[LLVMbugs] [Bug 2069] New: opt --std-compile-opts misses optimizations on first pass

bugzilla-daemon at cs.uiuc.edu bugzilla-daemon at cs.uiuc.edu
Tue Feb 19 11:46:55 PST 2008


           Summary: opt --std-compile-opts misses optimizations on first
           Product: tools
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: opt
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: daniel at zuster.org
                CC: llvmbugs at cs.uiuc.edu

Created an attachment (id=1431)
 --> (http://llvm.org/bugs/attachment.cgi?id=1431)
Poorly optimized test case (hacked up pcregrep).

(I'm not sure whether I should consider this a bug, feedback appreciated)

On the given test file opt is significantly more effective (in terms of
emmitted bytecode size) when run twice.

ddunbar at ozzy:lli$ llvm-as -o=- pcregrep.ll | opt --std-compile-opts | llvm-dis
| wc -l
ddunbar at ozzy:lli$ llvm-as -o=- pcregrep.ll | opt --std-compile-opts | opt
--std-compile-opts | llvm-dis | wc -l

Sorry for the complexity of the test case, it is hand trimmed from an llvm
built pcregrep and there is a lot of dead code in the initial test. I don't
have an easy way to trim further while still reproducing the bug.

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