Bug 82312 - DFG OSR exit should not generate an exit for variables of inlinees if the inlinees are not in scope
Summary: DFG OSR exit should not generate an exit for variables of inlinees if the inl...
Alias: None
Product: WebKit
Classification: Unclassified
Component: JavaScriptCore (show other bugs)
Version: 528+ (Nightly build)
Hardware: All All
: P2 Normal
Assignee: Filip Pizlo
Depends on:
Reported: 2012-03-27 02:13 PDT by Filip Pizlo
Modified: 2012-03-27 14:55 PDT (History)
5 users (show)

See Also:

the patch (3.58 KB, patch)
2012-03-27 02:18 PDT, Filip Pizlo
oliver: review+
Details | Formatted Diff | Diff

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Description Filip Pizlo 2012-03-27 02:13:08 PDT
Currently DFG OSR exit computes a value recovery, and generates recovery code, for every variable within the DFG code block's Graph::m_localVars, which ends up being the high watermark of the stack for all inlinees.  This means that for example in this code:

function foo(a, b) {
    return a + b;

function bar(a, b, c) {
    var x = foo(a, b);
    return x + c.f;

If we OSR exit at c.f, then the exit will include code to restore local variables within foo(), which is clearly redundant since foo() is out of scope at that point.

Patch forthcoming.
Comment 1 Filip Pizlo 2012-03-27 02:18:16 PDT
Created attachment 134007 [details]
the patch
Comment 2 Eric Seidel (no email) 2012-03-27 12:36:40 PDT
Attachment 134007 [details] was posted by a committer and has review+, assigning to Filip Pizlo for commit.
Comment 3 Filip Pizlo 2012-03-27 14:55:01 PDT
Landed in http://trac.webkit.org/changeset/112320