8003585: strength reduce or eliminate range checks for power-of-two sized arrays
Summary: change ((x & m) u<= m) to always true and ((x & (m - 1)) u< m) into (m > 0)
Reviewed-by: kvn, roland
--- a/hotspot/src/share/vm/opto/addnode.cpp Mon Feb 01 19:45:26 2016 +0300
+++ b/hotspot/src/share/vm/opto/addnode.cpp Tue Jan 19 14:52:33 2016 +0100
@@ -61,7 +61,7 @@
//------------------------------commute----------------------------------------
// Commute operands to move loads and constants to the right.
-static bool commute( Node *add, int con_left, int con_right ) {
+static bool commute(Node *add, bool con_left, bool con_right) {
Node *in1 = add->in(1);
Node *in2 = add->in(2);
@@ -110,8 +110,8 @@
Node *AddNode::Ideal(PhaseGVN *phase, bool can_reshape) {
const Type *t1 = phase->type( in(1) );
const Type *t2 = phase->type( in(2) );
- int con_left = t1->singleton();
- int con_right = t2->singleton();
+ bool con_left = t1->singleton();
+ bool con_right = t2->singleton();
// Check for commutative operation desired
if( commute(this,con_left,con_right) ) return this;
--- a/hotspot/src/share/vm/opto/subnode.cpp Mon Feb 01 19:45:26 2016 +0300
+++ b/hotspot/src/share/vm/opto/subnode.cpp Tue Jan 19 14:52:33 2016 +0100
@@ -1334,6 +1334,65 @@
return new BoolNode( ncmp, _test.negate() );
}
+ // Change ((x & m) u<= m) or ((m & x) u<= m) to always true
+ // Same with ((x & m) u< m+1) and ((m & x) u< m+1)
+ if (cop == Op_CmpU &&
+ cmp1->Opcode() == Op_AndI) {
+ Node* bound = NULL;
+ if (_test._test == BoolTest::le) {
+ bound = cmp2;
+ } else if (_test._test == BoolTest::lt &&
+ cmp2->Opcode() == Op_AddI &&
+ cmp2->in(2)->find_int_con(0) == 1) {
+ bound = cmp2->in(1);
+ }
+ if (cmp1->in(2) == bound || cmp1->in(1) == bound) {
+ return ConINode::make(1);
+ }
+ }
+
+ // Change ((x & (m - 1)) u< m) into (m > 0)
+ // This is the off-by-one variant of the above
+ if (cop == Op_CmpU &&
+ _test._test == BoolTest::lt &&
+ cmp1->Opcode() == Op_AndI) {
+ Node* l = cmp1->in(1);
+ Node* r = cmp1->in(2);
+ for (int repeat = 0; repeat < 2; repeat++) {
+ bool match = r->Opcode() == Op_AddI && r->in(2)->find_int_con(0) == -1 &&
+ r->in(1) == cmp2;
+ if (match) {
+ // arraylength known to be non-negative, so a (arraylength != 0) is sufficient,
+ // but to be compatible with the array range check pattern, use (arraylength u> 0)
+ Node* ncmp = cmp2->Opcode() == Op_LoadRange
+ ? phase->transform(new CmpUNode(cmp2, phase->intcon(0)))
+ : phase->transform(new CmpINode(cmp2, phase->intcon(0)));
+ return new BoolNode(ncmp, BoolTest::gt);
+ } else {
+ // commute and try again
+ l = cmp1->in(2);
+ r = cmp1->in(1);
+ }
+ }
+ }
+
+ // Change (arraylength <= 0) or (arraylength == 0)
+ // into (arraylength u<= 0)
+ // Also change (arraylength != 0) into (arraylength u> 0)
+ // The latter version matches the code pattern generated for
+ // array range checks, which will more likely be optimized later.
+ if (cop == Op_CmpI &&
+ cmp1->Opcode() == Op_LoadRange &&
+ cmp2->find_int_con(-1) == 0) {
+ if (_test._test == BoolTest::le || _test._test == BoolTest::eq) {
+ Node* ncmp = phase->transform(new CmpUNode(cmp1, cmp2));
+ return new BoolNode(ncmp, BoolTest::le);
+ } else if (_test._test == BoolTest::ne) {
+ Node* ncmp = phase->transform(new CmpUNode(cmp1, cmp2));
+ return new BoolNode(ncmp, BoolTest::gt);
+ }
+ }
+
// Change "bool eq/ne (cmp (Conv2B X) 0)" into "bool eq/ne (cmp X 0)".
// This is a standard idiom for branching on a boolean value.
Node *c2b = cmp1;
@@ -1496,4 +1555,3 @@
double d = t1->getd();
return TypeD::make( StubRoutines::intrinsic_log10( d ) );
}
-
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/compiler/rangechecks/PowerOf2SizedArraysChecks.java Tue Jan 19 14:52:33 2016 +0100
@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 8003585
+ * @summary strength reduce or eliminate range checks for power-of-two sized arrays
+ * @run main/othervm -XX:CompileCommand=compileonly,PowerOf2SizedArraysChecks::test* -XX:-BackgroundCompilation PowerOf2SizedArraysChecks
+ *
+ */
+
+import java.util.function.*;
+
+public class PowerOf2SizedArraysChecks {
+
+ static void check_result(String name, int x, int m, boolean expected, boolean res) {
+ if (expected != res) {
+ throw new RuntimeException("Bad result in " + name + " for x = " + x + " m = " + m + " expected " + expected + " got " + res);
+ }
+ }
+
+ static void helper(String name, BiFunction<Integer, int[], Boolean> test, int[] x_values, int[] m_values, boolean[][] expected) {
+ for (int i = 0; i < x_values.length; i++) {
+ int x = x_values[i];
+ for (int j = 0; j < m_values.length; j++) {
+ int m = m_values[j];
+ int[] array = new int[m];
+ boolean res = test.apply(x, array);
+ check_result(name, x, m, expected[i][j], res);
+ }
+ }
+ }
+
+ static void check_result(String name, int m, boolean expected, boolean res) {
+ if (expected != res) {
+ throw new RuntimeException("Bad result in " + name + " for m = " + m + " expected " + expected + " got " + res);
+ }
+ }
+
+ static void helper2(String name, Function<int[], Boolean> test, int[] m_values, boolean[] expected) {
+ for (int j = 0; j < m_values.length; j++) {
+ int m = m_values[j];
+ int[] array = new int[m];
+ boolean res = test.apply(array);
+ check_result(name, m, expected[j], res);
+ }
+ }
+
+ // ((x & m) u<= m) is always true
+ static boolean test1(int x, int[] array) {
+ int m = array.length;
+ if ((x & m) < 0 || (x & m) > m) {
+ return false;
+ }
+ return true;
+ }
+
+ // ((x & (m - 1)) u< m) iff (m > 0)
+ static boolean test2(int x, int[] array) {
+ int m = array.length;
+ if ((x & (m-1)) < 0 || (x & (m-1)) >= m) {
+ return false;
+ }
+ return true;
+ }
+
+ static boolean test3(int x, int[] array) {
+ try {
+ int v = array[x & (array.length-1)];
+ } catch(ArrayIndexOutOfBoundsException aioobe) {
+ return false;
+ }
+ return true;
+ }
+
+ // arraylength <= 0 to arraylength u<= 0
+ static boolean test4(int[] array) {
+ if (array.length <= 0) {
+ return false;
+ }
+ return true;
+ }
+
+ // arraylength == 0 to arraylength u<= 0
+ static boolean test5(int[] array) {
+ if (array.length == 0) {
+ return false;
+ }
+ return true;
+ }
+
+ // arraylength != 0 to arraylength u> 0
+ static boolean test6(int[] array) {
+ if (array.length != 0) {
+ return false;
+ }
+ return true;
+ }
+
+ static public void main(String[] args) {
+ int[] x_values = {-10, -5, 0, 5, 8, 16, 100};
+ int[] m_values = { 16, 10, 0 };
+
+ boolean[][] test1_expected = new boolean[x_values.length][m_values.length];
+ for (int i = 0; i < x_values.length; i++) {
+ for (int j = 0; j < m_values.length; j++) {
+ test1_expected[i][j] = true;
+ }
+ }
+
+ boolean[][] test2_expected = new boolean[x_values.length][m_values.length];
+ for (int i = 0; i < x_values.length; i++) {
+ for (int j = 0; j < m_values.length; j++) {
+ test2_expected[i][j] = (m_values[j] > 0);
+ }
+ }
+
+ boolean[] test4_expected = new boolean[m_values.length];
+ for (int i = 0; i < m_values.length; i++) {
+ test4_expected[i] = (m_values[i] > 0);
+ }
+ boolean[] test5_expected = new boolean[m_values.length];
+ for (int i = 0; i < m_values.length; i++) {
+ test5_expected[i] = (m_values[i] != 0);
+ }
+ boolean[] test6_expected = new boolean[m_values.length];
+ for (int i = 0; i < m_values.length; i++) {
+ test6_expected[i] = (m_values[i] == 0);
+ }
+
+ for (int i = 0; i < 20000; i++) {
+ helper("test1", PowerOf2SizedArraysChecks::test1, x_values, m_values, test1_expected);
+ helper("test2", PowerOf2SizedArraysChecks::test2, x_values, m_values, test2_expected);
+ helper("test3", PowerOf2SizedArraysChecks::test3, x_values, m_values, test2_expected);
+ helper2("test4", PowerOf2SizedArraysChecks::test4, m_values, test4_expected);
+ helper2("test5", PowerOf2SizedArraysChecks::test5, m_values, test5_expected);
+ helper2("test6", PowerOf2SizedArraysChecks::test6, m_values, test6_expected);
+ }
+ }
+}