[LLVMbugs] [Bug 2786] New: in correct branch code produced by code generator, under certain circumstances

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=2786

           Summary: in correct branch code produced by code generator, under
                    certain circumstances
           Product: libraries
           Version: 2.3
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Common Code Generator Code
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: lefever at crhc.uiuc.edu
                CC: llvmbugs at cs.uiuc.edu


The the machine code generator produces incorrect machine code when processing
the attached bitcode file.  The bitcode has a main function that sets up a few
variables and calls strtol___efw______augfun___().
strtol___efw______augfun___() peforms roughly as such:

---------------------------------
1: ...
2: int tmp = (memcmp(...) == 0);
3: ...
4: printf(stderr, "%d\n", tmp);
5: ...
6: if(tmp != 0){
7:   printf(stderr, "%d\n", tmp);
8: }
9: ...
10: // later code causes a seg fault
-----------------------------

The problem is that lines 4 and 7 print tmp to be 1; however, we should never
execute line 7, if tmp is 1.

This bug is confirmed on version 2.3 of LLVM.  I tried to test with the latest
SVN version of LLVM, but I could not get the gcc frontend to compile on my
x86-64 Linux machine.

I will attach appropriate bugpoint files shortly.


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