GCC Bugzilla Bug 36137

The attached program prints (unsigned) -1 as opposed to 1.
This doesn't happen if intermediate variables are used somewhere in the
process.

I tested gcc 3.4, 4.2.3 (on both x86 and x86-64) with -O0 and -O2, all ended up
with -1.
suncc printed 1.

Created an attachment (id=15581) [edit]
testcase

test.c.t02.original says:

  u = MAX_EXPR <(unsigned int) i, 1>;

... but this is wrong.

fold_binary sees both MAX_EXPRs and reassociates.
(I think this is why it works with intermediate variables.)

Then associate_trees creates a new MAX_EXPR, converting each
argument to unsigned:

  return fold_build2 (code, type, fold_convert (type, t1),
                      fold_convert (type, t2));

So, this is where the error enters.
I'm not sure where this is best fixed though.

Subject: Bug 36137

Author: jakub
Date: Wed May  7 07:40:01 2008
New Revision: 135028

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=135028
Log:
        PR middle-end/36137
        * fold-const.c (fold_binary): Use STRIP_SIGN_NOPS instead of
        STRIP_NOPS on arguments even for MIN_EXPR and MAX_EXPR.

        * gcc.c-torture/execute/20080506-1.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/20080506-1.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fold-const.c
    trunk/gcc/testsuite/ChangeLog

Subject: Bug 36137

Author: jakub
Date: Wed May  7 07:58:33 2008
New Revision: 135031

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=135031
Log:
        PR middle-end/36137
        * fold-const.c (fold_binary): Use STRIP_SIGN_NOPS instead of
        STRIP_NOPS on arguments even for MIN_EXPR and MAX_EXPR.

        * gcc.c-torture/execute/20080506-1.c: New test.

Added:
    branches/gcc-4_3-branch/gcc/testsuite/gcc.c-torture/execute/20080506-1.c
Modified:
    branches/gcc-4_3-branch/gcc/ChangeLog
    branches/gcc-4_3-branch/gcc/fold-const.c
    branches/gcc-4_3-branch/gcc/testsuite/ChangeLog

Fixed in 4.3 and on the trunk.