https://issues.dlang.org/show_bug.cgi?id=19148

--- Comment #1 from Yuxuan Shui <yshuiv7@gmail.com> ---
Whops, not the problem. But ldc still crashes, looking into it...

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https://issues.dlang.org/show_bug.cgi?id=19148

Yuxuan Shui <yshuiv7@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|dmd doesn't keep stack      |ldc compiled with dmd and
                   |aligned at 16 bytes         |musl segment faults on
                   |boundary                    |unaligned SIMD instruction.

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https://issues.dlang.org/show_bug.cgi?id=19148

--- Comment #2 from Yuxuan Shui <yshuiv7@gmail.com> ---
Looks like dmd mis-aligned a __gshared variable. .alignof reports an alignment of 16 bytes, while the variable is aligned only to 8 bytes.

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https://issues.dlang.org/show_bug.cgi?id=19148

Yuxuan Shui <yshuiv7@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ldc compiled with dmd and   |Alignment of section does
                   |musl segment faults on      |not reflect the maximum
                   |unaligned SIMD instruction. |alignment of its contents

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https://issues.dlang.org/show_bug.cgi?id=19148

Yuxuan Shui <yshuiv7@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P1                          |P3
           Severity|enhancement                 |major

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https://issues.dlang.org/show_bug.cgi?id=19148

Yuxuan Shui <yshuiv7@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4

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https://issues.dlang.org/show_bug.cgi?id=19148

Yuxuan Shui <yshuiv7@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P4                          |P1

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https://issues.dlang.org/show_bug.cgi?id=19148

--- Comment #3 from Yuxuan Shui <yshuiv7@gmail.com> ---
I found the actual bug in codegen. In elfobj.c data_start(), when a symbol
doesn't have a explicit alignment (Salignment <= 0), the symbol itself is
aligned, but its section's alignment is not updated.

To reproduce:

__gshared real x;
pragma(msg, x.alignof);

Compiling it prints: 16LU, but the .data section of the resulting object file is only aligned to 8 bytes.

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https://issues.dlang.org/show_bug.cgi?id=19148

--- Comment #4 from Joakim <dbugz@joakim.fea.st> ---
Which ldc and DMD versions? Does the just-released LDC 1.11 have this problem?

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https://issues.dlang.org/show_bug.cgi?id=19148

--- Comment #5 from Yuxuan Shui <yshuiv7@gmail.com> ---
(In reply to Joakim from comment #4)
> Which ldc and DMD versions? Does the just-released LDC 1.11 have this problem?

Most recent ldc release fix the build problem. But this is a dmd bug nonetheless.

This bug still exists in dmd master

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