Thread overview
[Issue 2127] New: inliner turns struct "return *this" from by-value into by-ref
May 24, 2008
d-bugmail
Jan 15, 2010
Don
[Issue 2127] inliner turns struct "return *this" from by-value into by-ref (D1 only)
May 25, 2010
Brad Roberts
May 25, 2010
Brad Roberts
May 30, 2010
Walter Bright
May 24, 2008
http://d.puremagic.com/issues/show_bug.cgi?id=2127

           Summary: inliner turns struct "return *this" from by-value into
                    by-ref
           Product: D
           Version: 1.030
          Platform: PC
        OS/Version: All
            Status: NEW
          Keywords: wrong-code
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: fvbommel@wxs.nl


The following code:
-----
module evbug;
import std.stdio;

struct S {
  int last = 0;
  S opCall(int i) {
    writefln("%s %s", last, i);
    last = i;
    return *this;
  }
}

void main() {
  S t;
  t(1)(2);
  t(3);
}
-----
should output
=====
0 1
1 2
1 3
=====
(Note that opCall returns a copy of the original struct, so the first and last
calls will be passed &t as 'this', but the second is passed a pointer to a
copy)
With "dmd -run test.d", this all works fine.

However, when run with "dmd -inline -run test.d":
=====
0 1
1 2
2 3
=====
(note the last line)
The "return *this" seems suddenly to have compiled as a reference return
instead of a value return. (This can be verified by making opCall print the
address as well; the uninlined version will only report the same address for
the first and last call, while the inlined version reports the same address
every time)

GDC doesn't exhibit this problem, presumably because it uses the GCC inliner.


-- 

January 15, 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2127


Don <clugdbug@yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clugdbug@yahoo.com.au
           Severity|major                       |critical


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May 25, 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2127



--- Comment #1 from Brad Roberts <braddr@puremagic.com> 2010-05-25 01:59:48 PDT ---
Created an attachment (id=642)
tentative fix for this for the d2 branch (might work on d1 as well, untested)

This bug exists in the d2 code base as well.  This patch fixes the test case and passes the test suite.

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May 25, 2010
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Brad Roberts <braddr@puremagic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
 Attachment #642 is|0                           |1
           obsolete|                            |


--- Comment #2 from Brad Roberts <braddr@puremagic.com> 2010-05-25 03:05:16 PDT ---
Created an attachment (id=643)
d2 fix, version 2

Oops.. the version I attached previously was an older copy.  This is the newer version that moves the changes down from FuncDeclaration::inlineScan to doInline and fixes a problem with the first version.

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May 30, 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2127


Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla@digitalmars.com
         Resolution|                            |FIXED


--- Comment #3 from Walter Bright <bugzilla@digitalmars.com> 2010-05-30 11:03:31 PDT ---
http://www.dsource.org/projects/dmd/changeset/505

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