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digitalmars.D.bugs - [Issue 5549] New: [64-bit] Internal error: backend/cgcod.c 1845

reply d-bugmail puremagic.com writes:
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           Summary: [64-bit] Internal error: backend/cgcod.c 1845
           Product: D
           Version: D2
          Platform: x86_64
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: dsimcha yahoo.com


--- Comment #0 from David Simcha <dsimcha yahoo.com> 2011-02-08 16:55:28 PST ---
This is another insanely hard to reproduce bug.  The following code produces a
"Internal error: backend/cgcod.c 1845" only when compiled with -O -inline
-release -unittest -m64.  I reduced it as far as I could.  All of the seemingly
unnecessary stuff is actually necessary for reproducing this bug.  Also, when I
copy/paste the implementation of Map into the same module as the code below, it
seems to prevent the bug from being reproduced.

import std.algorithm;

void cleanUp() {}

void doStuff(T)(T data) {
    scope(exit) cleanUp();  // Taking this out gets rid of the bug.
    size_t N = 0;

    foreach(i, rng; data) {  // Taking this loop out gets rid of the bug.
        auto rngLen = rng.length;
        N += rngLen;
    }

    int[] dataArray;
    size_t pos = 0;
    foreach(rng; data) {   // This loop is necessary.
        foreach(elem; rng) {
            dataArray[pos] = elem;
            pos++;
        }
    }

    double rBar = 0.5 * (N + 1);  // Even this line is necessary.
}

void main() {
    // Only happens on instantiations with Map.
    doStuff(
        [map!"a"([3,1,4,1])]
    );
}

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next sibling parent d-bugmail puremagic.com writes:
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bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
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                 CC|                            |bearophile_hugs eml.cc


--- Comment #1 from bearophile_hugs eml.cc 2011-02-08 17:08:59 PST ---
(In reply to comment #0)

 This is another insanely hard to reproduce bug.


As (I think) Don has said, back-end bugs are often harder to locate.

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Don <clugdbug yahoo.com.au> changed:

           What    |Removed                     |Added
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                 CC|                            |clugdbug yahoo.com.au


--- Comment #2 from Don <clugdbug yahoo.com.au> 2011-02-08 23:12:53 PST ---
This sounds quite similar to bug 5455. Both involve register allocation and a
complicated and fragile code sequence.

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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla digitalmars.com


--- Comment #3 from Walter Bright <bugzilla digitalmars.com> 2011-02-09
17:56:20 PST ---
https://github.com/D-Programming-Language/dmd/commit/a2b0280ebe1cb40b24c62d199d234bff55bf8024

https://github.com/D-Programming-Language/dmd/commit/8fd6ff07ae7f043e5eff9eb35148f73c54482f96

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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


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