Revert "Call target_can_do_single_step from maybe_software_singlestep"

This reverts commit 14de1447c9c52c1bfc52588f8652836f66ac6c47.

An automated tester said that this patch caused a regression on
aarch64:

FAIL: gdb.arch/aarch64-atomic-inst.exp: Step through the ldxr/stxr sequence (timeout)

I looked into it a bit yesterday but couldn't see an obvious problem;
and it's somewhat of a pain to try to debug it at the moment.

Tom de Vries also noticed this and filed it in bugzilla.  So, I'm
backing the patch out until I can port the failing test to the AdaCore
internal test suite in order to find out what went wrong.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28440
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33255

diff --git a/gdb/arm-linux-tdep.c b/gdb/arm-linux-tdep.c
index 2f034afcd8047109d89b384b506063cdb97d15c6..08526d8e39ddb624e5291689279cdb26496d9209 100644 (file)
--- a/gdb/arm-linux-tdep.c
+++ b/gdb/arm-linux-tdep.c
@@ -960,6 +960,11 @@ arm_linux_software_single_step (struct regcache *regcache)
   struct gdbarch *gdbarch = regcache->arch ();
   struct arm_get_next_pcs next_pcs_ctx;
 
+  /* If the target does have hardware single step, GDB doesn't have
+     to bother software single step.  */
+  if (target_can_do_single_step () == 1)
+    return {};
+
   arm_get_next_pcs_ctor (&next_pcs_ctx,
                         &arm_linux_get_next_pcs_ops,
                         gdbarch_byte_order (gdbarch),

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index f795d7b9931359d07bc08abdd082604a7b41e59c..d704ad1e3e2001c2fedab92ec7d46756ad1db7c6 100644 (file)
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -13998,26 +13998,11 @@ insert_single_step_breakpoint (struct gdbarch *gdbarch,
   update_global_location_list (UGLL_INSERT);
 }
 
-/* Try to setup for software single stepping.  Return true if
-   target_resume() should use hardware single step.
+/* Insert single step breakpoints according to the current state.  */
 
-   GDBARCH is the current gdbarch.  */
-
-bool
-maybe_software_singlestep (struct gdbarch *gdbarch)
+int
+insert_single_step_breakpoints (struct gdbarch *gdbarch)
 {
-  if (execution_direction != EXEC_FORWARD)
-    return true;
-
-  if (target_can_do_single_step () == 1)
-    {
-      /* The target definitely has hardware single step.  */
-      return true;
-    }
-
-  if (!gdbarch_software_single_step_p (gdbarch))
-    return true;
-
   regcache *regcache = get_thread_regcache (inferior_thread ());
   std::vector<CORE_ADDR> next_pcs;
 
@@ -14031,10 +14016,10 @@ maybe_software_singlestep (struct gdbarch *gdbarch)
       for (CORE_ADDR pc : next_pcs)
        insert_single_step_breakpoint (gdbarch, aspace, pc);
 
-      return false;
+      return 1;
     }
   else
-    return true;
+    return 0;
 }
 
 /* See breakpoint.h.  */

diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index e9201bc63cdfd3f0234f8eb62e8cb55157d66134..93411122e9079925d4c828124a9624817a8f82c2 100644 (file)
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -1884,10 +1884,10 @@ extern void insert_single_step_breakpoint (struct gdbarch *,
                                           const address_space *,
                                           CORE_ADDR);
 
-/* Try to setup for software single stepping.  Return true if
-   target_resume() should use hardware single step.  GDBARCH is the
-   current gdbarch.  */
-extern bool maybe_software_singlestep (struct gdbarch *);
+/* Insert all software single step breakpoints for the current frame.
+   Return true if any software single step breakpoints are inserted,
+   otherwise, return false.  */
+extern int insert_single_step_breakpoints (struct gdbarch *);
 
 /* Check whether any hardware watchpoints have triggered or not,
    according to the target, and record it in each watchpoint's

diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h
index 1e5108135afa226204d972821cb24cdf378e8f95..281b97b7aa8ce00a350e18fc83d1b92e8da8c5b4 100644 (file)
--- a/gdb/gdbarch-gen.h
+++ b/gdb/gdbarch-gen.h
@@ -776,10 +776,16 @@ extern void set_gdbarch_get_memtag (struct gdbarch *gdbarch, gdbarch_get_memtag_
 extern CORE_ADDR gdbarch_memtag_granule_size (struct gdbarch *gdbarch);
 extern void set_gdbarch_memtag_granule_size (struct gdbarch *gdbarch, CORE_ADDR memtag_granule_size);
 
-/* Return a vector of addresses at which the software single step
-   breakpoints should be inserted.  An empty vector means software single
-   step is not used.
+/* FIXME/cagney/2001-01-18: This should be split in two.  A target method that
+   indicates if the target needs software single step.  An ISA method to
+   implement it.
 
+   FIXME/cagney/2001-01-18: The logic is backwards.  It should be asking if the
+   target can single step.  If not, then implement single step using breakpoints.
+
+   Return a vector of addresses on which the software single step
+   breakpoints should be inserted.  NULL means software single step is
+   not used.
    Multiple breakpoints may be inserted for some instructions such as
    conditional branch.  However, each implementation must always evaluate
    the condition and only put the breakpoint at the branch destination if

diff --git a/gdb/gdbarch_components.py b/gdb/gdbarch_components.py
index 55df10266657006f56e26552eee8c1a4c852f465..91c867e69bfb0e1b5023771840b24965e2720355 100644 (file)
--- a/gdb/gdbarch_components.py
+++ b/gdb/gdbarch_components.py
@@ -1378,10 +1378,16 @@ For a non-zero value, this represents the number of bytes of memory per tag.
 
 Function(
     comment="""
-Return a vector of addresses at which the software single step
-breakpoints should be inserted.  An empty vector means software single
-step is not used.
+FIXME/cagney/2001-01-18: This should be split in two.  A target method that
+indicates if the target needs software single step.  An ISA method to
+implement it.
 
+FIXME/cagney/2001-01-18: The logic is backwards.  It should be asking if the
+target can single step.  If not, then implement single step using breakpoints.
+
+Return a vector of addresses on which the software single step
+breakpoints should be inserted.  NULL means software single step is
+not used.
 Multiple breakpoints may be inserted for some instructions such as
 conditional branch.  However, each implementation must always evaluate
 the condition and only put the breakpoint at the branch destination if

diff --git a/gdb/infrun.c b/gdb/infrun.c
index e0e9ffa4caf82e790ff983e744280e57bad1ac45..9d3e1b7782e4ddf84089156e910f77c6396586a4 100644 (file)
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -93,6 +93,8 @@ static void insert_step_resume_breakpoint_at_caller (const frame_info_ptr &);
 
 static void insert_longjmp_resume_breakpoint (struct gdbarch *, CORE_ADDR);
 
+static bool maybe_software_singlestep (struct gdbarch *gdbarch);
+
 static void resume (gdb_signal sig);
 
 static void wait_for_inferior (inferior *inf);
@@ -2357,6 +2359,23 @@ set_schedlock_func (const char *args, int from_tty, struct cmd_list_element *c)
    process.  */
 bool sched_multi = false;
 
+/* Try to setup for software single stepping.  Return true if target_resume()
+   should use hardware single step.
+
+   GDBARCH the current gdbarch.  */
+
+static bool
+maybe_software_singlestep (struct gdbarch *gdbarch)
+{
+  bool hw_step = true;
+
+  if (execution_direction == EXEC_FORWARD
+      && gdbarch_software_single_step_p (gdbarch))
+    hw_step = !insert_single_step_breakpoints (gdbarch);
+
+  return hw_step;
+}
+
 /* See infrun.h.  */
 
 ptid_t

diff --git a/gdb/record-full.c b/gdb/record-full.c
index 7d4ef87fe76844fa344ed2b57b3537f3d35a413b..7e3da277998e36126a4e3903084515f15bb22be6 100644 (file)
--- a/gdb/record-full.c
+++ b/gdb/record-full.c
@@ -1105,7 +1105,7 @@ record_full_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
                  record_full_resume_step = 1;
                }
              else
-               step = maybe_software_singlestep (gdbarch);
+               step = !insert_single_step_breakpoints (gdbarch);
            }
        }
 
@@ -1277,7 +1277,7 @@ record_full_wait_1 (struct target_ops *ops,
                            };
 
                          reinit_frame_cache ();
-                         step = maybe_software_singlestep (gdbarch);
+                         step = !insert_single_step_breakpoints (gdbarch);
                        }
 
                      if (record_debug)