Revert "Call target_can_do_single_step from maybe_software_singlestep"

This reverts commit 14de1447c9.

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

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),

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
+/* Insert single step breakpoints according to the current state.  */
-   target_resume() should use hardware single step.
 
-   GDBARCH is the current gdbarch.  */
+int
-
+insert_single_step_breakpoints (struct gdbarch *gdbarch)
-bool
-maybe_software_singlestep (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.  */

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
+/* Insert all software single step breakpoints for the current frame.
-   target_resume() should use hardware single step.  GDBARCH is the
+   Return true if any software single step breakpoints are inserted,
-   current gdbarch.  */
+   otherwise, return false.  */
-extern bool maybe_software_singlestep (struct gdbarch *);
+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

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
+/* FIXME/cagney/2001-01-18: This should be split in two.  A target method that
-   breakpoints should be inserted.  An empty vector means software single
+   indicates if the target needs software single step.  An ISA method to
-   step is not used.
+   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

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
+FIXME/cagney/2001-01-18: This should be split in two.  A target method that
-breakpoints should be inserted.  An empty vector means software single
+indicates if the target needs software single step.  An ISA method to
-step is not used.
+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

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

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)