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* infrun.c (resume): Clarify logic that 

decides if a single thread must be resumed. Add
	comments.
This commit is contained in:
Vladimir Prus 2007-11-20 08:18:47 +00:00
parent 7514952146
commit cd76b0b7c4
2 changed files with 40 additions and 8 deletions
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6
gdb/ChangeLog
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@ -1,3 +1,9 @@
2007-11-20 Vladimir Prus <vladimir@codesourcery.com>
* infrun.c (resume): Clarify logic that
decides if a single thread must be resumed. Add
comments.
2007-11-20 Vladimir Prus <vladimir@codesourcery.com>
* breakpoint.c (disable_breakpoints_in_unloaded_shlib):

42
gdb/infrun.c
View File

@ -583,15 +583,41 @@ a command like `return' or `jump' to continue execution."));
resume_ptid = RESUME_ALL; /* Default */
if ((step || singlestep_breakpoints_inserted_p)
&& (stepping_past_singlestep_breakpoint
|| (!breakpoints_inserted && breakpoint_here_p (read_pc ()))))
{
/* Stepping past a breakpoint without inserting breakpoints.
Make sure only the current thread gets to step, so that
other threads don't sneak past breakpoints while they are
not inserted. */
/* If STEP is set, it's a request to use hardware stepping
facilities. But in that case, we should never
use singlestep breakpoint. */
gdb_assert (!(singlestep_breakpoints_inserted_p && step));
if (singlestep_breakpoints_inserted_p
&& stepping_past_singlestep_breakpoint)
{
/* The situation here is as follows. In thread T1 we wanted to
single-step. Lacking hardware single-stepping we've
set breakpoint at the PC of the next instruction -- call it
P. After resuming, we've hit that breakpoint in thread T2.
Now we've removed original breakpoint, inserted breakpoint
at P+1, and try to step to advance T2 past breakpoint.
We need to step only T2, as if T1 is allowed to freely run,
it can run past P, and if other threads are allowed to run,
they can hit breakpoint at P+1, and nested hits of single-step
breakpoints is not something we'd want -- that's complicated
to support, and has no value. */
resume_ptid = inferior_ptid;
}
if (step && breakpoint_here_p (read_pc ())
&& !breakpoint_inserted_here_p (read_pc ()))
{
/* We're stepping, have breakpoint at PC, and it's
not inserted. Most likely, proceed has noticed that
we have breakpoint and tries to single-step over it,
so that it's not hit. In which case, we need to
single-step only this thread, and keep others stopped,
as they can miss this breakpoint if allowed to run.
The current code either has all breakpoints inserted,
or all removed, so if we let other threads run,
we can actually miss any breakpoint, not the one at PC. */
resume_ptid = inferior_ptid;
}