search for: masked_store

...ple.com> wrote: > On May 8, 2013, at 4:00 PM, Eric Christopher <echristo at gmail.com> wrote: > > > Thinking that a masked store is conservatively a store of the full > width of the store right? > > > It depends on the optimization. Consider this example: > > masked_store(Val, Ptr , M) > X = masked_load(Ptr, M2) > > If you assume that your store actually overwrites everything in that > memory location then you don't need to load that memory location again. You > can simply use the stored value. However, in our example X != Val. > I'm not s...

On May 8, 2013, at 4:00 PM, Eric Christopher <echristo at gmail.com> wrote: > > Thinking that a masked store is conservatively a store of the full > width of the store right? It depends on the optimization. Consider this example: masked_store(Val, Ptr , M) X = masked_load(Ptr, M2) If you assume that your store actually overwrites everything in that memory location then you don't need to load that memory location again. You can simply use the stored value. However, in our example X != Val. > But Jim pointed out that anything me...

Chandler Carruth <chandlerc at google.com> writes: > What are the desired memory model semantics for a masked store? > Specifically, let me suppose a simplified vector model of <2 x i64> on > an i64-word-size platform. > > masked_store(<42, 42>, Ptr, <true, false>) > > Does this write to the entier <2 x i64> object stored at Ptr or not? No. It writes one element. > Put another way, consider: > > thread A: > ... > masked_store(<42, 42>, Ptr, <true, false>) > ... > > th...

...om> wrote: > Chandler Carruth <chandlerc at google.com> writes: > > > What are the desired memory model semantics for a masked store? > > Specifically, let me suppose a simplified vector model of <2 x i64> on > > an i64-word-size platform. > > > > masked_store(<42, 42>, Ptr, <true, false>) > > > > Does this write to the entier <2 x i64> object stored at Ptr or not? > > No. It writes one element. > Is this a statement about all of the existing hardware that supports masked stores, or about the desired semantics in...

...om> wrote: > Chandler Carruth <chandlerc at google.com> writes: > > > What are the desired memory model semantics for a masked store? > > Specifically, let me suppose a simplified vector model of <2 x i64> on > > an i64-word-size platform. > > > > masked_store(<42, 42>, Ptr, <true, false>) > > > > Does this write to the entier <2 x i64> object stored at Ptr or not? > > No. It writes one element. > > > Put another way, consider: > > > > thread A: > > ... > > masked_store(<42, 42>,...

On Wed, May 8, 2013 at 3:31 PM, Nadav Rotem <nrotem at apple.com> wrote: > > On May 8, 2013, at 1:59 PM, Eric Christopher <echristo at gmail.com> wrote: > > I can almost see that, but how is the intrinsic any different from a > conservative width for stores/loads where they're not handled by an > optimization pass? I'm assuming I'm missing something here.

On May 8, 2013, at 1:59 PM, Eric Christopher <echristo at gmail.com> wrote: > I can almost see that, but how is the intrinsic any different from a > conservative width for stores/loads where they're not handled by an > optimization pass? I'm assuming I'm missing something here. > > -eric I don't understand what you mean by "conservative width".