COND_EXPRs in GIMPLE code and vectorizer

[Roberto COSTA]

Daniel Berlin wrote:
> 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.

Thanks for the explanation.
The COND_EXPRs I saw were indeed of this second form.

What is a bit surprising at second sight (first sight was my point of 
view while writing the first message) is that gimplify pass expands the 
COND_EXPRs of the second form into control-flow. Therefore, it looks 
like the only ones that can be found after gimplification are those 
generated by a further pass.

Cheers,
Roberto