[Bug tree-optimization/72835] [7 Regression] Incorrect arithmetic optimization involving bitfield arguments

[kugan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72835

kugan at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kugan at gcc dot gnu.org

--- Comment #3 from kugan at gcc dot gnu.org ---
Looking into it. 

diff of .115t.dse2 and .116t.reassoc1 is for the c++ testcase:

+  unsigned int _16;
+  unsigned int _17;
+  unsigned int _18;

   <bb 2>:
   _1 = s1.m2;
   _2 = (unsigned int) _1;
   _3 = s1.m3;
   _4 = (unsigned int) _3;
-  _5 = -_4;
-  _6 = _2 * _5;
+  _5 = _4;
+  _6 = _5 * _2;
   var_32.0_7 = var_32;
   _8 = (unsigned int) var_32.0_7;
   _9 = s1.m1;
   _10 = (unsigned int) _9;
-  _11 = -_10;
-  _12 = _8 * _11;
-  c_14 = _6 + _12;
+  _11 = _10;
+  _12 = _11 * _8;
+  _16 = _12 + _6;
+  _18 = _16;
+  _17 = -_18;
+  c_14 = _17;
   if (c_14 != 4098873984)


Also works with -fno-tree-vrp