http://llvm.org/bugs/show_bug.cgi?id=11811
Bug #: 11811
Summary: Greedy Register Allocator taking a loooong time on
module with many cleanups
Product: new-bugs
Version: trunk
Platform: PC
OS/Version: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: new bugs
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 7912
--> http://llvm.org/bugs/attachment.cgi?id=7912
Original C++ testcase
This is the gcc testcase cleanup1.C (attached). At -O1 gcc takes less than 4
seconds to compile it, while dragonegg takes 20 minutes or so. Almost all of
the time is spent in codegen, and almost all of that is in register allocation,
namely Global Splitting. To reproduce, run llc on the attached gzipped .ll
file.
$ llc cleanup1.ll -time-passes
...
===-------------------------------------------------------------------------===
Register Allocation
===-------------------------------------------------------------------------===
Total Execution Time: 919.5335 seconds (920.2625 wall clock)
---User Time--- --System Time-- --User+System-- ---Wall Time--- ---
Name ---
908.0848 ( 98.8%) 0.2160 ( 93.1%) 908.3008 ( 98.8%) 908.9710 ( 98.8%)
Global Splitting
10.9647 ( 1.2%) 0.0160 ( 6.9%) 10.9807 ( 1.2%) 11.0408 ( 1.2%) Evict
0.1200 ( 0.0%) 0.0000 ( 0.0%) 0.1200 ( 0.0%) 0.1249 ( 0.0%)
Spiller
...
===-------------------------------------------------------------------------===
... Pass execution timing report ...
===-------------------------------------------------------------------------===
Total Execution Time: 929.9901 seconds (930.7424 wall clock)
---User Time--- --System Time-- --User+System-- ---Wall Time--- ---
Name ---
919.4535 ( 98.9%) 0.2320 ( 56.9%) 919.6855 ( 98.9%) 920.4247 ( 98.9%)
Greedy Register Allocator
2.8242 ( 0.3%) 0.0000 ( 0.0%) 2.8242 ( 0.3%) 2.8260 ( 0.3%)
Simple Register Coalescing
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