[llvm-bugs] [Bug 25153] New: PowerPC DAG Pattern Instruction Selection Slowdown in LLVM 3.7

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=25153

            Bug ID: 25153
           Summary: PowerPC DAG Pattern Instruction Selection Slowdown in
                    LLVM 3.7
           Product: new-bugs
           Version: 3.7
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: matt.davis at pgroup.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 15059
  --> https://llvm.org/bugs/attachment.cgi?id=15059&action=edit
Optimized llvm ir test

I have noted a considerable slowdown from llvm 3.5 regarding llc processing
optimized files.  Compiling the attached .llvm file went from ~15 seconds to ~3
minutes.

LLVM 3.7
--------
Compile: llvm/3.7/bin/llc test.ll -mcpu=native -O2 -o test.s -time-passes
Total:   3 Minutes with 190.9secs User Time in PowerPC DAG->DAG Pattern
Instruction Selection


Compile: llvm/3.7/bin/llc test_opt.llvm -mcpu=native -O2 -o test.s -time-passes
Total:   6 Seconds with 5.4secs User Time in PowerPC DAG->DAG Pattern
Instruction Selection 


LLVM 3.5
--------
Compile: llvm/3.5/bin/llc test.ll -mcpu=native -O2 -o test.s -time-passes
Total:   15 Seconds with 14.5secs User Time in PowerPC DAG->DAG Pattern
Instruction Selection

Compile: llvm/3.5/bin/llc test_opt.llvm -mcpu=native -O2 -o test.s -time-passes
Total:   1.3 Seconds with 1.01secs User Time in PowerPC DAG->DAG Pattern
Instruction Selection

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