8265325: Optimize StubRoutines::dpow() for Math.pow(x, 0.5)
Reviewed-by: kvn, neliasso
diff --git a/src/hotspot/cpu/x86/macroAssembler_x86_pow.cpp b/src/hotspot/cpu/x86/macroAssembler_x86_pow.cpp
index 61f1865..af8c85b 100644
--- a/src/hotspot/cpu/x86/macroAssembler_x86_pow.cpp
+++ b/src/hotspot/cpu/x86/macroAssembler_x86_pow.cpp
@@ -1,5 +1,6 @@
/*
* Copyright (c) 2016, Intel Corporation.
+* Copyright (C) 2021 THL A29 Limited, a Tencent company. All rights reserved.
* Intel Math Library (LIBM) Source Code
*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
@@ -765,6 +766,16 @@
0x00000000UL, 0x40000000UL
};
+ATTRIBUTE_ALIGNED(8) juint _DOUBLE0[] =
+{
+ 0x00000000UL, 0x00000000UL
+};
+
+ATTRIBUTE_ALIGNED(8) juint _DOUBLE0DOT5[] =
+{
+ 0x00000000UL, 0x3fe00000UL
+};
+
//registers,
// input: xmm0, xmm1
// scratch: xmm1, xmm2, xmm3, xmm4, xmm5, xmm6, xmm7
@@ -789,6 +800,7 @@
Label L_2TAG_PACKET_52_0_2, L_2TAG_PACKET_53_0_2, L_2TAG_PACKET_54_0_2, L_2TAG_PACKET_55_0_2;
Label L_2TAG_PACKET_56_0_2;
Label B1_2, B1_3, B1_5, start;
+ Label L_POW;
assert_different_registers(tmp1, tmp2, eax, ecx, edx);
jmp(start);
@@ -804,6 +816,8 @@
address HALFMASK = (address)_HALFMASK;
address log2 = (address)_log2_pow;
address DOUBLE2 = (address)_DOUBLE2;
+ address DOUBLE0 = (address)_DOUBLE0;
+ address DOUBLE0DOT5 = (address)_DOUBLE0DOT5;
bind(start);
@@ -818,7 +832,17 @@
mulsd(xmm0, xmm0);
jmp(B1_5);
+ // Special case: pow(x, 0.5) => sqrt(x)
bind(B1_2);
+ cmp64(tmp1, ExternalAddress(DOUBLE0DOT5));
+ jccb(Assembler::notEqual, L_POW); // For pow(x, y), check whether y == 0.5
+ movdq(tmp2, xmm0);
+ cmp64(tmp2, ExternalAddress(DOUBLE0));
+ jccb(Assembler::less, L_POW); // pow(x, 0.5) => sqrt(x) only for x >= 0.0 or x is +inf/NaN
+ sqrtsd(xmm0, xmm0);
+ jmp(B1_5);
+
+ bind(L_POW);
pextrw(eax, xmm0, 3);
xorpd(xmm2, xmm2);
mov64(tmp2, 0x3ff0000000000000);
diff --git a/test/hotspot/jtreg/compiler/intrinsics/math/TestPow0Dot5Opt.java b/test/hotspot/jtreg/compiler/intrinsics/math/TestPow0Dot5Opt.java
new file mode 100644
index 0000000..9ba042e
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/intrinsics/math/TestPow0Dot5Opt.java
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2021 THL A29 Limited, a Tencent company. 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 8265325
+ * @summary test the optimization of pow(x, 0.5)
+ * @requires os.arch=="amd64" | os.arch=="x86_64"
+ * @run main/othervm TestPow0Dot5Opt
+ * @run main/othervm -Xint TestPow0Dot5Opt
+ * @run main/othervm -Xbatch -XX:TieredStopAtLevel=1 TestPow0Dot5Opt
+ * @run main/othervm -Xbatch -XX:-TieredCompilation TestPow0Dot5Opt
+ */
+
+public class TestPow0Dot5Opt {
+
+ static void test(double a) throws Exception {
+ // pow(x, 0.5) isn't replaced with sqrt(x) for x < 0.0
+ if (a < 0.0) return;
+
+ double r1 = Math.sqrt(a);
+ double r2 = Math.pow(a, 0.5);
+ if (r1 != r2) {
+ throw new RuntimeException("pow(" + a + ", 0.5), expected: " + r1 + ", actual: " + r2);
+ }
+ }
+
+ public static void main(String[] args) throws Exception {
+ for (int i = 0; i < 10; i++) {
+ for (int j = 1; j < 100000; j++) {
+ test(j * 1.0);
+ test(1.0 / j);
+ }
+ }
+
+ test(0.0);
+
+ // Special case: pow(+0.0, 0.5) = 0.0
+ double r = Math.pow(+0.0, 0.5);
+ if (Double.doubleToRawLongBits(r) != Double.doubleToRawLongBits(0.0)) {
+ throw new RuntimeException("pow(+0.0, 0.5), expected: 0.0, actual: " + r);
+ }
+
+ // Special case: pow(-0.0, 0.5) = 0.0
+ r = Math.pow(-0.0, 0.5);
+ if (Double.doubleToRawLongBits(r) != Double.doubleToRawLongBits(0.0)) {
+ throw new RuntimeException("pow(-0.0, 0.5), expected: 0.0, actual: " + r);
+ }
+
+ // Special case: pow(Double.POSITIVE_INFINITY, 0.5) = Infinity
+ r = Math.pow(Double.POSITIVE_INFINITY, 0.5);
+ if (!(r > 0 && Double.isInfinite(r))) {
+ throw new RuntimeException("pow(+Infinity, 0.5), expected: Infinity, actual: " + r);
+ }
+
+ // Special case: pow(Double.NEGATIVE_INFINITY, 0.5) = Infinity
+ r = Math.pow(Double.NEGATIVE_INFINITY, 0.5);
+ if (!(r > 0 && Double.isInfinite(r))) {
+ throw new RuntimeException("pow(-Infinity, 0.5), expected: Infinity, actual: " + r);
+ }
+
+ // Special case: pow(Double.NaN, 0.5) = NaN
+ r = Math.pow(Double.NaN, 0.5);
+ if (!Double.isNaN(r)) {
+ throw new RuntimeException("pow(NaN, 0.5), expected: NaN, actual: " + r);
+ }
+ }
+
+}
diff --git a/test/micro/org/openjdk/bench/java/lang/MathBench.java b/test/micro/org/openjdk/bench/java/lang/MathBench.java
index b010fcd..27d8033 100644
--- a/test/micro/org/openjdk/bench/java/lang/MathBench.java
+++ b/test/micro/org/openjdk/bench/java/lang/MathBench.java
@@ -60,7 +60,7 @@
public int int1 = 1, int2 = 2, int42 = 42, int5 = 5;
public long long1 = 1L, long2 = 2L, long747 = 747L, long13 = 13L;
public float float1 = 1.0f, float2 = 2.0f, floatNegative99 = -99.0f, float7 = 7.0f, eFloat = 2.718f;
- public double double1 = 1.0d, double2 = 2.0d, double81 = 81.0d, doubleNegative12 = -12.0d, double4Dot1 = 4.1d;
+ public double double1 = 1.0d, double2 = 2.0d, double81 = 81.0d, doubleNegative12 = -12.0d, double4Dot1 = 4.1d, double0Dot5 = 0.5d;
@Setup
public void setupValues() {
@@ -409,6 +409,38 @@
}
@Benchmark
+ public double powDoubleLoop() {
+ double sum = 0.0;
+ for (int i = 0; i < 1000; i++) {
+ for (int j = 0; j < 1000; j++) {
+ sum += i + Math.pow(j * 1.0, i * 1.0);
+ }
+ }
+ return sum;
+ }
+
+ @Benchmark
+ public double powDouble0Dot5() {
+ return Math.pow(double4Dot1, double0Dot5);
+ }
+
+ @Benchmark
+ public double powDouble0Dot5Const() {
+ return Math.pow(double4Dot1, 0.5);
+ }
+
+ @Benchmark
+ public double powDouble0Dot5Loop() {
+ double sum = 0.0;
+ for (int i = 0; i < 1000; i++) {
+ for (int j = 0; j < 1000; j++) {
+ sum += i + Math.pow(j * 1.0, 0.5);
+ }
+ }
+ return sum;
+ }
+
+ @Benchmark
public double random() {
return Math.random();
}
