[Bug debug/36748] New: scev const-prop pass adds bad line numbers

[Bug debug/36748] New: scev const-prop pass adds bad line numbers

[drow at gcc dot gnu dot org]

I'm testing inlined function support for GCC.  When I compile the attached
testcase with GCC (Debian's 4.3 package or unmodified trunk) and -g -O2, "break
main" in the patched GDB puts a breakpoint at the start of main and again
inside the inlined copy of factorial.

This happens because there are several bits of code associated with the line
containing main's opening brace.

The bad line numbers are introduced by pass_scev_cprop (why is this dumped into
"sccp"; having a dump named sccp shortly after one named store_ccp is
confusing).  Here's the relevant piece of the diff between 096t.lim and
099t.sccp:

@@ -88,7 +100,11 @@

 <bb 8>:
   # mult_acc.12_13 = PHI <mult_acc.12_15(6)>
-  # value_16 = PHI <value_14(6)>
+  [../break.c : 13] D.2700_29 = value_11 + -1;
+  [../break.c : 13] D.2701_7 = (unsigned int) D.2633_10;
+  [../break.c : 13] D.2702_30 = 2 - D.2701_7;
+  [../break.c : 13] D.2703_31 = (int) D.2702_30;
+  value_16 = D.2700_29 + D.2703_31;

 <bb 9>:
   # mult_acc.12_19 = PHI <mult_acc.12_13(8), 1(4)>

There are no other lines associated with break.c:13 in the dump at this point.  

The location came from internal_get_tmp_var.

644       if (EXPR_HAS_LOCATION (val))
645         SET_EXPR_LOCUS (mod, EXPR_LOCUS (val));
646       else
647         SET_EXPR_LOCATION (mod, input_location);

input_location has nothing to do with anything at this point.


-- 
           Summary: scev const-prop pass adds bad line numbers
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: drow at gcc dot gnu dot org
  GCC host triplet: x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36748

[Bug debug/36748] scev const-prop pass adds bad line numbers

[drow at gcc dot gnu dot org]

------- Comment #1 from drow at gcc dot gnu dot org  2008-07-07 13:56 -------
Created an attachment (id=15869)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15869&action=view)
Test case


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36748

[Bug debug/36748] scev const-prop pass adds bad line numbers

[jan dot kratochvil at redhat dot com]

------- Comment #2 from jan dot kratochvil at redhat dot com  2008-12-06 13:22 -------
It looks fixed in 4.4 for me, tested on:
GNU C (GCC) version 4.4.0 20081202 (experimental) (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.4.0 20081202 (experimental), GMP version
4.2.2, MPFR version 2.3.2.
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096

Line 13 in .line_debug is now assigned only to the "main" address (in Fedora
gcc-4.3.2-7.x86_64 it was assigned also to the "factorial" address).

Expecting it got fixed by Jakub Jelinek as a part of the Bug 36690.


-- 

jan dot kratochvil at redhat dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jan dot kratochvil at redhat
                   |                            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36748

[Bug debug/36748] scev const-prop pass adds bad line numbers

[drow at gcc dot gnu dot org]

------- Comment #3 from drow at gcc dot gnu dot org  2008-12-06 15:18 -------
I tried 4.4.0 20081130; it does not look fixed.

<bb 8>:
  # mult_acc.14_40 = PHI <mult_acc.14_17(6)>
  [break.c : 12] D.2737_41 = value_13 + -1;
  [break.c : 12] D.2738_42 = (unsigned int) D.2674_12;
  [break.c : 12] D.2739_43 = 2 - D.2738_42;
  [break.c : 12] D.2740_44 = (int) D.2739_43;
  value_39 = D.2737_41 + D.2740_44;

There are no references to code on line 13 or 25, which are the opening braces.
 But those lines are now associated with line 12 and 24, which are the
declarations of main and factorial respectively.  The references are still
introduced by scev.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36748

[Bug debug/36748] scev const-prop pass adds bad line numbers

[drow at gcc dot gnu dot org]

-- 

drow at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-12-06 15:19:06
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36748