RFR(L): Remove global safepoint code

[Doerr, Martin]

Hi Robbin,

thanks for removing the dead code and for taking care of all platforms.

PPC64 and s390 code looks good and seems to work fine on linux.

Only AIX doesn't build. I suggest to fix it like this:

diff -r efebab2fd109 src/hotspot/os/aix/safepointMechanism_aix.cpp
--- a/src/hotspot/os/aix/safepointMechanism_aix.cpp     Thu Mar 19 13:30:39 2020 +0100
+++ b/src/hotspot/os/aix/safepointMechanism_aix.cpp     Thu Mar 19 14:33:09 2020 +0100
@@ -101,7 +101,9 @@
   MemTracker::record_virtual_memory_reserve_and_commit(map_address, map_size, CALLER_PC, mtSafepoint);

   // Use same page for thread local handshakes without SIGTRAP
-  os::protect_memory(_polling_page, page_size, os::MEM_PROT_NONE);
+  if (!os::guard_memory((char*)_polling_page, page_size)) {
+    fatal("Could not protect polling page");
+  }
   intptr_t bad_page_val  = reinterpret_cast<intptr_t>(map_address),
            good_page_val = bad_page_val + os::vm_page_size();
   _poll_armed_value    = reinterpret_cast<void*>(bad_page_val  + poll_bit());


Thanks and best regards,
Martin



> -----Original Message-----
> From: hotspot-dev <hotspot-dev-bounces at openjdk.java.net> On Behalf Of
> Robbin Ehn
> Sent: Donnerstag, 19. März 2020 13:44
> To: hotspot-dev at openjdk.java.net
> Subject: RFR(L): Remove global safepoint code
> 
> Hi all, please build, test and review.
> 
> We removed (obsoleted) the flag ThreadLocalHandshakes in JDK 14.
> Any platform defining THREAD_LOCAL_POLL can only use per thread poll.
> Since all platforms now define THREAD_LOCAL_POLL the global poll code is
> dead.
> Let's remove it!
> 
> Issue: https://bugs.openjdk.java.net/browse/JDK-8220051
> Changeset:
> http://cr.openjdk.java.net/~rehn/8220051/v1/webrev/index.html
> 
> I have built fastdebug:
> linux-aarch64
> linux-arm32
> linux-ppc64le
> linux-s390x
> linux-x86_64-zero
> linux-x86_64 (no PCH)
> linux-x86_64 (slowdebug) (no PCH)
> linux-x86
> osx-x86_64
> windows-x86_64
> solaris-sparcv9
> 
> Tested t1-5:
> linux-x86_64
> osx-x86_64
> windows-x86_64
> solaris-sparcv9
> 
> Manually:
> linux-aarch64
> linux-x86_64-zero
> 
> Any extra help building and testing is appreciated, especially on arm32,
> ppc64le, s390x.
> 
> Thanks, Robbin