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Non-stop + software single-step archs: don't force displaced-stepping for all single-steps

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This finally reverts this bit of commit 929dfd4f:

  2009-07-31  Pedro Alves  <pedro@codesourcery.com>
	      Julian Brown  <julian@codesourcery.com>

	 ...
	 (resume): If this is a software single-stepping arch, and
	 displaced-stepping is enabled, use it for all single-step
	 requests.
	 ...

That means that in non-stop (or really displaced-stepping) mode, on
software single-step archs - even those that only use sss breakpoints
to deal with atomic sequences, like PPC - if we have more than one
thread single-stepping, we'll always serialize the threads'
single-steps, as only one thread may be displaced stepping at a given
time, because there's only one scratch pad.

We originally did that because GDB didn't support having multiple
threads software-single-stepping simultaneously.  The previous patches
fixed that limitation, so we can now finally revert this too.

Tested on:

  - x86_64 Fedora 20, on top of the 'software single-step on x86'
    series.

gdb/
2014-10-15  Pedro Alves  <palves@redhat.com>

	* infrun.c (resume): Don't force displaced-stepping for all
	single-steps on software single-stepping archs.
This commit is contained in:
Pedro Alves 2014-10-15 20:18:32 +01:00
parent 34b7e8a6ad
commit 36728e82bd
2 changed files with 6 additions and 2 deletions
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5
gdb/ChangeLog
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@ -1,3 +1,8 @@
2014-10-15 Pedro Alves <palves@redhat.com>
* infrun.c (resume): Don't force displaced-stepping for all
single-steps on software single-stepping archs.
2014-10-15 Pedro Alves <palves@redhat.com>
* breakpoint.c (single_step_breakpoints): Delete global.

3
gdb/infrun.c
View File

@ -2089,8 +2089,7 @@ a command like `return' or `jump' to continue execution."));
event, displaced stepping breaks the vfork child similarly as single
step software breakpoint. */
if (use_displaced_stepping (gdbarch)
&& (tp->control.trap_expected
|| (step && gdbarch_software_single_step_p (gdbarch)))
&& tp->control.trap_expected
&& sig == GDB_SIGNAL_0
&& !current_inferior ()->waiting_for_vfork_done)
{