http://llvm.org/bugs/show_bug.cgi?id=18747
Bug ID: 18747
Summary: Add an option to allow an exhaustive search during
last chance recoloring
Product: libraries
Version: trunk
Hardware: All
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: Register Allocator
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
Since r200883, the greedy register allocator features a last chance recoloring
mechanism.
This mechanism allows to find a valid assignment of the variables (if any) when
the regular heuristic fails.
It uses a backtracking algorithm which is currently cutoff with some heuristics
to avoid uncontrolled compile time.
There is two things to improve here:
1. When the assignment fails because of the early cutoffs, this should be
reported instead of the current obscur “ran out of registers”.
2. We should provide an option (e.g., -fexhaustive-register-search) to allow to
explore all the possibilities when the allocation failed because of a cutoffs
(which we would know thanks to 1.).
For testing the reporting in 1., one can use the test-case of r200883 and
artificially cut the search space with:
- lcr-max-depth=<uint>
- lcr-max-interf=<uint>
--
You are receiving this mail because:
You are on the CC list for the bug.
_______________________________________________
LLVMbugs mailing list
[email protected]
http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs
