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Re: How to update reg_dead notes


it is a good policy to do a run with full checking every once in a while. it is easy to have some garbage sneak in. df is particularly sensitive to bad rtl so that was my first suggestion. i had forgotten that df (as well as a lot of the infrastructure) does not work very late.
On 02/25/2015 01:54 PM, Georg-Johann Lay wrote:
Am 02/24/2015 um 07:33 PM schrieb Kenneth Zadeck:
when i suggested that you do a build with all of the checking turned on, i wanted you to this without you new code in it. there is a good possibility
that the problem is that your port is generating bad rtl.

Ah, ok. This actually revealed an ice-checking; but that was not related to the df problems...

I think the problem was that I tried to run passes needing df after free_cfg.

My current solution works so far: It fixes the test case (correct code + insn lengths) and it did not ICE up to now.

Stuff is running a bit slow with all checks on so building and running tests will take a while...

FYI, you find my current patch attached.

Thanks for your help and time,

Johann



Index: config/avr/avr.c
===================================================================
--- config/avr/avr.c    (revision 220963)
+++ config/avr/avr.c    (working copy)
@@ -51,6 +51,8 @@
 #include "target-def.h"
 #include "params.h"
 #include "df.h"
+#include "context.h"
+#include "tree-pass.h"

 /* Maximal allowed offset for an address in the LD command */
 #define MAX_LD_OFFSET(MODE) (64 - (signed)GET_MODE_SIZE (MODE))
@@ -285,6 +287,58 @@ avr_to_int_mode (rtx x)
 }


+static const pass_data avr_pass_data_recompute_notes =
+{
+  RTL_PASS, /* type */
+  "avr-xx", /* name (will be patched) */
+  OPTGROUP_NONE, /* optinfo_flags */
+  false, /* has_gate */
+  true, /* has_execute */
+  TV_DF_SCAN, /* tv_id */
+  0, /* properties_required */
+  0, /* properties_provided */
+  0, /* properties_destroyed */
+  0, /* todo_flags_start */
+  (TODO_df_finish | TODO_verify_rtl_sharing
+   | TODO_verify_flow ), /* todo_flags_finish */
+};
+
+
+class avr_pass_recompute_notes : public rtl_opt_pass
+{
+public:
+  avr_pass_recompute_notes (gcc::context *ctxt, const char *pass_name)
+    : rtl_opt_pass (avr_pass_data_recompute_notes, ctxt)
+  {
+    name = pass_name;
+  }
+
+  unsigned int execute ()
+  {
+    df_note_add_problem ();
+    df_analyze ();
+
+    return 0;
+  }
+}; // avr_pass_recompute_notes
+
+
+static void
+avr_register_passes (void)
+{
+ /* This avr-specific pass (re)computes insn notes, in particular REG_DEAD
+     notes which are used by `avr.c::reg_unused_after' and branch offset
+     computations.  These notes must be correct, i.e. there must be no
+ dangling REG_DEAD notes; otherwise wrong code might result, cf. PR64331.
+
+     DF needs (correct) CFG, hence right before free_cfg is the last
+     opportunity to rectify notes.  */
+
+  register_pass (new avr_pass_recompute_notes (g, "avr-notes-free-cfg"),
+                 PASS_POS_INSERT_BEFORE, "*free_cfg", 1);
+}
+
+
 /* Implement `TARGET_OPTION_OVERRIDE'.  */

 static void
@@ -346,6 +400,11 @@ avr_option_override (void)
   init_machine_status = avr_init_machine_status;

   avr_log_set_avr_log();
+
+ /* Register some avr-specific pass(es). There is no canonical place for
+     pass registration.  This function is convenient.  */
+
+  avr_register_passes ();
 }

 /* Function to set up the backend function structure.  */



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