1023300 - Do edgeCaseAnalysis on ranges for MDiv

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, defect)

Description

[Hannes Verschore [:h4writer]]

Bug 998485 for MDiv:

We calculate 
- canBeDivideByZero_
- canBeNegativeOverflow_
- canBeNegativeZero_
based on particular values flowing in during MDiv::analyzeEdgeCasesForward.
(http://dxr.mozilla.org/mozilla-central/source/js/src/jit/MIR.cpp#1498)

We should do the same in:
MDiv::collectRangeInfoPreTrunc
(http://dxr.mozilla.org/mozilla-central/source/js/src/jit/RangeAnalysis.cpp#2671)

But now based on the input range instead of the value.

Comment 1

[Sushant Dinesh]

Attachment: RangeAnalysis for MDiv

Comment 2

[Hannes Verschore [:h4writer]]

Comment on attachment 8439937 [details] [diff] [review]
RangeAnalysis for MDiv

Review of attachment 8439937 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/jit/RangeAnalysis.cpp
@@ +2694,5 @@
> +    // negative zero check can be skipped.
> +    if (!lhsRange.canBeZero())
> +        canBeNegativeZero_ = false;
> +
> +    // If rhsRange does not contain a zero likewise.

This comment is incorrect. It checks if rhs is non-negative.

::: js/src/jit/RangeAnalysis.h
@@ +454,5 @@
>      bool canHaveRoundingErrors() const {
>          return canHaveFractionalPart() || max_exponent_ >= MaxTruncatableExponent;
>      }
>  
> +    //Test if an integer x belongs to the range.

Space between // and Test

Comment 3

[Hannes Verschore [:h4writer]]

Try:
https://tbpl.mozilla.org/?tree=Try&rev=9490456a5653

Comment 4

[Sushant Dinesh]

Attachment: RangeAnalysis for MDiv

Comment 5

[Sushant Dinesh]

Attachment: RangeAnalysis for MDiv

Comment 6

[Hannes Verschore [:h4writer]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/a8449471a038

Comment 7

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/a8449471a038