[Bug middle-end/44069] [4.5 Regression] optimization bug initializing from cast array

[rguenth at gcc dot gnu dot org]

--- Comment #5 from rguenth at gcc dot gnu dot org  2010-05-12 20:16 ---
So, the issue is that the loop copying vals to m looks like

:
  D.21310_23 = r_22 * 4;
  D.21309_25 = D.21310_23 + c_24;
  D.21308_26 = (long unsigned int) D.21309_25;
  D.21305_29 = vals[0][D.21308_26];
  m.m[D.21309_25] = D.21305_29;
  c_30 = c_24 + 1;

:
  # c_24 = PHI 
  if (c_24 <= 3)
goto ;
  else
goto ;

:
  r_31 = r_22 + 1;

:
  # r_22 = PHI <0(2), r_31(5)>
  if (r_22 <= 3)
goto ;
  else
goto ;

:
  # c_32 = PHI <0(6)>
  goto ;

where vals[0][D.21308_26] does not represent a use of vals[i][j] with
i > 0.  This is because get_ref_base_and_extent restricts the valid
extent of D.21308_26 to 3.  Note that the issue is exposed by
re-constructing an array-reference from the pointer access in the
inlined constructor.  After inlining into main() we have

:
  D.21310_23 = r_22 * 4;
  D.21309_25 = D.21310_23 + c_24;
  D.21308_26 = (long unsigned int) D.21309_25;
  D.21307_27 = D.21308_26 * 8;
  D.21306_28 = &vals[0][D.21308_26];
  D.21305_29 = *D.21306_28;
  m.m[D.21309_25] = D.21305_29;
  c_30 = c_24 + 1;

from the non-inlined variant

:
  D.21286_7 = r_1 * 4;
  D.21287_8 = D.21286_7 + c_2;
  D.21286_9 = r_1 * 4;
  D.21287_10 = D.21286_9 + c_2;
  D.21288_11 = (long unsigned int) D.21287_10;
  D.21289_12 = D.21288_11 * 8;
  D.21290_14 = arr_13(D) + D.21289_12;
  D.21291_15 = *D.21290_14;
  this_16(D)->m[D.21287_10] = D.21291_15;
  c_17 = c_2 + 1;


-- 

rguenth at gcc dot gnu dot org changed:

   What|Removed |Added

  Component|c++ |middle-end
   Keywords||wrong-code
Summary|optimization bug|[4.5 Regression]
   |initializing from cast array|optimization bug
   ||initializing from cast array
   Target Milestone|--- |4.5.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44069

[Bug middle-end/44069] [4.5 Regression] optimization bug initializing from cast array

[rguenth at gcc dot gnu dot org]

--- Comment #9 from rguenth at gcc dot gnu dot org  2010-05-25 15:53 ---
Fixed for 4.6 sofar.


-- 

rguenth at gcc dot gnu dot org changed:

   What|Removed |Added

  Known to work||4.6.0
Summary|[4.5/4.6 Regression]|[4.5 Regression]
   |optimization bug|optimization bug
   |initializing from cast array|initializing from cast array


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44069

[Bug middle-end/44069] [4.5 Regression] optimization bug initializing from cast array

[rguenth at gcc dot gnu dot org]

--- Comment #10 from rguenth at gcc dot gnu dot org  2010-05-26 11:44 
---
Subject: Bug 44069

Author: rguenth
Date: Wed May 26 11:44:44 2010
New Revision: 159865

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=159865
Log:
2010-05-26  Richard Guenther  

PR middle-end/44069
* tree-ssa-ccp.c (maybe_fold_stmt_addition): Avoid generating
out-of-bounds array accesses.

* g++.dg/torture/pr44069.C: New testcase.

Added:
branches/gcc-4_5-branch/gcc/testsuite/g++.dg/torture/pr44069.C
Modified:
branches/gcc-4_5-branch/gcc/ChangeLog
branches/gcc-4_5-branch/gcc/testsuite/ChangeLog
branches/gcc-4_5-branch/gcc/tree-ssa-ccp.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44069

[Bug middle-end/44069] [4.5 Regression] optimization bug initializing from cast array

[rguenth at gcc dot gnu dot org]

--- Comment #11 from rguenth at gcc dot gnu dot org  2010-05-26 11:46 
---
Fixed.


-- 

rguenth at gcc dot gnu dot org changed:

   What|Removed |Added

 Status|ASSIGNED|RESOLVED
  Known to fail||4.5.0
  Known to work|4.6.0   |4.5.1 4.6.0
 Resolution||FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44069