On Wed, Apr 20, 2011 at 2:17 PM, Eli Friedman <[email protected]>wrote:
> On Wed, Apr 20, 2011 at 10:58 AM, Justin Holewinski > <[email protected]> wrote: > > > > > > On Wed, Apr 20, 2011 at 1:52 PM, Eli Friedman <[email protected]> > > wrote: > >> > >> On Wed, Apr 20, 2011 at 10:50 AM, Eli Friedman <[email protected]> > >> wrote: > >> > On Wed, Apr 20, 2011 at 10:14 AM, Justin Holewinski > >> > <[email protected]> wrote: > >> >> The attached patch adds target triples for the PTX back-end, and adds > >> >> the > >> >> currently implemented PTX intrinsics as builtin functions. I would > >> >> like for > >> >> someone familiar with the Clang targets/triples and builtins code to > >> >> review > >> >> this patch. I have been involved in the PTX back-end for several > >> >> months > >> >> now, but this is my first patch to Clang. > >> > > >> > + PTXTargetInfo(const std::string& triple) : TargetInfo(triple) { > >> > + TLSSupported = false; > >> > + IntWidth = IntAlign = 32; > >> > + LongWidth = LongLongWidth = LongAlign = LongLongAlign = 64; > >> > + } > >> > > >> > You can skip setting IntWidth/IntAlign/LongLongWidth/LongLongAlign; > >> > the defaults are correct. > > > > Okay, will do. > > > >> > >> > > >> > + class PTX32TargetInfo : public PTXTargetInfo { > >> > + public: > >> > + PTX32TargetInfo(const std::string& triple) : PTXTargetInfo(triple) > { > >> > + PointerWidth = PointerAlign = 32; > >> > + DescriptionString > >> > + = > "e-p:32:32-i64:32:32-f64:32:32-v128:32:128-v64:32:64-n32:64"; > >> > + } > >> > + }; > >> > > >> > The target description string isn't using the same alignment for long > >> > and for double as the clang TargetInfo. Also, the alignment for v64 > >> > and v128 looks wrong. > > > > Would there be any issue with just removing the v64 and v128 specifiers > for > > now? The back-end does not currently support them. > > That's fine. > > >> > >> > > >> > BUILTIN(__builtin_ptx_read_tid_x, "i", "nc") > >> > > >> > The "c" means that the value returned by these builtins never changes; > >> > that doesn't seem right. > >> > > > > > This is an interesting case. I assumed the "const" meant that successive > > calls to the builtin will return the same value (which is true). > However, > > different threads will see different values. What is the recommended > > behavior here? For a given piece of C code that will compile down to > PTX, > > it is perfectly valid for constant propagation to eliminate any > successive > > calls. > > It should be fine for __builtin_ptx_read_tid_x, but it seems a bit > weird for __builtin_ptx_read_clock, and very wrong for > __builtin_ptx_bar_sync. > Oops, that is a copy-paste error. > > >> > >> Oh, one more thing: this description unconditionally defines size_t > >> and friends to a 64-bit type; that isn't wrong, exactly, but probably > >> not what you want. > > > > Where exactly is this defined? I'm not too familiar with Clang's > TargetInfo > > class yet. > > SizeType, PtrDiffType, IntPtrType. > Fixed. > > -Eli > Attached is an updated patch. -- Thanks, Justin Holewinski
0001-PTX-Add-PTX-intrinsics-as-builtins-and-add-ptx32-and.patch
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