[Bug debug/39432] New: [4.4 Regression] gdb.base/store.exp failures

[Bug debug/39432] New: [4.4 Regression] gdb.base/store.exp failures

[jakub at gcc dot gnu dot org]

Running ../../../gdb/testsuite/gdb.base/store.exp ...
FAIL: gdb.base/store.exp: upvar charest l; print old l, expecting -1 .*
FAIL: gdb.base/store.exp: upvar short l; print old l, expecting -1
FAIL: gdb.base/store.exp: upvar int l; print old l, expecting -1
FAIL: gdb.base/store.exp: upvar long l; print old l, expecting -1
FAIL: gdb.base/store.exp: upvar longest l; print old l, expecting -1
FAIL: gdb.base/store.exp: upvar doublest l; print old l, expecting -1

are new failures in gdb testsuite when compiled with 4.4 compared to store.c
compiled with 4.3.x.  The difference seems to be introduced by IRA, when
compiled with -fno-ira (when trunk still had that option) the test worked.

With the old RA, -g -O0 -dA -fverbose-asm compiled:
unsigned int foo (unsigned int, unsigned int);

unsigned int bar (register unsigned int a, register unsigned int b)
{
  register unsigned int c = a, d = b;
  c = foo (c, d);
  return c + d;
}

d is allocated in a call-saved register (%ebx), which is fine and c is assigned
a stack slot.  With IRA d is still allocated in %ebx, but c is in %eax,
call-clobbered register.  So when gdb in the foo call does up and checks the
value in c and d, it finds correct value of d, but garbage in c.

Could we perhaps at -O0 avoid allocating user variables that are live accross
function calls in call-clobbered registers?  For -O1 it is obviously a fine
decision.


-- 
           Summary: [4.4 Regression] gdb.base/store.exp failures
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jakub at gcc dot gnu dot org
GCC target triplet: x86_64-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39432

[Bug debug/39432] [4.4 Regression] gdb.base/store.exp failures

[vmakarov at redhat dot com]

------- Comment #1 from vmakarov at redhat dot com  2009-03-11 16:57 -------
Jakub, how is about the following patch.  Is it ok for you?  I mean correct
user variable identification.

2009-03-11  Vladimir Makarov  <vmakarov@redhat.com>

        PR debug/39432
        * ira-int.h (struct allocno): Fix comment for calls_crossed_num.
        * ira-conflicts.c (ira_build_conflicts): Prohibit call used
        registers for allocnos created from user-defined variables.

Index: ira-int.h
===================================================================
--- ira-int.h   (revision 144543)
+++ ira-int.h   (working copy)
@@ -333,7 +333,7 @@ struct ira_allocno
   /* Accumulated frequency of calls which given allocno
      intersects.  */
   int call_freq;
-  /* Length of the previous array (number of the intersected calls).  */
+  /* Accumulated number of the intersected calls.  */
   int calls_crossed_num;
   /* Non NULL if we remove restoring value from given allocno to
      MEM_OPTIMIZED_DEST at loop exit (see ira-emit.c) because the
Index: ira-conflicts.c
===================================================================
--- ira-conflicts.c     (revision 144543)
+++ ira-conflicts.c     (working copy)
@@ -800,29 +800,33 @@ ira_build_conflicts (void)
     }
   FOR_EACH_ALLOCNO (a, ai)
     {
-      if (ALLOCNO_CALLS_CROSSED_NUM (a) == 0)
-       continue;
-      if (! flag_caller_saves)
+      reg_attrs *attrs;
+      tree decl;
+
+      if ((! flag_caller_saves && ALLOCNO_CALLS_CROSSED_NUM (a) != 0)
+         /* For debugging purposes don't put user defined variables in
+            callee-clobbered registers.  */
+         || (optimize <= 1
+             && (attrs = REG_ATTRS (regno_reg_rtx [ALLOCNO_REGNO (a)])) !=
NULL
+             && (decl = attrs->decl) != NULL
+             && VAR_OR_FUNCTION_DECL_P (decl)
+             && DECL_NAME (decl) != NULL))
        {
          IOR_HARD_REG_SET (ALLOCNO_TOTAL_CONFLICT_HARD_REGS (a),
                            call_used_reg_set);
-         if (ALLOCNO_CALLS_CROSSED_NUM (a) != 0)
-           IOR_HARD_REG_SET (ALLOCNO_CONFLICT_HARD_REGS (a),
-                             call_used_reg_set);
+         IOR_HARD_REG_SET (ALLOCNO_CONFLICT_HARD_REGS (a),
+                           call_used_reg_set);
        }
-      else
+      else if (ALLOCNO_CALLS_CROSSED_NUM (a) != 0)
        {
          IOR_HARD_REG_SET (ALLOCNO_TOTAL_CONFLICT_HARD_REGS (a),
                            no_caller_save_reg_set);
          IOR_HARD_REG_SET (ALLOCNO_TOTAL_CONFLICT_HARD_REGS (a),
                            temp_hard_reg_set);
-         if (ALLOCNO_CALLS_CROSSED_NUM (a) != 0)
-           {
-             IOR_HARD_REG_SET (ALLOCNO_CONFLICT_HARD_REGS (a),
-                               no_caller_save_reg_set);
-             IOR_HARD_REG_SET (ALLOCNO_CONFLICT_HARD_REGS (a),
-                               temp_hard_reg_set);
-           }
+         IOR_HARD_REG_SET (ALLOCNO_CONFLICT_HARD_REGS (a),
+                           no_caller_save_reg_set);
+         IOR_HARD_REG_SET (ALLOCNO_CONFLICT_HARD_REGS (a),
+                           temp_hard_reg_set);
        }
     }
   if (optimize && ira_conflicts_p




-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39432

[Bug debug/39432] [4.4 Regression] gdb.base/store.exp failures

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2009-03-11 17:02 -------
You should use DECL_ARTIFICIAL I think.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39432

[Bug debug/39432] [4.4 Regression] gdb.base/store.exp failures

[vmakarov at redhat dot com]

------- Comment #3 from vmakarov at redhat dot com  2009-03-11 17:10 -------
Thanks, Richard.

So instead of "DECL_NAME (decl) != NULL" I should use "! DECL_ARTIFICIAL
(decl)".  Right?

Ok, I'll test the new patch then and send it for approval after testing.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39432

[Bug debug/39432] [4.4 Regression] gdb.base/store.exp failures

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2009-03-11 17:11 -------
Also perhaps should test DECL_HARD_REGISTER, for DECL_HARD_REGISTER we
shouldn't limit them in any way to allow the user to shoot himself.

In any case, I'll test your patch momentarily.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39432

[Bug debug/39432] [4.4 Regression] gdb.base/store.exp failures

[vmakarov at redhat dot com]

------- Comment #5 from vmakarov at redhat dot com  2009-03-11 17:28 -------
As for DECL_HARD_REGISTER, such decl regs are never considered by IRA for
allocation.   So I think there is no necessity to check them here.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39432

[Bug debug/39432] [4.4 Regression] gdb.base/store.exp failures

[jakub at gcc dot gnu dot org]

------- Comment #6 from jakub at gcc dot gnu dot org  2009-03-11 19:38 -------
I can confirm that trunk with the #c1 patch modified as mentioned in #c3 cures
all the gdb.base/store.exp failures.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39432

[Bug debug/39432] [4.4 Regression] gdb.base/store.exp failures

[vmakarov at gcc dot gnu dot org]

------- Comment #7 from vmakarov at gcc dot gnu dot org  2009-03-12 14:40 -------
Subject: Bug 39432

Author: vmakarov
Date: Thu Mar 12 14:39:55 2009
New Revision: 144812

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=144812
Log:
2009-03-12  Vladimir Makarov  <vmakarov@redhat.com>

        PR debug/39432
        * ira-int.h (struct allocno): Fix comment for calls_crossed_num.
        * ira-conflicts.c (ira_build_conflicts): Prohibit call used
        registers for allocnos created from user-defined variables.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/ira-conflicts.c
    trunk/gcc/ira-int.h


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39432

[Bug debug/39432] [4.4 Regression] gdb.base/store.exp failures

[jakub at gcc dot gnu dot org]

------- Comment #8 from jakub at gcc dot gnu dot org  2009-03-12 15:49 -------
Fixed, thanks.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39432