[Issue 7750] New: while(true) loop with try/catch block causes segfault

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=7750

           Summary: while(true) loop with try/catch block causes segfault
           Product: D
           Version: D2
          Platform: All
        OS/Version: Mac OS X
            Status: NEW
          Severity: critical
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: brian+d at codekitchen.net


--- Comment #0 from Brian Palmer <brian+d at codekitchen.net> 2012-03-21 21:56:22 PDT ---
I ran into a segfault when using a try/catch block inside a while(true) loop
when there are other statements after the try/catch block. I reduced it down to
this consistent segfault:

import std.stdio;

void main() {
  while (true) {
    try {
      throw new Exception("ah");
    } catch (Exception e) {
    }
    writeln("remove this line and it won't segfault");
  }
}

This segfaults in the first iteration on DMD 2.058 on OS X 10.7.3. It segfaults
with both -m32 and -m64. Stacktrace:

0   libdyld.dylib                     0x00007fff8f3436cd
misaligned_stack_error_entering_dyld_stub_binder + 0
1   ???                               0x000000010f535030 0 + 4552085552
2   bug1.d.DC445724916B27653F5E50703AE848DF    0x000000010f51f133 _Dmain + 103
3   bug1.d.DC445724916B27653F5E50703AE848DF    0x000000010f52f8dd
D2rt6dmain24mainUiPPaZi7runMainMFZv + 29
4   bug1.d.DC445724916B27653F5E50703AE848DF    0x000000010f52f28d
D2rt6dmain24mainUiPPaZi7tryExecMFMDFZvZv + 45
5   bug1.d.DC445724916B27653F5E50703AE848DF    0x000000010f52f92f
D2rt6dmain24mainUiPPaZi6runAllMFZv + 63
6   bug1.d.DC445724916B27653F5E50703AE848DF    0x000000010f52f28d
D2rt6dmain24mainUiPPaZi7tryExecMFMDFZvZv + 45
7   bug1.d.DC445724916B27653F5E50703AE848DF    0x000000010f52f210 main + 232
8   bug1.d.DC445724916B27653F5E50703AE848DF    0x000000010f51f0c4 start + 52


Removing the writeln, or changing it to a non-infinite loop like int
x;while(++x<3) will avoid the segfault, so it seems likely DMD is making a bad
assumption about the loop related to it being infinite.

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