RFR: 8224974: Implement JEP 352

[Andrew Dinn]

HI Vladimir,

Thank you for reviewing the patch.

On 29/05/2019 20:49, Vladimir Kozlov wrote:
> I tried to test these changes and build failed on all systems except
> Linux because:
> 
> workspace/open/src/hotspot/share/prims/unsafe.cpp:446:3: error: use of
> undeclared identifier 'JNU_ThrowRuntimeException'
>    JNU_ThrowRuntimeException(env, "writeback is not implemented");
>    ^

Apologies for that. I forgot to test this via the submit repo after
cut-and-pasting the checks for OS and CPU support from the map0 native
method to the Unsafe writeback method.

I had to make some tweaks to this code anyway in order to spot an issue
Alan noticed when checking the CSR (the map code was not distinguishing
the precise cases where IOException and UnsupportedOperationException
needed to be thrown and would sometimes have replaced the latter with
the former on Windows/x86_64).

I have uploaded a new webrev which attempts to address the problem.

  http://cr.openjdk.java.net/~adinn/8224974/webrev.03

The test to see whether writeback is enabled on the current cpu_os
combination is now performed in Java from methods Unsafe.writebackMemory
and FileChannelImpl.map, using a call to Unsafe.isWritebackEnabled()

There are also 'belt and braces' checks in the corresponding native
implementation methods:

Unsafe asserts that VM_Version::supports_data_cache_line_writeback()
returns true. The result of this method indicates whether support is
available on both CPU and OS. It returns a value computed using a call
to a new OS-specific method os::supports_map_sync() and, on hardware for
which that is true (AArch64 and x86_64), a test of the relevant CPU
status bits.

FileChannelImpl still relies on conditional compilation to reject calls
on invalid OS/CPU combinations (the VM_VERSION method is not available
for it to call). In the branch for !LINUX || !(AArch64 || amd64) it
throws an InternalError as this path not be reached.

Unfortunately, this latest webrev still fails when uploaded to the
submit repo. The problem seems to be specific to Windows/x86_64 builds.
The branch that failed is JDK-8224974-03. The returned text is appended
after my signature. Would you be able to provide some details about the
errors?

> ------------------------------------------------------------
> Also Graal test should be fixed for new intrinsics (add them to
> 'toBeInvestigated' for isJDK13orHigher):
> 
> src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot.test/src/org/graalvm/compiler/hotspot/test/CheckGraalIntrinsics.java
That has been fixed in the webrev mentioned above.

regards,


Andrew Dinn
-----------
Senior Principal Software Engineer
Red Hat UK Ltd
Registered in England and Wales under Company Registration No. 03798903
Directors: Michael Cunningham, Michael ("Mike") O'Neill, Eric Shander


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BuildId: 2019-05-30-1509485.adinn.source
No failed tests
Tasks Summary

    UNABLE_TO_RUN: 18
    NOTHING_TO_RUN: 0
    KILLED: 0
    EXECUTED_WITH_FAILURE: 4
    FAILED: 0
    HARNESS_ERROR: 0
    NA: 0
    PASSED: 55
    Build

        1 Unable to run
            windows-x64-install-windows-x64-build-19 Dependency task
failed: mach5...1512-2804499-windows-x64-windows-x64-build-12
        4 Executed with failure
            windows-x64-windows-x64-build-12 error while building,
return value: 2
            windows-x64-debug-windows-x64-build-13 error while building,
return value: 2
            windows-x64-open-windows-x64-build-14 error while building,
return value: 2
            windows-x64-open-debug-windows-x64-build-15 error while
building, return value: 2

    Test

        17 Unable to run

tier1-product-open_test_hotspot_jtreg_tier1_common-windows-x64-22
Dependency task failed:
mach5...1512-2804499-windows-x64-windows-x64-build-12

tier1-debug-open_test_hotspot_jtreg_tier1_common-windows-x64-debug-28
Dependency task failed:
mach5...804499-windows-x64-debug-windows-x64-build-13

tier1-debug-open_test_hotspot_jtreg_tier1_compiler_1-windows-x64-debug-31 Dependency
task failed: mach5...804499-windows-x64-debug-windows-x64-build-13

tier1-debug-open_test_hotspot_jtreg_tier1_compiler_2-windows-x64-debug-34 Dependency
task failed: mach5...804499-windows-x64-debug-windows-x64-build-13

tier1-debug-open_test_hotspot_jtreg_tier1_compiler_3-windows-x64-debug-37 Dependency
task failed: mach5...804499-windows-x64-debug-windows-x64-build-13

tier1-debug-open_test_hotspot_jtreg_tier1_compiler_not_xcomp-windows-x64-debug-40
Dependency task failed:
mach5...804499-windows-x64-debug-windows-x64-build-13

tier1-debug-open_test_hotspot_jtreg_tier1_gc_1-windows-x64-debug-43
Dependency task failed:
mach5...804499-windows-x64-debug-windows-x64-build-13

tier1-debug-open_test_hotspot_jtreg_tier1_gc_2-windows-x64-debug-46
Dependency task failed:
mach5...804499-windows-x64-debug-windows-x64-build-13

tier1-product-open_test_hotspot_jtreg_tier1_gc_gcbasher-windows-x64-25
Dependency task failed:
mach5...1512-2804499-windows-x64-windows-x64-build-12

tier1-debug-open_test_hotspot_jtreg_tier1_gc_gcbasher-windows-x64-debug-49
Dependency task failed:
mach5...804499-windows-x64-debug-windows-x64-build-13
            See all 17...