Match-and-simplify and COND_EXPR

Andrew Pinski
Wed Nov 5 22:34:00 GMT 2014

  I was trying to hook up tree-ssa-phiopt to match-and-simplify using
either gimple_build (or rather using gimple_simplify depending on if
we want to produce cond_expr for conditional move).  I ran into a
With the pattern below:
/* a ? 0 : 1 -> a if 0 and 1 are integral types. */
  (cond_expr @0 integer_zerop integer_onep)
  (if (INTEGRAL_TYPE_P (type))
    (convert @0)))

This produces a gimple statement with an incorrect gimple statement
where we have have a convert with an compare expression.

t.c: In function ‘f’:
t.c:1:5: error: invalid operand in unary operation
 int f(int c, int a, int b)
_4 = (int) (c_2(D) != 0);

Did I implement the pattern incorrectly or is there a bug due to the
way cond_expr handles its 0th operand in that it is valid for compares
there in gimple form.

I don't have a good patch to test tree-ssa-phiopt.c connection due the
patch having extra code in it already which handles creating cond_expr
for conditional moves already.

Andrew Pinski

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