[Bug tree-optimization/53774] New: Reassociator generates non-canonical addition

[wschmidt at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53774

             Bug #: 53774
           Summary: Reassociator generates non-canonical addition
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: wschmidt@gcc.gnu.org
                CC: bergner@vnet.ibm.com, rguenther@suse.de


There is one test in the regression testsuite for which the reassociator
generates a GIMPLE addition that is not canonical.  Specifically, it generates
an add where rhs1 is a constant and rhs2 is an SSA name.  The test is:

gcc.c-torture/compiler/pr41634.c

The generated GIMPLE includes:

  D.1393_7 = 4294967293 + fp_6(D);

Probably best just to run this test from the testsuite to reproduce, but here
is the command I used.

/home/wschmidt/gcc/build/gcc-mainline-slsrpt1a/gcc/xgcc
-B/home/wschmidt/gcc/build/gcc-mainline-slsrpt1a/gcc/
-fno-diagnostics-show-caret -O0 -w -c -m32 -o pr41634.o
/home/wschmidt/gcc/gcc-mainline-slsrpt1a/gcc/testsuite/gcc.c-torture/compile/pr41634.c