[llvm-bugs] [Bug 33320] New: Bitcode file with a large flat function takes a long time to compile with llc -O3

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=33320

            Bug ID: 33320
           Summary: Bitcode file with a large flat function takes a long
                    time to compile with llc -O3
           Product: libraries
           Version: 4.0
          Hardware: Macintosh
                OS: MacOS X
            Status: NEW
          Keywords: performance
          Severity: normal
          Priority: P
         Component: Register Allocator
          Assignee: unassignedbugs at nondot.org
          Reporter: chris.schaf at verizon.net
                CC: llvm-bugs at lists.llvm.org

My Common Lisp compiler (github.com/drmeister/clasp) generates a RUN-ALL
function for generating Common Lisp objects at startup.  The time it takes
clang to compile this function scales roughly as N^3 where N is the number of
instructions.

Use llc -O3 biglist20000.bc

This builds a 20,000 entry list 
It takes more than 2 minutes on my machine.
With 7,000 entries it takes 7 seconds.

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