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Add SVE, SVE2, SVEBITPERM, and FP16 feature detection on Windows/ARM64 #55

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37 changes: 37 additions & 0 deletions src/hotspot/os_cpu/windows_aarch64/sve_helper_windows_aarch64.S
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Original file line number Diff line number Diff line change
@@ -0,0 +1,37 @@
; Copyright (c) 2026, 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.
;

; int get_sve_vector_length_impl(void);
;
; Returns the current SVE vector length in bytes.
; Uses the RDVL instruction which returns imm * VL in bytes.
; With imm=1 this gives the SVE vector length directly.

ALIGN 4
EXPORT get_sve_vector_length_impl
AREA sve_helper_text, CODE, READONLY

get_sve_vector_length_impl
rdvl x0, 1
ret

END
54 changes: 49 additions & 5 deletions src/hotspot/os_cpu/windows_aarch64/vm_version_windows_aarch64.cpp
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Expand Up @@ -26,32 +26,76 @@
#include "runtime/os.hpp"
#include "runtime/vm_version.hpp"

// Since PF_ARM_SVE_INSTRUCTIONS_AVAILABLE and related constants were added in
// Windows 11 (version 24H2) and in Windows Server 2025, we define them here for
// compatibility with older SDK versions.
#ifndef PF_ARM_SVE_INSTRUCTIONS_AVAILABLE
#define PF_ARM_SVE_INSTRUCTIONS_AVAILABLE 46
#endif

#ifndef PF_ARM_SVE2_INSTRUCTIONS_AVAILABLE
#define PF_ARM_SVE2_INSTRUCTIONS_AVAILABLE 47
#endif

#ifndef PF_ARM_SVE_BITPERM_INSTRUCTIONS_AVAILABLE
#define PF_ARM_SVE_BITPERM_INSTRUCTIONS_AVAILABLE 51
#endif

#ifndef PF_ARM_V82_FP16_INSTRUCTIONS_AVAILABLE
#define PF_ARM_V82_FP16_INSTRUCTIONS_AVAILABLE 67
#endif

// Assembly helper implemented in sve_helper_windows_aarch64.S. Executes the
// RDVL instruction to return the vector length in bytes.
extern "C" int get_sve_vector_length_impl(void);

int VM_Version::get_current_sve_vector_length() {
assert(VM_Version::supports_sve(), "should not call this");
ShouldNotReachHere();
return 0;
return get_sve_vector_length_impl();
}

int VM_Version::set_and_get_current_sve_vector_length(int length) {
assert(VM_Version::supports_sve(), "should not call this");
ShouldNotReachHere();
return 0;

// Unlike Linux, Windows does not present a way to modify the VL (the
// rationale is that the OS expects the application to use the maximum vector
// length supported by the hardware), so we simply return the current VL. The
// caller (`VM_Version::initialize()`) will print a warning and move on.
return get_sve_vector_length_impl();
}

void VM_Version::get_os_cpu_info() {

if (IsProcessorFeaturePresent(PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE)) {
set_feature(CPU_CRC32);
}

if (IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE)) {
set_feature(CPU_AES);
set_feature(CPU_SHA1);
set_feature(CPU_SHA2);
}

if (IsProcessorFeaturePresent(PF_ARM_VFP_32_REGISTERS_AVAILABLE)) {
set_feature(CPU_ASIMD);
}
// No check for CPU_PMULL, CPU_SVE, CPU_SVE2

if (IsProcessorFeaturePresent(PF_ARM_SVE_INSTRUCTIONS_AVAILABLE)) {
set_feature(CPU_SVE);
}

if (IsProcessorFeaturePresent(PF_ARM_SVE2_INSTRUCTIONS_AVAILABLE)) {
set_feature(CPU_SVE2);
}

if (IsProcessorFeaturePresent(PF_ARM_SVE_BITPERM_INSTRUCTIONS_AVAILABLE)) {
set_feature(CPU_SVEBITPERM);
}

if (IsProcessorFeaturePresent(PF_ARM_V82_FP16_INSTRUCTIONS_AVAILABLE)) {
set_feature(CPU_FPHP);
set_feature(CPU_ASIMDHP);
}

__int64 dczid_el0 = _ReadStatusReg(0x5807 /* ARM64_DCZID_EL0 */);

Expand Down
189 changes: 189 additions & 0 deletions test/hotspot/jtreg/compiler/c2/aarch64/TestSVEFeatureDetection.java
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@@ -0,0 +1,189 @@
/*
* Copyright (c) 2025, 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
* @summary Verify SVE/SVE2 feature detection for both Windows and Linux.
*
* @requires os.arch == "aarch64" & vm.compiler2.enabled
* @library /test/lib /
* @build jdk.test.whitebox.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller
* jdk.test.whitebox.WhiteBox
*
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions
* -XX:+WhiteBoxAPI compiler.c2.aarch64.TestSVEFeatureDetection
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@raneashay raneashay Mar 31, 2026

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Inspect other similar tests that use multiple @run lines. This might help with removing an explicit driver.

*/

package compiler.c2.aarch64;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import jdk.test.lib.Asserts;
import jdk.test.lib.process.ProcessTools;
import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.whitebox.WhiteBox;

public class TestSVEFeatureDetection {
private static final WhiteBox WB = WhiteBox.getWhiteBox();
private static final String KEY_USE_SVE = "UseSVE=";
private static final String KEY_MAX_VECTOR = "MaxVectorSize=";
private static final String KEY_HAS_SVE = "has_sve=";
private static final String KEY_HAS_SVE2 = "has_sve2=";

public static void main(String[] args) throws Exception {
if (args.length > 0 && args[0].equals("flagCheck")) {
printFlags();
} else {
runDriver();
}
}

private static void printFlags() {
int sveLevel = WB.getUintVMFlag("UseSVE").intValue();
long maxVectorSize = WB.getIntxVMFlag("MaxVectorSize");
List<String> features = Arrays.asList(WB.getCPUFeatures().split(", "));
boolean hasSve = features.contains("sve");
boolean hasSve2 = features.contains("sve2");

System.out.println(KEY_USE_SVE + sveLevel);
System.out.println(KEY_MAX_VECTOR + maxVectorSize);
System.out.println(KEY_HAS_SVE + hasSve);
System.out.println(KEY_HAS_SVE2 + hasSve2);
}

private static void runDriver() throws Exception {
int sveLevel = WB.getUintVMFlag("UseSVE").intValue();
long maxVectorSize = WB.getIntxVMFlag("MaxVectorSize");
List<String> features = Arrays.asList(WB.getCPUFeatures().split(", "));
boolean hasSve = features.contains("sve");
boolean hasSve2 = features.contains("sve2");

// If SVE is not present, just verify a consistent disabled state.
if (!hasSve) {
Asserts.assertEquals(sveLevel, 0,
"UseSVE must be 0 when hardware lacks SVE");
Asserts.assertFalse(hasSve2,
"sve2 must be absent when sve is absent");
return;
}

Asserts.assertTrue(sveLevel > 0,
"UseSVE should be auto-set to > 0 when SVE hardware is present");
Asserts.assertTrue(maxVectorSize >= 16,
"MaxVectorSize must be >= 16 for SVE, got " + maxVectorSize);
Asserts.assertTrue(Long.bitCount(maxVectorSize) == 1,
"MaxVectorSize must be a power of two, got " + maxVectorSize);
Asserts.assertTrue(maxVectorSize % 16 == 0,
"MaxVectorSize must be a multiple of 16, got " + maxVectorSize);
Asserts.assertTrue(maxVectorSize <= 256,
"MaxVectorSize must be <= 256 (2048 bits), got " + maxVectorSize);

if (hasSve2) {
Asserts.assertEquals(sveLevel, 2,
"UseSVE should be 2 when hardware supports SVE2");
} else {
Asserts.assertEquals(sveLevel, 1,
"UseSVE should be 1 when hardware supports SVE but not SVE2");
}

OutputAnalyzer out = spawnFlagCheck("-XX:UseSVE=0");
out.shouldHaveExitValue(0);
out.shouldContain(KEY_USE_SVE + "0");
out.shouldContain(KEY_HAS_SVE + "false");
out.shouldContain(KEY_HAS_SVE2 + "false");

out = spawnFlagCheck("-XX:UseSVE=1", "-XX:MaxVectorSize=512");
out.shouldHaveExitValue(0);
out.shouldContain("warning");

boolean isWindows = System.getProperty("os.name").toLowerCase().contains("windows");
out = spawnFlagCheck("-XX:UseSVE=1", "-XX:MaxVectorSize=16");
out.shouldHaveExitValue(0);
if (isWindows && maxVectorSize > 16) {
out.shouldContain("warning");
out.shouldContain(KEY_MAX_VECTOR + maxVectorSize);
} else {
out.shouldContain(KEY_MAX_VECTOR + "16");
}

if (hasSve2) {
out = spawnFlagCheck("-XX:UseSVE=2");
out.shouldHaveExitValue(0);
out.shouldContain(KEY_USE_SVE + "2");
out.shouldContain(KEY_HAS_SVE + "true");
out.shouldContain(KEY_HAS_SVE2 + "true");

out = spawnFlagCheck("-XX:UseSVE=1");
out.shouldHaveExitValue(0);
out.shouldContain(KEY_USE_SVE + "1");
out.shouldContain(KEY_HAS_SVE + "true");
out.shouldContain(KEY_HAS_SVE2 + "false");
} else {
out = spawnFlagCheck("-XX:UseSVE=2");
out.shouldHaveExitValue(0);
out.shouldContain("SVE2 specified, but not supported on current CPU");
out.shouldContain(KEY_USE_SVE + "1");
out.shouldContain(KEY_HAS_SVE + "true");
out.shouldContain(KEY_HAS_SVE2 + "false");
}

out = spawnFlagCheck("-XX:UseSVE=1");
out.shouldHaveExitValue(0);
out.shouldContain(KEY_USE_SVE + "1");
out.shouldContain(KEY_HAS_SVE + "true");
out.shouldMatch("MaxVectorSize=\\d+");

if (maxVectorSize >= 32) {
out = spawnFlagCheck("-XX:UseSVE=1", "-XX:MaxVectorSize=32");
out.shouldHaveExitValue(0);
if (isWindows && maxVectorSize > 32) {
out.shouldContain("warning");
out.shouldContain(KEY_MAX_VECTOR + maxVectorSize);
} else {
out.shouldContain(KEY_MAX_VECTOR + "32");
}
}
}

private static OutputAnalyzer spawnFlagCheck(String... extraFlags)
throws Exception {
List<String> args = new ArrayList<>();
args.add("-Xbootclasspath/a:.");
args.add("-XX:+UnlockDiagnosticVMOptions");
args.add("-XX:+WhiteBoxAPI");
for (String f : extraFlags) {
args.add(f);
}
args.add(TestSVEFeatureDetection.class.getName());
args.add("flagCheck");

ProcessBuilder pb = ProcessTools.createLimitedTestJavaProcessBuilder(
args.toArray(new String[0]));
OutputAnalyzer output = new OutputAnalyzer(pb.start());
output.reportDiagnosticSummary();
return output;
}
}
16 changes: 12 additions & 4 deletions test/hotspot/jtreg/compiler/c2/irTests/TestFloat16ScalarOperations.java
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Expand Up @@ -714,9 +714,13 @@ public void testSqrtConstantFolding() {

@Test
@IR(counts = {IRNode.FMA_HF, " 0 ", IRNode.REINTERPRET_S2HF, " 0 ", IRNode.REINTERPRET_HF2S, " 0 "},
applyIfCPUFeatureOr = {"avx512_fp16", "true", "zfh", "true"})
applyIfCPUFeatureOr = {"avx512_fp16", "true", "zfh", "true"},
// On Windows, both GCC and MSVC don't set __STDC_IEC_559__, so FMAs on constants are not folded.
applyIfPlatform = {"windows", "false"})
@IR(counts = {IRNode.FMA_HF, " 0 ", IRNode.REINTERPRET_S2HF, " 0 ", IRNode.REINTERPRET_HF2S, " 0 "},
applyIfCPUFeatureAnd = {"fphp", "true", "asimdhp", "true"})
applyIfCPUFeatureAnd = {"fphp", "true", "asimdhp", "true"},
// On Windows, both GCC and MSVC don't set __STDC_IEC_559__, so FMAs on constants are not folded.
applyIfPlatform = {"windows", "false"})
@Warmup(10000)
public void testFMAConstantFolding() {
// If any argument is NaN, the result is NaN.
Expand Down Expand Up @@ -752,9 +756,13 @@ public void testFMAConstantFolding() {

@Test
@IR(failOn = {IRNode.ADD_HF, IRNode.SUB_HF, IRNode.MUL_HF, IRNode.DIV_HF, IRNode.SQRT_HF, IRNode.FMA_HF},
applyIfCPUFeatureOr = {"avx512_fp16", "true", "zfh", "true"})
applyIfCPUFeatureOr = {"avx512_fp16", "true", "zfh", "true"},
// On Windows, both GCC and MSVC don't set __STDC_IEC_559__, so FMAs on constants are not folded.
applyIfPlatform = {"windows", "false"})
@IR(failOn = {IRNode.ADD_HF, IRNode.SUB_HF, IRNode.MUL_HF, IRNode.DIV_HF, IRNode.SQRT_HF, IRNode.FMA_HF},
applyIfCPUFeatureAnd = {"fphp", "true", "asimdhp", "true"})
applyIfCPUFeatureAnd = {"fphp", "true", "asimdhp", "true"},
// On Windows, both GCC and MSVC don't set __STDC_IEC_559__, so FMAs on constants are not folded.
applyIfPlatform = {"windows", "false"})
@Warmup(10000)
public void testRounding1() {
dst[0] = float16ToRawShortBits(add(RANDOM1, RANDOM2));
Expand Down
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