8081823: C2 performs unsigned comparison against -1 (original) (raw)

Roland Westrelin roland.westrelin at oracle.com
Tue Jun 9 13:04:11 UTC 2015

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Thanks for the reviews, Vladimir & Vladimir.

Roland.

On Jun 8, 2015, at 7:45 PM, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:

Looks good. Best regards, Vladimir Ivanov On 6/8/15 6:38 PM, Roland Westrelin wrote: http://cr.openjdk.java.net/~roland/8081823/webrev.00/

C2 folds: if (i <= a || i > b) { as: if (i - a - 1 >u b - a - 1) { a == b is allowed and the test becomes then if (i-1 >u -1) { which is never true. Same is true with if (i > b || i <= a) {_ _The fix folds it as:_ _if (i - a - 1 >=u b - a) { which is always true for a == b Roland.

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