[Mono-bugs] [Bug 705186] New: soft-float decompose causes segfaults under some circumstances

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https://bugzilla.novell.com/show_bug.cgi?id=705186

https://bugzilla.novell.com/show_bug.cgi?id=705186#c0


           Summary: soft-float decompose causes segfaults under some
                    circumstances
    Classification: Mono
           Product: Mono: Runtime
           Version: 2.10.x
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: JIT
        AssignedTo: mono-bugs at lists.ximian.com
        ReportedBy: mirko.wischer at sma.de
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---
           Blocker: ---


User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.2.18)
Gecko/20110614 Firefox/3.6.18 ( .NET CLR 3.5.30729; .NET4.0E)

It seems that branch-opts optimizes a branch away so that you can have a
situation like this:
 ...
 fcompare RXX RYY
 nop 

Now the ARM specific soft-float decompose in mono/mini/decompose.c tries 
to replace OP_FCOMPARE + next instruction with some soft-float ARM code.
But the next instruction pointer is null so line 1588 in decompose.c segfaults. 


Reproducible: Always

Steps to Reproduce:
1. Compile attached example code
2. Run on x86 
3. Run on ARM with soft-float
Actual Results:  
Output is like this on ARM:
===========================
This makes the JIT work
Stacktrace:

  at foo.bar.Main () <IL 0x00006, 0x0000f>
  at (wrapper runtime-invoke) object.runtime_invoke_void
(object,intptr,intptr,intptr) <IL 0x0004c, 0xffffffff>
Aborted


Expected Results:  
No stacktrace

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