Now the condition (for the then-clause) and the inverse condition (for
the else-clause) get written to separate temporary variables. In the
presence of complex conditions, this shouldn't result in more code
being generated. If the original if-statement was
if (a && b && c && d && e) {
...
} else {
...
}
The lowered code will be
if_to_cond_assign_then = a && b && c && d && e;
...
if_to_cond_assign_else = !if_to_cond_assign_then;
...
Reviewed-by: Eric Anholt <eric@anholt.net>
Previously, if max_depth were 1, the following code would see the
first if-statement (correctly) not get flattened, but the second
if-statement would (incorrectly) get flattened:
void main()
{
if (a)
gl_Position = vec4(0);
if (b)
gl_Position = vec4(1);
}
This is because the visit_leave(ir_if*) method would not decrement the
depth before returning on the first if-statement.
NOTE: This is a candidate for the 7.10 and 7.11 branches.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This adds a new optional max_depth parameter (defaulting to 0) to
lower_if_to_cond_assign, and makes the pass only flatten if-statements
nested deeper than that.
By default, all if-statements will be flattened, just like before.
This patch also renames do_if_to_cond_assign to lower_if_to_cond_assign,
to match the new naming conventions.
