[llvm-bugs] [Bug 44249] New: [Compile Time] 50% of time spent in Elim phi nodes

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=44249

            Bug ID: 44249
           Summary: [Compile Time]  50% of time spent in Elim phi nodes
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Register Allocator
          Assignee: unassignedbugs at nondot.org
          Reporter: paulsson at linux.vnet.ibm.com
                CC: llvm-bugs at lists.llvm.org, quentin.colombet at gmail.com

clang -O3 -march=z13 tc_ctime_elimphi_gvn.i -o a.out -w -ftime-report

---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name
---
230.3186 ( 51.8%)   0.1120 ( 16.9%)  230.4306 ( 51.7%)  232.3138 ( 51.7%) 
Eliminate PHI nodes for register allocation
101.7915 ( 22.9%)   0.1046 ( 15.8%)  101.8961 ( 22.9%)  102.6262 ( 22.8%) 
Global Value Numbering
 17.3571 (  3.9%)   0.0178 (  2.7%)  17.3749 (  3.9%)  17.5102 (  3.9%)  Memory
SSA #2
  8.7322 (  2.0%)   0.0129 (  2.0%)   8.7451 (  2.0%)   8.8148 (  2.0%)  Greedy
Register Allocator
  8.4621 (  1.9%)   0.0887 ( 13.4%)   8.5508 (  1.9%)   8.6025 (  1.9%) 
SystemZ DAG->DAG Pattern Instruction Selection


gcc -O3: 74s
clang -O3: 446s

(csmith)

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