[PATCH v3] Fix hardware watchpoints in replay mode

[Hannes Domani <ssbssa@yahoo.de>]

Changes introduced by commit 9e8915c6cee5c37637521b424d723e990e06d597
caused a regression that meant hardware watchpoint stops would not
trigger in reverse execution or replay mode.  This was documented in
PR breakpoints/21969.
The problem is that record_check_stopped_by_breakpoint always overwrites
record_full_stop_reason, thus loosing the TARGET_STOPPED_BY_WATCHPOINT
value which would be checked afterwards.

This commit fixes that by not overwriting the stop-reason in
record_full_stop_reason if we're not stopped at a breakpoint.

And the test for hw watchpoints in gdb.reverse/watch-reverse.exp actually
tested sw watchpoints again, since "set can-use-hw-watchpoints 1"
doesn't convert enabled watchpoints to use hardware.
This is fixed by disabling said watchpoint while enabling hw watchpoints.
The same is not done for gdb.reverse/watch-precsave.exp, since it's not
possible to use hw watchpoints in restored recordings anyways.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=21969
---
 gdb/record.c                                | 1 -
 gdb/testsuite/gdb.reverse/watch-reverse.exp | 4 ++++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdb/record.c b/gdb/record.c
index f7c82665b05..88235e36da7 100644
--- a/gdb/record.c
+++ b/gdb/record.c
@@ -248,7 +248,6 @@ record_check_stopped_by_breakpoint (const address_space *aspace,
       return 1;
     }
 
-  *reason = TARGET_STOPPED_BY_NO_REASON;
   return 0;
 }
 
diff --git a/gdb/testsuite/gdb.reverse/watch-reverse.exp b/gdb/testsuite/gdb.reverse/watch-reverse.exp
index 6b81a6fdf88..a7126ac9b1d 100644
--- a/gdb/testsuite/gdb.reverse/watch-reverse.exp
+++ b/gdb/testsuite/gdb.reverse/watch-reverse.exp
@@ -118,8 +118,12 @@ gdb_test "continue" \
     ".*\[Ww\]atchpoint.*ival3.*Old value = 0.*New value = -1.*ival3 = count; ival4 = count;.*" \
     "watchpoint hit in reverse, fifth time"
 
+gdb_test_no_output "disable \$bpnum" "disable non-hw watchpoint"
+
 gdb_test_no_output "set can-use-hw-watchpoints 1" "enable hw watchpoints"
 
+gdb_test_no_output "enable \$bpnum" "enable hw watchpoint"
+
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-- 
2.35.1