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From: "mjw at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: systemtap@sourceware.org
Subject: [Bug translator/12609] New: Cannot see variable values in partial inlined functions with gcc 4.6
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http://sourceware.org/bugzilla/show_bug.cgi?id=12609

           Summary: Cannot see variable values in partial inlined
                    functions with gcc 4.6
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap@sourceware.org
        ReportedBy: mjw@redhat.com


Take the following program foo.c:

$ cat foo.c 
/* { dg-options "-g -O2" } */

extern void abort (void);
volatile int v;
#define V1 v++; v++; v++; v++; v++; v++; v++; v++; v++; v++;
#define V2 V1 V1 V1 V1 V1 V1 V1 V1 V1 V1
static int
foo (int x)
{
  int a = 2 * x + 4;
  int b = 6;
  if (x < 30)
    {
      int c = 8;
      int d = 8 * x;
      return 6;
    }
  else
    {
      int e = 134;
      int f = 9 * x;
      V2
      return v + 17;
    }
}

int
main (void)
{
  if (foo (v) > 10000)
    abort ();
  foo (70);
  return 0;
}

Compiled with gcc 4.5 -g -O2 -o foo.old foo.c systemtap is happy to probe the
(inlined) foo and variables:

$ stap -e 'probe process ("./foo.old").function("foo") { printf("%s@0x%x\n",
pp(), uaddr()); log ($$vars) }' -c ./foo.old
process("/tmp/foo.old").function("foo@/tmp/foo.c:8")@0x4004d0
x=0x0 a=0x4 b=0x6
process("/tmp/foo.old").function("foo@/tmp/foo.c:8")@0x4004d0
x=0x46 a=0x90 b=0x6

But compiled with gcc 4.6 (actually my test was with gcc trunk, but that is
still fairly similar) -g -O2 -o foo.new foo.c systemtap is unable to find the
value of most variables:

$ stap -e 'probe process ("./foo.new").function("foo") { printf("%s@0x%x\n",
pp(), uaddr()); log ($$vars) }' -c ./foo.new
process("/tmp/foo.new").function("foo@/tmp/foo.c:8")@0x400aaa
x=0x0
process("/tmp/foo.new").function("foo@/tmp/foo.c:8")@0x4004b0
a=? x=? b=?

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