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Bug 25879 - Incorrect schedule is generated
Summary: Incorrect schedule is generated
Status: RESOLVED FIXED
Alias: None
Product: Polly
Classification: Unclassified
Component: Optimizer (show other bugs)
Version: unspecified
Hardware: PC Linux
: P normal
Assignee: Polly Development Mailinglist
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2015-12-18 04:26 PST by Johannes Doerfert
Modified: 2016-02-01 06:00 PST (History)
2 users (show)

See Also:
Fixed By Commit(s):

Attachments
Testcase (2.96 KB, application/octet-stream)
2015-12-18 04:26 PST, Johannes Doerfert 		Details
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Description Johannes Doerfert 2015-12-18 04:26:16 PST 
Created attachment 15482 [details]
Testcase

The Schedule generation relies on a reverse post order traversal as the domain generation does. Though, for the former this is not the right choice as it does not guarantee loops are visited completely after the header was visited. Instead, blocks after the loop can be visited first causing them to appear prior in the schedule than they should. An example test case is attached.

This bug was detected due to a SSA-Codegen failure in an lnt benchmark. It does apperently not cause a result change for the current code generation, even though we basically load/use an uninitialized value...

I am working on a patch for the schedule generation but ideas are welcome.
Comment 1 Tanya Lattner 2016-01-18 16:51:06 PST 
Move bugs to Polly product.
Comment 2 Tobias Grosser 2016-02-01 06:00:45 PST 
https://llvm.org/svn/llvm-project/polly/trunk@259354