Luc Bourhis:
With "auto a = new double[1000]", is there any guarantee that
a.ptr is aligned on a 16-byte boundary?
Arrays are aligned on a 16-byte. But if you slice them, this
alignment can be broken.
In past I suggested to put the alignment of an array in the D
type system, as an optiona
On Friday, 9 January 2015 at 00:23:47 UTC, bearophile wrote:
Luc Bourhis:
With "auto a = new double[1000]", is there any guarantee that
a.ptr is aligned on a 16-byte boundary?
Arrays are aligned on a 16-byte.
Good news!
But if you slice them, this alignment can be broken.
Yes, of cours
On Friday, 9 January 2015 at 00:23:47 UTC, bearophile wrote:
Luc Bourhis:
With "auto a = new double[1000]", is there any guarantee that
a.ptr is aligned on a 16-byte boundary?
Arrays are aligned on a 16-byte. But if you slice them, this
alignment can be broken.
IMO, If you slice a double
Robert burner Schadek:
IMO, If you slice a double array it is always aligned. Because
doubles are 8 bytes long aka 64bit which would align them to
every fourth 16bit boundary.
If you have a 16-byte aligned array of doubles and you slice the
first double away, what's the alignment of the resu
On 1/9/15 6:08 AM, Robert burner Schadek wrote:
On Friday, 9 January 2015 at 00:23:47 UTC, bearophile wrote:
Luc Bourhis:
With "auto a = new double[1000]", is there any guarantee that a.ptr
is aligned on a 16-byte boundary?
Arrays are aligned on a 16-byte. But if you slice them, this alignme
On Friday, 9 January 2015 at 11:18:18 UTC, Steven Schveighoffer
wrote:
not 16 bit, 16 byte.
SIMD on Intel Mic is 64 bytes, AVX2 is probably 32 bytes.
not 16 bit, 16 byte.
-Steve
known how to read helps, of course you're right.
On Friday, 9 January 2015 at 11:19:47 UTC, bearophile wrote:
If you have a 16-byte aligned array of doubles and you slice
the first double away, what's the alignment of the result?
the first double[0] is 16-byte aligned, double[1] would be
20-byte aligned as a double is 4 byte long.
p.s. I'm
On 1/9/15 7:43 AM, Robert burner Schadek wrote:
On Friday, 9 January 2015 at 11:19:47 UTC, bearophile wrote:
If you have a 16-byte aligned array of doubles and you slice the first
double away, what's the alignment of the result?
the first double[0] is 16-byte aligned, double[1] would be 20-byt
On 1/9/15 8:02 AM, Steven Schveighoffer wrote:
On 1/9/15 7:43 AM, Robert burner Schadek wrote:
On Friday, 9 January 2015 at 11:19:47 UTC, bearophile wrote:
If you have a 16-byte aligned array of doubles and you slice the first
double away, what's the alignment of the result?
the first double[
Keeping alignment when slicing is easy since it matches the size
of the xmm registers: one has to partition the array by blocks of
2 doubles, 4 floats, etc. For AVX, the ideal alignment is on
32-byte boundaries but the really bad performance hit happens
only when an unaligned access crosses a c
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