[SYCL] Add support for discard access modes - #89

  CONFLICT (content): Merge conflict in clang/tools/clang-offload-bundler/ClangOffloadBundler.cpp

Apply the change of fc83fc7 ("updated built-in variable names to match
LLVM for SPIR-V documentation (issue intel#89)", 2016-03-14) to the script
generating `SPIRVNameMapEnum.h`, such that the output of the script
for builtins is aligned with the current code.

This PR adds support for thread names in lldb on Windows.

```
(lldb) thr list
Process 2960 stopped
  thread #53: tid = 0x03a0, 0x00007ff84582db34 ntdll.dll`NtWaitForMultipleObjects + 20
  thread #29: tid = 0x04ec, 0x00007ff845830a14 ntdll.dll`NtWaitForAlertByThreadId + 20, name = 'SPUW.6'
  thread #89: tid = 0x057c, 0x00007ff845830a14 ntdll.dll`NtWaitForAlertByThreadId + 20, name = 'PPU[0x1000019] physics[main]'
  thread #3: tid = 0x0648, 0x00007ff843c2cafe combase.dll`InternalDoATClassCreate + 39518
  thread #93: tid = 0x0688, 0x00007ff845830a14 ntdll.dll`NtWaitForAlertByThreadId + 20, name = 'PPU[0x100501d] uMovie::StreamingThread'
  thread #1: tid = 0x087c, 0x00007ff842e7a104 win32u.dll`NtUserMsgWaitForMultipleObjectsEx + 20
  thread #96: tid = 0x0890, 0x00007ff845830a14 ntdll.dll`NtWaitForAlertByThreadId + 20, name = 'PPU[0x1002020] HLE Video Decoder'
<...>
```

…iltin

[compiler] Update lit tests to use mux builtins

Summary

This builds on the accelerator plugin protocol
(llvm/llvm-project#201489) by letting a plugin
ask the client to create and connect a second
target — the mechanism a real backend (e.g. a GPU debug stub) uses to
surface
  the accelerator alongside the CPU process being debugged.

  ### What this adds

**Protocol** — a new `AcceleratorConnectionInfo` describing how the
client
  should bring up the accelerator target.

  **Client** — when an `AcceleratorActions` carries `connect_info`,
`ProcessGDBRemote` creates a new (empty) target, reverse-connects it to
the GDB
  server the plugin points.

  **Mock server (for testing)** — to exercise this end to end, the mock
accelerator plugin stands up an in-process GDB server backed by a
minimal fake
process: `ProcessMockAccelerator`, `ThreadMockAccelerator` and
`RegisterContextMockAccelerator`.

  ### Scope

Intentionally minimal: the goal is to create and show the second
(accelerator)
target. There is no register/memory modeling beyond what a connection
requires. Next set of PRs will build up on this.

  ### Testing


Demo of how this looks with this PR. (explicitly asking the native
process to stop at every breakpoint for testability)

```
satyajanga@devgpu011:toolchain $ ./bin/lldb
(lldb) file /home/satyajanga/llvm-sand/build/Debug/fbcode-x86_64/toolchain/lldb-test-build.noindex/accelerator/mock/TestMockAcceleratorActions/a.out                                     Current executable set to '/home/satyajanga/llvm-sand/build/Debug/fbcode-x86_64/toolchain/lldb-test-build.noindex/accelerator/mock/TestMockAcceleratorActions/a.out' (x86_64).
(lldb) log enable -f /tmp/packets.log gdb-remote packets                                                                                                                                 (lldb) r
Process 1430531 launched: '/home/satyajanga/llvm-sand/build/Debug/fbcode-x86_64/toolchain/lldb-test-build.noindex/accelerator/mock/TestMockAcceleratorActions/a.out' (x86_64)
Process 1430531 stopped
(lldb) target list
Current targets:
* target #0: /home/satyajanga/llvm-sand/build/Debug/fbcode-x86_64/toolchain/lldb-test-build.noindex/accelerator/mock/TestMockAcceleratorActions/a.out ( arch=x86_64-unknown-linux-gnu, platform=host, pid=1430531, state=stopped )
(lldb) c
Process 1430531 resuming
Process 1 stopped
* thread #1, name = 'Mock Accelerator Thread', stop reason = trace
       frame #0: 0x0000000000001004
error: memory read failed for 0x1000
Target 0: (a.out) stopped.
(lldb) target list
Current targets:
  target #0: /home/satyajanga/llvm-sand/build/Debug/fbcode-x86_64/toolchain/lldb-test-build.noindex/accelerator/mock/TestMockAcceleratorActions/a.out ( arch=x86_64-unknown-linux-gnu, platform=host, pid=1430531, state=stopped )
* target #1: <none> ( arch=x86_64-unknown-linux-gnu, platform=host, pid=1, state=stopped )
(lldb) c
Process 1 resuming
(lldb) target select 0
Current targets:
* target #0: /home/satyajanga/llvm-sand/build/Debug/fbcode-x86_64/toolchain/lldb-test-build.noindex/accelerator/mock/TestMockAcceleratorActions/a.out ( arch=x86_64-unknown-linux-gnu, platform=host, pid=1430531, state=stopped )
  target #1: <none> ( arch=x86_64-unknown-linux-gnu, platform=host, pid=1, state=running )
(lldb) c
Process 1430531 resuming
Process 1430531 stopped
(lldb) target list
Current targets:
* target #0: /home/satyajanga/llvm-sand/build/Debug/fbcode-x86_64/toolchain/lldb-test-build.noindex/accelerator/mock/TestMockAcceleratorActions/a.out ( arch=x86_64-unknown-linux-gnu, platform=host, pid=1430531, state=stopped )
  target #1: <none> ( arch=x86_64-unknown-linux-gnu, platform=host, pid=1, state=running )
(lldb)
a.out │ internal accelerator-plugin (mock) breakpoint(-4).
```

Packet log, 
you can notice the actions set with breakpoint info and later responding
with connection info. and you can also see the 5 GPRs

```
lldb             < 104> send packet: $qSupported:xmlRegisters=i386,arm,mips,arc;multiprocess+;fork-events+;vfork-events+;swbreak+;hwbreak+#cd
lldb             < 299> read packet: $PacketSize=131072;QStartNoAckMode+;qEcho+;native-signals+;QThreadSuffixSupported+;QListThreadsInStopReply+;qXfer:features:read+;QNonStop+;jMultiBreakpoint+;QPassSignals+;qXfer:auxv:read+;qXfer:libraries-svr4:read+;qXfer:siginfo:read+;accelerator-plugins+;multiprocess+;fork-events+;vfork-events+#86
..
lldb             <  32> send packet: $jAcceleratorPluginInitialize#50
lldb             < 238> read packet: $[{"breakpoints":[{"by_address":null,"by_name":{"function_name":"mock_gpu_accelerator_initialize","shlib":null}],"identifier":1,"symbol_names":["mock_gpu_accelerator_compute"]}]],"identifier":1,"plugin_name":"mock","session_name":""}]]#2f
..
intern-state     < 314> send packet: $jAcceleratorPluginBreakpointHit:{"breakpoint":{"by_address":null,"by_name":{"function_name":"mock_gpu_accelerator_initialize","shlib":null}],"identifier":1,"symbol_names":["mock_gpu_accelerator_compute"]}],"plugin_name":"mock","symbol_values":[{"name":"mock_gpu_accelerator_compute","value":93824992235840}]]}]#e7
intern-state     < 487> read packet: ${"actions":{"breakpoints":[{"by_address":null,"by_name":{"function_name":"mock_gpu_accelerator_finish","shlib":"a.out"}],"identifier":3,"symbol_names":[]}],{"by_address":{"load_address":93824992235840}],"by_name":null,"identifier":2,"symbol_names":[]}],{"by_address":null,"by_name":{"function_name":"mock_gpu_accelerator_connect","shlib":null}],"identifier":4,"symbol_names":[]}]],"identifier":2,"plugin_name":"mock","session_name":""}],"auto_resume_native":false,"disable_bp":true}]#7d
..
..
intern-state     < 218> send packet: $jAcceleratorPluginBreakpointHit:{"breakpoint":{"by_address":null,"by_name":{"function_name":"mock_gpu_accelerator_connect","shlib":null}],"identifier":4,"symbol_names":[]}],"plugin_name":"mock","symbol_values":[]}]#d1
intern-state     < 268> read packet: ${"actions":{"breakpoints":[],"connect_info":{"connect_url":"connect://localhost:32893","exe_path":null,"synchronous":true,"triple":null}],"identifier":4,"plugin_name":"mock","session_name":"Mock Accelerator Session"}],"auto_resume_native":false,"disable_bp":true}]#8e
intern-state     <   1> send packet: +
intern-state     history[1] tid=0x15d41f <   1> send packet: +
intern-state     <  19> send packet: $QStartNoAckMode#b0
intern-state     <   1> read packet: +
intern-state     <   6> read packet: $OK#9a
intern-state     <   1> send packet: +
intern-state     < 104> send packet: $qSupported:xmlRegisters=i386,arm,mips,arc;multiprocess+;fork-events+;vfork-events+;swbreak+;hwbreak+#cd
intern-state     < 159> read packet: $PacketSize=131072;QStartNoAckMode+;qEcho+;native-signals+;QThreadSuffixSupported+;QListThreadsInStopReply+;qXfer:features:read+;QNonStop+;jMultiBreakpoint+#f3
intern-state     <  26> send packet: $QThreadSuffixSupported#e4
intern-state     <   6> read packet: $OK#9a
intern-state     <  27> send packet: $QListThreadsInStopReply#21
intern-state     <   6> read packet: $OK#9a
intern-state     <  13> send packet: $qHostInfo#9b
intern-state     < 364> read packet: $triple:7838365f36342d2d6c696e75782d676e75;ptrsize:8;watchpoint_exceptions_received:after;endian:little;os_version:6.13.2;os_build:362e31332e322d305f66626b355f
68617264656e65645f7263325f305f67313733613962316463613431;os_kernel:233120534d5020576564204a756c2032332030393a32343a3330205044542032303235;hostname:6465766770753031312e656167322e66616365626f6f6b2e6
36f6d;#c4
intern-state     <  10> send packet: $vCont?#49
intern-state     <  19> read packet: $vCont;c;C;s;S;t#11
intern-state     <  27> send packet: $qVAttachOrWaitSupported#38
intern-state     <   6> read packet: $OK#9a
intern-state     <  23> send packet: $QEnableErrorStrings#8c
intern-state     <   6> read packet: $OK#9a
intern-state     <  16> send packet: $qProcessInfo#dc
intern-state     <   7> read packet: $E01#a6
intern-state     <   6> send packet: $qC#b4
intern-state     <   7> read packet: $QC1#c5
intern-state     <   5> send packet: $?#3f
intern-state     < 291> read packet: $T00thread:1;name:Mock Accelerator Thread;threads:1;thread-pcs:0000000000001004;00:0010000000000000;01:0110000000000000;02:0210000000000000;03:0310000000000000
;04:0410000000000000;05:0510000000000000;reason:trace;description:6d6f636b20616363656c657261746f72207468726561642073746f70706564;#83
intern-state     <  16> send packet: $qProcessInfo#dc
intern-state     <   7> read packet: $E01#a6
intern-state     <  16> send packet: $qProcessInfo#dc
intern-state     <   7> read packet: $E01#a6
intern-state     <  43> send packet: $qXfer:features:read:target.xml:0,131071#78
intern-state     < 889> read packet: $l<?xml version="1.0"?>
<target version="1.0">
  <architecture>x86_64</architecture>
  <feature>
    <reg name="r0" bitsize="64" regnum="0" offset="0" encoding="uint" format="hex" group="General Purpose Registers" />
    <reg name="r1" bitsize="64" regnum="1" offset="8" encoding="uint" format="hex" group="General Purpose Registers" />
    <reg name="sp" bitsize="64" regnum="2" offset="16" encoding="uint" format="hex" group="General Purpose Registers" generic="sp" />
    <reg name="fp" bitsize="64" regnum="3" offset="24" encoding="uint" format="hex" group="General Purpose Registers" generic="fp" />
    <reg name="pc" bitsize="64" regnum="4" offset="32" encoding="uint" format="hex" group="General Purpose Registers" generic="pc" />
    <reg name="flags" bitsize="64" regnum="5" offset="40" encoding="uint" format="hex" group="General Purpose Registers" />
  </feature>
</target>
#82
intern-state     <  19> send packet: $p0;thread:0001;#89
intern-state     <  20> read packet: $0010000000000000#01
intern-state     <  16> send packet: $qProcessInfo#dc
intern-state     <   7> read packet: $E01#a6
intern-state     <  19> send packet: $p0;thread:0001;#89
intern-state     <  20> read packet: $0010000000000000#01
intern-state     <  16> send packet: $qProcessInfo#dc
intern-state     <   7> read packet: $E01#a6
intern-state     <  16> send packet: $qProcessInfo#dc
intern-state     <   7> read packet: $E01#a6
intern-state     <  16> send packet: $qProcessInfo#dc
intern-state     <   7> read packet: $E01#a6
intern-state     <  26> send packet: $qStructuredDataPlugins#02
intern-state     <   6> read packet: $[]#b8
intern-state     <  26> send packet: $qMemoryRegionInfo:1004#d9
intern-state     <  41> read packet: $error:6e6f7420696d706c656d656e746564;#f7
intern-state     <  16> send packet: $jThreadsInfo#c1
intern-state     < 198> read packet: $[{"description":"mock accelerator thread stopped","name":"Mock Accelerator Thread","reason":"trace","registers":{"2":"0210000000000000","3":"0310000000000000"
,"4":"0410000000000000"}],"tid":1}]]#4a

```

This extends the functionality to other libraries that may contain SYCL
objects. When SYCL objects are being unloaded from third party
libraries, this PR checks whether Windows process teardown is happening,
and prevents any backend calls for non level zero backends for the same
reason noted in previous commits.