https://bugs.llvm.org/show_bug.cgi?id=41263
Bug ID: 41263
Summary: [CompileTime] [DAGCombiner] Large amount of
compile-time spent in getStoreMergeCandidates for
inputs with lots of stores
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: Common Code Generator Code
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Created attachment 21687
--> https://bugs.llvm.org/attachment.cgi?id=21687&action=edit
Script to trigger worst case in DAGCombiner and Pre-RA-scheduler
Currently DAGCombiner spends a huge amount of time in getStoreMergeCandidates
for inputs with lots of stores, because it iterates over all stores in the same
token factor for each store it visits.
The attached script generates ll files with N stores in a single BB, that
cannot be merged.
For 10000 stores, bin/llc -o /dev/null -stop-before=machine-scheduler
-time-passes reports
===-------------------------------------------------------------------------===
... Pass execution timing report ...
===-------------------------------------------------------------------------===
Total Execution Time: 19.3153 seconds (24.4060 wall clock)
---User Time--- --System Time-- --User+System-- ---Wall Time--- ---
Name ---
18.4783 ( 99.5%) 0.7263 ( 97.3%) 19.2046 ( 99.4%) 24.2557 ( 99.4%) X86
DAG->DAG Instruction Selection
0.0299 ( 0.2%) 0.0093 ( 1.2%) 0.0392 ( 0.2%) 0.0545 ( 0.2%) MIR
Printing Pass
===-------------------------------------------------------------------------===
Instruction Selection and Scheduling
===-------------------------------------------------------------------------===
Total Execution Time: 19.1471 seconds (24.1911 wall clock)
---User Time--- --System Time-- --User+System-- ---Wall Time--- ---
Name ---
9.1751 ( 49.8%) 0.3746 ( 52.2%) 9.5496 ( 49.9%) 12.7750 ( 52.8%) DAG
Combining 2
7.4307 ( 40.3%) 0.1554 ( 21.6%) 7.5861 ( 39.6%) 8.5715 ( 35.4%) DAG
Combining 1
1.7270 ( 9.4%) 0.1716 ( 23.9%) 1.8986 ( 9.9%) 2.6702 ( 11.0%)
Instruction Scheduling
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
