Fix bad code-generation for nested-ifs in for loops.

Fix bad code-generation for nested-ifs in for loops.

In the builder we compile (x && y && z) into nested ifs. Before
code-emission we try to detect this pattern:


            If
          /    \
         /      \
      1 expr1    \
       If         \
      /  \         \
     /    \         goto
  1 expr2            |
    goto    goto     |
      \     /        |
       \   /         |
   phi1(expr2, true|false)   <=== nested if's join block
          \          |
           \         |
             phi(phi1, true|false)

However we forgot to verify that the nested if's join block didn't
contain any expression.

Fixes issue 4826.

Committed: https://code.google.com/p/dart/source/detail?r=11627

[ngeoffray, 2012-08-30 16:46:10]

LGTM

https://chromiumcodereview.appspot.com/10917012/diff/1/tests/language/nested_...
File tests/language/nested_if_test.dart (right):

https://chromiumcodereview.appspot.com/10917012/diff/1/tests/language/nested_...
tests/language/nested_if_test.dart:13: /*------- Avoid inlining
----------------------*/
WebToolkitFramework? Maybe it's time to have a @NoInline annotation.

[floitsch, 2012-08-30 16:51:35]

https://chromiumcodereview.appspot.com/10917012/diff/1/tests/language/nested_...
File tests/language/nested_if_test.dart (right):

https://chromiumcodereview.appspot.com/10917012/diff/1/tests/language/nested_...
tests/language/nested_if_test.dart:13: /*------- Avoid inlining
----------------------*/
On 2012/08/30 16:46:10, ngeoffray wrote:
> WebToolkitFramework? Maybe it's time to have a @NoInline annotation.
I agree that we need that annotation. In a different CL. Then we need to go
through all tests and add it where necessary.
Alternatively a flag: --no-inlining.