COND_EXPRs in GIMPLE code and vectorizer

[Daniel Berlin]

On 9/27/06, Roberto COSTA <roberto.costa@st.com> wrote:
> Hello,
> I have a question about the form of COND_EXPR nodes allowed in GIMPLE
> representation.
> By looking at what gimplify.c does (more precisely, at function
> gimplify_cond_expr (...) ), I understood that GIMPLE only allows a
> restricted form of COND_EXPR, in which both 'then' and 'else' operands
> are GOTO_EXPR nodes.

This is true for the conditional form that appears as a statement

> However, when compiling with -ftree-vectorize command-line option, there
> are cases of COND_EXPR nodes generated and not gimplified (in the sense
> of my previous sentence).

However, it is possible for them to also appear on the RHS of a
MODIFY_EXPR in order to represent the results of if-conversion.

IE
a = b ? c : d

In this form, I believe each arm is required to be an SSA_VAR_P

The way to differentiate the two is that the first form *only* appears
as a statement, and the second form *only* appears on the RHS of a
MODIFY_EXPR.

HTH,
Dan