDownInt(int n) {
+ // Complete loop is replaced by last-value.
+ int lI = 1;
+ for (int i1 = n - 1; i1 >= 0; i1--) {
+ lI = (1486662021 - lI);
+ }
+ return lI;
+ }
+
+ /// CHECK-START: float Main.doitUpFloat(int) loop_optimization (before)
+ /// CHECK-DAG: <<Phi:i\d+>> Phi loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: Phi loop:<<Loop>> outer_loop:none
+ //
+ /// CHECK-START: float Main.doitUpFloat(int) loop_optimization (after)
+ /// CHECK-DAG: <<Phi:i\d+>> Phi loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: Phi loop:<<Loop>> outer_loop:none
+ static float doitUpFloat(int n) {
+ // FP arithmetic is not sufficiently precise.
+ // The loop remains.
+ float lF = 1.0f;
+ for (int i1 = 0; i1 < n; i1++) {
+ lF = (1486662021.0f - lF);
+ }
+ return lF;
+ }
+
+ /// CHECK-START: float Main.doitDownFloat(int) loop_optimization (before)
+ /// CHECK-DAG: <<Phi:i\d+>> Phi loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: Phi loop:<<Loop>> outer_loop:none
+ //
+ /// CHECK-START: float Main.doitDownFloat(int) loop_optimization (after)
+ /// CHECK-DAG: <<Phi:i\d+>> Phi loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: Phi loop:<<Loop>> outer_loop:none
+ static float doitDownFloat(int n) {
+ // FP arithmetic is not sufficiently precise.
+ // The loop remains.
+ float lF = 1.0f;
+ for (int i1 = n - 1; i1 >= 0; i1--) {
+ lF = (1486662021.0f - lF);
+ }
+ return lF;
+ }
+
+ /// CHECK-START: float Main.doitUpFloatAlt(int) loop_optimization (before)
+ /// CHECK-DAG: <<Phi:i\d+>> Phi loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: Phi loop:<<Loop>> outer_loop:none
+ //
+ /// CHECK-START: float Main.doitUpFloatAlt(int) loop_optimization (after)
+ /// CHECK-NOT: Phi
+ static float doitUpFloatAlt(int n) {
+ // Complete loop is replaced by last-value
+ // since the values are now precise.
+ float lF = 1.0f;
+ float l2 = 1486662020.0f;
+ for (int i1 = 0; i1 < n; i1++) {
+ float old = lF;
+ lF = l2;
+ l2 = old;
+ }
+ return lF;
+ }
+
+ /// CHECK-START: float Main.doitDownFloatAlt(int) loop_optimization (before)
+ /// CHECK-DAG: <<Phi:i\d+>> Phi loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: Phi loop:<<Loop>> outer_loop:none
+ //
+ /// CHECK-START: float Main.doitDownFloatAlt(int) loop_optimization (after)
+ /// CHECK-NOT: Phi
+ static float doitDownFloatAlt(int n) {
+ // Complete loop is replaced by last-value
+ // since the values are now precise.
+ float lF = 1.0f;
+ float l2 = 1486662020.0f;
+ for (int i1 = n - 1; i1 >= 0; i1--) {
+ float old = lF;
+ lF = l2;
+ l2 = old;
+ }
+ return lF;
+ }
+
+ // Main driver.
+ public static void main(String[] args) {
+ for (int i = 0; i < 10; i++) {
+ int ei = (i & 1) == 0 ? 1 : 1486662020;
+ int ci = doitUpInt(i);
+ expectEquals(ei, ci);
+ }
+ for (int i = 0; i < 10; i++) {
+ int ei = (i & 1) == 0 ? 1 : 1486662020;
+ int ci = doitDownInt(i);
+ expectEquals(ei, ci);
+ }
+ for (int i = 0; i < 10; i++) {
+ float ef = i == 0 ? 1.0f : ((i & 1) == 0 ? 0.0f : 1486662021.0f);
+ float cf = doitUpFloat(i);
+ expectEquals(ef, cf);
+ }
+ for (int i = 0; i < 10; i++) {
+ float ef = i == 0 ? 1.0f : ((i & 1) == 0 ? 0.0f : 1486662021.0f);
+ float cf = doitDownFloat(i);
+ expectEquals(ef, cf);
+ }
+ for (int i = 0; i < 10; i++) {
+ float ef = (i & 1) == 0 ? 1.0f : 1486662020.0f;
+ float cf = doitUpFloatAlt(i);
+ expectEquals(ef, cf);
+ }
+ for (int i = 0; i < 10; i++) {
+ float ef = (i & 1) == 0 ? 1.0f : 1486662020.0f;
+ float cf = doitDownFloatAlt(i);
+ expectEquals(ef, cf);
+ }
+ System.out.println("passed");
+ }
+
+ private static void expectEquals(int expected, int result) {
+ if (expected != result) {
+ throw new Error("Expected: " + expected + ", found: " + result);
+ }
+ }
+
+ private static void expectEquals(float expected, float result) {
+ if (expected != result) {
+ throw new Error("Expected: " + expected + ", found: " + result);
+ }
+ }
+}
+
+
