llvm-project

38b252aa - Disable ThreadPlanSingleThreadTimeout during step over breakpoint (#104532)

Disable ThreadPlanSingleThreadTimeout during step over breakpoint (#104532) This PR fixes another race condition in https://github.com/llvm/llvm-project/pull/90930. The failure was found by @labath with this log: https://paste.debian.net/hidden/30235a5c/: ``` dotest_wrapper. < 15> send packet: $z0,224505,1#65 ... b-remote.async> < 22> send packet: $vCont;s:p1dcf.1dcf#4c intern-state GDBRemoteClientBase::Lock::Lock sent packet: \x03 b-remote.async> < 818> read packet: $T13thread:p1dcf.1dcf;name:a.out;threads:1dcf,1dd2;jstopinfo:5b7b226e616d65223a22612e6f7574222c22726561736f6e223a227369676e616c222c227369676e616c223a31392c22746964223a373633317d2c7b226e616d65223a22612e6f7574222c22746964223a373633347d5d;thread-pcs:0000000000224505,00007f4e4302119a;00:0000000000000000;01:0000000000000000;02:0100000000000000;03:0000000000000000;04:9084997dfc7f0000;05:a8742a0000000000;06:b084997dfc7f0000;07:6084997dfc7f0000;08:0000000000000000;09:00d7e5424e7f0000;0a:d0d9e5424e7f0000;0b:0202000000000000;0c:80cc290000000000;0d:d8cc1c434e7f0000;0e:2886997dfc7f0000;0f:0100000000000000;10:0545220000000000;11:0602000000000000;12:3300000000000000;13:0000000000000000;14:0000000000000000;15:2b00000000000000;16:80fbe5424e7f0000;17:0000000000000000;18:0000000000000000;19:0000000000000000;reason:signal;#b9 ``` It shows an async interrupt "\x03" was sent immediately after `vCont;s` single step over breakpoint at address `0x224505` (which was disabled before vCont). And the later stop was still at the original PC (0x224505) not moving forward. The investigation shows the failure happens when timeout is short and async interrupt is sent to lldb-server immediately after vCont so ptrace() resumes and then async interrupts debuggee immediately so debuggee does not get a chance to execute and move PC. So it enters stop mode immediately at original PC. `ThreadPlanStepOverBreakpoint` does not expect PC not moving and reports stop at the original place. To fix this, the PR prevents `ThreadPlanSingleThreadTimeout` from being created during `ThreadPlanStepOverBreakpoint` by introduces a new `SupportsResumeOthers()` method and `ThreadPlanStepOverBreakpoint` returns false for it. This makes sense because we should never resume threads during step over breakpoint anyway otherwise it might cause other threads to miss breakpoint. --------- Co-authored-by: jeffreytan81 <jeffreytan@fb.com>