https://issues.dlang.org/show_bug.cgi?id=16274

Luís Marques <luis@luismarques.eu> changed:

           What    |Removed                     |Added
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           Hardware|x86                         |x86_64
           Severity|enhancement                 |major

--- Comment #1 from Luís Marques <luis@luismarques.eu> ---
(I'm using the latest DMD, v2.071.1, although this problem has existed for
quite a while)

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https://issues.dlang.org/show_bug.cgi?id=16274

ag0aep6g@gmail.com changed:

           What    |Removed                     |Added
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           Keywords|                            |wrong-code
                 CC|                            |ag0aep6g@gmail.com

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https://issues.dlang.org/show_bug.cgi?id=16274

Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
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           Keywords|                            |backend
                 CC|                            |bugzilla@digitalmars.com

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https://issues.dlang.org/show_bug.cgi?id=16274

--- Comment #2 from Walter Bright <bugzilla@digitalmars.com> ---
A smaller version:

  extern(C) int init_pair(short pair, short f, short b);
  void test() { init_pair(1, 2, 3); }

which generates:

  _D4testQfFZv:
        push    RBP
        mov     RBP,RSP
        mov     8D,3
        mov     DX,2
        mov     CX,1
        sub     RSP,020h
        call    init_pair
        add     RSP,020h
        pop     RBP
        ret

Indeed, you are correct in that the upper 16 bits of the register is not set. But I believe this correct code generation. The problem may be in the implementation of init_pair(), which is assuming the upper 16 bits are zero.

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https://issues.dlang.org/show_bug.cgi?id=16274

--- Comment #3 from Walter Bright <bugzilla@digitalmars.com> ---
gcc, however, does indeed set the upper 16 bits to zero. I suppose dmd should behave the same way, regardless of the spec.

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https://issues.dlang.org/show_bug.cgi?id=16274

--- Comment #4 from Walter Bright <bugzilla@digitalmars.com> ---
Curiously, I implemented init_pair() and it turns out that gcc sign extends each parameter before using it.

So this problem does depend on what's going on with init_pair's implementation.

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https://issues.dlang.org/show_bug.cgi?id=16274

Dlang Bot <dlang-bot@dlang.rocks> changed:

           What    |Removed                     |Added
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           Keywords|                            |pull

--- Comment #5 from Dlang Bot <dlang-bot@dlang.rocks> ---
@WalterBright created dlang/dmd pull request #11651 "fix Issue 16274 - The curses of debugging: short argument passed in 1…" fixing this issue:

- fix Issue 16274 - The curses of debugging: short argument passed in 16-bit register, against ABI

https://github.com/dlang/dmd/pull/11651

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https://issues.dlang.org/show_bug.cgi?id=16274

--- Comment #6 from Dlang Bot <dlang-bot@dlang.rocks> ---
@ibuclaw created dlang/dmd pull request #11719 "fix Issue 16274 - short argument passed in 16 bit register" fixing this issue:

- fix Issue 16274 - short argument passed in 16 bit register

https://github.com/dlang/dmd/pull/11719

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https://issues.dlang.org/show_bug.cgi?id=16274

Dlang Bot <dlang-bot@dlang.rocks> changed:

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

--- Comment #7 from Dlang Bot <dlang-bot@dlang.rocks> ---
dlang/dmd pull request #11651 "fix Issue 16274 - short argument passed in 16 bit register" was merged into master:

- 00271210bfe8fe9dc4d4bfe17045b17b1621df59 by Walter Bright:
  fix Issue 16274 - short argument passed in 16-bit register, against ABI

https://github.com/dlang/dmd/pull/11651

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