[Bug gdb/31214] [gdb, aarch64] FAIL: gdb.base/watch-bitfields.exp: -location watch against bitfields: q.e: 0->5: continue

["vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=31214

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #1)
> Put differently, aarch64_stopped_data_address should report back 0x440028
> and 0x440029 in both cases, and the caller should figure out which of the
> two is actually triggered.  Alternatively, it could report back a range
> [0x440028-0x44002a].

This tentative patch addresses it slightly differently.  It reports back no
address:
...
diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
index 5b4e3c2bde1..624884cd375 100644
--- a/gdb/aarch64-linux-nat.c
+++ b/gdb/aarch64-linux-nat.c
@@ -972,9 +972,7 @@ aarch64_linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p)
 bool
 aarch64_linux_nat_target::stopped_by_watchpoint ()
 {
-  CORE_ADDR addr;
-
-  return stopped_data_address (&addr);
+  return stopped_data_address (nullptr);
 }

 /* Implement the "can_do_single_step" target_ops method.  */
diff --git a/gdb/aarch64-nat.c b/gdb/aarch64-nat.c
index ee8c5a1e21d..2cc0a0b707c 100644
--- a/gdb/aarch64-nat.c
+++ b/gdb/aarch64-nat.c
@@ -232,6 +232,7 @@ aarch64_stopped_data_address (const struct
aarch64_debug_reg_state *state,
                              CORE_ADDR addr_trap, CORE_ADDR *addr_p)
 {
   int i;
+  bool found = false;

   for (i = aarch64_num_wp_regs - 1; i >= 0; --i)
     {
@@ -265,12 +266,19 @@ aarch64_stopped_data_address (const struct
aarch64_debug_reg_state *state,
             range.  ADDR_WATCH <= ADDR_TRAP < ADDR_ORIG is a false
             positive on kernels older than 4.10.  See PR
             external/20207.  */
-         *addr_p = addr_orig;
-         return true;
+
+         if (addr_p != nullptr)
+           if (found && *addr_p != addr_orig)
+             return false;
+
+         found = true;
+
+         if (addr_p != nullptr)
+           *addr_p = addr_orig;
        }
     }

-  return false;
+  return found;
 }

 /* Define AArch64 maintenance commands.  */

...

So, if called from stopped_by_watchpoint (addr_p == nullptr), if there is any
hit, it returns true.

Otherwise (addr_p != nullptr) if there are multiple hits with conflicting
addresses, it return false.

Fixes the test-case.

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