[PATCH v4 1/9] gdb/jit: pass the jiter objfile as an argument to jit_event_handler

[Tankut Baris Aktemur]

This is a refactoring that adds a new parameter to the `jit_event_handler`
function: the JITer objfile.  The goal is to distinguish which JITer
triggered the JIT event, in case there are multiple JITers -- a capability
that is added in a subsequent patch.

gdb/ChangeLog:
2020-06-15  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* jit.h: Forward-declare `struct objfile`.
	(jit_event_handler): Add a second parameter, the JITer objfile.
	* jit.c (jit_read_descriptor): Change the signature to take the
	JITer objfile as an argument instead of the jit_program_space_data.
	(jit_inferior_init): Update the call to jit_read_descriptor.
	(jit_event_handler): Use the new JITer objfile argument when calling
	jit_read_descriptor.
	* breakpoint.c (handle_jit_event): Update the call to
	jit_event_handler to pass the JITer objfile.
---
 gdb/breakpoint.c |  3 ++-
 gdb/jit.c        | 27 +++++++++++++++------------
 gdb/jit.h        |  7 +++++--
 3 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 6d81323dd92..414208469f9 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -5448,8 +5448,9 @@ handle_jit_event (void)
 
   frame = get_current_frame ();
   gdbarch = get_frame_arch (frame);
+  objfile *jiter = symbol_objfile (get_frame_function (frame));
 
-  jit_event_handler (gdbarch);
+  jit_event_handler (gdbarch, jiter);
 
   target_terminal::inferior ();
 }
diff --git a/gdb/jit.c b/gdb/jit.c
index e8a843de390..41ed81ab4b0 100644
--- a/gdb/jit.c
+++ b/gdb/jit.c
@@ -332,9 +332,9 @@ get_jit_program_space_data ()
    memory.  Returns true if all went well, false otherwise.  */
 
 static bool
-jit_read_descriptor (struct gdbarch *gdbarch,
-		     struct jit_descriptor *descriptor,
-		     struct jit_program_space_data *ps_data)
+jit_read_descriptor (gdbarch *gdbarch,
+		     jit_descriptor *descriptor,
+		     objfile *jiter)
 {
   int err;
   struct type *ptr_type;
@@ -344,16 +344,16 @@ jit_read_descriptor (struct gdbarch *gdbarch,
   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
   struct jit_objfile_data *objf_data;
 
-  if (ps_data->objfile == NULL)
-    return false;
-  objf_data = get_jit_objfile_data (ps_data->objfile);
+  gdb_assert (jiter != nullptr);
+  objf_data = get_jit_objfile_data (jiter);
+
   if (objf_data->descriptor == NULL)
     return false;
 
   if (jit_debug)
     fprintf_unfiltered (gdb_stdlog,
 			"jit_read_descriptor, descriptor_addr = %s\n",
-			paddress (gdbarch, MSYMBOL_VALUE_ADDRESS (ps_data->objfile,
+			paddress (gdbarch, MSYMBOL_VALUE_ADDRESS (jiter,
 								  objf_data->descriptor)));
 
   /* Figure out how big the descriptor is on the remote and how to read it.  */
@@ -363,7 +363,7 @@ jit_read_descriptor (struct gdbarch *gdbarch,
   desc_buf = (gdb_byte *) alloca (desc_size);
 
   /* Read the descriptor.  */
-  err = target_read_memory (MSYMBOL_VALUE_ADDRESS (ps_data->objfile,
+  err = target_read_memory (MSYMBOL_VALUE_ADDRESS (jiter,
 						   objf_data->descriptor),
 			    desc_buf, desc_size);
   if (err)
@@ -1255,9 +1255,13 @@ jit_inferior_init (struct gdbarch *gdbarch)
   if (!jit_breakpoint_re_set_internal (gdbarch, ps_data))
     return;
 
+  /* There must be a JITer registered, otherwise we would exit early
+     above.  */
+  objfile *jiter = ps_data->objfile;
+
   /* Read the descriptor so we can check the version number and load
      any already JITed functions.  */
-  if (!jit_read_descriptor (gdbarch, &descriptor, ps_data))
+  if (!jit_read_descriptor (gdbarch, &descriptor, jiter))
     return;
 
   /* Check that the version number agrees with that we support.  */
@@ -1330,7 +1334,7 @@ jit_inferior_exit_hook (struct inferior *inf)
 }
 
 void
-jit_event_handler (struct gdbarch *gdbarch)
+jit_event_handler (gdbarch *gdbarch, objfile *jiter)
 {
   struct jit_descriptor descriptor;
   struct jit_code_entry code_entry;
@@ -1338,8 +1342,7 @@ jit_event_handler (struct gdbarch *gdbarch)
   struct objfile *objf;
 
   /* Read the descriptor from remote memory.  */
-  if (!jit_read_descriptor (gdbarch, &descriptor,
-			    get_jit_program_space_data ()))
+  if (!jit_read_descriptor (gdbarch, &descriptor, jiter))
     return;
   entry_addr = descriptor.relevant_entry;
 
diff --git a/gdb/jit.h b/gdb/jit.h
index cc135037812..71e78a5167d 100644
--- a/gdb/jit.h
+++ b/gdb/jit.h
@@ -20,6 +20,8 @@
 #ifndef JIT_H
 #define JIT_H
 
+struct objfile;
+
 /* When the JIT breakpoint fires, the inferior wants us to take one of
    these actions.  These values are used by the inferior, so the
    values of these enums cannot be changed.  */
@@ -76,8 +78,9 @@ extern void jit_inferior_created_hook (void);
 extern void jit_breakpoint_re_set (void);
 
 /* This function is called by handle_inferior_event when it decides
-   that the JIT event breakpoint has fired.  */
+   that the JIT event breakpoint has fired.  JITER is the objfile
+   whose JIT event breakpoint has been hit.  */
 
-extern void jit_event_handler (struct gdbarch *gdbarch);
+extern void jit_event_handler (gdbarch *gdbarch, objfile *jiter);
 
 #endif /* JIT_H */
-- 
2.17.1