1021310 - Optimization-blocking intrinsics

Status: NEW

(Core :: JavaScript Engine: JIT, enhancement, P5)

Description

[Dan Gohman [:sunfish]]

For testing purposes, it would be very useful to be able to hide certain values from the optimizer, to prevent it from folding them or using other specialized evaluation techniques.

My first thought was an intrinsic like identity(x) which returns x, except that the optimizer is not allowed to know that. Waldo on irc also suggested identityInt32, identityValue, to preserve varying levels of type visibility.

These intrinsics should be used to make the testcases added in bug 1017275 more resilient against optimizer cleverness.

Comment 1

[Dan Gohman [:sunfish]]

The testcase in bug 998704 could also use this.