[llvm-bugs] [Bug 33387] New: -verify-scev is causing hang or just taking forever

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=33387

            Bug ID: 33387
           Summary: -verify-scev is causing hang or just taking forever
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Loop Optimizer
          Assignee: unassignedbugs at nondot.org
          Reporter: paulsson at linux.vnet.ibm.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 18604
  --> https://bugs.llvm.org/attachment.cgi?id=18604&action=edit
test case

(Csmith)

This test case takes a second to compile with clang, but with -mllvm
-verify-scev, it does not seem to terminate after even an hour...

It seems that GlobalsModRef.cpp is recursing very heavily in
Constant::isConstantUsed(). 

When I try this->dump() on the Constant, the dumping never ends, so this seems
to be either crazy or something that the algorithm should guard against.

bin/clang -cc1 -triple s390x-ibm-linux -S  -target-cpu z13 -O3 -vectorize-loops
-vectorize-slp  -o /dev/null -x ir ~/build-dev/test4.bc -mllvm -verify-scev

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