Ian,
I am sure I comes across trouble for the following code.
(function main
(signature void
(parameters
)
(
(loop ((declare () int i@0x8d19434)) ((constant int (0)) )
((constant int (32)) ) ((constant int (1)) ) (
(call foo ((var_ref sampler2d@0x8eef134) (var_ref
myTexCoord@0x8eef05c) ))
))
the loop is generated by hand, using the following code.
ir_loop * loop = new (ctx)ir_loop();
ir_variable * indvar = new (ctx)
ir_variable(glsl_type::int_type, "i",ir_var_auto);
ir_dereference * idx = new (ctx)
ir_dereference_variable(indvar);
loop->from = new(ctx) ir_constant(0);
loop->to = new(ctx) ir_constant(32);
loop->increment = new (ctx) ir_constant(1);
loop->cmp = ir_binop_less;
loop->counter = indvar;
loop->body_instructions = sig->body;
sig->body.make_empty();
call_link_visitor(link_function.cpp) can not see the variable
i@0x8d19434. it's because call_link_visitor extends from
ir_hierachical_visitor. ir_loop::accept(ir_hierarchical_visitor
*v)**doesn't look at ir_loop::counter .
that is to say, it assumes the indvar is out of loop contruct, right?
perhaps my usage is wrong.
my changeset makes it like breeze.
index be8b36a..4e4dd4c 100644*
*--- a/src/glsl/ir_hv_accept.cpp
+++ b/src/glsl/ir_hv_accept.cpp
@@ -71,6 +71,7 @@ ir_loop::accept(ir_hierarchical_visitor *v)
if (s != visit_continue)
return (s == visit_continue_with_parent) ? visit_continue : s;
+ if (this->counter) s = this->counter->accept(v);
s = visit_list_elements(v, &this->body_instructions);
if (s == visit_stop)
return s;
*
*
thanks,
--lx
On 10/12/2013 05:39 AM, Ian Romanick wrote:
On 10/10/2013 11:14 PM, Liu Xin wrote:
Hi, Mesa developers,
According to glsl v1.0, we have loop construct:
for (for-init-statement; condition(opt); expression)
statement-no-new-scope
Variables declared in for-init-statement or condition are only in scope
until the end of the
statement-no-new-scope of the for loop.
let's assume I have a fragment shader:
~/testbed$ cat indvar.frag
void main(void)
{
vec4 a[32];
for(int i=0; i<10; ++i) {
if (i == 9)
gl_FragColor = a[i];
}
}
I found current glsl compiler emits HIR like this:
The HIR loses all notions of scope.
(function main
(signature void
(parameters
)
(
(declare () int i@0x988eb84)
(declare () (array vec4 32) a@0x988ec5c)
(declare (temporary ) int assignment_tmp@0x988eaac)
(assign (constant bool (1)) (x) (var_ref
assignment_tmp@0x988eaac) (constant int (0)) )
(assign (constant bool (1)) (x) (var_ref i@0x988eb84) (var_ref
assignment_tmp@0x988eaac) )
(loop () () () () (
(if (expression bool ! (expression bool < (var_ref i@0x988eb84)
(constant int (10)) ) ) (
break
)
())
(if (expression bool all_equal (var_ref i@0x988eb84) (constant
int (9)) ) (
(declare (temporary ) vec4 assignment_tmp@0x987cee4)
(assign (constant bool (1)) (xyzw) (var_ref
assignment_tmp@0x987cee4) (array_ref (var_ref a@0x988ec5c) (var_ref
i@0x988eb84) ) )
(assign (constant bool (1)) (xyzw) (var_ref
gl_FragColor@0x96d8fc4) (var_ref assignment_tmp@0x987cee4) )
)
())
(declare (temporary ) int assignment_tmp@0x987cb84)
(assign (constant bool (1)) (x) (var_ref
assignment_tmp@0x987cb84) (expression int + (var_ref i@0x988eb84)
(constant int (1)) ) )
(assign (constant bool (1)) (x) (var_ref i@0x988eb84) (var_ref
assignment_tmp@0x987cb84) )
))
))
)
I think glsl compiler translates AST like this
int i = 0;
for (;;) {
if (i < 10) break;
if (i == 9) gl_FragColor = a [ i ] ;
i = i + 1;
}
Is it correct?
I believe this block is implicitly surrounded by { and }. I'm pretty
sure that we have test cases for the situation you're describing, but
I'd have to go dig around.
Another question, for class ir_loop, why is ir_loop::counter ir_variable
while from/to/increment are all ir_rvalue? I create an ir_variable for
ir_loop counter, but hierarchical visitor won't access it. I don't think
ir_loop::accept(ir_hierarchical_visitor *v) will visit ir_loop::counter
at all.
ir_loop::counter is the variable that hold the loop counter.
ir_loop::from is the initial value of the counter, ir_loop::to is the
end value, and ir_loop::increment is the value that ::counter is
modified by on each iteration.
thanks,
--lx
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