The fix is to enable type inference.
The old `List(n)` constructor was replaced by `List.filled`. `List(n)`
could be recognized as fixed-length purely by syntax. The test failed
after the replacement because `List.filled` is not recognized to be
fixed-length purely syntactically in the SSA builder, but rather by
type inference.
With type inference enabled, `List.filled` is recognized, but other
parts of the test need to be more realistic, as type inference also
detects the element type and length.
Bug: #52139
Change-Id: Icfaeb3e341b448bbc263efe43f48a2b76d05bf5b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/298020
Reviewed-by: Nate Biggs <natebiggs@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
This CL replaces https://dart-review.googlesource.com/c/sdk/+/296900
The `List` constructor is removed in Dart 3.0.
Some of the `@patch` implementations were not removed.
This is *high priority*. It seems the left-over `@patch factory List` constructor did not cause any errors, instead it *added* a constructor to `List` that can be used in web compiled code. Even if `List` doesn't have such a constructor in the SDK code proper.
The VM and analyzer will say the invocation is an error, but dart2js happily compiles it and runs.
(It used to be that patches couldn't add public members, that security seems to have been removed.)
Also removes code which tries to detect "the unnamed List constructor",
which is no longer a thing, and a number of invocations of the constructor, where it's not clear that the test is aware that the constructor no longer exists, and is not marked as `@dart=2.x` with x < 12.
TEST=ci
Change-Id: I4ffaf3ae2c4e75ca06e7ba0bf19187b6376f3888
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/297100
Reviewed-by: Brian Quinlan <bquinlan@google.com>
Reviewed-by: Nate Bosch <nbosch@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
`int` variables can attain NaN values because web int arithmetic
implemented by JavaScript numbers (doubles) is not closed under many
operations. It is possible get NaN using only addition:
int a = 1, b = -1;
while (a + a != a) { a += a; b += b; }
int nan = a + b;
On the VM, a, b and nan are all zero.
On the web, a, b and nan are Infinity, -Infinity and NaN, respectively.
Since NaN can leak into int arithmetic, is it helpful if bounds checks
catch NaN indexes. NaN compares false in any comparison, so a test
of the form
if (index < 0 || index >= a.length) throw ioore(a, index);
fails to detect a NaN value of `index`.
This is fixed by negating the comparisons, and applying De Morgan's law:
if (!(index >= 0 && index < a.length)) throw ioore(a, index);
These changes have been applied to JSArray.[], JSArray.[]= and String.[]
For dart2js the change is a little more involved. Primitive indexing is
lowered to code with a HBoundsCheck check instruction. The code generated
for the instruction now uses, e.g. `!(i>=0)` instead of `i<0`.
This leads to a small code size regression.
There is no regression at -O4 since bounds checks are omitted at -O4.
At -O3 (where the regression is largest) the regression is
0.01% for cm
0.06% for flutter gallery -- array-heavy diff and layout
0.21% for Meteor -- array-heavy code
0.30% for Box2DOctane -- array-heavy code
I believe the regression can be largely alleviated by determining if
NaN is impossible at the index check, and if so, reverting to the smaller
code pattern. The analysis could be global, incorporating NaN into the
global abstract value domain, or a much simpler a local dataflow
analysis. Many indexes are loop driven and cannot reach infinity because
they are incremented by a small bump and eventually (even without a loop
guard) the index would stop growing when the increment falls below the
rounding error in O(2^53) iterations.
Change-Id: I23ab1eb779f1d0c9c6655e13d69f65d453db9284
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/210321
Commit-Queue: Stephen Adams <sra@google.com>
Reviewed-by: Mayank Patke <fishythefish@google.com>
Stephen Adams