Recognize basic block entries in the flow graph.

Recognize basic block entries in the flow graph.

Also, instead of keeping a list of all instructions, keep a list of only
block entries.  The printing implementation is changed (for the better) to
use the new representation.  With --use_new_compiler and --print_flow_graph
the function:

main() {
  var f = 1;
  var n = 5;
  while (n > 0) {
    f = f * n;
    n = n - 1;
  }
  print(f);
}

prints as:

 0: [target]
    StoreLocal(f, #1)
    StoreLocal(n, #5) goto 1
 1: [join]
    t0 <-LoadLocal(n)
    t0 <-InstanceCall(>, t0, #0)
    if t0 goto(2, 3)
 2: [target]
    t0 <-LoadLocal(f)
    t1 <-LoadLocal(n)
    t0 <-InstanceCall(*, t0, t1)
    StoreLocal(f, t0)
    t0 <-LoadLocal(n)
    t0 <-InstanceCall(-, t0, #1)
    StoreLocal(n, t0) goto 1
 3: [target]
    t0 <-LoadLocal(f)
    StaticCall(print, t0)
    return #null

R=srdjan@google.com
BUG=
TEST=

Committed: https://code.google.com/p/dart/source/detail?r=4515

[Kevin Millikin (Google), 2012-02-22 17:06:06]

I already know that:

(1) it's obvious that we need some type testing or casting support for
instructions so we can eliminate some of these virtual functions, and

(2) support for some sort of graph visitor would be nice because the "loop over
blocks, inner loop over instructions" will get tedious.

I'll do that next.

[srdjan, 2012-02-22 17:41:10]

LGTM

https://chromiumcodereview.appspot.com/9429056/diff/1/runtime/vm/flow_graph_b...
File runtime/vm/flow_graph_builder.cc (right):

https://chromiumcodereview.appspot.com/9429056/diff/1/runtime/vm/flow_graph_b...
runtime/vm/flow_graph_builder.cc:878: while (current != NULL &&
!current->IsBlockEntry()) {
More parenthesis, please

https://chromiumcodereview.appspot.com/9429056/diff/1/runtime/vm/flow_graph_b...
runtime/vm/flow_graph_builder.cc:899: intptr_t index =
postorder_block_entries_.length() - 1;
AS a for loop maybe?

intptr_t number = 0;
for (intptr_t index = postorder_block_entries_.length() - 1;
    i >=0; index--) {

}

[srdjan, 2012-02-22 18:31:45]

Make sure you run the tests with --use_new_compiler

On 2012/02/22 17:41:10, srdjan wrote:
> LGTM
> 
>
https://chromiumcodereview.appspot.com/9429056/diff/1/runtime/vm/flow_graph_b...
> File runtime/vm/flow_graph_builder.cc (right):
> 
>
https://chromiumcodereview.appspot.com/9429056/diff/1/runtime/vm/flow_graph_b...
> runtime/vm/flow_graph_builder.cc:878: while (current != NULL &&
> !current->IsBlockEntry()) {
> More parenthesis, please
> 
>
https://chromiumcodereview.appspot.com/9429056/diff/1/runtime/vm/flow_graph_b...
> runtime/vm/flow_graph_builder.cc:899: intptr_t index =
> postorder_block_entries_.length() - 1;
> AS a for loop maybe?
> 
> intptr_t number = 0;
> for (intptr_t index = postorder_block_entries_.length() - 1;
>     i >=0; index--) {
> 
> }

[Kevin Millikin (Google), 2012-02-23 09:08:04]

https://chromiumcodereview.appspot.com/9429056/diff/1/runtime/vm/flow_graph_b...
File runtime/vm/flow_graph_builder.cc (right):

https://chromiumcodereview.appspot.com/9429056/diff/1/runtime/vm/flow_graph_b...
runtime/vm/flow_graph_builder.cc:878: while (current != NULL &&
!current->IsBlockEntry()) {
On 2012/02/22 17:41:10, srdjan wrote:
> More parenthesis, please

Thanks for the reminder.

https://chromiumcodereview.appspot.com/9429056/diff/1/runtime/vm/flow_graph_b...
runtime/vm/flow_graph_builder.cc:899: intptr_t index =
postorder_block_entries_.length() - 1;
On 2012/02/22 17:41:10, srdjan wrote:
> AS a for loop maybe?
> 
> intptr_t number = 0;
> for (intptr_t index = postorder_block_entries_.length() - 1;
>     i >=0; index--) {
> 
> }

Done.